Vehicle integrated charger and power converter

Abstract

The present disclosure provides a "vehicle integrated charger and power converter." A vehicle includes an electric motor having two sets of galvanically isolated windings and a controller. During charging, the controller isolates a first inverter from a first of the two sets and electrically couples a power converter between a traction battery and a second inverter, causing a charging current to flow through the first set and induce a voltage in the second set to charge the battery.

Description

Technical Field

[0001] The present disclosure relates to an electric drive system for a motor vehicle, and a charging device associated with the electric drive system. Background Art

[0002] Hybrid electric vehicles (HEVs) and battery electric vehicles (BEVs) can rely on a traction battery to power a traction motor for propulsion, and a power inverter between the traction battery and the traction motor 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 three sinusoidal signals, each driven 120 degrees apart in phase. Additionally, many electrified vehicles may include a DC-DC converter to convert the traction battery's voltage to the operating voltage level of the traction motor. Summary of the Invention

[0003] A vehicle includes: an electric motor including two sets of galvanically isolated windings; and a switching device. During propulsion, the switching device couples a first inverter to one of the sets and a second inverter to a traction battery, while bypassing a power converter to allow power from the battery to flow through the set. During charging, the switching device isolates the first inverter from the electric motor and electrically couples the converter between the battery and the second inverter, so that current from a charging port coupled to a power source flows through one of the sets and induces a voltage in the other of the sets for rectification via the second inverter and boosting via the power converter to charge the battery, while isolating the power source from the battery.

[0004] A vehicle power method includes: in response to a charging mode, a controller isolating a first inverter from a first set of windings of an electric machine, and electrically coupling a power converter between a traction battery and a second inverter so that a charging current flows through the first set and induces a voltage in a second set of windings of the electric machine to charge the battery, the second set being galvanically isolated from the first set.

[0005] A vehicle includes an electric machine including two sets of galvanically isolated windings; and a controller. During charging, the controller isolates a first inverter from a first set of the two sets and electrically couples a power converter between a traction battery and a second inverter, such that a charging current flows through the first set and induces a voltage in a second set of the two sets to charge the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 Figure 1 is a block diagram of a typical on-board motor vehicle charger.

[0007] Figure 2 is a schematic diagram of a multi-phase motor.

[0008] Figure 3 is the phasor diagram of a multiphase motor.

[0009] Figure 4A and Figure 4B is a schematic diagram of the effective inductance of the motor.

[0010] Figure 5 is a block diagram of a vehicle with an integrated charger.

[0011] Figure 6 is a schematic diagram of an electric drive for a six-phase electric motor.

[0012] Figure 7 is another schematic diagram of an electric drive for a six-phase electric motor. DETAILED DESCRIPTION

[0013] Various embodiments of the present disclosure are described herein. However, the disclosed embodiments are exemplary only, and other embodiments may take various and alternative forms not expressly shown or described. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching one of ordinary skill in the art to utilize the invention in various ways. As will be understood by one of ordinary skill in the art, the various features shown and described with reference to any of the figures in the accompanying drawings may be combined with features shown in one or more other figures to produce embodiments not expressly shown or described. The combinations of features shown provide representative embodiments of typical applications. However, for particular applications or implementations, various combinations and modifications of features may be required that are consistent with the teachings of the present disclosure.

[0014] The disclosed processes, methods, logic, or strategies can be transmitted to and / or implemented by a processing device, controller, or computer, which may include any existing programmable electronic control unit or dedicated electronic control unit. Similarly, the processes, methods, logic, or strategies can be stored as data and instructions executable by a controller or computer in many forms, including but not limited to information permanently stored on various types of articles of manufacture, which may include persistent non-writable storage media such as ROM devices; and information mutably stored on writable storage media such as floppy disks, magnetic tapes, CDs, RAM devices, and other magnetic and optical media. The processes, methods, logic, or strategies can also be implemented in software executable objects. Alternatively, they can be embodied in whole or in part using suitable hardware components (such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), state machines, controllers, or other hardware components or devices) or a combination of hardware, software, and firmware components.

[0015] Despite the differences in the architecture of electric vehicles, there are similarities in the structure of electric vehicles (EVs). For example, batteries, inverters and electric motors are generally the main components of any EV. To supply energy to the batteries and power the motors, two types of chargers are used: on-board chargers and off-board (stand-alone) chargers. On-board chargers provide the flexibility of charging anywhere there is an available power outlet. The on-board type has the potential disadvantage of increasing the weight, volume and cost of the vehicle. Therefore, any possibility of avoiding the weight, space and cost issues of additional chargers by charging the batteries using available hardware (primarily the electric motor and inverter) is desirable. Considering the situation in EVs where the vehicle is not driven during charging time and the battery pack is not intended to be charged during driving time except for regenerative braking, the integration of the on-board charger and the traction system seems to be a viable option.

[0016] There are specific onboard charger requirements (including galvanic isolation) that need to be met for any integrated system. Other aspects to consider with integrated chargers are voltage level adaptation, unwanted torque in the motor during charging, efficiency, low harmonic content in the current from the grid, and possibly forced unity power factor operation.

[0017] Due to the many advantages that integrated chargers can bring to a system, different types of integrated chargers have been previously reported. However, most of these integrated chargers lack galvanic isolation in their structure. Here, some proposed integrated chargers provide galvanic isolation for the charging process.

[0018] Currently, some manufacturers do not use integrated chargers, but instead focus on on-board chargers that do not utilize electric drive components. Figure 1 A vehicle 10 is shown having an onboard charger device 12 operatively arranged with a power source 14. The onboard charger device 12 includes a charging port 16, an electromagnetic interference (EMI) filter 18, a diode bridge 20, a DC / AC converter 22, a transformer 24, an AC / DC converter 26, a boost converter 28, and a traction battery 30. The EMI filter 18 reduces high-frequency electronic noise before providing input to the diode bridge 20. The transformer 24 provides isolation between the DC / AC converter 22 and the AC / DC converter 26. The boost converter 28 performs power factor correction (and possibly voltage regulation) for the output from the AC / DC converter 26 before providing input to the traction battery 30.

[0019] For high power applications (e.g., electric vehicles), large AC motors sometimes include multiple windings fed by multiple inverters ( Figure 2). Here, a1 is the inductance of phase a of winding group 1, a2 is the inductance of phase a of winding group 2, b1 is the inductance of phase b of winding group 1, b2 is the inductance of phase b of winding group 2, c1 is the inductance of phase c of winding group 1, c2 is the inductance of phase c of winding group 2, d1 is the inductance of winding group 1 along the d-axis, d2 is the inductance of winding group 2 along the d-axis, q1 is the inductance of winding group 1 along the q-axis, q2 is the inductance of winding group 2 along the q-axis, and ω is the electrical speed. The rotor d-axis makes an angle θ1 relative to the axis of phase a1 and an angle θ2 relative to the axis of phase a2, and α = θ2 - θ1.

[0020] Due to the structure of these multiphase motors, in addition to the individual phases, mutual inductance (magnetic coupling) between groups of phases is unavoidable. This is beneficial not only for determining performance and designing control systems, but also for analyzing fault tolerance. When energy is injected into only one winding set, this cross-coupling between windings (phases) can form a transformer.

[0021] Under AC steady-state conditions, the d-axis and q-axis flux linkages Ψ d and Ψ q The RMS values ​​can be combined into phasors:

[0022] Ψ i =Ψ di +jΨ qi (1)

[0023] I i =I di +jI qi (2)

[0024] V i =V di +jV qi =R i I i +jωΨ i (3)

[0025] Where i = 1, 2 and V di =R i I di –X qi I qi –X q1q2 I q2 And V qi =E qi +R i I qi +X di I di +X d1d2 I d2 These equations have been Figure 3 is described graphically in , where Ψ diis the flux connection number of winding group i along the d axis, Ψ qi is the flux connection number of winding group i along the q axis, Ψ i is the total flux connection number of winding group i, I di is the current of winding group i along the d-axis, I qi is the current of winding group i along the q axis, I i is the total current of winding group i, V di is the voltage applied to winding group i along the d-axis, V qi is the voltage applied to winding group i along the q axis, V i is the total voltage applied to winding group i, Ri is the resistance of winding group i, ω is the electrical speed, E q1 is the back electromotive force (EMF) along the q-axis seen by winding set 1, X d1 is the reactance of winding group 1 along the d-axis, X q1 is the reactance of winding group 1 along the q axis, X d1d2 is the mutual inductance of winding set 1 and winding set 2 along the d-axis, X q1q2 is the mutual inductance of winding set 1 and winding set 2 along the q axis, φ is the angle between I1 and V1, and γ is the angle between I1 and E q1 and δ is the angle between V q1 With E q1 The angle between.

[0026] Cross-coupling terms appear as additional voltage drops in phasor diagrams, which tend to limit current. If α = 0 (the angle between the phases of the groups), then, as already observed, there is a tightly coupled inductance between the two groups; and if the groups are fed from a common voltage source, the current in each group will be approximately half of the current that would flow in one group if the other group were open-circuited. This is a practical point, as it means that in a two-winding system, if one group is open-circuited, the current in the other group can increase by nearly 200% if left unregulated. Similarly, if one group is short-circuited, the impedance of the second group will decrease, and the current in the second group can also increase to high values ​​if left unregulated.

[0027] The behavior of the two groups is similar to that of parallel inductors, see Figure 4A and Figure 4B , where the equivalent inductance is

[0028]

[0029] In this case, if L1 = L2 = L, the effective inductance becomes

[0030]

[0031] Where Ψ1 is the magnetic flux of coil 1, Ψ2 is the magnetic flux of coil 2, M is the mutual inductance of the coils, L1 is the inductance of coil 1, L2 is the inductance of coil 2, and i is the total current. Furthermore, when α = 0, M becomes close to L and the effective equivalent inductance becomes L. At the same time, the coupling coefficient between the phases will be k = 1 (theoretically). The total current is the current limited by L, and half of the current flows in each group. However, if one group is open, the same total current will tend to flow in one group. This means that current regulation may be helpful.

[0032] Since the traction system and the on-board charger cannot function simultaneously, and given the acceptable amount of coupling between phases as described above, using a multi-phase motor as a transformer to create isolation for the on-board charger seems to be a logical approach. Figure 5 A high-level proposed architecture for integrating an onboard charger and traction system is shown. In this example, vehicle 32 includes a transmission 33 and a differential 34, which are arranged to directly drive a wheel / tire assembly 36. (Wheel / tire assembly 37 follows the driven wheel / tire assembly 36). Vehicle 32 also includes an electric drive system 38, which is configured to selectively couple with transmission 33 via clutch 40. Electric drive system 38 includes an electric motor 42, an inverter and winding switching device 44, and a traction battery 46. The inverter and winding switching device 44 are arranged to receive power from an external charging line 48. The power received from the external charging line 48 can be provided to the traction battery 46 via the inverter and winding switching device 44 for charging purposes. Similarly, the power received from the traction battery 46 can be provided to the electric motor 42 via the inverter and winding switching device 44 to operate the electric motor 42. The controller 49 (or controller, used interchangeably herein) communicates with and controls the electric drive system 38. Of course, other and / or different vehicle configurations are also contemplated. Such configurations, for example, need not include the transmission 33 or the clutch 40, etc.

[0033] As described in further detail below, the inverter and winding switching arrangement 44 and the electric motor 42 function as a traction system during vehicle propulsion and participate in the charging process during charging of the traction battery 46 .

[0034] Figure 6 A proposed method for Figure 5The topology of the electric drive system 38 is shown. In this example, the electric motor 42 includes two sets of windings 52, 54, and the inverter and winding switching device 44 includes a pair of inverters 56, 58, a DC-DC boost converter 60, and switches S1 to S4. The vehicle 32 also includes an EMI filter 62 and a charging port 64. The charging port 64 is shown coupled to a remote power source 66. In the towing mode, the controller 49 ( Figure 5 ) connects switches S1, S2, and S3 between the winding 52 and the inverter 56, and connects switch S4 (position 2) between the traction battery 46 and the inverter 58 to bypass the DC-DC boost converter 60—with its switching elements open—and isolate the charging port 64 from the inverter and winding switch arrangement 44. (In traction mode, the charging port 64 is of course not coupled to the remote power source 66.) In charging mode, the controller 49 connects switches S1, S2, and S3 between the winding 52 and the EMI filter 62, and connects switch S4 between the traction battery 46 and the DC-DC boost converter 60 (position 1) to couple the traction battery 46 to the remote power source 66. The switching elements of the DC-DC boost converter 60 can then be selectively activated via a known timing sequence under the command of the controller 49 to boost the voltage output by the inverter 58 and correct the power factor for presentation to the traction battery 46.

[0035] The electric motor 42 acts as a transformer, which is connected to a power source 66 via an EMI filter 62. These components provide an isolation stage. The inverter 58 acts as a rectifier that feeds a DC-DC boost converter 60. The DC-DC boost converter 60 provides voltage regulation for charging and also acts as a power factor correction stage. In some configurations, the DC link capacitor of the DC-DC boost converter 60 can be eliminated and the DC link capacitor of the inverter 56 can be used instead. Since the DC link capacitor of the inverter 56 is already connected in parallel with the output of the DC-DC boost converter 60 when the switch S4 is in position 1, no additional components or operational changes are required.

[0036] Some embodiments may offer certain advantages. The power supply can be single-phase, two-phase, or three-phase. The main rectification stage of the on-board charger can be removed. The DC / AC converter can be removed. The electric motor can be used as a transformer. The AC / DC stage can be implemented by using an existing inverter. Eliminating the rectification stage and DC / AC converter can improve system efficiency.

[0037] Figure 7 Another proposed topology for an electric drive system is shown. Numbered elements are the same except for the addition of digits. Figure 6Therefore, like numbered elements share a common description, which will not be repeated for the sake of brevity. Figure 7 The switching scheme and operation of the embodiment are similar to Figure 6 switching scheme and operation. However, Figure 7 The design can provide certain options. The DC link capacitor of inverter 56' or inverter 58' can be eliminated. Therefore, inverters 56' and 58' can share a capacitor. Inverters 56' and 58' can also be manufactured as a single unit to share the DC link capacitor.

[0038] The words used in the specification are descriptive rather than restrictive, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure and claims. As previously mentioned, the features of the various embodiments can be combined to form other embodiments that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages in one or more desired characteristics or being superior to other embodiments or prior art implementations in one or more desired characteristics, those of ordinary skill in the art recognize that in order to achieve the desired overall system properties, one or more features or characteristics may be compromised, and the desired overall system properties depend on the specific application and implementation. These properties include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, applicability, weight, manufacturability, ease of assembly, etc. Therefore, embodiments described as being less ideal than other embodiments or prior art implementations in one or more characteristics are not outside the scope of the present disclosure and may be desirable for specific applications.

Claims

1. A vehicle comprising: A motor comprising two sets of current-isolated windings; and A switch device configured to: During propulsion, coupling a first inverter to a first set of the two sets of galvanically isolated windings and coupling a second inverter to a traction battery while bypassing the power converter to allow power from the traction battery to flow through the second set of windings, and During charging, the first inverter is isolated from the first set of windings of the electric machine and the power converter is electrically coupled between the traction battery and a second inverter, so that current from a charging port coupled to a power source flows through the first of the two sets of galvanically isolated windings and induces a voltage in the second of the two sets of galvanically isolated windings for rectifying via the second inverter and boosting via the power converter to charge the traction battery, the second set of windings being galvanically isolated from the first set of windings while isolating the power source from the traction battery. 2 . The vehicle of claim 1 , further comprising a controller configured to operate the power converter to correct a power factor associated with the voltage.

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

4. A vehicle power method comprising: In response to a charging mode, a controller isolates a first inverter from a first set of windings of the electric machine and electrically couples a power converter between a traction battery and a second inverter so that a charging current flows through the first set of windings and induces a voltage in a second set of windings of the electric machine to charge the traction battery, the second set of windings being galvanically isolated from the first set of windings. The method of claim 4 , further comprising rectifying the voltage via the second inverter. The method of claim 4 , further comprising boosting the voltage via the power converter. 7 . The method of claim 4 , further comprising correcting a power factor associated with the voltage via the power converter.

8. The method of claim 4 further comprising, in response to a propulsion mode, coupling the first inverter to the first set and coupling the second inverter to the traction battery while bypassing the power converter to allow power from the traction battery to flow through the second set of windings.

9. A vehicle comprising: A motor comprising two sets of current-isolated windings; and A controller is configured to isolate the first inverter from a first set of the two galvanically isolated windings during charging, and electrically couple a power converter between a traction battery and a second inverter so that a charging current flows through the first set of windings and induces a voltage in a second set of the two galvanically isolated windings to charge the traction battery, the second set of windings being galvanically isolated from the first set of windings. 10 . The vehicle of claim 9 , wherein the second inverter is configured to rectify the voltage.

11. The vehicle of claim 9, wherein the power converter is configured to boost the voltage.

12. The vehicle of claim 9, wherein the power converter is configured to correct a power factor associated with the voltage.

13. The vehicle of claim 9, wherein the controller is further configured to couple the first inverter to the first set and the second inverter to the traction battery during propulsion, while bypassing the power converter to allow power from the traction battery to flow through the second set of windings.

14. The vehicle of claim 9, wherein the electric motor is a six-phase electric motor.

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