Current sensor decoupling

Abstract

In some implementations, the device may include at least one processor. In addition, the device may include a memory including instructions, which when executed on the at least one processor, cause the at least one processor to: obtain current data that is indicative of current measurements in phases at a plurality of busbars, the current data having a current measurement accuracy; and execute an architecture that is configured to generate a nonphysical shield between the plurality of busbars so as to improve the current measurement by decoupling an effect of adjacent terminals among the plurality of busbars.

Description

CURRENT SENSOR DECOUPLINGFIELD

[0001] The following disclosure relates to a current sensor system, and more particularly, to a current measurement system and method for correcting a current measurement error.BACKGROUND

[0002] Some current sensor systems include sensing elements, which may be mounted on metal carriers with a busbar. The sensor chips may be configured to capture magnetic fields induced by an electrical current flowing through the busbar. Current sensors are positioned near a current-carrying busbar to sense a magnetic field generated by the electrical current flowing through the busbar. The current sensor generates an output signal having a magnitude proportional to the magnetic field induced by the current through the busbar.SUMMARY

[0003] A system of one or more computers can be configured to perform particular operations or actions by virtue of having software, firmware, hardware, or a combination of them installed on the system that in operation causes or cause the system to perform the actions. One or more computer programs can be configured to perform particular operations or actions by virtue of including instructions that, when executed by data processing apparatus, cause the apparatus to perform the actions.

[0004] In one general aspect, method may include receiving a first current through a first current-carrying element of the plurality of current-carrying elements. Method may also include receiving a test signal from a second current carried by a second current-carrying element of the plurality of current-carrying elements, the test signal corresponding to an amount of coupling effects between the first and second current-carrying elements as a result of current being carried by the second current-carrying element, the second current-carrying element being adjacent to the first current currying element so as to be within range of coupling effects associated with the current being carried by the second current-carrying element. Method may furthermore include generating a control logic for operating the multiphase system based on a current measurement ofthe first current-carrying element, the control logic including an algorithm to decouple the coupling effects of the second current-carrying element on the first current-carrying element so as to inhibit inaccuracies in the current measurement. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0005] Implementations may include one or more of the following features. Method where the test current is carried by the first current-carrying element while the current is being carried by the second current-carrying element. Method where the first and second currents are generated using a single current. Method where the current measurement is a first current measurement, the method may include monitoring at least one of the first current measurement of the first currentcarrying element and a second current measurement of the second current-carrying element. Method where the method constitutes a pre-deployment calibration of the multiphase system, the method may include repeating the pre-deployment calibration for each of the current-carrying elements in the plurality of current-carrying elements. Method where the algorithm is a zero-sum transform where an algebraic sum of corrected current measurements for each of the currentcarrying elements in the plurality of current-carrying elements is zero, and where each of the corrected current measurements is equal to a respective current measurement minus a summation of each of the other current measurements multiplied by a respective coupling factor. Method where the coupling factors are a constant value that corresponds to the amounts of test signal experienced by a respective current carrying element during the pre-deployment calibration. Method where the coupling factors are obtained by applying a first current in the first currentcarrying element and measuring a second current in the second current-carrying element and dividing the second current by the first current. Method may include repeating the pre-deployment calibration for all phases in the multiphase system. Method where repeating the pre-deployment calibration for all phases in the multiphase system is performed using the same sample and the same hold time. Method may include running the algorithm after deployment of the multiphase system by: measuring the current to obtain a measured current carried by each of the currentcarrying elements in the plurality of current-carrying elements; and obtaining a respective current measurement for each of the current-carrying elements in the plurality of current-carrying elements where the respective current measurement is a corrected current measurement that is equal to the measured current for the respective current-carrying element minus an adjusted current for eachof the other current-carrying elements in the plurality of current carrying elements, where the adjusted current is equal to the measured current for a respective current-carrying element multiplied by a coupling factor for the respective current-carrying element. Method may include: monitoring the first current for indicia of coupling effects on the current measurement; and adjusting the algorithm based on the current measurement. Implementations of the described techniques may include hardware, a method or process, or a computer tangible medium.

[0006] In one general aspect, current sensor may include A current sensor for integration in a system having a plurality of adjacent terminals with first and second adjacent terminals. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0007] Implementations may include one or more of the following features. Current sensor where the nonphysical shield is generated by running an algorithm that is a zero-sum transform where an algebraic sum of corrected current measurements for each terminal in the plurality of terminals is zero, and where each of the corrected current measurements is equal to a respective current measurement of a terminal in the plurality of terminals minus a summation of each of the other current measurements multiplied by a respective coupling factor. Energy storage system. Hybrid generator system. Circuit board. Power electronics device. Implementations of the described techniques may include hardware, a method or process, or a computer tangible medium.

[0008] In one general aspect, controller may include at least one processor. Controller may also include a memory including instructions, which when executed on the at least one processor, cause the at least one processor to: obtain current data that is indicative of current measurements in phases at a plurality of busbars, the current data having a current measurement accuracy; and execute an architecture that is configured to generate a nonphysical shield between the plurality of busbars so as to improve the current measurement by decoupling an effect of adjacent terminals among the plurality of busbars. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0009] Implementations may include one or more of the following features. Controller where the busbars are asymmetrically arranged within a current sensor. Implementations of the described techniques may include hardware, a method or process, or a computer tangible medium.

[0010] While multiple embodiments are disclosed, still other embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a schematic diagram of a system having an electrical power system with a current sensor system according to principles of the present disclosure;

[0012] FIG. 2 illustrates a current sensor system comprising three parallel, unshielded current sensors disposed adjacent to one another on busbars, each busbar carrying a current phase of the three-phase current system;

[0013] FIG. 3 is a schematic diagram of the current sensor system of FIG. 1, showing the interaction among the magnetic fields of the current sensors;

[0014] FIG. 4 is a graph showing a sinusoidal profile of a three-phase system representing the measured current at each of the current sensors of FIGS. 1 and 2;

[0015] FIG. 5 is a schematic diagram of a triangular arrangement of three busbars, each including current sensors;

[0016] FIG. 6 is a graph showing the measured current at each of the current sensors of FIG. 4;

[0017] FIG. 7 illustrates a shielded current sensor comprising a current sensor with shielding installed to prevent magnetic interference;

[0018] FIG. 8 is a graph showing the measured current at each of the current sensors of FIG. 6, the sum of the currents being equal to zero;

[0019] FIG. 9 is a flowchart showing a process for calibrating a current sensor decoupling algorithm according to an embodiment of the present disclosure; and

[0020] FIG. 10 is a flowchart showing a process for implementing a current sensor decoupling algorithm according to an embodiment of the present disclosure.

[0021] While the disclosed subject matter is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the disclosure to the particular embodiments described. On the contrary, the disclosure is intended to cover all modifications,equivalents, and alternatives falling within the scope of the disclosure as defined by the appended claims.DETAILED DESCRIPTION

[0022] Among current measurement devices, there is a hall sensor type current measurement apparatus having a hall element installed in an air gap of a C-shaped magnetic core. The voltage generated in the hall element is measured to detect a strength of a magnetic field. In the current measurement system, the magnetic core is excited by a magnetomotive force generated by a current to be measured, and the hall element installed in the air gap of the magnetic core measures a magnetic flux density in the form of a voltage proportional to the current to be measured. The magnetic core basically has hysteresis characteristics between the current to be measured and the magnetic flux density induced therefrom.

[0023] Typically, an amount of the current to be measured is measured from a voltage value outputted from the hall element using a simple circuit, but a current measurement error occurs due to the hysteresis characteristics of the magnetic core.

[0024] The accuracy with which a magnetic field-based current sensor senses an intended current may be affected by exposure to stray magnetic fields. Some conventional current sensors employ a ferromagnetic core to increase the coupling between the current flowing in the busbar and the magnetic field magnitude. The core may provide a shielding to stray field immunity or, if no ferromagnetic core is used, the magnetic field is directly sensed, and a ferromagnetic shield may be provided around the system to reduce any effects of stray fields disturbing the current measurement.

[0025] Sensing elements include a variety of electronic devices capable of sensing a magnetic field. These elements generate a magnetic field signal in response to the sensed magnetic field. The sensing element may be a Hall-effect element, a fluxgate, a magnetoresistance element, or a magnetotransistor. Different types of Hall-effect elements include a planar Hall element, a vertical Hall element, and a Circular Vertical Hall element. Examples of magnetoresistance elements include semiconductor magnetoresistance elements, such as Indium Antimonide elements, giant magnetoresistance elements, such as spin valves, anisotropic magnetoresistance elements, tunneling magnetoresistance elements, and magnetic tunnel junctions. The sensing element may be a single element or, alternatively, may include two or more sensing elementsarranged in various configurations, such as a half bridge or full (Wheatstone) bridge. Depending on the device type and other application requirements, the sensing element may be a device made of a type IV semiconductor material such as Silicon (Si) or Germanium (Ge), or a type III-V semiconductor material like Gallium- Arsenide (GaAs) or an Indium compound, e.g., Indium- 10 Antimonide (InSb).

[0026] Disclosed herein are devices, systems, and methods for nonphysical sensor shielding. In particular, this disclosure includes current sensor decupling algorithms to cancel current signal pick-up from nearby equipment (e.g., adjacent busbars, cables, etc.) disturbing the measured currents. In examples, the algorithm is based on mathematical compensation equations to be used in control software. In examples, the measured current is from on-busbar hall current sensors. These sensors are a cost-effective current measurement solution, but they can pick up signals from adjacent busbars. This affects the accuracy of the sensor and control, causing distortion. As well-known control methods based on the Clark-Park transformation assume that the three-phase system is symmetric and satisfies this condition: Ia+Ib+Ic=0. If the magnetic field of other current-carrying elements is close to the Hall sensor, this sensor measures a portion of the other busbar current, which adds to the measured busbar current. A physical shield can be used to protect against this pick-up, but this increases the volume of the component and adds cost.

[0027] Principles of the present disclosure include decoupling and calibration methods and related devices and systems. For instance, this disclosure includes mathematical compensation / decoupling algorithms in controls to decouple the effect of adjacent busbars on current measurement accuracy. Such algorithms are appropriate for Unsymmetrical Couplings in flat busbars arrangements and Symmetrical Coupling arrangements (e.g., triangular for 3 -phase arrangements). While occasionally discussed in relation to Three phase system busbars with current sensors without physical shielding, the disclosed algorithms may be used for all phase systems: 3, 6, 9 etc.

[0028] Calibration algorithms are also disclosed herein. These calibration algorithms can be run before production (e.g., one or more times beforehand). To perform the calibration, first calibrate the sensor gain and offsets. Then run test current in Phase A and measure coupling gain based on the measurement signals in other phases. Repeat this step for all phases. Then calculate coupling factors (e.g., Ka, Kb, and Kcdescribed elsewhere herein). Now the decoupling algorithm can be run. First, measure currents (ia, ib, and icas discussed elsewhere herein) in all phases, likelybest done with the same sample and hold time. Then use the equations below for calculating decoupled currents:Benefits of implementing principles of the present disclosure include at least the following: a low / no-cost solution, no extra hardware parts, easily implemented, improved control quality, improved system overall performance, and improved current measurement accuracy.

[0029] With reference to the figures, FIG. 1 depicts a system 2 having an electrical power system 20 of a further embodiment of the present application. In examples, system 2 can be a vehicle, a power grid, a power generator, an electric motor, and the like though these are just some examples of what will be apparent to one skilled in the art. Electrical power system 20 includes an electric power generation genset subsystem 22. Genset 22 includes a prime mover 22 a in the form of an internal combustion engine 24 and an alternator or electric power generator 30 to provide a three-phase, Alternating Current (AC), voltage at a target magnitude and frequency. In other arrangements, power may be supplied as a single phase or in such other configuration as would occur to those skilled in the art.

[0030] Engine 24 provides rotational mechanical power to generator 30 with rotary drive mechanism 26. Mechanism 26 can be a direct drive member, a device that provides a nonunity turn ratio, a torque converter, a transmission, and / or a different form of rotary linkage as would occur to those skilled in the art. In one arrangement, mechanism 26 is in the form of an extension of a crankshaft of engine 24 that serves as a rotor within generator 30 and thus the engine and generator have a one-to-one turning ratio. The depicted form of engine 24 includes one or more reciprocating pistons 23 in corresponding cylinders and is structured for Spark Ignition (SI) combustion. Correspondingly, engine 24 utilizes an SI compatible fuel such as natural gas, liquid petroleum gas, molecular hydrogen, a different gaseous fuel; gasoline; or other SI compatible fuel type. Alternatively, the genset engine can be of a Compression Ignition (CI) type (such as a diesel- fueled engine) utilizing a Cl-compatible fuel such as diesel, JP8 or JP5. Fuel may be introduced through fuel injection. In certain diesel engine embodiments, fuel is injected on a per cylinder basisusing direct injection or port injection-such that there is one fuel injector per cylinder-facilitating independent cylinder-by-cylinder fueling control. System 20 includes fuel source 24 a, supplied by conduit 24 / ?, which is coupled to engine 24. Fuel from source 24 a is mixed with air from air intake 25 upstream of pistons 23 to provide a fuel charge thereto.

[0031] In other forms, engine 24, mechanism 26, and / or generator 30 can be of other types; engine 24 may be alternatively fueled and / or have different combustion modes or cycles; and / or a different form of engine-based prime mover 22 a can be used to provide mechanical power to generator 30 as an alternative or addition to engine 24, like a Cl engine type, a gas turbine engine type, a two-stroke engine type, among others. Different forms of prime mover 22 a further include, without limitation, a wind turbine, a hydraulic turbine, and / or a steam turbine.

[0032] Generator 30 includes excitation field windings 32 operatively coupled to controller 70 to be further described hereinafter. The electric power output of generator 30 is coupled to switchgear 40 to selectively couple and decouple the generator electric power output to / from the load 46 (e.g., a grid such as a public utility power grid, a genset, a vehicle powertrain, and the like). For arrangements in which system 20 is dedicated to supply power to load 46 in the form of a grid, switchgear 40 typically is in the form of breakers for each power line. Alternatively, for a stand-by or back-up power application of system 20, switchgear 40 would typically include a transfer switch coupled to load 46 and a local electrical load (not shown). Furthermore, one or more transformers may be provided between switchgear 40 and the connection to load 46 (not shown). In one nonlimiting implementation, genset 22 includes engine 24 in the form of a multiplecylinder, reciprocating piston, gaseous-fueled SI type and generator 30 in the form of an alternator with a rotor, which may be provided on an extension of the engine crankshaft (not shown).

[0033] Electrical power system 20 further includes voltage sensors 64 to monitor the magnitude of voltage output by generator 30 on conductors 34. Sensors 64 may be in the form of circuitry that samples a voltage drop across a known resistance or the like. Electrical power system 20 further includes current sensors 62 that monitor magnitude of electric current flow through conductors 34, neutral (N), and ground (GND), in association with generator 30. Sensors 62 may be of a standard current transformer type or such other variety as would be known to those skilled in the art. Sensor 66 is of a standard type that provides a sensor signal representing rotational speed of engine 24. In some forms, the sensor signal of sensor 66 is representative of the frequency of the electric power output of generator 30; however frequency of the electric power output can bedetermined using other techniques. Sensors 62, 64, and 66 are converted to a digital form for processing using standard techniques. Alternatively or additionally, in other embodiments, an analog form of sensor signal processing may be used.

[0034] Electrical power system 20 further includes controller 70 coupled to sensors 62, 64, and 66. Controller 70 may be provided with generator 30 as part of the power generation genset 22 and may be in the form of one controlling device for both engine 24 and generator 30 or may be in the form of two or more controlling devices such as a dedicated Engine Control Module (ECM) in communication with a dedicated generator / genset control module, just to name a few nonlimiting examples. In one particular form, engine 24, generator 30, and controller 70 are provided as integrated equipment. Controller 70 includes inputs from current sensors 62 corresponding to the three phases of the electrical output of generator 30 designated as “3ol,” any detected neutral current designated as “NI,” and any detected electric earth ground current designated as “GNDI.” Sensors 64 provide voltages corresponding to the three-phase electric output of generator 24 designated as “30V.” The engine speed input from sensor 66 is designated as “RPM.” Operation of engine 24 is regulated by controller 70 in response to signals therefrom.

[0035] Controller 70 includes memory 74. Controller 70 executes operating logic that defines various control, management, and / or regulation functions. This operating logic may be in the form of dedicated hardware, such as a hardwired state machine, programming instructions, and / or a different form as would occur to those skilled in the art. Controller 70 may be provided as a single component or a collection of operatively coupled components; and may be comprised of digital circuitry, analog circuitry, software, or a hybrid combination of any of these types. Controller 70 can include multiple processing units arranged to operate independently, in a pipeline processing arrangement, in a parallel processing arrangement, and / or such different arrangement as would occur to those skilled in the art. When controller 70 is of a multi-component form, it may have one or more components remotely located relative to the others. In one embodiment, controller 70 is a programmable microprocessor device of a solid-state, integrated circuit type that includes one or more processing units and memory. In one form, controller 70 can include a computer network interface to facilitate communications using one or more standard communication protocols. Such an interface may be used to report system status information, receive sensor / detector inputs, operator input / output, communicate other data used in its operation, perform remote debugging or monitoring of controller 70, and / or to receive operating logic updatesin the form of programming instructions or the like. It should be appreciated that one or more operator input controls, such as a keyboard, pointer, switches, or the like; and one or more operator outputs, such as a display, alarm, indicator, or the like can be included in genset 22 with appropriate interfacing to controller 70.

[0036] Memory 74 may be comprised of one or more types including but not limited to semiconductor, magnetic, and / or optical varieties, and / or may be of a volatile and / or nonvolatile variety. In one form, memory 74 stores programming instructions executed by controller 70 to embody at least a portion of its operating logic. Alternatively or additionally, memory 74 stores data that is manipulated by the operating logic of controller 70. Controller 70 may include signal conditioners, modulators, demodulators, Arithmetic Logic Units (ALUs), Central Processing Units (CPUs), oscillators, control clocks, amplifiers, communication ports, delay devices, signal format converters (such as analog-to-digital and digital-to-analog converters), limiters, clamps, filters, power supplies, and the like as needed to perform various control, management, and regulation operations described in the present application.

[0037] Controller 70 may control / monitor a number of aspects of genset 22 operation, such as electrical load change / transience, electronic governor control, automatic voltage regulation, regulated short circuit current, engine speed sensing, engine fault monitor, overload / overcurrent fault, neutral current fault, earth ground fault, short circuit fault, automatic synchronization with other AC power sources, permissive paralleling with other generators, paralleling control, over / undervoltage faults, remote metering and control, generator start-up control, output power calculation and display, reverse power fault, real power load sharing control during parallel operation, reactive power load sharing control during parallel operation, built-in self-diagnostics, and provision for external diagnostics equipment, just to name a few. Two common control functions are: (1) the regulation of the frequency of the generator output waveform typically performed by adjusting engine operation and, (2) the regulation of the voltage and / or electric current produced by generator 30.

[0038] In a vehicle 2, the battery or other power system of the vehicle 2 provides a power supply to various electronic accessories. The accessories may include, for example, accessories relating to engine performance, safety features, comfort features, and any other type of vehicle subsystem. Various conditions may impact the ability of the power train or power system of the vehicle 2 to deliver power to the accessories. For example, external conditions such as the drivingenvironment around the vehicle 2 may impact vehicle performance. Conditions such as the road the vehicle 2 is driving on, the speed limit on the road, the traffic around the vehicle 2, and the weather may impact the power system, as the power required to operate the accessories in the conditions may vary. For example, when traveling uphill or in heavy traffic conditions, more power may be required to be focused on more critical vehicle subsystems, rather than systems like the HVAC unit. Further, there may be some conditions in which one or more accessories or subsystems may be able to advantageously produce an energy supply for the power system.

[0039] Converters perform a number of different functions in vehicle applications and power conversion, such as traction inverters for multi-phase (e.g., three-phase, four-phase, etc.) electrical machines including, for example, permanent magnet motors, induction motors and switched reluctance motors, battery chargers, air compressors, power steering systems, high efficiency alternators, AC power output to an electrical load or power grid from an inverter, heat, ventilation and air conditioning systems (HVAC), electrical fans, etc. Traditionally, separate, fixed converters are used for different functions and configurations.

[0040] The in-phase current sensor 62 may be used in high power drive applications to determine phase currents delivered by a power module to, for example, an electric motor. One implementation of such an in-phase current sensor 62 uses magnetic core-based magnetic current sensing principles. In general, a magnetic core-based in-phase current sensor 62 is a magnetic sensor that employs a field concentrator (e.g., a core wound around a current rail) to concentrate a magnetic field generated by a current flowing through the current rail onto a magnetic induction element so that a measurement can be taken. Another implementation of an in-phase current sensor 62 uses a coreless magneto-electric current sensing principle. In general, a coreless in-phase current sensor 62 is a magnetic sensor that implements one or more sensing elements in proximity to a current rail such that measurements may be taken based on a magnetic field (as sensed by one or more of the sensing elements) generated by current flowing through the current rail. Such in- phase current sensors 62 may be used, for example, in direct current to alternating current (DC / AC) inverters, DC / DC converters, AC / DC converters, DC / AC converters, AC / AC converters, and the like.

[0041] Such a sensor 62 can be integrated into a control board (not shown) that is configured to receive the sensor signal provided by the magnetic sensor and control the power module based on the sensor signal. That is, the control board may be configured to provide controlto the power module based on measurements of the sensor signals, and the power module may regulate the current based on feedback from the control board. In this manner, a motor control loop may be configured to maintain proper current balance supplied to the motor. In some implementations, the control board may be a Printed Circuit Board (PCB) or another type of carrier material suitable for receiving the sensor module and providing routing and / or electrical connections for the sensor module, such as an Integrated Metal Substrate (IMS), a ceramic substrate, a lead frame, a stamped lead frame, and so forth.

[0042] As mentioned above, FIG. 1 is provided as an example. Other examples may be different than that described with respect to FIG. 1. For example, although FIG. 1 shows an example of an electrical power system, another system or a subsystem of power electronic converters is also possible, such as a DC / AC inverter, a DC / DC converter, an AC / DC converter, a DC / AC converter, an AC / AC converter, or the like. Further, the number and arrangement of components shown in FIG. 1 are provided as examples. In fact, there may be more components, fewer components, different components, or differently arranged components than those shown in FIG. 1

[0043] Having described various structural and relational aspects of system 2 and its constituents, various modes of operating system 20 are next described. These operating modes / processes can be implemented, as applicable, via the operating logic executed by controller 70 and / or using such other techniques as would occur to those skilled in the art.

[0044] In more detail, the current sensor system of FIG. 2 has a plurality of current sensors and a plurality of current-carrying elements (e.g., conductive wires, busbars, and the like), according to the present disclosure. As illustrated, current sensor system 100 comprises three rectangular-shaped conductors (i.e., busbars) carrying three currents. While in some examples, the current carried by these busbars can be independent to each busbar, it is contemplated herein that there are some example where this will not be the case. As illustrated, the busbars are positioned adjacent to each other in a linear arrangement, each busbar is configured to carry a current to be measured, according to the present disclosure.

[0045] Current sensor system 100 includes a plurality of current-carrying elements (e.g., conductors, wires, busbars, etc.). As shown, current sensor system 100 includes a first busbar 102, a second busbar 104, and a third busbar 106. Each busbar has a current sensor attached thereto, though other arrangements are contemplated herein. First current sensor 108 is attached to firstbusbar 102, second current sensor 110 is attached to second busbar 104, and third current sensor 112 is attached to third busbar 106. Other devices, such as transistors, may also be attached to the busbars 102, 104, 106 without departing from the substance of this disclosure.

[0046] Current sensors employed herein may directly or indirectly measure current and may facilitate monitoring currents to be measured. Each of the current sensors 108, 110, 112 includes one or more sensing elements capable of measuring the current through one or more of the busbars 102, 104, 106. In addition, or in alternative, the sensing elements can measure a magnetic field. In examples, measuring the magnetic field can be performed using the linear relationship between the magnetic field measured by the sensors and the current flowing in the busbars. Current sensors 108, 110, 112 can be magnetic field-based current sensors which include at least one sensing element. The sensing element generates a magnetic field signal in response to a magnetic field. The term "magnetic field-based current sensor" includes one or more sensing elements which, in combination with other circuits, is used to determine an amount of current flowing through the system. Although some embodiments may only show or describe one sensing element, it will be appreciated that each current sensor may have more than one sensing element.

[0047] Current sensor system 100 may be used in a variety of applications, such as to sense a magnetic field generated by a current carried by a current-carrying busbar or a magnetic field sensor that senses a magnetic field density of a magnetic field to determine a current. The sensing element of each current sensor 108, 110, 112 may be any sensing element disclosed herein (e.g., Hall effect element, a magnetoresistance element, or a magnetotransistor), and each current sensor may include one or more such elements of the same or different types. Each of the current sensors 108, 110, 112 can include one or more sensing elements configured to sense currents and / or a resulting magnetic field generated by a current through one or more of busbars 102, 104, 106. Magnetic coupling from one or more busbars adjacent to the current sensor may occur. As such, fluctuations in sensed current and / or magnetic field can be used to indicate detection of an interfering magnetic field. This indication can be followed by generating a magnetic field signal indicative of a detected magnetic field.

[0048] FIG. 3 shows a cross-sectional two-dimensional figure, as denoted by the X-axis and Y-axis, with current flowing in the Z direction (e g., into or out of the X-Y plane). Three current sensors 108, 110, 112, each having one or more sensing elements, are positioned adjacent to each other and coplanar with each other in an asymmetrical arrangement. As discussedelsewhere herein, these sensors 108, 110, 112, measure the current and / or field. As illustrated, each busbar 102, 104, 106 has a magnetic field (the direction of which is indicated by circular arrows) associated with a positive (+) or negative (-) current flowing therethrough. Intersections between the circular arrows indicates an interaction between the magnetic fields produced by current sensor system 100.

[0049] First busbar 102 has a first current sensor 108 attached thereto and an associated magnetic field 114. Second busbar 104 has a second current sensor 110 attached thereto and an associated second magnetic field 116. Third busbar has a third current sensor 112 attached thereto and an associated third magnetic field 118. The three magnetic fields 114, 116, 118 interact with each other as illustrated by the intersecting circular arrows shown in FIG. 3. As mentioned elsewhere herein, the arrows illustrate the direction of the magnetic field. And intersections between the arrows show potential interferences that can distort readings from the current sensors 108, 110, 112

[0050] A calibration process can be used to generate algorithms that erect nonphysical barriers between adjacent busbars 102, 104, 106 reduce distortions in readings from the current sensors 108, 110, 112. Busbars 102, 104, 106 may be coupled to a current source that provides a current to each of busbars 102, 104, 106. This current can be a reference current generated by a reference current source. This source may be integrated with current sensor system 100 or may be externally coupled to current sensor system 100. The current sensor may be an integrated circuit comprising a Hall sensor or a Hall integrated circuit. In other embodiments, the magnetic field sensor chip may be an xMR sensor, in particular an AMR sensor, a GMR sensor or a TMR sensor. Signal amplification, analog / digital conversion, digital signal processing and offset and temperature compensation may also be carried out in the Hall integrated circuit. In addition to the Hall plates, the components for the signal amplification and / or analog / digital conversion may or may not be considered to be part of the sensor elements.

[0051] The sensing element may be a differential sensing element, which determines a difference between the magnetic field strengths respectively captured in the sensing elements. In some embodiments, each of current sensors 108, 110, 112 may include integrated sensing elements. For example, one or more sensing elements may be provided in the form of an integrated circuit and / or include additional processing circuitry and may be encapsulated with an electrically insulating material within current sensors 108, 110, 112. The sensing elements and additionalcircuitry may form a single integrated circuit current sensor or may be included on a separate semiconductor die coupled in multiple integrated circuits.

[0052] FIG. 4 is a graph showing the amount of current measured at each of the current sensors of FIGS. 1 to 3 plotted against time. First current profile 302 depicts the current (e.g., a first phase current) measured at first current sensor 108, second current profile 304 depicts the current (e.g., a second phase current) measured at second current sensor 110, and third current profile 306 depicts the current measured (e.g., a third phase current) at third current sensor 112. Combined current profile 308 depicts the sum of the three current profiles 302, 304, 306.

[0053] FIG. 5 shows the interaction among magnetic fields produced by three current sensors positioned adjacent to one another in a symmetrical arrangement. While depicted in a triangular arrangement, other arrangements are contemplated herein. Like current sensor system 100 shown in FIG. 3, the illustrated current sensor system 100 here includes a first busbar 402, a second busbar 404, and a third busbar 406. First current sensor 408 is attached to first busbar 402, which creates first magnetic field 414 when current is flown therethrough. Second current sensor 410 is attached to second busbar 404, which creates second magnetic field 416 when current is flown therethrough. Third current sensor 412 is attached to third busbar 406, which creates third magnetic field 418 when current is flown therethrough.

[0054] FIG. 6 is a graph showing the amount of current measured at each of the current sensors of FIG. 5 plotted against time. This graph can be similar to the graph shown in FIG. 4. For instance, first current profile 502 describes the current measured at first current sensor 408, second current profile 504 describes the current measured at second current sensor 410, and third current profile 506 describes the current measured at third current sensor 412. Combined current profile 508 describes the sum of the three current profiles 502, 504, 506. Notably, this combined current profile 508 is not equal to zero across the sample time plotted. This indicates that a coupling effect is present among the busbars 402, 404, 406.

[0055] FIG. 7 illustrates a shielded current sensor comprising a current sensor with shielding installed to prevent magnetic interference. Shielded current sensor 600 is attachable to a busbar (in a manner similar to system 100). The shielded current sensor 600 is attached to a circuit board 602 and includes a current sensor 604 in communication with the circuit board 602 (in a manner similar to system 100). A first shield 606 and a second shield 608 are also attached to busbar 602 on both sides of current sensor 604. Providing shields, such as first shield 606 andsecond shield 608, helps to shield current sensor 604 from interference created by any adjacent busbars. However, this can be an expensive solution because each of these shields could cost more than the current sensor itself, causing the total cost of a current sensor system to more than triple. Such expenses can be justifiable depending on the desired application. As such, in addition or in alternative, there can be provided together with the decoupling one or more physical shields between current sensors. As noted above, the decoupling algorithm disclosed herein can calculate a corrected current measurement. Corrected readings are calculated by subtracting the coupling effects from adjacent current sensors as discussed elsewhere herein.

[0056] FIG. 8 is a graph showing corrected amounts of current measured at each of three current sensors, such as the current sensors of FIGS. 1-7, plotted against time. First current profile 702 describes the current measured at a first current sensor, second current profile 704 describes the current measured at a second current sensor, and third current profile 706 describes the current measured at a third current sensor. Combined current profile 708 describes the sum of the three current profiles. Current profile 708 equals zero across time showing that the coupling effects from adjacent current loan has been successfully subtracted.

[0057] FIGS. 9 and 10 are flow diagrams showing a method for determining a current in one or more busbars of current sensor systems, such as the current sensor system 100, according to the present disclosure. For each sensing element, a magnetic coupling is characterized between the sensing element and each of the plurality of busbars. The magnetic coupling from each sensing element to the busbars can be determined and used to compensate for unwanted coupling. The controller generates coupling factors for each of the sensing elements. To determine the magnetic coupling between a sensing element of a current sensor and each of the busbars, a reference current is provided to each of the busbars.

[0058] As the reference current is provided to each of the busbars, the busbars generate a magnetic field that is sensed by sensing elements of each of the current sensors. The sensing elements can generate a magnetic field signal corresponding to the sensed field. Current sensors 108, 110, 112 may include additional circuitry to receive the magnetic field signal and generate an output signal, such as an output voltage, corresponding to the sensed magnetic field.

[0059] The reference current may be provided at a predetermined level that is a sufficiently high current to allow a resulting magnetic field to be detected by each of the current sensors in the system. Thus, the level of the reference current may be based at least in part on the types,dimensions, and properties of the busbars and / or the current sensors as well as on the configuration of the current sensors within the current sensor system.

[0060] The coupling factor of a given sensing element is be determined by various means. For instance, coupling factors can be measured, derived from models, and / or analytically calculated. With regards to measuring coupling factors, this process can be performed in a lab. As an example procedure for this measurement, begin by running current in phase A only and measure the current in other phases (B, C, D, etc.). Calculate the coupling factors as follow: Kab = Ib / Ia, Kac= Ic / Ia etc. Next, run the current in second phase B only and measure the signals in other phases. Calculate the coupling factors as follow: Kba= Ia / Ib, Kbc= L / Ib, etc. And continue in this manner for all other phases. In this regard, the coupling factors can be a ratio of currents (e.g., of the current measured divided by the current run) and / or can be a ratio of induced currents (e.g., experienced by the other phases from running the current in phase A only) to the applied current. Optionally, the coupling factors can be derived from finite element electromagnetic simulations. Optionally, analytical calculations can be used though they may be the least preferred option due to large errors. In general, these derivations of coupling factors are repeated for each of the current sensor in the system and may be performed by a controller coupled to each of the current sensors. The coupling factors are then used to determine the current in one or more of the plurality of busbars.

[0061] In practice, the decoupling algorithm described above can include two procedures: a calibration process and an implementation process. FIG. 9 describes calibration process 800 where coupling factors are calculated for later use in the implementation process. The process 800 begins at block 802 where a test current is passed through a first current sensor while no current is passed through the other current sensors in the plurality of current sensors. At block 804, the amount of test current transferred from the first current sensor to the other current sensors is measured by collecting the readings from the other current sensors through which no test current has been passed.

[0062] At block 806, a test current is passed through a second current sensor while no current is passed through the other current sensors in the plurality of current sensors, including the first current sensor. At block 808, the amount of test current transferred from the first current sensor to the other current sensors is measured by collecting the readings from the other current sensors through which no test current has been passed, including the first current sensor.

[0063] At block 810, the algorithm determines whether any other current sensors are present in the current sensor system. If a subsequent current sensor is found, the algorithm repeats block 806, and a test current is passed through the subsequent current sensor. However, if at block 810 no other current sensors are found, the algorithm proceeds to block 812 where the measurements collected at each current sensor through which current is not being passed is used to calculate coupling factors. Based on the configuration of the current sensor system, a coupling factor is determined for each of the current sensors. This calculation of coupling factors can be carried out using any of the derivations discussed elsewhere herein, including via lab measurements, electromagnetic simulations, and analytical calculations.

[0064] Once the coupling factors are calculated, the calibrated algorithm can now be used to determine corrected readings from the current sensors. As shown in FIG. 10, the implementation process 900 (or post-deployment process) begins with block 902 where a current to be measured is simultaneously passed through all current sensors without restriction. At block 904, readings are collected from each of the current sensors. These readings represent the amount of current passed through each of the current sensors plus the amount of current transferred to each current sensor from the adjacent current sensors. At block 906, corrected current measurements are calculated by subtracting the amount of current transferred to each current sensor from the adjacent current sensors. Therefore, the results of this calculation represent the true amount of current passed through each of the current sensors without the additional amount of current transferred to each current sensor due to the coupling effect.

[0065] Discussion now turns to specific example implementation of principles of the present disclosure. These examples are some of many examples disclosed herein that one skilled in the art armed with this disclosure will discern.

[0066] In Example 1, a method of measuring current for a multiphase system comprising a plurality of current-carrying elements disposed adjacent to each other, the method comprising the steps of: receiving a first current through a first current-carrying element of the plurality of current-carrying elements; receiving a test signal from a second current carried by a second current-carrying element of the plurality of current-carrying elements, the test signal corresponding to an amount of coupling effects between the first and second current-carrying elements as a result of current being carried by the second current-carrying element, the second current-carrying element being adjacent to the first current currying element so as to be withinrange of coupling effects associated with the current being carried by the second current-carrying element; and generating a control logic for operating the multiphase system based on a current measurement of the first current-carrying element, the control logic including an algorithm to decouple the coupling effects of the second current-carrying element on the first current-carrying element so as to inhibit inaccuracies in the current measurement.

[0067] In Example 2, the method as Example 1 describes, wherein the test current is carried by the first current-carrying element while the current is being carried by the second currentcarrying element.

[0068] In Example 3, the method as either of Examples 1 or 2 describe, wherein the first and second currents are generated using a single current.

[0069] In Example 4, the method as any of Examples 1-3 describe, wherein the current measurement is a first current measurement, the method further comprising monitoring at least one of the first current measurement of the first current-carrying element and a second current measurement of the second current-carrying element.

[0070] In Example 5, the method as any of Examples 1-4 describe, wherein the method constitutes a pre-deployment calibration of the multiphase system, the method further comprising repeating the pre-deployment calibration for each of the current-carrying elements in the plurality of current-carrying elements.

[0071] In Example 6, the method as any of Examples 1-5 describe, wherein the algorithm is a zero-sum transform where an algebraic sum of corrected current measurements for each of the current-carrying elements in the plurality of current-carrying elements is zero, and wherein each of the corrected current measurements is equal to a respective current measurement minus a summation of each of the other current measurements multiplied by a respective coupling factor.

[0072] In Example 7, the method as any of Examples 1-6 describe, wherein the coupling factors are a constant value that corresponds to the amounts of test signal experienced by a respective current carrying element during the pre-deployment calibration.

[0073] In Example 8, the method as any of Examples 1-7 describe, wherein the coupling factors are calculated / obtained by applying a first current in the first current-carrying element and measuring a second current in the second current-carrying element and dividing the second current by the first current.

[0074] In Example 9, the method as any of Examples 1-8 describe, further comprising repeating the pre-deployment calibration for all phases in the multiphase system.

[0075] In Example 10, the method as any of Examples 1-9 describe, wherein repeating the pre-deployment calibration for all phases in the multiphase system is performed using the same sample and the same hold time.

[0076] In Example 11, the method as any of Examples 1-10 describe, further comprising running the algorithm after deployment of the multiphase system by: measuring the current to obtain a measured current carried by each of the current-carrying elements in the plurality of current-carrying elements; and obtaining a respective current measurement for each of the currentcarrying elements in the plurality of current-carrying elements where the respective current measurement is a corrected current measurement that is equal to the measured current for the respective current-carrying element minus an adjusted current for each of the other currentcarrying elements in the plurality of current carrying elements, wherein the adjusted current is equal to the measured current for a respective current-carrying element multiplied by a coupling factor for the respective current-carrying element.

[0077] In Example 12, the method as any of Examples 1-11 describe, further comprising: monitoring the first current for indicia of coupling effects on the current measurement; and adjusting the algorithm based on the current measurement.

[0078] In Example 13, a current sensor, comprising circuitry and a plurality of terminals in electrical communication with the circuitry, the plurality of terminals having first and second adjacent terminals, the first and second adjacent terminals having a nonphysical shield therebetween with which to decouple an effect of the first adjacent terminal on a current measurement accuracy of the second adjacent terminal.

[0079] In Example 14, the current sensor as Example 13 describes, wherein the nonphysical shield is generated by running an algorithm that is a zero-sum transform where an algebraic sum of corrected current measurements for each terminal in the plurality of terminals is zero, and wherein each of the corrected current measurements is equal to a respective current measurement of a terminal in the plurality of terminals minus a summation of each of the other current measurements multiplied by a respective coupling factor.

[0080] In Example 15, an energy storage system comprising: an energy storage device; and a controller configured to run the algorithm as either of Examples 13 or 14 describe.

[0081] In Example 16, a hybrid generator system comprising: a generator set configured to generate power to drive a load; and the energy storage system as any of Examples 13-15 describe.

[0082] In Example 17, a circuit board comprising the current sensor as any of Examples 13-16 describe.

[0083] In Example 18, a power electronics device comprising the circuit board as any of Examples 13-17 describe.

[0084] In Example 19, a controller for decoupling sensors, the controller comprising: at least one processor; and a memory including instructions, which when executed on the at least one processor, cause the at least one processor to: obtain current data that is indicative of current measurements in phases at a plurality of busbars, the current data having a current measurement accuracy; and execute an architecture that is configured to generate a nonphysical shield between the plurality of busbars so as to improve the current measurement by decoupling an effect of adjacent terminals among the plurality of busbars.

[0085] In Example 20, the controller as Example 19 describes, wherein the busbars are asymmetrically arranged within a current sensor.

[0086] It is well understood that methods that include one or more steps, the order listed is not a limitation of the claim unless there are explicit or implicit statements to the contrary in the specification or claim itself. It is also well settled that the illustrated methods are just some examples of many examples disclosed, and certain steps can be added or omitted without departing from the scope of this disclosure. Such steps can include incorporating devices, systems, or methods or components thereof as well as what is well understood, routine, and conventional in the art.

[0087] The connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and / or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections can be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that can cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements. The scope is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitlyso stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone can be present in an embodiment, B alone can be present in an embodiment, C alone can be present in an embodiment, or that any combination of the elements A, B or C can be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C.

[0088] In the detailed description herein, references to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment can not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art with the benefit of the present disclosure to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.

[0089] Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f), unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0090] While various embodiments of the disclosure have been shown and described, it is understood that these embodiments are not limited thereto. The embodiments may be changed, modified and further applied by those skilled in the art. Therefore, these embodiments are not limited to the detail shown and described previously, but also include all such changes and modifications.

Claims

WHAT IS CLAIMED IS:

1. A method of measuring current for a multiphase system comprising a plurality of currentcarrying elements disposed adjacent to each other, the method comprising the steps of: receiving a first current through a first current-carrying element of the plurality of currentcarrying elements; receiving a test signal from a second current carried by a second current-carrying element of the plurality of current-carrying elements, the test signal corresponding to an amount of coupling effects between the first and second current-carrying elements as a result of current being carried by the second current-carrying element, the second current-carrying element being adjacent to the first current currying element so as to be within range of coupling effects associated with the current being carried by the second current-carrying element; and generating a control logic for operating the multiphase system based on a current measurement of the first current-carrying element, the control logic including an algorithm to decouple the coupling effects of the second current-carrying element on the first current-carrying element so as to inhibit inaccuracies in the current measurement.

2. The method of claim 1, wherein the second current is carried by the first current-carrying element while the current is being carried by the second current-carrying element.

3. The method of any preceding claim, wherein the first and second currents are generated using a single current.

4. The method of any preceding claim, wherein the algorithm is a zero-sum transform where an algebraic sum of corrected current measurements for each of the current-carrying elements in the plurality of current-carrying elements is zero, and wherein each of the corrected current measurements is equal to a respective current measurement minus a summation of each of the other current measurements multiplied by a respective coupling factor.

5. The method of any preceding claim, wherein the current measurement is a first current measurement, the method further comprising monitoring at least one of the first currentmeasurement of the first current-carrying element and a second current measurement of the second current-carrying element.

6. The method of claim 5, wherein the method constitutes a pre-deployment calibration of the multiphase system, the method further comprising repeating the pre-deployment calibration for each of the current-carrying elements in the plurality of current-carrying elements.

7. The method of claim 6, wherein the algorithm includes coupling factors that are a constant value corresponding to amounts of test signal experienced by a respective current carrying element during the pre-deployment calibration.

8. The method of claim 6, wherein the algorithm includes coupling factors that are obtained by applying a first current in the first current-carrying element and measuring a second current in the second current-carrying element and dividing the second current by the first current.

9. The method as in any one of claims 6 to 8, further comprising repeating the predeployment calibration for all phases in the multiphase system.

10. The method of claim 9, wherein repeating the pre-deployment calibration for all phases in the multiphase system is performed using the same sample and the same hold time.

11. The method as in any one of claims 6 to 10, further comprising running the algorithm after deployment of the multiphase system by: measuring the current to obtain a measured current carried by each of the currentcarrying elements in the plurality of current-carrying elements; and obtaining a respective current measurement for each of the current-carrying elements in the plurality of current-carrying elements where the respective current measurement is a corrected current measurement that is equal to the measured current for the respective current-carrying element minus an adjusted current for each of the other current-carrying elements in the plurality of current carrying elements, wherein the adjusted current is equal to the measured current for arespective current-carrying element multiplied by a coupling factor for the respective current-carrying element.

12. The method of any preceding claim, further comprising: monitoring the first current for indicia of coupling effects on the current measurement; and adjusting the algorithm based on the current measurement.

13. A current sensor for integration in a system having a plurality of adjacent terminals with first and second adjacent terminals, the current sensor comprising circuitry and a first terminal of the plurality of adjacent terminals, the first terminal in electrical communication with the circuitry, the first adjacent terminal being shielded from the second adjacent terminal by a nonphysical shield therebetween, the nonphysical shield decoupling an effect of the first adjacent terminal on a current measurement accuracy of the second adjacent terminal.

14. The current sensor of claim 13, wherein the nonphysical shield is generated by running an algorithm that is a zero-sum transform where an algebraic sum of corrected current measurements for each terminal in the plurality of adjacent terminals is zero, and wherein each of the corrected current measurements is equal to a respective current measurement of a terminal in the plurality of adjacent terminals minus a summation of each of the other current measurements multiplied by a respective coupling factor.

15. A controller for decoupling sensors, the controller comprising: at least one processor; and a memory including instructions, which when executed on the at least one processor, cause the at least one processor to: obtain current data that is indicative of current measurements in phases at a plurality of busbars, the current data having a current measurement accuracy; and execute an architecture that is configured to generate a nonphysical shield between the plurality of busbars so as to improve a current measurement by decouplingan effect of adjacent terminals among the plurality of busbars, and optionally, wherein the busbars are asymmetrically arranged within a current sensor.

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