Configurable hybrid drive system

Abstract

The present disclosure relates to a configurable hybrid drive system. A powertrain system for a vehicle includes an electric motor and a controller. The electric motor has electrically isolated windings, and the electric motor is connected to an inverter. The controller can be configured to: configure the terminals of the windings to form a Y-shaped connection, and in response to the electrical connection between the vehicle and a three-phase power grid, reconfigure the terminals of the windings so that each terminal of the windings is connected to a corresponding phase of the three-phase power grid.

Description

Technical Field

[0001] The present application generally relates to electric machines and inverter systems that are selectively configurable to operate in a charger mode or a propulsion mode. Background Art

[0002] Electrified vehicles, including hybrid electric vehicles (HEVs) and battery electric vehicles (BEVs), rely on traction batteries to provide power to traction motors for propulsion, and rely on power inverters between the traction battery and the traction motors to convert direct current (DC) power to alternating current (AC) power. A typical AC traction motor is a three-phase motor that can be powered by 3 sinusoidal signals, each of which is driven with 120 degrees of phase separation. The traction battery is configured to operate within a specific voltage range and provide maximum current. Alternatively, the traction battery is referred to as a high voltage battery. However, improved performance of the motor can be achieved by operating at a different voltage range, typically a voltage higher than the traction battery terminal voltage. As such, the current demand for driving the onboard motor is typically referred to as high current.

[0003] In addition, many electrified vehicles include a DC-DC converter (also referred to as a variable voltage converter (VVC)) to convert the voltage of the traction battery to the operating voltage level of the electric machine. The electric machine (which may include a traction motor and a generator) may require high voltage and high current. Due to the voltage requirements and current requirements, the battery module and the power electronics module are usually in constant communication. Summary of the invention

[0004] A powertrain system for a vehicle includes an electric motor and a controller. The electric motor includes electrically isolated windings and is connected to an inverter. The controller may be configured to configure the terminals of the windings to form a Y-shaped connection, and in response to an electrical connection between the vehicle and a three-phase power grid, reconfigure the terminals so that each terminal is connected to a corresponding phase of the three-phase power grid.

[0005] According to an embodiment of the present invention, the controller is further configured to: when the winding of the motor is connected to the three-phase grid, modulate the switches of the inverter so that the charge flows to the battery through the winding of the motor.

[0006] A method of controlling a powertrain system by a controller includes disconnecting Y-connected windings of a motor of the powertrain system to electrically isolate the windings in response to an electrical connection between a three-phase power grid and an electric vehicle including the powertrain system, and connecting each of the electrically isolated windings to a phase of the three-phase power grid.

[0007] According to one embodiment of the present invention, the switches of the inverter include high-side switches and low-side switches, and when charging the battery using a three-phase grid, all high-side switches of the three-phase bridges are modulated together, and all low-side switches of the three-phase bridges are modulated together.

[0008] According to one embodiment of the present invention, each winding has a first terminal and a second terminal, and the method further includes: in response to the electrical connection between the single-phase power grid and the electric vehicle, connecting a capacitor between the second terminal of the first winding and the second terminal of the second winding, and connecting the second terminal of the second winding and the second terminal of the third winding to the single-phase power grid.

[0009] According to one embodiment of the present invention, the method of controlling a power transmission system by a controller further includes: modulating switches of an inverter of the power transmission system according to ripple power from a single-phase power grid to induce a field in each of the electrically isolated windings, thereby buffering the ripple power in a capacitor.

[0010] A vehicle powertrain system includes an electric machine and a switch. The electric machine has electrically isolated windings. The switch can be configured to connect the terminals of the windings to form a Y-connection, and in response to an electrical connection between the vehicle and a single-phase power grid, disconnect the Y-connection, connect a capacitor between a first winding terminal and a second winding terminal, and connect the second winding terminal and a third winding terminal to the single-phase power grid.

[0011] According to one embodiment of the invention, the charging current in the motor causes a transient torque of the motor, which is eliminated within a time period defined by a predetermined number of cycles in which the switch is modulated, so that the torque reaches a steady state.

[0012] According to one embodiment of the present invention, the switch includes a high-side switch and a low-side switch, and the switch is also configured to: when charging the battery using a single-phase power grid system, evenly modulate all high-side switches of the two phase bridges, and evenly modulate all low-side switches of the two phase bridges, and the switch of the third phase bridge is modulated independently of the switches of the two phase bridges.

[0013] According to an embodiment of the present invention, the switch is further configured to connect the winding terminals together to form a Y-connection in response to a disconnection between the vehicle powertrain and a power grid.

[0014] According to an embodiment of the invention, the switch is further configured to: in response to an electrical connection between the vehicle and the three-phase grid, disconnect the Y-connection and connect each winding terminal to a phase of the three-phase grid.

[0015] According to one embodiment of the present invention, the switch is a three-pole three-throw switch, which is configured to: connect the winding terminals at a first throw position so that the motor forms a Y-shaped connection, connect the winding terminals to the corresponding phases of the three-phase power grid at a second throw position, and connect the single-phase power grid and the capacitor to the winding terminals at a third throw position. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a diagram of an electrified vehicle having an inverter and an electric machine, wherein the inverter and the electric machine can be selectively configured to provide propulsion or to be charged from an AC grid.

[0017] Figure 2 is a diagram of a hybrid vehicle showing a typical powertrain and energy storage component including an AC grid charging component.

[0018] Figure 3 is a schematic diagram of a motor drive system powered by a power inverter.

[0019] Figure 4 is a diagram of a battery electric vehicle powertrain including a switch configured to switch between a charging mode and a propulsion mode.

[0020] Figure 5 A block diagram of a single-phase battery charging control method for a charger system, wherein the single-phase battery charging control method includes a control strategy for buffering dual line frequency ripple power.

[0021] Figure 6 is a graphical representation of AC characteristics of charging components and powertrain components during AC charging of a battery electric vehicle. DETAILED DESCRIPTION

[0022] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various and alternative forms. The drawings need not be drawn to scale; some features may be exaggerated or minimized to show the details of a particular component. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to utilize the present invention in various forms. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any of the figures may be combined with the features shown in one or more other figures to produce embodiments that are not explicitly shown or described. The combination of features shown provides representative embodiments for typical applications. However, various combinations and variations of features consistent with the teachings of the present disclosure may be desired for specific applications or embodiments.

[0023] Single-phase alternating current (AC) chargers for electric vehicles typically transmit AC ripples of various frequencies. Typically, the most significant frequency component is the component with a frequency of twice the grid frequency or line frequency, and the grid input power has a pulse shape with a direct current (dc) offset (Pin_dc), a large AC component (frequency is twice the line frequency), and a peak-to-peak value of 2 (Pin_dc). This power ripple causes the current ripple on the battery side to have a frequency of twice the grid frequency, so that additional circuits are required to protect the battery. In addition, there are current ripples at other frequencies, such as harmonics of different orders caused by grid distortion and the switching frequency of the semiconductor switches of the charger. In order to filter out these ripples, a large DC link capacitor is required in the charger. Such a large-capacity capacitor increases the cost, size, and weight of the charger.

[0024] Since the electric vehicle is not moving during AC grid charging, the electric drive system (e.g., powertrain or electric drive system) of the electric vehicle, which includes a traction drive inverter and a motor, is typically disconnected from the battery. An apparatus and method are presented herein that utilize an electric drive system and operate the electric drive system as a low-frequency current compensator during charging. In another embodiment, a controller for the powertrain is configured to modulate switches of an inverter at a frequency higher than the line frequency during AC grid charging so that current flows through one phase winding of the motor so that the current returns via another phase winding of the motor.

[0025] An integrated on-board battery charger system for an electric vehicle is disclosed in U.S. Pat. No. 5,341,075, issued on August 23, 1994, the entire contents of which are included by reference. During battery charging, the motor does not rotate. The powertrain is a combined battery charger and motor drive system that uses a conventional pulse width modulation (PWM) inverter and motor that can be configured to operate in a battery charging mode and a propulsion mode. Single-phase AC power is applied to a circuit configured to be in a single-phase mode, and the inverter switch is then controlled to operate as a boost switching regulator. In another embodiment, three-phase AC power is applied to a circuit configured to be in a three-phase mode, and the inverter switch is then controlled to operate as a boost switching regulator. The integrated on-board battery charging system eliminates the need for additional AC / DC converters, power factor correction (PFC), and DC-DC converters. Although additional switches are required to reconfigure the circuit, the additional weight, volume, and cost of the circuit are significantly reduced compared to conventional on-board / off-board battery charging systems.

[0026] However, during battery charging, there is twice the line frequency ripple power flowing back and forth between the AC side and the DC side. Assume that the voltage and current of the single-phase grid connected to the inverter are:

[0027]

[0028]

[0029] Where ω is the line angular frequency, is the phase angle. The instantaneous power flowing through the DC side and the AC side is:

[0030]

[0031] The instantaneous power includes the constant active power P for charging the battery. dc (i.e., DC power) and twice the line frequency (2ω) ripple power flowing back and forth between the AC side and the DC side. When the system is at unity power factor, the battery charging power P dc By comparison, the maximum power flowing into the DC side is the battery charging power P dc If the power factor is less than 1, reactive instantaneous power flows into the DC side.

[0032] For example, a conventional integrated on-board battery charging system operates at unity power factor, and when an average power of 14.4 kW is charged into the battery, the peak power entering the battery can reach a peak of 28.8 kW, where the current on the DC side exhibits twice the line frequency characteristic, and the (2ω) current ripple component can have an amplitude of up to 44.5 amps, which increases the total current ripple.

[0033] Here, the novel integrated on-board battery charging system can be configured to remove the two times line frequency ripple power from the DC side, resulting in a significant reduction in the ripple current of the battery and DC capacitor.

[0034] Figure 1A battery electric vehicle is depicted showing internal electric powertrain components configured to cause current to flow through the windings of the motor 8 by operating the motor inverter 6 when charging the high voltage traction battery 2 and the associated capacitor 4 via a switch 14 connected between the AC grid (e.g., a single-phase AC grid 10 or a three-phase AC grid 12) and the motor 8. In an embodiment, a controller (e.g., a motor inverter controller) can selectively engage or connect the windings of the motor 8 in a "Y-shaped" configuration to form a neutral node used during operation in a propulsion mode. In addition, the controller can configure the switch 14 so that each phase winding of the motor 8 is connected to a corresponding phase of the three-phase AC grid power supply 12, or to the single-phase AC grid power supply 10 and the capacitor 11. The controller can then modulate the switches of the inverter 6 to reduce the double line frequency ripple current on the DC side. Here, the controller (e.g., the motor inverter controller) can selectively modulate the switches of the inverter 6 so that the capacitor 11 absorbs the ripple current from the AC grid 10. In this figure, the switch is shown as a triple-pole triple-throw switch, but if, for example, the system is configured with a charging mode and a propulsion mode, the switch can be implemented as a double-pole triple-throw switch. In another embodiment, the switch 14 can be an independent switch controlled by the controller to protect against breakdown conditions during conversion.

[0035] The on-board battery charger system includes three operating modes: first, a motor drive mode, in which the motor provides propulsion; second, a three-phase battery charging mode, in which each phase of the motor is directly connected to a corresponding phase of a three-phase grid; and third, a single-phase charging mode, in which two phases of the motor are directly connected to a single-phase grid and the third phase is connected to the single-phase grid via a capacitor. For the second and third modes, the motor does not substantially rotate, and the battery is charged through the motor windings (motor phase windings) connected to the grid.

[0036] Figure 2An electrified vehicle 112, which may be referred to as a plug-in hybrid electric vehicle (PHEV), is depicted. The plug-in hybrid electric vehicle 112 may include one or more motors 114 mechanically connected to a hybrid transmission 116. The motor 114 can operate as a motor or a generator. In addition, the hybrid transmission 116 is mechanically connected to an engine 118. The hybrid transmission 116 is also mechanically connected to a drive shaft 120, which is mechanically connected to wheels 122. The motor 114 can provide propulsion and deceleration capabilities when the engine 118 is started or shut down. The motor 114 can also be used as a generator and can provide fuel economy benefits by recovering energy that would normally be lost as heat in a friction braking system. The motor 114 can also reduce vehicle emissions by allowing the engine 118 to operate at a more efficient speed and allowing the hybrid electric vehicle 112 to operate in an electric mode with the engine 118 shut down under certain conditions. The electrified vehicle 112 can also be a battery electric vehicle (BEV). In a BEV configuration, the engine 118 may not be present. In other configurations, the electrified vehicle 112 may be a full hybrid electric vehicle (FHEV) without plug-in capability.

[0037] The traction battery or battery pack 124 stores energy that can be used by the motor 114. The vehicle battery pack 124 can provide a high voltage direct current (DC) output. The traction battery 124 can be electrically connected to one or more power electronics modules 126. One or more contactors 142 can isolate the traction battery 124 from other components when open, and can connect the traction battery 124 to other components when closed. The power electronics module 126 is also electrically connected to the motor 114 and provides the ability to transfer energy bidirectionally between the traction battery 124 and the motor 114. For example, the traction battery 124 can provide a DC voltage, and the motor 114 can operate using three-phase alternating current (AC). The power electronics module 126 can convert the DC voltage into a three-phase AC current to operate the motor 114. In the regenerative mode, the power electronics module 126 can convert the three-phase AC current from the motor 114 used as a generator into a DC voltage compatible with the traction battery 124.

[0038] The vehicle 112 may include a variable voltage converter (VVC) 152 electrically connected between the traction battery 124 and the power electronics module 126. The VVC 152 may be a DC / DC boost converter configured to increase or step up the voltage provided by the traction battery 124. By increasing the voltage, the current demand may be reduced, resulting in a reduction in the wiring size of the power electronics module 126 and the motor 114. In addition, the motor 114 may operate with higher efficiency and lower losses.

[0039] The traction battery 124 may provide energy for other vehicle electrical systems in addition to providing energy for propulsion. The vehicle 112 may include a DC / DC converter module 128 that converts the high voltage DC output of the traction battery 124 into a low voltage DC supply compatible with low voltage vehicle loads. The output of the DC / DC converter module 128 may be electrically connected to an auxiliary battery 130 (e.g., a 12V battery) for charging the auxiliary battery 130. The low voltage system may be electrically connected to the auxiliary battery 130. One or more electrical loads 146 may be connected to the high voltage bus. The electrical load 146 may have an associated controller that operates and controls the electrical load 146 in a timely manner. Examples of the electrical load 146 may be a fan, an electric heating element, and / or an air conditioning compressor.

[0040] The electrified vehicle 112 may be configured to recharge the traction battery 124 via an external power source 136. The external power source 136 may be connected to an electrical outlet. The external power source 136 may be electrically connected to a charger or electric vehicle supply equipment (EVSE) 138. The external power source 136 may be a power distribution grid or grid provided by a public power company. The EVSE 138 may provide circuitry and control to regulate and manage energy transfer between the power source 136 and the vehicle 112. The external power source 136 may provide DC power or AC power to the EVSE 138. The EVSE 138 may have a charging connector 140 for plugging into a charging port 134 of the vehicle 112. The charging port 134 may be any type of port configured to transfer power from the EVSE 138 to the vehicle 112. The charging port 134 may be electrically connected to a charger or an onboard power conversion module 132. The power conversion module 132 may regulate the power supplied from the EVSE 138 to provide a suitable voltage level and current level to the traction battery 124. The power conversion module 132 may interface with the EVSE 138 to coordinate power delivery to the vehicle 112. The EVSE connector 140 may have pins that mate with corresponding recesses of the charging port 134. Alternatively, the various components described as being electrically coupled or connected may transfer power using wireless inductive coupling.

[0041] One or more wheel brakes 144 may be provided to decelerate the vehicle 112 and prevent the vehicle 112 from moving. The wheel brakes 144 may be hydraulically actuated, electrically actuated, or some combination thereof. The wheel brakes 144 may be part of a braking system 150. The braking system 150 may include other components for operating the wheel brakes 144. For simplicity, the drawings depict a single connection between the braking system 150 and one of the wheel brakes 144. The connection between the braking system 150 and the other wheel brakes 144 is implicit. The braking system 150 may include a controller to monitor and coordinate the braking system 150. The braking system 150 may monitor the brake components and control the wheel brakes 144 to decelerate the vehicle. The braking system 150 may respond to driver commands and may also operate autonomously to implement functions such as stability control. The controller of the braking system 150 may implement a method of applying a requested braking force when requested by another controller or sub-function.

[0042] The electronic modules in the vehicle 112 may communicate via one or more vehicle networks. The vehicle network may include multiple channels for communication. One channel of the vehicle network may be a serial bus such as a controller area network (CAN). One of the channels of the vehicle network may include Ethernet as defined by the Institute of Electrical and Electronics Engineers (IEEE) 802 family of standards. Other channels of the vehicle network may include discrete connections between modules and may include power signals from the auxiliary battery 130. Different signals may be transmitted over different channels of the vehicle network. For example, a video signal may be transmitted over a high-speed channel (e.g., Ethernet) while control signals may be transmitted over CAN or discrete signals. The vehicle network may include any hardware components and software components that assist in transmitting signals and data between modules. The vehicle network is not described in detail in the accompanying drawings. Figure 2 1, but may imply that the vehicle network may be connected to any electronic modules present in the vehicle 112. A vehicle system controller (VSC) 148 may be present to coordinate the operation of the various components.

[0043] Typically, the VVC 152 is configured as a boost converter. The VVC 152 may include an input terminal that may be connected to a terminal of the traction battery 124 via a contactor 142. The VVC 152 may include an output terminal connected to a terminal of the power electronics module 126. The VVC 152 may be operated such that a voltage at the output terminal is higher than a voltage at the input terminal. The vehicle 112 may include a VVC controller that monitors and controls electrical parameters (e.g., voltage and current) at multiple locations within the VVC 152. In some configurations, the VVC controller may be included as part of the VVC 152. The VVC controller may determine an output voltage reference The VVC controller can be based on electrical parameters and voltage reference A control signal sufficient to cause the VVC 152 to achieve the desired output voltage is determined. In some configurations, the control signal may be implemented as a pulse width modulation (PWM) signal, wherein the duty cycle of the PWM signal is varied. The control signal may operate at a predetermined switching frequency. The VVC controller may command the VVC 152 to provide the desired output voltage using the control signal. The specific control signal that operates the VVC 152 may be directly related to the amount of voltage boost provided by the VVC 152.

[0044] Reference Figure 2 , the VVC 152 can increase or "step up" the voltage potential of the power provided by the traction battery 124. The traction battery 124 can provide high voltage (HV) DC power. In some configurations, the traction battery 124 can provide a voltage between 150 volts and 400 volts. The contactor 142 can be electrically connected in series between the traction battery 124 and the VVC 152. When the contactor 142 is closed, the HV DC power can be transferred from the traction battery 124 to the VVC 152. The input capacitor can be electrically connected in parallel with the traction battery 124. The input capacitor can reduce any voltage ripple and current ripple. The VVC 152 can receive the HV DC power and increase or "step up" the voltage potential of the input voltage according to the duty cycle. Typically, the output capacitor is electrically connected between the output terminal of the VVC 152 and the input of the power electronics module 126 to stabilize the bus voltage and reduce the voltage ripple and current ripple at the output of the VVC 152.

[0045] Reference Figure 3 , a system 300 is provided for controlling a power electronics module (PEM) 126 . Figure 3 The PEM 126 is shown to include a plurality of switches 302 (e.g., IGBTs) configured to operate together as an inverter having a first phase leg 316, a second phase leg 318, and a third phase leg 320. Although the inverter is shown as a three-phase converter, the inverter may include additional phase bridges. For example, the inverter may be a four-phase converter, a five-phase converter, a six-phase converter, etc. In addition, the PEM 126 may include a plurality of converters, each inverter in the PEM 126 including three or more phase bridges. For example, the system 300 may control two or more inverters in the PEM 126. The PEM 126 may also include a DC to DC converter having more power switches (e.g., IGBTs) to convert a power electronics module input voltage to a power electronics module output voltage via step-up, step-down, or a combination thereof.

[0046] like Figure 3As shown, the inverter may be a DC to AC converter. In operation, the DC to AC converter receives DC power from a DC power link 306 via a DC bus 304 (including DC buses 304A and 304B) and converts the DC power into AC power. The AC power is transmitted via phase current i a 、i b and i c is transmitted to drive an AC motor, also referred to as motor 114 (such as Figure 3 306). In such an example, the DC power link 306 may include a DC battery to provide DC power to the DC bus 304. In another example, the inverter may be an AC to DC converter that converts AC power from the AC motor 114 (e.g., a generator) to DC power, wherein the DC bus 304 may provide the DC power to the DC power link 306. In addition, the system 300 may control the PEM 126 in other power electronic topologies.

[0047] Continue to refer to Figure 3 Each of the phase bridges 316, 318, and 320 in the inverter includes a power switch 302, which can be implemented by various types of controllable switches. In one embodiment, each power switch 302 can include a diode and a transistor (eg, an IGBT). Figure 3 The diode in the a1 , D a2 , D b1 , D b2 , D c1 and D c2 ,and Figure 3 The IGBTs in the a1 , S a2 , S b1 , S b2 , S c1 and S c2 . Power switch S a1 , S a2 , D a1 and D a2 It is part of the phase bridge A of the three-phase converter. Figure 3 In FIG. 3 , the first phase bridge A 316 is marked. Similarly, the power switch S b1 , S b2 , D b1 and D b2 It is part of the phase bridge B 318 of the three-phase converter. The power switch S c1 , S c2 , D c1 and D c2The inverter may include any number of power switches 302 or circuit elements depending on the specific configuration of the inverter. xx ) and IGBT(S xx ) are connected in parallel, however, since the polarity is reversed for proper operation, this configuration is often referred to as an anti-parallel connection. The diodes in this anti-parallel configuration are also referred to as freewheeling diodes.

[0048] like Figure 3 As shown, the current sensor CS a , CS b and CS c is provided to sense the current in each of the phase bridges 316 , 318 , and 320 . Figure 3 The current sensor CS is shown separated from the PEM 126 a , CS b and CS c However, according to the configuration of the PEM 126, the current sensor CS a , CS b and CS c May be integrated as part of the PEM 126 . Figure 3 Current sensor CS in a , CS b and CS c are installed to be connected to phase bridges A, B and C respectively (i.e. Figure 3 The phase bridges 316, 318 and 320 in the system are connected in series and provide respective feedback signals i for the system 300. as 、i bs and i cs (also Figure 3 The feedback signal i as 、i bs and i cs The current sensing capability may be a raw current signal processed by the logic device (LD) 310, or may be embedded with data or information about the current flowing through each phase bridge 316, 318, and 320, or may be encoded with the data or information. In addition, the power switch 302 (e.g., IGBT) may include current sensing capability. The current sensing capability may include a device configured with a current sensing device that can provide a current indication of i as 、i bs and i cs The data / signal may indicate the direction, magnitude, or both direction and magnitude of the current flowing through each phase bridge A, B, and C.

[0049] Refer again Figure 3, the system 300 includes a logic device (LD) or controller 310. The controller or LD 310 may be implemented by various types of electronic devices and / or microprocessor-based computers or controllers, or a combination thereof. To implement the method of controlling the PEM 126, the controller 310 may execute a computer program or algorithm embedded with or encoded with the method and stored in a volatile memory 312 and / or a permanent memory 312. Alternatively, the logic may be encoded into discrete logic, a microprocessor, a microcontroller, or logic or gate arrays stored on one or more integrated circuit chips. As Figure 3 As shown in the embodiment of FIG. 1 , the controller 310 receives and processes the feedback signal i as 、i bs and i cs To control the phase current i a 、i b and i c , so that the phase current i a 、i b and i c The currents flow through the phase bridges 316, 318, and 320 and into the corresponding windings of the motor 114 according to various current patterns or voltage patterns. For example, the current pattern may include the phase current i a 、i b and i c The pattern of flow into and out of the DC bus 304 or the DC bus capacitor 308 . Figure 3 The DC bus capacitor 308 in FIG. 1 is shown as being separate from the PEM 126 . However, the DC bus capacitor 308 may be integrated as part of the PEM 126 .

[0050] like Figure 3 As shown, a storage medium 312 such as a computer readable memory (hereinafter referred to as "memory") can store a computer program or algorithm embedded with or encoded with the method. In addition, the memory 312 can store data or information about various operating conditions or components in the PEM 126. For example, the memory 312 can store data or information about the current flowing through each phase bridge 316, 318, and 320. Figure 3 As shown, the memory 312 may be part of the controller 310. However, the memory 312 may be located in any suitable location accessible to the controller 310.

[0051] like Figure 3As shown, the controller 310 sends at least one control signal 236 to the power converter system 126. The power converter system 126 receives the control signal 236 to control the switch configuration of the inverter, thereby controlling the current flowing through each phase bridge 316, 318 and 320. The switch configuration is a set of switching states of the power switch 302 in the inverter. In general, the switch configuration of the inverter determines how the inverter converts power between the DC power link 306 and the motor 114.

[0052] To control the switching configuration of the inverter, the inverter changes the switching state of each power switch 302 in the inverter to an on state or an off state based on the control signal 236. In the illustrated embodiment, to switch the power switch 302 to an on state or an off state, the controller or LD 310 provides a gate voltage (Vg) to each power switch 302, thereby driving the switching state of each power switch 302. The gate voltage Vg a1 , Vg a2 , Vg b1 , Vg b2 , Vg c1 and Vg c2 (exist Figure 3 ) controls the switching state and characteristics of each power switch 302. Figure 3 302 is shown as a voltage driven device, but the inverter can be a current driven device, or can be controlled by other strategies that switch the power switch 302 between an on state and an off state. The controller 310 can change the gate drive signal of each IGBT based on the speed of the motor 114, the mirror current, or the temperature of the IGBT switch. The change in gate drive can be selected according to multiple gate drive currents, in which the change in gate drive current is proportional to the change in IGBT switching speed.

[0053] Also like Figure 3 As shown, each of the phase bridges 316, 318 and 320 includes two switches 302. However, only one switch in each of the phase bridges 316, 318 and 320 can be in an open state without short-circuiting the DC power link 306. Therefore, in each phase bridge, the switch state of the lower switch is usually opposite to the switch state of the corresponding upper switch. The upper switch is usually referred to as a high-side switch (i.e., 302A, 302B, 302C), and the lower switch is usually referred to as a low-side switch (i.e., 302D, 302E, 302F). Therefore, the high state of the phase bridge refers to the upper switch in the phase bridge being in an open state and the lower switch being in a closed state. Similarly, the low state of the phase bridge refers to the upper switch in the phase bridge being in a closed state and the lower switch being in an open state.

[0054] exist Figure 3During the active state of the three-phase converter example shown in FIG, two situations may occur: (1) two phase bridges are in a high state while the third phase bridge is in a low state, or (2) one phase bridge is in a high state while the other two phase bridges are in a low state. Thus, one phase bridge in the three-phase converter (which may be defined as the "reference" phase for a particular active state of the inverter) is in a state opposite to the states of the other two phase bridges (or "non-reference" phases) having the same state. Thus, the non-reference phases are either both in a high state or both in a low state during the active state of the inverter.

[0055] Solid-state devices (SSDs), such as insulated gate bipolar transistors (IGBTs), metal oxide semiconductor field effect transistors (MOSFETs), or bipolar junction transistors (BJTs), are widely used in a variety of automotive and industrial applications, such as electric motor drives, power inverters, DC / DC converters, and power modules. The operation of IGBTs and MOSFETs is voltage-controlled, where the operation is based on the voltage applied to the gate of the IGBT or MOSFET, while the operation of BJTs is current-controlled, where the operation is based on the current applied to the base of the BJT. Here, SSDs or high-power relays may be used to control, change, or modulate the current between the battery and the motor of the vehicle.

[0056] Figure 44 is a schematic diagram of a battery electric vehicle powertrain 400 including a traction battery 402, a DC bus capacitor 404, an inverter 406, and a motor 408, which can be configured to provide torque to drive the wheels of the vehicle or generate current by utilizing the rotational force of the wheels to rotate the motor 408. The motor is connected to the motor inverter 406, which converts direct current (DC) current to alternating current (AC) current. During vehicle operation, the high voltage traction battery 402 is used to provide propulsion to rotate the motor, and is used to store energy captured by the motor from the rotational energy of the wheels. When the vehicle is not moving, it may be desirable to increase the state of charge (SOC) of the battery 402 by connecting the battery 402 to the AC grid 410 and the AC grid 412 via a switch 414. One effect of using the AC grid 410 is that low frequency harmonics may be propagated to the battery 402 and components of the powertrain. Here, capacitor 404 and battery 402 are selectively connected to grid 410 and grid 412 via switch 414, and switches (418A, 418B, 418C, 420A, 420B, and 420C) of inverter 406 are modulated to reduce ripple power on the DC side via inductive windings 416A, 416B, and 416C of motor 408. This also allows ripple current to be absorbed by capacitor 404 when capacitor 404 is enabled via switch 418 and switch 420. Current is controlled via pull-up switches 418A, 418B, and 418C and pull-down switches 420A, 420B, and 420C, which are also referred to as high-side switches 418A, 418B, and 418C and low-side switches 420A, 420B, and 420C.

[0057] The on-board battery charger system 400 includes three operating modes: first, a motor drive mode, in which the motor 408 provides propulsion; second, a three-phase battery charging mode, in which each phase 416 of the motor 408 is directly connected to a corresponding phase (U2, V2, and W2) of the three-phase grid 412; and third, a single-phase charging mode, in which two phases (416A and 416B) of the motor 408 are directly connected to the single-phase grid 422, and the third phase 416C is connected to one of V1 or U1 of the single-phase grid 422 via a capacitor 424. For the second and third modes, the motor 408 does not rotate, and the battery 402 is charged through the motor winding 416 (motor phase winding) connected to the grids 410 and 412.

[0058] In the motor drive mode, the switch 414 is moved downward so that X is connected to Y and Y is connected to Z, so that the three terminals (X, Y and Z) are connected together and the motor windings are connected in a Y shape.

[0059] In the process of charging the battery through the three-phase grid, switches 414 connect U2, V2 and W2 to phase windings U, V and W (416A, 416B and 416C), respectively. A control strategy (such as a current closed loop or a voltage closed loop for the inverter 406) is used to perform three-phase grid-tie rectification to charge the battery 402 without twice the line frequency ripple power.

[0060] In the single-phase battery charging mode, the battery is charged through the single-phase grid 422 when the switch 414 connects the single-phase grid 422 to the phase bridge U (416A) and the phase bridge V (416B). The control method (such as current closed loop or voltage closed loop) can be applied to generate Figure 5 The modulated signal v m The third phase bridge W 416C is configured and connected to capacitor 424 via switch 414 to absorb the 2ω ripple power from the outside of the H-bridge inverter. Figure 5 Also shown is a control method for managing switch S5 ( 418C) and switch S6 ( 420C) to buffer the 2ω ripple power in capacitor 424 .

[0061] like Figure 5 As shown, a control method (such as a current closed loop or a voltage closed loop) is used to generate a modulation signal v m , to charge the battery (e.g., 402). The control action is implemented by switches S1 to S4 (e.g., 418A, 418B, 420A, and 420B). The phase bridge W with switches S5 and S6 (e.g., 418C and 420C) is controlled to eliminate the two times line frequency ripple power from the DC side, and the control method is explained as follows.

[0062] like Figure 4 As shown, during the charging of the single-phase grid, the capacitor C f 424 is used to buffer the ripple power, where the capacitor power can be expressed as:

[0063]

[0064] Based on this circuit and control, the twice line frequency ripple power flowing into the DC side can be reduced to substantially zero.

[0065] By solving equation (4), the capacitor C f The command voltage of 424 can be expressed by the following equation:

[0066]

[0067] With capacitor C fThe 2ω ripple power is fully buffered in the 424.

[0068] Figure 5 It shows that the actual voltage u cf (t) and reference voltage A method 500 for closed-loop control of capacitor voltage matching is provided, wherein the regulator may be a proportional resonant (PR) controller. Here, a carrier signal 502 is input to three different amplifiers (504, 506, and 508). The first amplifier 504 and the second amplifier 506 have a modulation signal v m input to control the single-phase control bridge (e.g., 416A and 416B). The third amplifier 508 is regulated by the regulator 510 and then by v m The compensation equation (5) is driven. Subtract v from the output of regulator 510 m To eliminate the influence of battery charging control. V in equation (5) is obtained from the grid voltage and grid current by using conventional methods (such as discrete Fourier transform). o ,I o and phase angle

[0069] Figure 6 600 is a graphical representation of the AC characteristics of the charging components and the powertrain components during AC charging of a battery electric vehicle. Here, capacitor voltage 602, capacitor current 604, grid voltage 606, grid current 608, DC bus current 610, average charging power 612, and capacitor / single-phase grid power 614 are shown relative to time 616. When the on-board charger system charges the battery at unity power factor, the waveform of po 632 is the grid power waveform, the waveform of pC 630 is the power of capacitor Cf, the waveform of pin 628 is the power entering the DC side, the waveforms of I 624 and v 622 are the grid current and grid voltage, the waveform of Idc 626 is the current flowing into the DC side, and the waveforms of uC 618 and iC 620 are the voltage and current of capacitor Cf. It is shown that capacitor Cf compensates for the two times line frequency ripple power, so that pin=po+pC, which is constant on the DC side. Because no two times line frequency ripple power enters the DC side, a constant power of 14.4kW is charged into the battery. Here, eliminating the two times line frequency current ripple component on the DC side results in an 11% reduction in total current ripple compared to the conventional approach.

[0070] The control logic or function performed by the controller may be represented by a flowchart or similar diagram in one or more figures. These figures provide representative control strategies and / or logic, which may be implemented using one or more processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). Therefore, the various steps or functions shown may be executed in the order shown, executed in parallel, or omitted in some cases. Although not always explicitly shown, it will be recognized by those of ordinary skill in the art that one or more steps or functions shown may be repeatedly executed according to the specific processing strategy used. Similarly, the order of processing does not necessarily need to achieve the functions and advantages described herein, but is provided for ease of illustration and description. The control logic may be implemented primarily in the form of software executed by a microprocessor-based vehicle, engine and / or powertrain controller (such as a controller). Of course, the control logic may be implemented in the form of software, hardware, or a combination of software and hardware in one or more controllers according to a specific application. When implemented in software form, the control logic may be provided in one or more computer-readable storage devices or media that have stored data representing a code or instruction executed by a computer to control a vehicle or its subsystems. The computer-readable storage device or medium may include one or more of a number of known physical devices that utilize electronic, magnetic, and / or optical storage to store executable instructions and associated calibration information, operating variables, or the like.

[0071] The processes, methods or algorithms disclosed herein may be transmitted to or implemented by a processing device, a controller or a computer, wherein the processing device, the controller or the computer may include any existing programmable electronic control unit or a dedicated electronic control unit. Similarly, the processes, methods or algorithms may be stored in a variety of forms as data and instructions executable by a controller or a computer, wherein the various forms include but are not limited to information being permanently stored in a non-writable storage medium (such as a read-only memory (ROM) device) and information being variably stored in a writable storage medium (such as a floppy disk, a magnetic tape, a compact disk (CD), a random access memory (RAM) device, and other magnetic and optical media). The processes, methods or algorithms may also be implemented in a software executable object. Optionally, the processes, methods or algorithms may be implemented in whole or in part using suitable hardware components (such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a state machine, a controller or other hardware components or devices) or a combination of hardware components, software components and firmware components.

[0072] Although the exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms covered by the claims. The words used in the specification are descriptive words rather than restrictive words, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As mentioned above, the features of each embodiment can be combined to form further embodiments of the present invention that may not be clearly described or shown. Although for one or more desired characteristics, each embodiment may have been described as providing advantages or being superior to other embodiments or prior art embodiments, it will be appreciated by those of ordinary skill in the art that one or more features or characteristics can be compromised to achieve the desired overall system properties according to specific applications and embodiments. These properties may include but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc. Therefore, the embodiments described as being inferior to other embodiments or prior art embodiments in one or more characteristics are not outside the scope of the present disclosure and can be expected to be used for specific applications.

Claims

1. A power transmission system for a vehicle, comprising: A motor having electrically isolated windings, wherein the motor is connected to an inverter; a controller configured to: configure the terminals of the winding to form a Y-connection, and in response to an electrical connection between the vehicle and a three-phase power grid, reconfigure the terminals of the winding so that each terminal of the winding is connected to a corresponding phase of the three-phase power grid, The controller is further configured to, in response to an electrical connection between the vehicle and a single-phase grid, disconnect the Y connection, connect a capacitor between the first winding terminal and the second winding terminal, and connect the second winding terminal and the third winding terminal to the single-phase grid.

2. The power transmission system of claim 1 further comprises a three-pole three-throw switch, wherein the three-pole three-throw switch is configured to: connect the winding terminals at a first throw position so that the motor forms a Y-shaped connection, connect the winding terminals to corresponding phases of the three-phase power grid at a second throw position, and connect a single-phase power grid and a capacitor to the winding terminals at a third throw position.

3. The power transmission system according to claim 1, wherein: The controller is further configured to modulate switches of the inverter to buffer ripple power passing through the winding of the motor in the capacitor when the winding of the motor is connected to the single-phase grid.

4. The power transmission system according to claim 3, wherein: The switches of the inverter include high-side switches and low-side switches, and the controller is further configured to: equally modulate all high-side switches of two phase bridges, equally modulate all low-side switches of the two phase bridges, and individually modulate the third phase bridge to buffer ripple power.

5. The power transmission system according to claim 1, wherein: The controller is further configured to modulate switches of the inverter to balance reactive power passing through the windings of the motor when the windings of the motor are connected to the three-phase grid.

6. A method for controlling a power transmission system, comprising: disconnecting wye-connected windings of an electric machine of the powertrain to electrically isolate the windings, and connecting each of the electrically isolated windings to a phase of the three-phase grid in response to an electrical connection between the three-phase grid and an electric vehicle including the powertrain, Each winding has a first terminal and a second terminal, and the method further includes: in response to the electrical connection between the single-phase power grid and the electric vehicle, connecting a capacitor between the second terminal of the first winding and the second terminal of the second winding, and connecting the second terminal of the second winding and the second terminal of the third winding to the single-phase power grid.

7. The method of claim 6, further comprising: According to the ripple power from the three-phase grid, switches of the inverter of the powertrain are modulated to induce a field in each of the electrically isolated windings to buffer a portion of the ripple power in a capacitor.

8. The method of claim 7, wherein: The switches of the inverter include high-side switches and low-side switches, and all high-side switches of two phase bridges are modulated together, all low-side switches of the two phase bridges are modulated together, and switches of the third phase bridge are modulated independently of the switches of the two phase bridges.

9. A vehicle power transmission system, comprising: An electric motor having electrically isolated windings; A switch is configured to connect the terminals of the winding to form a Y-connection, and in response to an electrical connection between the vehicle and the single-phase grid, disconnect the Y-connection, connect a capacitor between the first winding terminal and the second winding terminal, and connect the second winding terminal and the third winding terminal to the single-phase grid.

10. The vehicle powertrain system of claim 9, further comprising an inverter connected to the motor, and wherein: The switch is also configured to modulate the switches of the inverter to buffer ripple power through the windings of the motor in the capacitor.

11. The vehicle powertrain system of claim 9, further comprising an inverter connected to the motor and a controller configured to modulate switches of the inverter to balance reactive power through windings of the motor.

12. The vehicle powertrain system of claim 11, wherein: The charging current in the motor causes a transient torque in the motor that is eliminated over a period of time defined by a predetermined number of cycles that the switch is modulated such that a steady state torque is zero.

13. The vehicle powertrain system of claim 11, wherein: The switches of the inverter include high-side switches and low-side switches, and the switches are further configured to modulate all high-side switches equally and modulate all low-side switches equally.

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