Integrated charger and motor control system isolated from the motor

Abstract

According to one aspect of the disclosure, an apparatus is provided that includes a battery, a direct current (DC) bus connected to the battery, and a DC-DC converter connected to the battery in parallel with the DC bus. A motor control unit (MCU) is connected between the DC-DC converter and a motor. An alternating current (AC) port is connected to the motor. A switch connects the DC bus and the DC-DC converter as inputs to the MCU in series in a drive mode and disconnects the DC bus from the MCU in a charging mode.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to the field of power circuits, for example, power circuits used in electric vehicles. BACKGROUND

[0002] Power circuits include AC-DC power converters and DC-DC power converters. Power converters have a wide range of uses, including but not limited to charging batteries of electric vehicles (EVs) in on-board chargers (OBCs). Power converters are potentially dangerous due to high voltages and currents. Isolation can reduce the danger and can be required by certain safety standards.

[0003] Electric motors, for example, motors of EVs, can be controlled by a motor control unit (MCU). For example, the MCU can control current from a battery to an electric motor of an EV. SUMMARY

[0004] According to one aspect of the present disclosure, an apparatus is provided, comprising a battery, a direct current (DC) bus connected to the battery, and a DC-DC converter connected to the battery in parallel with the DC bus. A motor control unit (MCU) is connected between the DC-DC converter and an electric motor. An alternating current (AC) port is connected to the electric motor. A plurality of switches are provided to connect the DC bus and an output of the DC-DC converter as inputs in series to the MCU in a drive mode, and to disconnect the DC bus from the MCU in a charging mode.

[0005] Optionally, in the foregoing aspect, in the drive mode, the MCU receives a voltage that is a sum of a voltage on the DC bus and a configurable voltage from the DC-DC converter, the configurable voltage being selected from a range of voltages.

[0006] Optionally, in any of the foregoing aspects, in the charging mode, AC from the AC port is rectified by the electric motor and the MCU to produce a first DC voltage, the first DC voltage is converted by a DC-DC converter to a second DC voltage, the second DC voltage is provided to charge the battery.

[0007] Optionally, in any of the foregoing aspects, the DC-DC converter comprises a first multi-level power converter stage connected to the battery, a second multi-level power converter stage connected to the MCU, and a transformer connected to the first and second multi-level power converter stages.

[0008] Optionally, in any of the foregoing aspects, the DC-DC converter is a resonant converter having a resonant frequency, the DC-DC converter is controlled by a processor to operate within a narrow range around the resonant frequency.

[0009] Optionally, in any of the preceding aspects, the DC-DC converter includes a first transformer connected to a first arm of the bridge and a second transformer connected to a second arm of the bridge, the first arm connected in parallel with the second arm.

[0010] Optionally, in any of the preceding aspects, the DC-DC converter includes a plurality of switches to connect outputs of the first and second transformers in series mode and in parallel mode.

[0011] Optionally, in any of the preceding aspects, the MCU includes a first node connected to a first winding of the motor, a second node connected to a second winding of the motor, and a third node connected to a third winding of the motor, each of the first, second, and third nodes connected to the first terminal and the second terminal through a switch, the switch operable to invert a DC voltage received at the first and second terminals in the drive mode and to rectify an AC voltage received by the first, second, and third motor windings in the charging mode.

[0012] Optionally, in any of the preceding aspects, a voltage doubler is connected between the first terminal and the second terminal.

[0013] Optionally, in any of the preceding aspects, the voltage doubler includes a series connected diode connected between the first terminal and the second terminal, a series connected capacitor connected in parallel with the series connected diode between the first terminal and the second terminal, a first node between the series connected diode connected to a neutral of the AC port, a second node between the series connected capacitor, and a switch connected between the first node and the second node to selectively enable voltage doubling.

[0014] Optionally, in any of the preceding aspects, an additional MCU is connected in parallel with the MCU, the MCU connected to a first end of a winding of the motor, the additional MCU connected to a second end of the winding of the motor, a first terminal of the AC port connected to a neutral of the winding, a second terminal of the AC port connected to a neutral of the additional winding of the motor, and a third terminal of the AC port connected to a neutral of a third winding of the motor.

[0015] Optionally, in any of the preceding aspects, an additional MCU is connected in parallel with the MCU, the MCU connected to a first end of a winding of the motor, the additional MCU connected to a second end of the winding of the motor, a first terminal of the AC port connected to a midpoint of a first winding of the motor, a second terminal of the AC port connected to a midpoint of a second winding of the motor, and a third terminal of the AC port connected to a midpoint of a third winding of the motor.

[0016] According to another aspect of the disclosure, a method is provided that includes receiving alternating current (AC), converting the AC to a first direct current (DC) voltage by a motor and a motor control unit (MCU); converting the first DC voltage to a second DC voltage in a DC-DC converter; providing the second DC voltage to a battery to charge the battery. The method also includes providing a third DC voltage from the battery to the DC-DC converter; converting the third DC voltage to a fourth DC voltage in the DC-DC converter; and providing the third DC voltage from the battery in series with the fourth DC voltage from the DC-DC converter to the MCU to power the motor.

[0017] Optionally, in any of the preceding aspects, the method further includes, while converting the first DC voltage to the second DC voltage, controlling the DC-DC converter to maintain the second DC voltage within a battery charging range; and while converting the third DC voltage to the fourth DC voltage, controlling the DC-DC converter according to a requirement of the motor.

[0018] Optionally, in any of the preceding aspects, converting the first DC voltage to the second DC voltage and converting the third DC voltage to the fourth DC voltage includes converting in a resonant converter having a resonant frequency, the method further including operating the resonant converter within a frequency range around the resonant frequency.

[0019] Optionally, in any of the preceding aspects, the method further includes reconfiguring using a plurality of switches connected between a DC bus between the battery and the MCU to provide, in a drive mode when powering the motor, the third DC voltage from the battery in series with the fourth DC voltage from the DC-DC converter, and to disconnect the DC bus from the MCU in a charging mode when receiving the AC.

[0020] Optionally, in any of the preceding aspects, converting the AC to the first DC voltage by the motor and MCU includes passing at least one component of the AC through one or more windings of the motor to provide isolation between an AC power source and the battery.

[0021] According to another other aspect of the disclosure, there is provided an electric vehicle comprising a battery, an electric motor to propel the electric vehicle, a direct current (DC) bus connected to the battery; a DC-DC converter connected to the battery in parallel with the DC bus. A motor control unit (MCU) is connected between the DC-DC converter and the electric motor. An alternating current (AC) port is connected to the MCU through one or more windings of the electric motor. A plurality of switches are connected in series the DC bus and an output of the DC-DC converter in a drive mode to provide a combined voltage of the DC bus and DC-DC converter as an input to the MCU, disconnect the DC bus from the MCU, and provide an output voltage of the MCU to the DC-DC converter in a charging mode.

[0022] Optionally, in any of the preceding aspects, the processor is configured to control the switches in the DC-DC converter to regulate an output of the DC-DC converter such that the combined voltage of the DC bus and DC-DC converter matches a requirement of the electric motor.

[0023] Optionally, in any of the preceding aspects, the DC-DC converter comprises a resonant converter having a resonant frequency, and the processor is configured to control the switches in the DC-DC converter within a frequency range around the resonant frequency.

[0024] This Summary is provided to introduce some concepts in a simplified form, which are further described below in the DETAILED DESCRIPTION. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background. BRIEF DESCRIPTION OF DRAWINGS

[0025] Aspects of the disclosure are illustrated by way of example, and not limitation, in the figures of the drawing and in which like references indicate similar elements. The embodiments of the present application are not limited to the diagnostic steps, procedures, and / or test methods of the figures.

[0026] Figure 1A Output voltage and current of a charging station are shown.

[0027] Figure 1B An example of a two-stage fast charger is shown.

[0028] Figure 2A A diagram of an embodiment of an electric vehicle (EV).

[0029] Figure 2B A diagram of an embodiment of an EV with OBC / MCU circuitry.

[0030] Figure 2C Operation range of an electric motor in an EV is shown.

[0031] Figure 2D An example of an MCU is shown.

[0032] Figure 2E Another example of an MCU is shown.

[0033] Figure 3A -D shows an example of a circuit including a DC-DC converter connected to a battery in parallel with a DC bus and its operation.

[0034] Figure 4A -E shows an example of a DC-DC converter circuit.

[0035] Figure 5 An example of an MCU with a voltage doubler is shown.

[0036] Figure 6 An example of an open winding motor connected to a three-phase AC input is shown.

[0037] Figure 7 An example of an electric motor with dual windings connected to a single-phase AC input is shown.

[0038] Figure 8 An example of two electric motors with respective MCUs and different couplings to the DC bus and converter bus is shown. DETAILED DESCRIPTION

[0039] The present disclosure will now be described with reference to the accompanying drawings, which generally relate to power circuits that can be used, for example, in electric vehicles. For example, the circuits described herein can be used to charge a battery from an external power source and to control power from the battery to an electric motor. Using shared circuitry to perform these different functions is efficient and can save costs.

[0040] In an electric vehicle (EV), in charging mode (e.g., when the EV is parked and the battery is being charged), power may be received as alternating current (AC), for example, from a household outlet. The AC may be connected through an electric motor in the EV, where motor windings and a motor control unit (MCU) may be used to rectify the AC to provide a first direct current (DC) voltage and provide isolation between the AC power source and the EV components. A DC-DC converter may convert the first DC voltage to a second DC voltage that is provided to the battery to charge the battery. By controlling the DC-DC converter, the second voltage may be maintained at an appropriate level to efficiently charge the battery under a wide range of conditions (e.g., for a range of AC input voltages and / or different battery charging conditions).

[0041] In drive mode (e.g., when the EV is being driven and pushed by the electric motor), the DC bus can be connected to the battery in parallel with the DC-DC converter (e.g., both receive the battery output voltage). The DC bus and the output of the DC-DC converter are connected in series to produce a combined voltage, which is the sum of the DC bus voltage (e.g., the third voltage directly from the battery) and the DC-DC converter output voltage (e.g., the fourth voltage). The combined voltage is provided to the MCU, which uses the combined voltage to power the electric motor. The combined voltage can be controlled by controlling the DC-DC converter. This arrangement combines the efficiency of the direct battery connection provided by the DC bus with the voltage control provided by the DC-DC converter.

[0042] The switch can change configuration between the charging mode and the drive mode. For example, the switch can connect the DC bus and the DC-DC converter output in series in drive mode. In charging mode, the switch can disconnect the DC bus and directly connect the DC-DC converter to the MCU. Thus, while in drive mode only a portion of the power goes through the DC-DC converter to the motor (the rest goes directly through the DC bus), in charging mode all of the power of the battery can go through the DC-DC converter (which is typically lower than the power used in drive mode). This facilitates providing high power to the motor without requiring a DC-DC converter sized to handle such high power. The switch for mode configuration can be controlled by a processor, which can also control components such as the DC-DC converter, the MCU, and / or other components. The processor can receive inputs related to battery conditions, motor conditions and requirements, and AC power.

[0043] The DC-DC converter can include a multi-level power converter stage, which is configurable to provide two or more different output voltages from a given input voltage. Using such a multi-level power converter stage provides flexibility in power conversion, for example, allowing compatibility with external power sources that provide power at different voltage ranges (e.g., an electric vehicle can be able to accommodate different charging stations that output different voltages and / or different countries’ household power outlets), and allowing operation over a range of different battery conditions.

[0044] It is understood that the embodiments of the disclosure can be implemented in many different forms and the scope of the claims should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the inventive embodiments' concepts to those skilled in the art. Indeed, the disclosure is intended to cover all modifications, alternatives, and equivalents of the embodiments of the disclosure that fall within the scope and spirit of the disclosure as defined by the appended claims. Furthermore, in the following detailed description of the embodiments of the disclosure, numerous specific details are set forth in order to provide a thorough understanding. However, it will be apparent to one skilled in the art that the embodiments of the disclosure can be practiced without these specific details.

[0045] The Electric Vehicle (EV) and Hybrid EV (EV / HEV) market is a fast growing segment facing many challenges requiring extensive deployment of fast chargers, with the most advanced charger designs typically involving the following examples of common practices and associated drawbacks:

[0046] 1. Universal EV voltage compatibility with isolation: As shown in Figure 1A , EV fast chargers need to be able to charge EV batteries using a wide range of DC voltages, for example, 200V-1000V DC as shown (output voltage (V) along the x-axis, output current (A) on the y-axis). For capital investment reasons, the charging station owner can require that the same charger can operate with the chargers of the customers' various EV / HEVs. However, designing the power supply output voltage range (e.g., 1:4 or 1:5 ratio) is very challenging.

[0047] 2. Full power capability at low output voltage levels: The charger needs to provide the same power capability when charging at low battery voltage to reduce the vehicle charging time. The fast charger's power rating can be as high as 100kW, and even higher in some cases. However, due to the current ratings of the components, the typical charger converter power capability can drop at lower output voltages. Otherwise, significant component margins can be required, resulting in increased cost, larger package size.

[0048] 3. High efficiency at low load power conditions: The EV charger can operate at low load power levels when the battery charging cycle is in the later stages and the charging current is correspondingly reduced. However, the efficiency of the typical AC-DC power converter drops significantly at low load power. Therefore, to meet the charging station operation economics, it is typically required to improve the charger operation efficiency (e.g., >96% or higher).

[0049] 4. Modular design and economies of scale: From a cost perspective, it is desirable to build high power fast chargers as modular designs as building blocks, so that multiple modules can be easily configured in parallel and scaled up for power rating. This also requires charger modules to handle different AC input voltage levels to cater to global markets. However, this is very challenging, and major suppliers have to provide different module designs for different regions of the world. This means cost penalties.

[0050] 5. High reliability and low maintenance: Commercial charger units can require less maintenance or replacement of critical components, such as cooling fans, mechanical contactors or relays, etc. Solid state switching components are generally more reliable and have longer lifetimes.

[0051] Some chargers in the market have to use DC contactors to switch modules between series and parallel operation. While this solution effectively achieves a universal charging voltage range, DC contactors are bulky, costly, and have limited lifetimes. Technical improvements can provide better options than DC contactors.

[0052] Figure 1B An example of a 2-stage fast charger 100 is shown, where a boost power factor correction (PFC) converter 102 receives power (as a 3-phase AC input in this example), regulates a variable voltage across a DC bus 104, which feeds a high frequency (HF) isolated LLC converter 106 (or PSFB converter) that provides a DC output. Typically, LLC converters modulate can only effectively provide a small range of output voltage and load power levels; otherwise, their efficiency drops significantly (e.g., beyond a limit, the efficiency drops significantly). Therefore, in this arrangement, it is important to control the DC bus voltage up and down to a desired operating setpoint to help the LLC converter 106 provide better efficiency across a wide range of output voltage and load power levels.

[0053] Active PFC converters can have peak efficiency (e.g., around 98% or lower), which can result in significant loss of total charger efficiency. Furthermore, even with PFC actively controlling the bus voltage setpoint, the LLC converter 106 can still not provide a wide enough regulation range for EV load applications due to efficiency drop issues. In addition, full power rated pulse width modulation (PWM) switching boost PFC incurs major costs due to items such as fast switching MOSFETs / IGBTs and magnetic components.

[0054] In view of the limitations of the arrangement of Figure 1B there is a need for technical improvements to provide a range of benefits in areas including specification range, efficiency performance, and cost savings.

[0055] Typically, an EV should be able to charge its battery from at least two different power sources, e.g., DC power from a charging station and AC power from a utility AC grid. Thus, in addition to the MCU circuit that operates the EV motor during drive mode (or "traction mode"), an EV on-board power system can include DC and AC charging circuits.

[0056] An EV power system is sensitive to component size, weight, and converter efficiency. Power switching devices, e.g., gallium nitride (GaN) and silicon carbide (SiC) devices, can be used to improve efficiency, size, and weight. Integration can also provide further benefits in terms of cost and size.

[0057] Charging of an EV battery can include use of an on-board charging (OBC) circuit. Power from the battery can be used to power one or more electric motors to propel the electric vehicle under control of a motor control unit (MCU) circuit. In some cases, these circuits can share certain components, which can reduce cost and improve efficiency. Integration of the OBC and MCU circuits using advanced high frequency circuit topologies and using a common power converter stage (e.g., power bridge) between the OBC & MCU can reduce the cost, size, and weight of the overall EV power system. These solutions can address these technical challenges with different power ratings, isolation requirements, and wide voltage ranges by OBC and MCU integration.

[0058] Figure 2A An example of an EV 210 is shown connected to a charging station 212 to recharge the battery 214 of the EV 210. A cable 216 extends from the charging station 212 and ends with a connector 218 that connects with a corresponding connector 220 of the EV 210. An OBC 222 is connected to the connector 220 to receive power from an external power source (in this example, the charging station 212) and use the power to charge the battery 214 (e.g., convert AC to DC and control the voltage and current provided to the battery 214). The battery 214 is connected to provide power to an MCU 224, which controls the power provided to an electric motor 226 (e.g., convert DC from the battery 214 to AC and control the voltage and current provided to the electric motor 226).

[0059] Figure 2BAn example of another EV 230 connected to the charging station 212 through a cable 216 and connector 218 is shown, which is connected to the connector 220 (the respective components of the EVs 210, 230 use similar reference numerals). An OBC / MCU circuit 232 is connected to the connector 220 to receive power from an external power source (the charging station 212 in this example) and use the power to charge the battery 214 (e.g., similar to the OBC 222, converting AC to DC and controlling the voltage and current provided to the battery 214). The battery 214 is connected to provide power to the OBC / MCU circuit 232, which controls the power provided to the electric motor 226 (e.g., similar to the MCU 224, converting DC from the battery 214 to AC and controlling the voltage and current provided to the electric motor 226). Thus, the OBC / MCU circuit 232 of the EV 230 combines the functionality of the OBC 222 and the MCU 224 of the EV 210. Such a combined circuit saves some cost, weight, and space, and can improve efficiency. Aspects of the present technology are applicable to such a combined circuit (but not limited to only such a circuit). Although Figure 2A Examples of -B show charging from a charging station 212, but it should be understood that charging can be performed using other power sources, including a household AC power source, a solar panel, or an electric generator (including an electric generator of an HEV).

[0060] It can be challenging to effectively operate an electric motor within an EV over its operating range. Figure 2C An example of a force curve of an electric motor over its entire operating range (from speed = 0 to maximum speed) is shown, where speed (angular velocity) is on the x-axis and force is along the y-axis. The range can be divided into regions as shown, including a constant force region (where the speed ω is in the range: 0 < ω < ω b ) and a constant power region. The constant power region includes a field weakening region I or “partial field weakening region” (where the speed ω is in the range: ω b < ω < ω c ) and a field weakening region II, or “full field weakening region” (where the speed ω is in the range: ω c < ω). The motor characteristics can be different for each region, so it can be difficult to effectively control the motor over the entire range.

[0061] Figure 2DA first example of an MCU 236 connected between a battery 238 and a motor 240 (e.g., in an EV) is shown. A pair of switches 242, 243 connect the battery 238 to the MCU 236. Within the MCU 236, switches 244, 245 are connected in series between the terminals of the battery 238, with a terminal 246 (or "node") between switches 244 and 245. Terminal 246 is connected to a first winding 248 of the motor 240. Switches 250, 251 are connected in series between the terminals of the battery 238, with a terminal 252 between switches 250 and 251. Terminal 252 is connected to a second winding 254 of the motor 240. Switches 258, 259 are connected in series between the terminals of the battery 238, with a terminal 260 between switches 258 and 259. Terminal 260 is connected to a third winding 262 of the motor 240. Switches 244, 245, 250, 251, 258, 259 can be formed in any suitable manner, for example, using transistors with diodes connected between collector and emitter terminals. Such switches can be controlled to provide appropriate voltages to the windings of motor 240 (e.g., by switching to convert a DC voltage from battery 238 to an AC voltage provided to motor 240). Thus, MCU 236 acts as an inverter in this example and may also be referred to as inverter 236.

[0062] Figure 2E Another example of an MCU connected between a battery 238 and a motor 240 is shown. Similar components have Figure 2D Similar reference numbers. Except Figure 2D In addition to the inverter 236 shown in FIG. Figure 2E MCU 270 includes a boost converter 272 that receives voltage from battery 238 and provides a boosted voltage to inverter 236. Boost converter 272 includes an inductor 274 connected to battery 238 at one end through switch 276 and to node 278 at the other end. Node 278 is between switches 280 and 281, which are connected in series across the input terminals of inverter 236 to provide a boosted output voltage to inverter 236. Switches 280, 281 and / or switches 244, 245, 250, 251, 258, 259 of inverter 236 can be formed in any suitable manner, for example, using transistors (e.g., MOSFET transistors) having diodes connected between their source and drain terminals.

[0063] Figure 3AA circuit example is shown that can perform the functions of the OBC and MCU in an efficient manner by reconfiguring between a charging mode and a drive mode, so that certain components are used in both modes, for example, using the motor windings and MCU components to rectify AC and provide isolation in the charging mode, and using the common DC-DC converter to provide the battery charge voltage in the charging mode and boost the battery voltage provided to the MCU in the drive mode.

[0064] The battery 302 is connected to a DC bus 304 and a DC-DC converter 306, which is connected in parallel to the DC bus 304. A capacitor 308 is connected across the terminals of the battery 302, a capacitor 310 is connected across a first terminal of the DC-DC converter 306, and a capacitor 312 is connected across a second terminal of the DC-DC converter 306 to provide filtering. A diode 314 is connected in parallel to the capacitor 312. Switches 316, 317, 320 are used to configure the coupling of the DC bus 304 and the DC-DC converter 306. The switches 316 and 317 can operate together as a combined switch 318 to connect / disconnect the DC bus 304. The switch 320 can connect the terminals of the DC converter 306 directly to the MCU 322 when the DC bus 304 is disconnected, and can open when the DC bus 304 is connected, so that the DC bus 304 (e.g., the switch 320 can switch opposite to the combined switch 318, so that one opens and the other closes). A DC port 326 is connected to a converter bus 324. The DC port 326 can receive a DC voltage from an external power source to charge the battery 302.

[0065] The MCU 322 is connected to the DC-DC converter 306 through a high voltage bus 346. The MCU 322 is also connected to the electric motor 328. The coupling of the DC-DC converter 306, the DC bus 304, and the MCU 322 is controlled by the combined switches 318, 320, which are controlled by a processor 330. The processor 330 can also control additional components, for example, the processor 330 can control the switching of switches in the DC-DC converter 306 and / or the MCU 322. The processor can receive input from one or more components (e.g., input regarding the voltage at different points, such as the output voltage of the battery 302, the DC input voltage at the DC port 326, the AC input voltage, etc.).

[0066] The MCU 322 is connected to the windings 332, 333, 334 of the electric motor 328. The neutral terminal 336 of the electric motor 328 is connected to an AC port 340 through an electromagnetic interference (EMI) filter 338, which receives an AC input 342 from an external power source. The AC port 340 is also connected to the MCU 322 through the EMI filter 338 (e.g., the neutral connection bypasses the electric motor 328 and connects to the MCU 322). The AC port 340 can include one or more connectors in the EV (like the connector 220), for example, and the AC input 342 can be from a charging station, a household AC power source, or other power source.

[0067] Figure 3A The circuit shown in the middle can operate in two or more modes, using at least some of the components in both modes to reduce component cost and complexity, save space, and provide high efficiency. The modes can include a charging mode in which the battery 302 is charged using power from the external power source (e.g., the AC input 342) and a drive mode in which the electric motor 328 receives power from the battery 302.

[0068] Figure 3B An example of the operation of the circuit of Figure 3A in the charging mode is shown, in which power generally flows from right to left to charge the battery 302 using the AC input 342. Components that are not active in this mode (e.g., the DC bus 304 and the DC port 326) are omitted for clarity. The AC input 342 is provided to the MCU 322 through the AC port 340 and the EMI filter 338 to the windings 332-334 of the electric motor 328. The windings 332-334 (acting as inductors in a rectifier circuit in this mode) and the switches of the MCU 322 rectify the AC, such that a first DC voltage is provided at the high-voltage bus 346, and isolation is provided between the high-voltage bus 346 and the AC input 342 (some isolation can be required under certain standards).

[0069] The combination switch 318 is open, such that the DC bus 304 is disconnected (and thus not shown in this view). The switch 320 is closed, such that the high-voltage bus 346 is connected to the converter bus 324. Thus, the first DC voltage produced by the MCU 322 is provided as input to the DC-DC converter 306, which converts the first DC voltage to a second DC voltage. The second DC voltage is provided to the battery 302 to charge the battery 302. The second DC voltage can be a suitable voltage for charging the battery 302 (e.g., can be within a battery charging range that depends on the physical structure of the battery and the battery conditions). The processor 330 can ensure that the second DC voltage remains within the battery charging range by appropriately configuring the DC-DC converter 306 and / or the MCU 322 depending on the battery 302, the AC input 342, and / or other factors.

[0070] Figure 3B A processor 330 is shown connected to the AC ports 340 through channels 348. For example, the processor 330 can receive information about the AC input 342 through the channels 348 (e.g., the AC voltage of the AC input 342 can be obtained from one or more voltage sensors in the AC ports 340). The processor 330 is also connected to the battery 302 through channels 350. The processor 330 can receive battery condition information (e.g., information about the charge level of the battery 302) through the channels 350. The processor 330 is also connected to the DC-DC converter 306 through channels 352, and to the MCU 322 through channels 354. The processor 330 can control components (e.g., switches) in the DC-DC converter 306 and the MCU 322 through the channels 352, 354. For example, the processor 330 can determine a suitable battery charging voltage from the battery condition information received through the channels 350, and can select a suitable configuration for the DC-DC converter 306 and the MCU 322 based on the battery charging voltage and the AC voltage information received through the channels 348. The selected configuration can be implemented through signals sent through the channels 352 and 354. The configuration can be updated during the charging process while the battery 302 is being charged. The channels 348, 350, 352, and 354 can be implemented in any suitable manner, e.g., using suitable wiring and logic interfaces. Additional channels can connect the processor 330 to additional components. For example, the processor 330 can be connected to the electric motor 328 and / or a user input device to receive motor information and / or user input (e.g., acceleration commands), so that the voltage provided to the electric motor 328 can be adjusted accordingly in the drive mode.

[0071] Figure 3C A processor 330 is shown connected to the AC ports 340 through channels 348. For example, the processor 330 can receive information about the AC input 342 through the channels 348 (e.g., the AC voltage of the AC input 342 can be obtained from one or more voltage sensors in the AC ports 340). The processor 330 is also connected to the battery 302 through channels 350. The processor 330 can receive battery condition information (e.g., information about the charge level of the battery 302) through the channels 350. The processor 330 is also connected to the DC-DC converter 306 through channels 352, and to the MCU 322 through channels 354. The processor 330 can control components (e.g., switches) in the DC-DC converter 306 and the MCU 322 through the channels 352, 354. For example, the processor 330 can determine a suitable battery charging voltage from the battery condition information received through the channels 350, and can select a suitable configuration for the DC-DC converter 306 and the MCU 322 based on the battery charging voltage and the AC voltage information received through the channels 348. The selected configuration can be implemented through signals sent through the channels 352 and 354. The configuration can be updated during the charging process while the battery 302 is being charged. The channels 348, 350, 352, and 354 can be implemented in any suitable manner, e.g., using suitable wiring and logic interfaces. Additional channels can connect the processor 330 to additional components. For example, the processor 330 can be connected to the electric motor 328 and / or a user input device to receive motor information and / or user input (e.g., acceleration commands), so that the voltage provided to the electric motor 328 can be adjusted accordingly in the drive mode. Figure 3Aan example of the circuit's operation in a drive mode, in which power generally flows from left to right to power electric motor 328, which can be used to propel an EV in this mode. For clarity, components that are not active in this mode (e.g., AC port 340, EMI filter 338, and DC port 326) are omitted. Battery 302 produces a DC battery output voltage (a third DC voltage) on DC bus 304, which is connected by combined switch 318 as shown (closing switches 316, 317 to connect DC bus 304). Because DC-DC converter 306 is connected to battery 302 in parallel with DC bus 304, DC-DC converter 306 receives the third DC voltage, which it converts to a fourth DC voltage that is provided on converter bus 324. As shown, with combined switch 318 closed and switch 320 open, DC bus 304 and converter bus 324 (the output of DC-DC converter 306) are connected in series as inputs to MCU 322 (i.e., in series to high voltage bus 346). MCU 322 can invert the input it receives from high voltage bus 346 and provide corresponding AC components to windings 332-334 of electric motor 328 to power electric motor 328 and thus propel an EV.

[0072] In this configuration, high voltage bus 346 of the DC voltage supply has two components, a first component supplied directly from battery 302 along DC bus 304 (i.e., at the battery voltage), and a second component supplied through DC-DC converter 306, and which can be controlled accordingly by controlling DC-DC converter 306. At some times, the second component can be unnecessary, and DC-DC converter 306 can be inactive (and diode 314 can provide a connection between DC bus 304 and high voltage bus 346). At other times, the output voltage from DC-DC converter 306 can be used to boost the voltage provided to high voltage bus 346 above the battery voltage. For example, when electric motor 328 requires high voltage, the voltage on high voltage bus 346 can be increased by configuring DC-DC converter 306 to increase the voltage on converter bus 324 (for clarity, channels 352, 354 are omitted, but it is understood that these channels are used to control the components). Thus, a large amount of power can be transmitted directly from battery 302 to MCU 322 (through DC bus 304), and additional power can be provided in a flexible manner through DC-DC converter 306. This stacked arrangement takes advantage of the high efficiency of the direct connection and the flexibility of the connection through the DC-DC converter. DC-DC converter 306 can be sized accordingly, e.g., to accommodate a fraction of the maximum power of electric motor 328 rather than the entire maximum power of electric motor 328.

[0073] As can be seen, in a charge mode (Figure 3B ) and drive mode ( Figure 3C ) under different times use many of the same components. Reconfiguration between modes can include toggling one or more switches (e.g., switches 316, 317, 320). Reconfiguration can be triggered by detecting an input. For example, charging mode can be triggered by detecting AC input at AC port 340 when the EV is parked. Drive mode can be triggered by user input (e.g., selecting "drive" at a user input device).

[0074] Figure 3D An example of a method including charging mode and drive mode steps is shown. The method includes receiving alternating current (AC) 360, converting the AC to a first direct current (DC) voltage by a motor and a motor control unit (MCU) 362 (e.g., by motor 328 and MCU 322), converting the first DC voltage to a second DC voltage in a DC-DC converter 364 (e.g., in DC-DC converter 306), and providing the second DC voltage to a battery to charge the battery 366. These steps can be performed in charging mode to charge the battery when connected to AC power. Subsequently, the AC power can be disconnected and the configuration can be changed to drive mode, in which power is provided to the motor from the battery. The method includes providing a third DC voltage from the battery to a DC-DC converter 368, converting the third DC voltage to a fourth DC voltage in a DC-DC converter 370, and providing the third DC voltage from the battery in series with the fourth DC voltage from the DC-DC converter to the MCU to power the motor 372. For example, the third DC voltage can be provided on DC bus 304, which is connected in series with the fourth voltage from DC-DC converter 306 on converter bus 324.

[0075] Various circuits can be used to implement DC-DC converter 306. Figure 4A An example of an implementation of DC-DC converter 306 is shown in FIG. 47. In this embodiment, DC-DC converter 306 includes a first multi-level power converter stage 476, a transformer 478, and a second multi-level power converter stage 480. Power can flow in either direction through such a DC-DC converter.

[0076] For example, in charging mode, in Figure 4AThe power can flow from right to left. For example, a first DC voltage can be provided on converter bus 324 by MCU 322. Second multi-level power converter stage 480 is configured to generate and provide an AC signal (a first high frequency signal) accordingly to transformer 478. Transformer 478 generates a second high frequency signal from the first high frequency signal and provides the second high frequency signal to first multi-level power converter stage 476. Depending on the winding ratio of transformer 478, the first and second high frequency signals can be at different voltages. Subsequently, first multi-level power converter stage 476 generates a second DC voltage from the second high frequency signal and provides the second DC voltage on terminal 482, which can be connected to the battery terminals of battery 302. The second DC voltage can be controlled to be at an appropriate voltage to effectively charge battery 302.

[0077] In the drive mode, first terminal 482 can be connected to a battery (e.g., battery 302) and can be supplied with a third DC voltage (a battery voltage) from the battery. First multi-level power converter stage 476 is configured to generate a third high frequency signal from the third DC voltage and provide the third high frequency signal to transformer 478, which generates a fourth high frequency signal accordingly. Depending on the winding ratio of transformer 478, the third and fourth high frequency signals can be at different voltages. The fourth high frequency signal is provided to second multi-level power converter stage 480, which generates a fourth DC voltage on converter bus 324 from the fourth high frequency signal. The combination of multi-level power converter stages connected by one (or more) transformers provides a wide voltage range, such that this DC-DC converter can accommodate various power sources and can operate under various battery conditions. Various circuits are used to form the multi-level power converter stages, and using one or more transformers, the components of DC-DC converter 306 can be implemented.

[0078] Figure 4B An example embodiment of DC-DC converter 306 is shown, in which first multi-level power converter stage 476 (a three-level bridge in this embodiment) includes first capacitor 484 and second capacitor 486 connected in series between terminals 482. Switches 488, 489, 490, 491 are also connected in series between terminals 482. Capacitors 484, 486 are connected to switches 489, 490. Switches 488 and 489 are connected to first winding 498 of transformer 478 through capacitor 494 (a resonance capacitor) and inductor 496 (a resonance inductor). Switches 490 and 491 are also connected to first winding 498 of transformer 478. Transformer 478 includes inductor 402 (a field inductor) in parallel with first winding 498. Second winding 404 is coupled to first winding 498 (e.g., wound on a common magnetic core).

[0079] Inductor 496, inductor 402, and capacitor 494 represent the resonant inductance, the drive inductance, and the resonant capacitance in the LLC series resonant converter. In one embodiment, the LLC series resonant converter is operated near the resonant frequency, which is very efficient. In one embodiment, zero voltage switching (ZVS) is obtained by operating near the resonant frequency. ZVS is one example of a soft switching technique. Soft switching techniques can improve power efficiency by reducing switching losses.

[0080] Second multi-level power converter stage 480 (a three-level bridge in this embodiment) includes first and second capacitors 406, 408 connected in series across converter bus 324, which can be connected to MCU 322. Switches 410, 411, 412, 413 are also connected in series across converter bus 324. Capacitors 406, 408 are connected to switches 411, 412. Switches 410, 411 are connected to second winding 404 of transformer 478 through capacitor 416 (a resonant capacitor). Switches 412, 413 are also connected to second winding 404.

[0081] Switches 488-491 and 410-413 can be implemented by any suitable device or devices. Figure 4C An example implementation of switch 420, which can be used for switches 488-491 and 410-413, is provided. Switch 420 includes a transistor 422 with a diode 424 connected across its terminals (between the collector and emitter terminals). The base terminal of transistor 422 can be used to control switch 420, e.g., can be controlled by processor 330. Thus, the series-connected switches 488-491 and 410-413 can include a connection between the collector of the transistor of one switch and the emitter of the transistor of the adjacent switch.

[0082] Controlling the switching of switches 488-491 and 410-413 provides efficient DC-DC conversion over a wide voltage range. Figure 4BA DC-DC converter 306 is shown that includes inductors 496, 402 and capacitors 494, 486 forming an LLC converter, which is an example of a resonant converter having a resonant frequency. The processor 330 can switch the switches 488-491 and 410-413 at a frequency at or near the resonant frequency, thereby improving efficiency. Generally, a multi-level power converter stage allows for a wide range of voltage conversion without changing the frequency, such that the frequency can be kept in a range near the resonant frequency (e.g., within a narrow range defined as within 1%, 3%, 5%, or 10% of the resonant frequency). For example, when the battery is significantly discharged, the battery voltage can be about one third lower than the nominal battery voltage, e.g., in a DC voltage range of 270V-475V or 240V-490V depending on the battery conditions. The voltage across the converter can be in a DC voltage range of 50V-200V.

[0083] Another issue is that the battery voltage and the DC output voltage can have a wide range, which can result in the converter being less efficient than desired (e.g., operating a resonant converter at a frequency away from its resonant frequency). Using a multi-level switching bridge (e.g., a 3-level switching bridge) for the high voltage side and the low voltage side of a resonant converter can allow such a converter to be operated efficiently over a wide voltage range. In some cases, silicon carbide (SiC) devices can be used for the power converter stage (HF bridge) to improve efficiency and reduce size and weight.

[0084] Figure 4D An alternative implementation of a DC-DC converter 306 is shown that uses a dual active bridge (DAB) topology (different from the LLC topology of Figure 4B . Figure 4B Components common to the implementations of FIGS. 1-3 are numbered the same. A first multi-level power converter stage 476 (a 3-level bridge in this example) includes a first capacitor 484 and a second capacitor 486 connected in series between a terminal 482. Switches 488, 489, 490, 491 are also connected in series between the terminal 482. The capacitors 484, 486 are connected to the switches 489, 490. The switches 488 and 489 are connected to a first winding 498 of a transformer 478 through an inductor 430. The switches 490 and 491 are also connected to the first winding 498 of the transformer 478. The transformer 478 includes an inductor 402 in parallel with the first winding 498. A second winding 404 is coupled to the first winding 498 (e.g., wound on a common magnetic core).

[0085] The second multi-level power converter stage 480 (a three-level bridge) includes a first capacitor 406 and a second capacitor 408 connected in series across the converter bus 324, which can be connected to the MCU 322. Switches 410, 411, 412, 413 are also connected in series across the converter bus 324. The capacitors 406, 408 are connected to switches 411, 412. Switches 410, 411 are connected to the second winding 404 of the transformer 478. Switches 412, 413 are also connected to the second winding 404.

[0086] The switches 488-491 and 410-413 can be implemented by any suitable device or devices, for example, as shown in Figure 4C Controlling the switching of the switches 488-491 and 410-413 provides efficient DC-DC conversion over a wide voltage range. Figure 4D The DC-DC converter 306 (including the first bridge in the first multi-level power converter stage 476 and the second bridge in the second multi-level power converter stage 480) is implemented as a dual active bridge converter, which is an example of a resonant converter with a resonant frequency. The processor 330 can switch the switches 488-491 and 410-413 at a frequency at or near the resonant frequency, thereby improving efficiency. Generally, the multi-level power converter stages allow for a wide range of voltage conversion without changing the frequency, such that the frequency can be kept within a range near the resonant frequency (e.g., within a narrow range, defined as within 1%, 3%, 5%, or 10% of the resonant frequency).

[0087] Figure 4E An alternative embodiment is shown, which includes an additional transformer and additional components in the first multi-level power converter stage 476 (a three-level power converter stage) and has a second power converter stage 436 (PFC) for neutral point clamped (NPC) power flow control (NPC). In this example, the DC-DC converter 306 is configured as an LLC power converter (with two LLC circuits). Using two transformers in this way is advantageous for high power designs (e.g., over 20 kW).

[0088] The first multi-level power converter stage 476 (a three-level bridge in this embodiment) includes a first capacitor 484 and a second capacitor 486 connected in series between terminals 482. Switches 488, 489, 490, 491 are also connected in series to form a first arm between the terminals 482, and the capacitors 484, 486 are connected to switches 489, 490, as shown in Figure 4B In addition, switches 440, 441, 442, 443 are connected in series to form a second arm between the terminals 482 (i.e., in parallel with the switches 488-491 and the capacitors 484, 486), and are similarly connected to the capacitors 484 and 486.

[0089] Switches 488 and 489 are connected to transformer 478 (first transformer) through capacitor 494 and inductor 496, and switches 490 and 491 are also connected to transformer 478 (in Figure 4B Transformer 478 is shown in more detail in FIG. 4B, including connections to first multi-level power converter stage 476). Switches 442 and 443 are connected to transformer 450 (second transformer or additional transformer) through capacitor 446 and inductor 448, and switches 444 and 441 are also connected to transformer 450. Thus, each arm of first multi-level power converter stage 476 is connected to a corresponding transformer. Transformers 478 and 450 can be the same or substantially the same, and the coupling to the components of first multi-level power converter stage 476 can be similar, thereby forming two similar LLC circuits. Thus, the two LLC circuits can have the same resonant frequency, and can run in parallel to produce a high frequency AC output that can be in phase or out of phase (e.g., offset by 90 degrees, 180 degrees, or any other offset). Terminals of transformers 478 and 450 are connected to second power converter stage 436, which can connect transformers 478 and 450 in parallel or in series.

[0090] Second power converter stage 436 includes switches 452 and 453 connected in series between terminals of converter bus 324, with terminals of transformer 478 connected through a capacitor 416 between them to allow them to be connected to either terminal of converter bus 324. Second power converter stage 436 also includes switches 454 and 455 connected in series between terminals of converter bus 324, with another terminal of transformer 478 connected between them to allow connection to either terminal of converter bus 324. One terminal of transformer 450 is also connected between switches 454 and 455 (through capacitor 460). Second power converter stage 436 also includes switches 456 and 457 connected in series between terminals of converter bus 324, and with a terminal of transformer 450 connected between them to allow connection to either terminal of converter bus 324. Capacitor 462 is also connected between terminals of converter bus 324. Second power converter stage 436 can connect transformers 478, 450 to add pulses in series or in parallel to produce different output voltages from a given input voltage.

[0091] Switches 488-491, 440-443, and 452-457 can be implemented by any suitable device or devices (e.g., as described above with respect to FIG. 4A). Figure 4CAs shown). Over a wide voltage range, controlling the switching of switches 488-491, 440-443, and 452-457 can provide efficient DC-DC conversion. For example, the DC voltage provided at terminal 482 can be converted into two high-frequency signals by switches 488-491 and 440-443. These high-frequency signals are provided (with any desired phase difference according to the switching timing) to transformers 478 and 450 that generate two other high-frequency signals (for example, at different voltages). These high-frequency signals can be combined by switches 452-457 to generate a DC voltage at a range of different voltage levels on the converter bus 324. The high-frequency signals can be connected in parallel or in series to generate a DC output of the desired voltage. The processor 330 can apply switches at a frequency at or near the resonant frequency of the LLC circuit of the DC-DC converter 306, thereby improving efficiency.

[0092] MCU can be implemented in many ways. Aspects of the present technology can be used including Figure 2D (which includes the inverter) and Figure 2E (which includes inverter and boost circuit) within the scope of MCU design.

[0093] Figure 5 FIG. 3 shows an example embodiment of an MCU 322 connected to an electric motor 328, which may be used in any of the examples described above. The MCU 322 includes the above Figure 2D 2. Inverter 236 and voltage doubler 570 are shown. Inverter 236 includes switches 244, 245 connected in series across a high voltage bus 346 and having a terminal 246 between switches 244 and 245. Terminal 246 is connected to a first winding 333 of a motor 328. Switches 250, 251 are connected in series across the high voltage bus 346 and have a terminal 252 between switches 250 and 251. Terminal 252 is connected to a second winding 332 of the motor 328. Switches 258, 259 are connected in series across the high voltage bus 346 and have a terminal 260 between switches 258 and 259. Terminal 260 is connected to a third winding 334 of the motor 328. Switches 244, 245, 250, 251, 258, 259 may be formed in any suitable manner, for example, using transistors having diodes connected between collector and emitter terminals, such as Figure 4C Such switches can be controlled to provide appropriate voltages to the windings of motor 328 (e.g., by switching to convert a DC voltage to an AC voltage provided to motor 328), and can also be used in conjunction with windings 332, 333, 334 to convert AC voltage received at AC port 340 to a DC voltage that is output on high-voltage bus 346 while providing isolation between high-voltage bus 346 and AC port 340.

[0094] The voltage doubler 570 includes diodes 572 and 573 connected in series across the high voltage bus 346. Capacitors 574 and 575 are also connected in series across the high voltage bus 346. The AC port 340 (through the EMI filter 338) is connected to a node 578 between the diodes 572 and 573. For example, the neutral terminal of the AC port 340 can be connected to the node 578. A switch 580 selectively connects the node 578 to a node 582, which is between the capacitor 574 and the capacitor 575. By selectively closing the switch 580 (e.g., under control of the processor 330), the voltage doubling of the voltage doubler 570 can be enabled (i.e., the voltage doubling is enabled when the switch 580 is closed, and the voltage doubling is disabled when the switch 580 is open). This provides additional flexibility to accommodate a wide voltage range. For example, when a lower AC voltage (e.g., 110 volts) is received at the AC port 340, the voltage doubler 570 can be enabled, and when a higher AC voltage (e.g., 220 volts) is received at the AC port 340, the voltage doubler 570 can be disabled. The effect of using the voltage doubler 570 here is to provide the same voltage on the high voltage bus 346 in both cases. The voltage doubler 570 can be disabled in the drive mode.

[0095] Aspects of the technology can be applied to a wide range of electric motors in various arrangements (e.g., multiple electric motors in an EV). Some examples are shown here, but it should be understood that these examples are not limiting, and the technology is applicable to more types of electric motors in more configurations.

[0096] Figure 6 An example of an open-winding electric motor 684 connected to a three-phase AC input 686 is shown, which can be used with the technology (e.g., replacing the MCU 322 and electric motor 328 of Figure 3A The three-phase AC input 686 from an external power source such as a charging station passes through the AC port 340 and the EMI filter 338, and is connected three-phase to terminals at the midpoints of the windings 688, 689, 690 of the electric motor 684. An MCU 692 is connected to the first ends of the windings 688, 689, 670 (terminating at the left side of Figure 6 , while an MCU 694 is connected to the second ends of the windings 688, 689, 670 (terminating at the right side of Figure 6 The MCUs 692 and 694 can each be similar to the MCU 322, with both MCUs connected in parallel to the high voltage bus 346. Capacitors 696, 698 are connected across the terminals of the MCUs 692, 694, respectively, with the high voltage bus 346. In operation, the windings 688-690 and the MCUs 692, 694 rectify the three-phase AC input 686 to provide a DC voltage on the high voltage bus 346, and have the windings 688-690 provide isolation between the high voltage bus 346 and the three-phase AC input 686.

[0097] Figure 7 Another example of a motor 704 is shown, which in this embodiment is a two-winding motor including a first winding 706 and a second winding 708. The AC port 340 (e.g., from a household AC outlet) receives a single-phase AC input 710 and provides a neutral node to the first winding 706 and the second winding 708 through the EMI filter 338. The first winding 706 is connected to an MCU 712, and the second winding 708 is connected to an MCU 714. The MCU 712 is connected to the high-voltage bus 346 and has a capacitor 716 connected across its output. The MCU 714 is connected to the high-voltage bus 346 in parallel with the MCU 712 and has a capacitor 718 connected across its output. In operation, the first winding 706, the second winding 708, and the MCUs 712 and 714 rectify the single-phase AC input 710 to provide a DC voltage on the high-voltage bus 346, with the windings 706 and 708 providing isolation between the high-voltage bus 346 and the AC input 710.

[0098] Figure 8 An embodiment of two motors is shown including motor 820 and motor 822. Motor 822 is connected to MCU 824, which may be connected to DC bus 304 and converter bus 324, similar to Figure 3A 824 (i.e., the combination switch 318 is closed and the switch 320 is open, the DC bus 304 and the converter bus 324 are connected in series, so that the MCU 824 receives the sum of the voltages on the DC bus 304 and the converter bus 324). A single-phase AC input 342 is provided through the AC port 340 and the EMI filter 338 to a node between the motor 822 and capacitors 826, 827, which extend in series across the terminals of the MCU 824. In this configuration, the AC input 342 can be rectified by the motor 822 and the MCU 824, and the resulting DC voltage can be provided on the converter bus 324 with the windings of the motor 822 providing isolation with the combination switch 318 open and the switch 320 closed.

[0099] The motor 820 is connected to the MCU 830, which is shown as being connected directly to the DC bus 304 through the combination switch 318. Thus, in drive mode, the MCU 830 can receive voltage from the DC bus 304 (e.g., battery voltage), while the MCU 824 can receive voltage that is the sum of the voltage of the DC bus 304 and the converter bus 324. In this way, one motor can take advantage of the efficiency of a direct connection, while the other motor has the flexibility provided by stacking the DC bus 304 and the converter bus 324 to provide a variable voltage. In this embodiment, the motor 820 is not used in charge mode. The MCU 824 provides sufficient power for charging purposes (e.g., 20-40 kW). Since the MCU 830 is not needed in charge mode, in some cases the switch 320 can be implemented internally to the MCU 830 through the switch of the MCU 830. The switch 320 and its connections to the DC bus 304 and the processor 330 are shown by dashed lines to indicate that these components are optional. In drive mode, both the MCU 830 and the MCU 824 are used to provide greater power (e.g., in excess of 120 kW or 150 kW). Thus, while two motors are used, they are configured differently and only one is used for isolation during charge mode. In other examples, more than two motors can be connected in the same or different configurations. In some cases, isolation can be provided by more than one motor.

[0100] Aspects of the technology are not limited to any single type of motor and can be used with different motor designs, including single-winding motors, dual-winding motors, and open-winding motors, as well as any number of motors (of the same type or different types).

[0101] For purposes of this document, it should be noted that the dimensions of the features depicted in the drawings can not necessarily be to scale.

[0102] For purposes of this document, references to an “embodiment,” “one embodiment,” “some embodiments,” or “another embodiment” can be used to describe different embodiments or the same embodiment.

[0103] For purposes of this document, a connection can be a direct connection or an indirect connection (e.g., through one or more other parts). In some cases, when an element is referred to as being connected or coupled to another element, the element can be directly connected to the other element or indirectly connected to the other element through an intermediate element. When an element is referred to as being directly connected to another element, then there are no intermediate elements between the element and the other element. Two devices are “in communication” if they are directly or indirectly connected so that they can exchange electronic signals.

[0104] For the purposes of this document, the term “based on” can be read as “based, at least in part, on”.

[0105] For the purposes of this document, the use of numerical terms such as “first”, “second” and “third” object can not imply an ordering of objects, but can instead be used for identification purposes to identify different objects, in the absence of additional context.

[0106] For the purposes of this document, a “set” of object terms can refer to a “set” of one or more objects.

[0107] While this disclosure has been described with reference to particular features and embodiments, it will be apparent that various modifications and combinations can be made to the disclosure without departing from the scope of the disclosure. Accordingly, it is intended that the specification and drawings be considered as illustrative only, and that the scope of the disclosure be defined by the appended claims, and that equivalents be included within the scope of the disclosure.

[0108] The foregoing detailed description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the subject matter disclosed to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. The described embodiments were chosen in order to best illustrate the principles of the technology and its practical application to thereby enable others skilled in the art to best utilize the technology in various embodiments and with various modifications as are suited to the particular use contemplated. The scope is defined with the following claims.

Claims

1. A device, applied to an electric vehicle, comprising: a direct current (DC) bus, the DC bus being used to connect to a battery; a DC-DC converter connected to the battery in parallel with the DC bus; A motor control unit MCU connected between the DC-DC converter and the motor, wherein the MCU includes an inverter; an AC port connected to the electric motor; and A plurality of switches are provided to connect the DC bus and the output of the DC-DC converter in series as inputs to the MCU in a driving mode, and to disconnect the DC bus from the MCU in a charging mode.

2. The device according to claim 1, wherein In a driving mode, the MCU receives a voltage that is the sum of a voltage on the DC bus and a configurable voltage from the DC-DC converter, the configurable voltage being selected from a voltage range.

3. The device according to claim 1, wherein In the charging mode, AC from the AC port is rectified by the motor and the MCU to generate a first DC voltage, which is converted into a second DC voltage by a DC-DC converter and provided to charge the battery.

4. The device according to claim 1, wherein The DC-DC converter includes a first multilevel power converter stage connected to the battery, a second multilevel power converter stage connected to the MCU, and a transformer connected to the first and second multilevel power converter stages.

5. The device according to claim 1, wherein The DC-DC converter is a resonant converter having a resonant frequency, and the DC-DC converter is controlled by a processor to operate within a narrow range around the resonant frequency.

6. The device according to claim 1, wherein The DC-DC converter includes a first transformer connected to a first arm of a bridge and a second transformer connected to a second arm of the bridge, the first arm and the second arm being connected in parallel.

7. The device according to claim 6, wherein The DC-DC converter includes a plurality of switches, wherein the plurality of switches include: a first group of switches connected to one output terminal of the first transformer, a second group of switches connected to one output terminal of the second transformer, and a third group of switches connected to the other output terminal of the first transformer and the other output terminal of the second transformer, wherein the first group of switches, the second group of switches, and the third group of switches are connected in parallel.

8. The device according to claim 1, wherein The MCU includes a first node connected to the first winding of the motor, a second node connected to the second winding of the motor, and a third node connected to the third winding of the motor, each of the first, second and third nodes being connected to the first terminal and the second terminal via a switch, the switch being operable to invert the DC voltage received at the first and second terminals in the driving mode and to rectify the AC voltage received by the first, second and third motor windings in the charging mode.

9. The apparatus of claim 8, further comprising a voltage doubler connected between the first terminal and the second terminal.

10. The device according to claim 9, wherein The voltage doubler includes a series-connected diode connected between the first terminal and the second terminal, a series-connected capacitor connected in parallel with the series-connected diode between the first terminal and the second terminal, a first node between the series-connected diodes connected to a neutral terminal of the AC port, a second node between the series-connected capacitors, and a switch connected between the first node and the second node to selectively enable voltage doubling.

11. The apparatus of any one of claims 1-10, further comprising an additional MCU connected in parallel with the MCU, the MCU connected to one set of windings of the motor, the additional MCU connected to an additional set of windings of the motor, the first terminal of the AC port being connected to a neutral end of the one set of windings, and the second terminal of the AC port being connected to a neutral end of the additional set of windings.

12. The apparatus according to any one of claims 1 to 10, further comprising an additional MCU connected in parallel with the MCU, the MCU connected to a first end of a winding of the motor, the additional MCU connected to a second end of a winding of the motor, a first terminal of the AC port connected to a midpoint of the first winding of the motor, a second terminal of the AC port connected to a midpoint of the second winding of the motor, and a third end of the AC port connected to a midpoint of the third winding of the motor.

13. A method, said method being applied to an electric vehicle, comprising: Receive alternating current AC; Converting the AC voltage into a first DC voltage through an electric motor and a motor control unit MCU, wherein the MCU includes an inverter; converting the first DC voltage into a second DC voltage in a DC-DC converter; providing the second DC voltage to a battery to charge the battery; providing a third DC voltage from the battery to the DC-DC converter; converting the third DC voltage into a fourth DC voltage in the DC-DC converter; and A third DC voltage from the battery in series with a fourth DC voltage from the DC-DC converter is provided to the MCU to power the motor.

14. The method according to claim 13, further comprising: while converting the first DC voltage into the second DC voltage, controlling the DC-DC converter to maintain the second DC voltage within a battery charging range; as well as The DC-DC converter is controlled according to requirements of the motor while converting the third DC voltage into the fourth DC voltage.

15. The method according to claim 13, wherein Converting the first DC voltage to the second DC voltage and converting the third DC voltage to the fourth DC voltage includes converting in a resonant converter having a resonant frequency, the method further comprising operating the resonant converter within a frequency range around the resonant frequency.

16. The method of claim 13 , further comprising reconfiguring between a charging mode when receiving the AC and a driving mode when powering the electric motor using a plurality of switches, the plurality of switches connecting a DC bus between the battery and the MCU to provide the third DC voltage from the battery in series with the fourth DC voltage from the DC-DC converter in the driving mode, and disconnecting the DC bus from the MCU in the charging mode.

17. The method according to any one of claims 13 to 16, wherein: Converting the AC to the first DC voltage via the motor and MCU includes passing at least one component of the AC through one or more windings of the motor to provide isolation between an AC power source and the battery.

18. An electric vehicle comprising: Battery; an electric motor for propelling the electric vehicle; a direct current (DC) bus connected to the battery; a DC-DC converter connected to the battery in parallel with the DC bus; A motor control unit MCU connected between the DC-DC converter and the motor; connected to an AC port of the MCU through one or more windings of the motor; as well as a plurality of switches to connect the DC bus and the output of the DC-DC converter in series in a driving mode to provide a combined voltage of the DC bus and the DC-DC converter as an input to the MCU, disconnect the DC bus from the MCU, and provide an output voltage of the MCU to the DC-DC converter in a charging mode.

19. The electric vehicle of claim 18, further comprising a processor configured to control switches in the DC-DC converter to adjust the output of the DC-DC converter so that the combined voltage of the DC bus and the DC-DC converter matches the requirements of the electric motor.

20. The electric vehicle according to claim 19, wherein: The DC-DC converter includes a resonant converter having a resonant frequency, and the processor is configured to control switches in the DC-DC converter within a frequency range around the resonant frequency.

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