Multilevel inverter current sensing

Abstract

A conversion system comprises a conversion device. A multi-level inverter circuit includes a multi-level inverter configured to generate two alternating current (AC) output currents, a current sensor configured to sample a current through or from the multi-level inverter during a switching period, and a processor configured to estimate both the two AC output currents based on the sampled current from the current sensor.

Description

Technical Field

[0001] The subject disclosure relates to inverters, and more particularly to systems and methods for transferring power using multi-level inverters. Background Art

[0002] Vehicles, including gasoline and diesel powered vehicles, as well as electric vehicles and hybrid vehicles, have battery energy storage for purposes such as powering electric motors, electronic devices, and other vehicle subsystems. For example, electric vehicles typically include one or more battery assemblies connected to one or more electric motors for propulsion. Battery assemblies may also be used to power other vehicle systems (e.g., power electronics, control modules, heating and cooling systems, etc.).

[0003] Vehicle inverters facilitate the conversion of direct current (DC) power into alternating current (AC) power to drive motors using AC current. Inverters used in automotive applications are typically two-level inverters, although multi-level inverters are increasingly being used. Summary of the invention

[0004] In an exemplary embodiment, a conversion system includes a conversion device including a multilevel inverter configured to generate two alternating current (AC) output currents, a current sensor configured to sample current through or from the multilevel inverter during a switching cycle, and a processor configured to estimate both of the two AC output currents based on the sampled current from the current sensor.

[0005] In addition to one or more features described herein, the current sensor is configured to sample the current during a switching period when the output is zero voltage.

[0006] In addition to one or more features described herein, the current sensor is a two-dimensional magnetic field detector.

[0007] In addition to one or more of the features described herein, the multilevel inverter is a diode clamped inverter having a first set of switches connected by a first diode and a second set of switches connected by a second diode, and the current sensor is configured to simultaneously detect mutually orthogonal magnetic fields caused by current flowing through the first diode and the second diode.

[0008] In addition to one or more of the described features, the multilevel inverter has a full-bridge topology connecting a first set of switches to a second set of switches, the first set of switches being connected to the second set of switches through a bidirectional switch line.

[0009] In addition to one or more of the features described herein, a current sensor is arranged at the bidirectional switch line to detect a current passing through the bidirectional switch line.

[0010] In addition to one or more features described herein, the current sensor is a two-dimensional magnetic field sensor disposed at an orthogonal intersection between a branch of the full-bridge topology and one of the bidirectional switch lines and a direct current (DC) bus.

[0011] In addition to one or more of the features described herein, the multilevel inverter is connected to a first output conductor configured to carry a first output current and a second output conductor configured to carry a second output current, and the current sensor, the first output conductor, and the second output conductor are configured such that the current sensor detects a first magnetic field generated by the first output current and a second magnetic field generated by the second output current.

[0012] In another exemplary embodiment, a method of transmitting electric power includes receiving an input current from a direct current (DC) source at a conversion device including a multilevel inverter, and converting the input current by the multilevel inverter to generate two alternating current (AC) output currents, wherein the conversion includes performing a series of switching cycles. The method also includes sampling a current through or from the multilevel inverter by a single current sensor during the switching cycle, and estimating both of the two AC output currents based on the sampled current from the single current sensor.

[0013] In addition to one or more features described herein, sampling is performed during a switching period when the output is zero voltage.

[0014] In addition to one or more of the features described herein, the multilevel inverter is a diode clamped inverter having a first set of switches connected by a first diode and a second set of switches connected by a second diode, and the single current sensor simultaneously detects mutually orthogonal magnetic fields caused by current flowing through the first diode and the second diode.

[0015] In addition to one or more of the features described herein, the estimating includes decoupling the mutually orthogonal magnetic fields.

[0016] In addition to one or more of the features described herein, the multilevel inverter has a full-bridge topology connecting a first set of switches to a second set of switches, the first set of switches being connected to the second set of switches through a bidirectional switch line.

[0017] In addition to one or more features described herein, a single current sensor is disposed at the bidirectional switch line, and sampling is performed during a switching cycle when current flows through the bidirectional switch line.

[0018] In addition to one or more of the features described herein, the single current sensor is a two-dimensional magnetic field sensor arranged at an orthogonal intersection between a branch of the full-bridge topology and one of the bidirectional switch lines and the DC bus, and performs sampling when current flows through the orthogonal intersection.

[0019] In addition to one or more of the features described herein, the multilevel inverter is connected to a first output conductor configured to carry a first output current and a second output conductor configured to carry a second output current, and the sampling includes detecting a first magnetic field generated by the first output current and a second magnetic field generated by the second output current.

[0020] In yet another exemplary embodiment, a vehicle system includes a battery system, a conversion device connected to the battery system and including a multiphase inverter module, the multiphase inverter module including a multilevel inverter configured to output two alternating current (AC) output currents, and a processor configured to perform a method. The method includes: converting an input current by the multilevel inverter to generate the two AC output currents, wherein the conversion includes: performing a series of switching cycles, sampling a current through or from the multilevel inverter by a single current sensor during the switching cycles, and estimating both of the two AC output currents based on the sampled current from the single current sensor.

[0021] In addition to one or more of the features described herein, the multilevel inverter is a diode clamped inverter having a first set of switches connected by a first diode and a second set of switches connected by a second diode, and the current sensor simultaneously detects mutually orthogonal magnetic fields caused by current flowing through the first diode and the second diode.

[0022] In addition to one or more of the features described herein, the multilevel inverter has a full-bridge topology connecting a first group of switches to a second group of switches, the first group of switches being connected to the second group of switches via a bidirectional switch line, the single current sensor being disposed at the bidirectional switch line, and the sampling being performed during the switching cycle when current flows through the bidirectional switch line.

[0023] In addition to one or more of the features described herein, the multilevel inverter is connected to a first output conductor configured to carry a first output current and a second output conductor configured to carry a second output current, and the sampling includes detecting a first magnetic field generated by the first output current and a second magnetic field generated by the second output current.

[0024] The above features and advantages and other features and advantages of the present disclosure are apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, advantages and details appear, by way of example only, from the following detailed description, which refers to the accompanying drawings, in which:

[0026] Figure 1 is a top schematic view of a motor vehicle including a battery system and a charging system according to an exemplary embodiment;

[0027] Figure 2 depicts a conversion device including three dual-output multilevel inverters according to an exemplary embodiment;

[0028] Figure 3 Depicted is a circuit diagram including a current sensor according to an exemplary embodiment. Figure 2 A multilevel inverter for a conversion device;

[0029] Figure 4 depicts a conversion device including three dual-output multilevel inverters according to an exemplary embodiment;

[0030] Figure 5 Depicted is a schematic diagram of an exemplary embodiment of the present invention. Figure 4 A multilevel inverter of a conversion device, the multilevel inverter comprising a current sensor arranged at a neutral branch;

[0031] Figure 6 Depicted is a schematic diagram of an exemplary embodiment of the present invention. Figure 4 A multilevel inverter of a conversion device of the invention, the multilevel inverter comprising current sensors arranged at orthogonal intersections between phase legs and a bus;

[0032] Figure 7 Depicted is a schematic diagram of an exemplary embodiment of the present invention. Figure 4 A multilevel inverter of a conversion device of the invention, the multilevel inverter comprising current sensors arranged at orthogonal intersections between phase branches and neutral branches;

[0033] Figure 8 depicts a multilevel inverter including a current sensor disposed proximate a conductor carrying an output current according to an exemplary embodiment;

[0034] Fig. 9 depicts pairs of conductors configured to carry output current from a respective dual-output multilevel inverter including a current sensor disposed between each pair of conductors according to an exemplary embodiment;

[0035] Fig.10 depicts a pair of conductors configured to carry output current from a dual output multilevel inverter including a current sensor disposed proximate the pair of conductors according to an exemplary embodiment;

[0036] Fig.11 is a flow chart depicting aspects of a method of transferring power and controlling a conversion device according to an exemplary embodiment;

[0037] Fig.12 including a timing diagram showing sampling points performed during a switching cycle according to an exemplary embodiment; and

[0038] Fig.13 A computer system according to an exemplary embodiment is depicted. DETAILED DESCRIPTION

[0039] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate the same or corresponding parts and features.

[0040] According to one or more exemplary embodiments, methods, devices, and systems for converting and transmitting power between a battery system and a load using a multilevel inverter are provided. In an embodiment, a conversion system for an electric vehicle or a hybrid vehicle includes a multiphase converter including at least one dual-output multilevel inverter. For example, the conversion system includes three multilevel inverters, each of which outputs two phases (i.e., the conversion system is a six-phase system).

[0041] Each multilevel inverter includes a current sensor configured to measure dual current outputs from the inverter simultaneously or concurrently (e.g., within the same switching cycle). The current sensor can be disposed within the inverter circuit or disposed near an output lead or conductor (bus bar). For example, the current sensor is configured to detect a current flowing through a neutral branch of the inverter.

[0042] In an embodiment, the current sensor is a two-dimensional magnetic field sensor disposed in an inverter circuit and configured to detect mutually orthogonal magnetic fields from currents flowing through orthogonal branches or lines. For example, the inverter is a diode clamped X-type inverter, and the current sensor is disposed proximate mutually orthogonal conductors that connect the diodes to the switch groups in the inverter. In another example, the current sensor is disposed proximate mutually orthogonal conductors in the inverter, such as the crossover between the neutral branch and the phase branch of a full-bridge (H-type) inverter.

[0043] Embodiments also include methods of controlling a conversion device having a multilevel inverter. A method includes operating an inverter switch according to a modulation scheme (e.g., pulse width modulation), and sampling a current or magnetic field during one or more switching cycles. In an embodiment, sampling is performed during a switching cycle when the inverter is in a zero state (i.e., the output voltage is zero).

[0044] The embodiments described herein present many advantages and technical effects. The embodiments reduce the complexity, quantity or components of a dual output multilevel inverter by eliminating the need for a current sensor at each phase output of the conversion device. For example, a six-phase conversion device (three dual output multilevel inverters) connected to an electric vehicle motor typically requires six current sensors. The embodiments allow the use of a conversion device with only three current sensors.

[0045] Embodiments are not limited to use in any particular vehicle or device or system utilizing a battery assembly and may be applicable in a variety of environments. For example, embodiments may be used in automobiles, trucks, aircraft, construction equipment, agricultural equipment, automated factory equipment, and / or any other device or system that may use a high voltage battery pack or other battery assembly.

[0046] Figure 1 An embodiment of a motor vehicle 10 is shown that includes a body 12 that at least partially defines an occupant compartment 14. The body 12 also supports various vehicle subsystems, including a propulsion system 16, and other subsystems for supporting the functions of the propulsion system 16 and other vehicle components, such as a braking subsystem, a suspension system, a steering subsystem, and if the vehicle is a hybrid electric vehicle, a fuel injection subsystem, an exhaust subsystem, etc.

[0047] The vehicle 10 may be an electric vehicle (EV), a hybrid vehicle, or any other vehicle having an electric energy source. In an embodiment, the vehicle 10 is an electric vehicle that includes one or more motors and one or more drive systems. For example, the propulsion system 16 is a multi-drive system that includes a first drive unit 20 and a second drive unit 30. The first drive unit 20 includes a first electric motor 22 and a first conversion device 24, as well as other components such as a cooling system 26. The second drive unit 30 includes a second electric motor 32 and a second conversion device 34, as well as other components such as a cooling system 36.

[0048] The conversion devices 24 and 34 (e.g., traction power inverter units or TPIMs) include inverters for converting direct current (DC) power from a high voltage (HV) battery system 40 into multi-phase (e.g., two-phase, three-phase, six-phase, etc.) alternating current (AC) power to drive the motors 22 and 32. For example, the conversion device 24 and / or the conversion device 34 include at least one dual-output multi-level inverter circuit (multi-level inverter).

[0049] Also like Figure 1 As shown, the drive system is configured such that the first electric motor 22 drives the front wheels (not shown) and the second electric motor 32 drives the rear wheels (not shown). However, embodiments are not limited thereto, as any number of drive systems and / or motors may be present at various locations (e.g., a motor driving each wheel, dual motors per axle, etc.). For example, the vehicle may have a single drive unit.

[0050] In propulsion system 16, drive unit 20 and drive unit 30 are electrically connected to battery system 40. Battery system 40 may also be electrically connected to other components, such as vehicle electronics (e.g., via auxiliary power module or APM 42). Battery system 40 may be configured as a rechargeable energy storage system (RESS).

[0051] The battery system 40 includes one or more battery assemblies. For example, the battery system 40 includes a plurality of discrete battery assemblies, each of which can be independently charged and can be used to independently power one or more drive systems. For example, the battery system 40 includes a first battery assembly such as a first battery pack 44 connected to the conversion device 24, and a second battery pack 46 connected to the conversion device 34. The battery pack 44 includes a plurality of battery modules 48, and the battery pack 46 includes a plurality of battery modules 50. Each module 48, 50 includes a plurality of individual batteries (not shown).

[0052] The battery system 40 can be configured to provide different output voltage levels. For example, a battery switching device 52 is included to selectively connect the battery pack 44 in series to the battery pack 46 to provide a relatively high voltage (e.g., 800V). The battery switching device 52 can also be operated to connect the battery packs in parallel to provide a relatively low voltage (e.g., 400V).

[0053] The vehicle 10 also includes a charging system that can be used to charge the battery system 40 and / or to supply power from the battery system 40 to charge another energy storage system (e.g., vehicle-to-vehicle (V2V) and / or vehicle-to-everything (V2X) charging). The charging system is connected to one or more charging ports 54 for charging from an energy storage system such as a utility AC power source or from a DC fast charging (DCFC) station. The charging system can be controlled by, for example, at least one on-board charging module (OBCM) 56 electrically connected to the charging port 54.

[0054] The vehicle 10 also includes a computer system 60 including one or more processing devices 62 and a user interface 64. The computer system 60 can communicate with the charging system controller, for example, to provide commands thereto in response to user input. The various processing devices, modules, and units can communicate with each other via a communication device or system, such as a controller area network (CAN) or a transmission control protocol (TCP) bus.

[0055] As described above, the vehicle 10 includes one or more multi-level inverters. A "multi-level inverter" is an inverter that can output more than two voltage levels and can generate a step current output that approximates a desired waveform with a desired amplitude, frequency, and phase. Compared to a conventional two-level inverter, such an inverter provides an AC current output with lower voltage spikes and harmonic distortion. By generating more than two levels, a multi-level inverter can generate a smoother waveform than a two-level inverter.

[0056] In an embodiment, the multilevel inverter is a clamped inverter, such as a diode clamped inverter and a full bridge (H-type) inverter. However, the embodiment may be applicable to various other multilevel inverter topologies (e.g., cascade inverter, flying capacitor inverter, etc.). In addition, the embodiment is not limited to a three-level inverter, and may be applicable to other multilevel inverters (e.g., 5-level, 11-level, etc.).

[0057] In an embodiment, each multi-level inverter is a dual output inverter. A "dual output" inverter refers to an inverter that outputs two different currents. The output current includes a first AC current and a second AC current, and the first AC current and the second AC current are output simultaneously with the same amplitude and frequency, but separated by 180 degrees. Therefore, the three-phase dual output inverter outputs six AC phase currents. Each inverter includes a single current sensor, which can sample the current and / or magnetic field and measure the two output currents.

[0058] Figure 2 and Figure 3 An example of an inverter circuit in a conversion device such as conversion device 24 having three dual-output three-level inverters is depicted. Note that although only conversion device 24 is discussed, conversion device 34 may be similarly configured. Additionally, the embodiments discussed herein are not limited to the specific conversion devices and contexts described.

[0059] like Figure 2 As shown, the conversion device 24 includes three dual-output inverters 80a, 80b, and 80c, each of which has a multi-level inverter topology that generates two outputs, thereby generating a six-phase signal (current a1, a2, b1, b2, c1, and c2) transmitted to the motor and / or other loads via corresponding conductors (e.g., bus bars). The inverters are connected in parallel to the DC bus 82 and the capacitor C bus A diode is included and connected in parallel to the switch to perform voltage clamping. The inverter in this embodiment is referred to as an "X-type" inverter.

[0060] For example, Figure 3 As shown, the inverter 80a includes phase branches for alternately generating positive voltage and negative voltage, and a neutral (zero) branch for generating zero voltage. Each phase branch is controlled via a modulation scheme to output a first phase current a1 (corresponding to phase a1) and a second phase current a2 (corresponding to second phase a2). One phase branch includes a conductor 88 and a diode D 2 The neutral branch is connected to the switch S 1 , S 2 , S 7 and S 8 The other phase leg comprises a conductor 86 and a diode D 1 The neutral branch is connected to the switch S 3 , S 4 , S 5 and S 6 .

[0061] Each inverter 80a, 80b, and 80c includes a current sensor 84 configured to measure the output current from each inverter. One current sensor 84 is provided at each inverter and is positioned so that the current sensor 84 can measure two current outputs during a switching cycle.

[0062] Typically, a multilevel inverter, such as inverter 24, will have six current sensors (one for each output).This embodiment and other embodiments described herein allow only one sensor to be used for each dual output inverter, thereby reducing the required number of current sensors by half.

[0063] In an embodiment, the current sensor 84 is a two-dimensional (2D) magnetoresistive detector, such as a point field detector (PFD), which is configured to detect the magnetic field generated by the current passing through the inverter. The PFD detector detects the components of the induced magnetic field along the x-direction and the y-direction orthogonal to the x-direction.

[0064] The current sensor 84 is positioned so that the magnetic field measurement can be converted into a current measurement. In one embodiment, the current sensor 84 is disposed near the diode D 1 and D 2 and / or conductors 86 and 88. As used herein, "close" means close enough to capture the current flowing through diode D 1 and D 2 The dual currents produce mutually orthogonal fields.

[0065] For example, current sensor 84 is disposed sufficiently close to the X-intersection of conductors 86 and 88 so that current sensor 84 is disposed in the magnetic field generated when current is conducted through conductors 86 and 88. The magnetic fields are mutually orthogonal (i.e., one field is oriented in the x-direction and the other field is oriented in the y-direction orthogonal to the x-direction). A 2D field detector may be used to decouple these fields to allow estimation of the current output as phases A1 and A2.

[0066] For example, mutually orthogonal fields are decoupled according to the following equations:

[0067]

[0068] Among them I a is the output current corresponding to phase A1, and I b is the output current corresponding to phase A2. V is the output voltage, VB x is the voltage detected by the current sensor in the x direction, and VBy is the voltage detected by the current sensor in the y direction. xa , C ya is a coefficient related to the current Ia, and C xb and C ybis related to the current I b The coefficient of correlation.

[0069] The current sensor 84 is configured to be controlled to sample current measurements (e.g., magnetic field) at selected points during a switching cycle. As is known, the switches of the phase legs are operated to generate AC current based on a plurality of consecutive switching cycles. During a switching cycle, the inverter 80a alternates between various switching states. In a first switching state, the phase A1 output voltage is positive (e.g., at positive V dc / 2 voltage, where V dc is the input voltage from the battery system 40), and the phase A2 output is negative (e.g., at negative V dc / 2 or -V dc In the second switching state, the output voltage of phase A1 is negative (e.g., -V dc / 2), the output voltage of phase A2 is positive (for example, V dc / 2). In the neutral switching state, the voltage output is zero.

[0070] In an embodiment, the current sensor 84 is sampled during the switching cycle during the zero voltage state. During the zero voltage state, the output voltage from each phase is zero (ie, phases A1 and A2 are connected to create a virtual zero).

[0071] Figure 4-7 An example of an inverter circuit in a conversion device (such as conversion device 24) having three dual-output three-level inverters is depicted. Figure 4 As shown, the conversion device 24 includes three dual-output inverters 80a, 80b, and 80c, each inverter having a multi-level inverting topology with two outputs.

[0072] Each inverter is a full-bridge ("H-type") multilevel converter comprising phase legs connected by a neutral leg. Figure 5 As shown, the inverter 80a includes a phase branch switch S 11 , S 12 , S 13 and S 14 The phase branch can be connected by a conductor 90 and a neutral branch switch S 15 and S 16 The switching line or the bidirectional neutral branch is selectively connected.

[0073] During a switching cycle, the inverter 80a switches between various switching states. 11 and S 14 The first switching state is achieved by generating a positive voltage at the output of A2 and a negative voltage at the output of A1, and by closing the switch S 12 and S13 The second switching state is achieved by generating a negative voltage at the output of A2 and a positive voltage at the output of A1. 15 and open all other switches to provide a forward neutral condition, and by closing switch S 16 to provide a reverse neutral state.

[0074] In an embodiment, the current sensor 84 is disposed at the neutral branch and is positioned so that when the inverter 80a is in the neutral state and the current flows through the neutral branch (switch S 15 or S 16 The switch 84 can be positioned at any desired position, such as Figure 4 The switch S shown 15 and S 16 or between one of the switches and the connection between the neutral branch and the phase branch (e.g. Figure 5 shown).

[0075] Figure 6 and Figure 7 An embodiment is shown where the current sensor 84 is a 2D magnetic field sensor (e.g., PFD) and is positioned close to an orthogonal intersection. The current sensor 84 is oriented so that its measurement dimension spans two mutually orthogonal fields. The determination of the output current is based on decoupling the magnetic field as discussed herein.

[0076] For example, Figure 6 As shown, the current sensor 84 is positioned proximate to the orthogonal intersection between one of the phase legs and the DC bus 82. The current sensor 84 may be located at the intersection as shown, or at any other intersection between the DC bus and the phase legs. Figure 7 As shown, the current sensor 84 is located at the intersection between the neutral leg and one of the phase legs.

[0077] In an embodiment, the current sensor is disposed near an output conductor (eg, a bus bar) that carries the phase current from the inverter. The current sensor may be a PFD sensor or other suitable type of current sensor.

[0078] Figure 8 An embodiment of an inverter 80a is depicted having a current sensor 84 disposed adjacent to output conductors 92 and 94 (referred to as "phase leads"). Each conductor 92 and 94 may be any form of conductor, such as a bus bar. Although the inverter 80a is shown as an X-type inverter, the embodiments are applicable to other types of dual output multi-level inverters, such as an H-type inverter.

[0079] The current sensor 84 is positioned relative to the phase leads 92 and 94 so that the sensor 84 is disposed within the magnetic field generated by the phase currents (e.g., the A1 and A2 phases) flowing through the phase leads. The phase leads are routed or positioned so that the magnetic field generated by the A1 phase current is orthogonal to the magnetic field generated by the A2 phase current. For example, the phase leads are configured so that the phase lead 92 is orthogonal to the phase lead 94, and the current sensor 84 is disposed close to the intersection.

[0080] exist Figure 8 In the embodiment of , the current sensor 84 is a 2D PFD sensor that detects two magnetic fields. The estimation of the output current is performed by decoupling the magnetic fields according to the following equation:

[0081]

[0082] Among them I A is the output current through phase lead 92, and I B is the output current through the phase lead 94. V is the output voltage, VB x is the voltage detected by the current sensor in the x direction, VB y is the voltage detected by the current sensor in the y direction. x1 and D y1 is related to the current I A The correlation coefficient, and D x2 and D y2 is related to the current I B The coefficient of correlation.

[0083] In an embodiment, current sensors are disposed between phase leads from a given inverter to sample the output current. Fig. 9 An example is depicted where each inverter 80a, 80b, and 80c has a pair of output conductors or phase leads that are positioned sufficiently close to each other so that their respective magnetic fields combine. A current sensor 84 is disposed between a pair of phase leads from the inverter to detect a combined magnetic field that corresponds to twice the magnitude of the current in each phase lead.

[0084] For example, Fig. 9 As shown, the conductors or phase leads from the inverter 80a are shown as busbar 92a carrying phase current a1 (phase A1) from one phase output and busbar 94a carrying phase current a2 (phase A2). Busbars 92b and 94b carry phase currents b1 and b2, respectively, from the inverter 80b. Busbars 92c and 94c carry phase currents c1 and c2, respectively, from the inverter 80c.

[0085] The pairs of bus bars are separated so that crosstalk or coupling between adjacent pairs (e.g., between pairs of bus bars 92a, 94a and pairs of bus bars 92b, 94b) is minimized. For example, the magnetic field around each pair of bus bars is closed, and the pairs are separated so that the closed fields do not interact.

[0086] To estimate the output current, the current sensor 84 samples the magnetic field via a suitable type of current sensor 84 (e.g., Hall effect, magnetoresistive, etc.). The current through one of the bus bars (e.g., 92a) is opposite to the current through the other bus bar (e.g., 94a) in the pair. The current sensor detects the combined magnetic field. Since the currents have the same waveform but with opposite phases (180 degrees apart), the magnetic field strength is twice the magnetic field strength of either field. The detected magnetic field is converted into a current that represents twice the magnitude of the current in each bus bar.

[0087] Fig.10 An embodiment is depicted in which the current sensor comprises a magnetic field detector 94 and a magnetic core 96. The current is similarly measured by detecting a combined magnetic field B which is twice the strength of each magnetic field generated by each bus bar.

[0088] Fig.11 An embodiment of a method 100 for controlling a conversion device and controlling power transfer, such as power transfer from a battery system to a motor or other AC load, is shown. Aspects of the method 100 may be performed by one or more processors disposed in a vehicle, such as a controller connected to the conversion device, a vehicle controller, or other suitable processing device or system.

[0089] Method 100 includes a number of steps or phases represented by blocks 101-104. Method 100 is not limited to the number or order of steps therein, as some steps represented by blocks 101-104 may be performed in a different order than described below, or fewer than all of the steps may be performed.

[0090] For purposes of illustration, method 100 is described in conjunction with vehicle 10 and motor unit 20, but is not limited thereto. For example, the method may be used to control motor unit 30 (in addition to or in lieu of control of motor unit 20) or any other suitable conversion device having one or more multi-level inverters. In an automotive or other environment, method 100 may be used with any suitable conversion device or system.

[0091] At box 101, a vehicle such as vehicle 10 is operated and the motor 20 is engaged to generate torque and drive the vehicle 10. For example, the conversion device 24 includes a six-phase inverter circuit including three dual-output multi-level inverters.

[0092] Each inverter 80a, 80b, and 80c is controlled according to a switching sequence based on a modulation scheme. The modulation may be pulse width modulation (PWM) as discussed herein or any other suitable scheme.

[0093] At box 102, a current sensor 84 is provided in each inverter 80a, 80b, and 80c (or positioned relative to a phase output from each inverter). Each current sensor 84 samples the current or magnetic field at a selected point during a switching cycle.

[0094] If the current sensor is placed inside the inverter (e.g. Figure 2-7 As shown), the sampling point is selected so that the current is sampled when the inverter is in the zero state.

[0095] Fig.12 1 is a timing diagram 110 illustrating an example of sampling points during a switching cycle. This example may be applicable to embodiments where a current sensor is provided within each inverter (e.g., Figure 2-7 ).

[0096] The timing diagram depicts the output current and voltage levels from the output of each inverter. Curve 112 represents a portion of the switching cycle where the A1 phase output (current a1) from inverter 80a is positive (V is positive V dc Curve 114 represents the portion of the switching cycle where the B1 phase output (corresponding to current b1) is positive and zero, and curve 116 represents the C1 phase output (corresponding to current c1) from inverter 80c.

[0097] Timing diagram 110 also shows sampling points 118, which are the points in time at which each inverter is sampled. As shown, each current is sampled at a point when the inverter is in a zero state (zero voltage).

[0098] At block 103, the output current is estimated based on the current sensor samples. If the current sensor is a 2D PFD, this may be performed by decoupling as discussed herein.

[0099] At block 104, various actions may be performed based on the estimate of the current. Examples of actions include shutting down (eg, if overcurrent or a fault is detected), adjusting modulation parameters, and the like.

[0100] Fig.13 Aspects of an embodiment of a computer system 240 are shown that can perform various aspects of the embodiments described herein. The computer system 240 includes at least one processing device 242, which typically includes one or more processors for performing various aspects of the image acquisition and analysis methods described herein.

[0101] Components of computer system 240 include processing device 242 (such as one or more processors or processing units), memory 244, and bus 246, which couples various system components including system memory 244 to processing device 242. System memory 244 can be a non-transitory computer-readable medium and can include various computer system-readable media. Such media can be any available media that can be accessed by processing device 242, and includes volatile and non-volatile media and removable and non-removable media.

[0102] For example, system memory 244 includes non-volatile memory 248, such as a hard drive, and may also include volatile memory 250, such as random access memory (RAM) and / or cache memory. Computer system 240 may also include other removable / non-removable, volatile / non-volatile computer system storage media.

[0103] The system memory 244 may include at least one program product having a set (i.e., at least one) of program modules configured to perform the functions of the embodiments described herein. For example, the system memory 244 stores various program modules that generally perform the functions and / or methods of the embodiments described herein. A module 252 for performing functions associated with sampling and current estimation may be included, and a module 254 for performing functions associated with the control of the conversion device as discussed herein may be included. The system 240 is not limited thereto, as other modules may be included. As used herein, the term "module" refers to a processing circuit, which may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functions.

[0104] Processing device 242 may also communicate with one or more external devices 256, such as a keyboard, pointing device, and / or any device that enables processing device 242 to communicate with one or more other computing devices (e.g., a network card, a modem, etc.). Communication with various devices may occur via input / output (I / O) interfaces 264 and 265.

[0105] The processing device 242 may also communicate with one or more networks 266, such as a local area network (LAN), a general wide area network (WAN), a bus network, and / or a public network (e.g., the Internet) via a network adapter 268. It should be appreciated that, although not shown, other hardware and / or software components may be used in conjunction with the computer system 40. Examples include, but are not limited to, microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, and data archival storage systems, among others.

[0106] The terms "one" and "an" do not indicate a limitation of quantity, but rather indicate the presence of at least one of the referenced item. Unless the context clearly indicates otherwise, the term "or" means "and / or". References to "aspects" throughout the specification mean that a particular element (e.g., a feature, structure, step, or characteristic) described in conjunction with that aspect is included in at least one aspect described herein, and may or may not be present in other aspects. In addition, it should be understood that the described elements may be combined in any suitable manner in the various aspects.

[0107] When an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

[0108] Unless otherwise indicated herein, all test standards are the most current standards in effect as of the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the test standards appear.

[0109] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0110] Although the above disclosure has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for its elements without departing from its scope. In addition, many modifications may be made to adapt specific circumstances or materials to the teachings of the disclosure without departing from the basic scope of the disclosure. Therefore, it is intended that the disclosure is not limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A conversion system, comprising: A conversion device including a multilevel inverter configured to generate two alternating current (AC) output currents; a current sensor configured to sample current through or from the multilevel inverter during a switching cycle; as well as A processor is configured to estimate both of the two AC output currents based on the sampled current from the current sensor.

2. The conversion system according to claim 1, wherein: The current sensor is configured to sample the current during a switching period when zero voltage is output.

3. The conversion system according to claim 1, wherein: The current sensor is a two-dimensional magnetic field detector.

4. The conversion system according to claim 1, wherein: The multilevel inverter is a diode clamped inverter having a first set of switches connected by a first diode and a second set of switches connected by a second diode, and the current sensor is configured to simultaneously detect mutually orthogonal magnetic fields caused by current flowing through the first diode and the second diode.

5. The conversion system according to claim 1, wherein: The multilevel inverter has a full-bridge topology connecting a first set of switches to a second set of switches, the first set of switches being connected to the second set of switches through a bidirectional switch line.

6. The conversion system according to claim 5, wherein: The current sensor is disposed at the bidirectional switch line to detect a current passing through the bidirectional switch line.

7. The conversion system according to claim 5, wherein: The current sensor is a two-dimensional magnetic field sensor disposed at an orthogonal intersection between a branch of the full-bridge topology and one of the bidirectional switch line and a direct current (DC) bus.

8. The conversion system according to claim 1, wherein: The multilevel inverter is connected to a first output conductor configured to carry a first output current and a second output conductor configured to carry a second output current, and the current sensor, the first output conductor and the second output conductor are configured such that the current sensor detects a first magnetic field generated by the first output current and a second magnetic field generated by the second output current.

9. A method of transmitting electric power, comprising: receiving an input current from a direct current (DC) source at a conversion device including a multilevel inverter; converting the input current by the multilevel inverter to generate two alternating current (AC) output currents, wherein the converting includes performing a series of switching cycles; sampling the current through or from the multilevel inverter during a switching cycle by a single current sensor; and Both of the two AC output currents are estimated based on the sampled current from the single current sensor.

10. The method according to claim 9, wherein: The multilevel inverter comprises at least one of the following: a diode clamped inverter having a first set of switches connected by a first diode and a second set of switches connected by a second diode, and the single current sensor simultaneously detects mutually orthogonal magnetic fields caused by current flowing through the first diode and the second diode; as well as A full bridge topology connecting a first set of switches to a second set of switches, the first set of switches being connected to the second set of switches via a bidirectional switch line.

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