ASSESSMENT AND CORRECTION OF CURRENT SENSING DEVICES

Abstract

A system for evaluating current sensor measurements includes a current sensor configured to measure three-phase alternating current (AC) signals applied to a three-phase electrical device, the measured AC signals including a first measurement of a first phase current, a second measurement of a second phase current, and a third measurement of a third phase current, and a fault detection module configured to receive the measured AC signals.The error detection module is configured to apply a transformation to the measured AC signals to generate a plurality of reference currents, each reference current of the plurality of reference currents being represented as a current vector rotating in a two-dimensional reference frame, calculate a current angle between the plurality of reference currents, relate the current angle to a second-order harmonic function, and determine a gain error associated with the measured AC signals based on the relating.

Description

INTRODUCTION

[0001] The present invention relates to current sensing and, more particularly, to detection and correction of errors in three-phase current sensors.

[0002] For background information, reference is made at this point to the documents DE 11 2017 003 787 T5 and EP 0 119 583 B1, which disclose systems for evaluating current measurements, wherein a current sensor is designed to measure the respective currents of a three-phase system, and wherein these currents are transformed into vectors.

[0003] Vehicles, including gasoline and diesel-powered vehicles, as well as electric and hybrid electric vehicles, incorporate battery storage for purposes such as supplying power to electric motors, electronics, and other vehicle subsystems. Power electronics (e.g., inverters and direct current (DC) converters) in a vehicle are responsible for functions such as controlling the power and electrical energy to components such as electric motors and other electrical components. Various sensors, including current sensors, are important for ensuring proper motor control and the proper functioning of power electronic devices. For example, current sensors are important for effectively controlling phase currents when driving electric motors. SUMMARY

[0004] According to the invention, a system for evaluating current sensor measurements is presented, which is characterized by the features of claim 1. Furthermore, according to the invention, a method for evaluating current sensor measurements is presented, which is characterized by the features of claim 9.

[0005] The system includes a current sensor configured to measure three-phase alternating current (AC) signals applied to a three-phase electrical device, the measured AC signals including a first measurement of a first phase current, a second measurement of a second phase current, and a third measurement of a third phase current, and a fault detection module configured to receive the measured AC signals.The error detection module is configured to apply a transformation to the measured AC signals to generate a plurality of reference currents, each reference current of the plurality of reference currents being represented as a current vector rotating in a two-dimensional reference frame, calculate a current angle between the plurality of reference currents, relate the current angle to a second-order harmonic function, and determine a gain error associated with the measured AC signals based on the relating.

[0006] In addition to one or more of the features described herein, the three-phase electrical device includes an electric motor configured to propel a vehicle.

[0007] In addition to one or more of the features described here, the second-order harmonic function is a rotating second-order complex vector having a real part and an imaginary part.

[0008] In addition to one or more of the features described herein, determining the gain error includes estimating a first gain error associated with the first measurement based on the real part and determining a combined gain error associated with the second measurement and the third measurement based on the imaginary part.

[0009] In addition to one or more of the features described herein, the error detection module is configured to apply a gain correction to each of the first measurement, the second measurement, and the third measurement.

[0010] In addition to one or more of the features described herein, applying the gain correction includes distributing the combined gain error, correcting the second measurement based on a first portion of the combined gain error, and correcting the third measurement based on a second portion of the combined gain error.

[0011] In addition to one or more of the features described herein, the first section and the second section are selected to reduce or minimize current ripple and torque errors.

[0012] In addition to one or more of the features described herein, the error detection module is configured to correct an offset error of the plurality of reference streams based on applying a low-pass filter to the plurality of reference streams.

[0013] The method for evaluating current sensor measurements includes measuring, by a current sensor, three-phase alternating current (AC) signals applied to a three-phase electrical device, the measured AC signals including a first measurement of a first phase current, a second measurement of a second phase current, and a third measurement of a third phase current, and applying a transformation to the measured AC signals to generate a plurality of reference currents, each reference current of the plurality of reference currents being represented as a current vector rotating in a two-dimensional frame of reference.The method further includes calculating a current angle between the plurality of reference currents, relating the current angle to a second order harmonic function, and determining a gain error associated with the measured AC signals based on the relating.

[0014] In addition to one or more of the features described here, the second-order harmonic function is a rotating second-order complex vector having a real part and an imaginary part.

[0015] In addition to one or more of the features described herein, determining the gain error includes estimating a first gain error associated with the first measurement based on the real part and determining a combined gain error associated with the second measurement and the third measurement based on the imaginary part.

[0016] In addition to one or more of the features described herein, the method includes applying a gain correction to each of the first measurement, the second measurement, and the third measurement.

[0017] In addition to one or more of the features described herein, applying the gain correction includes distributing the combined gain error, correcting the second measurement based on a first portion of the combined gain error, and correcting the third measurement based on a second portion of the combined gain error.

[0018] In addition to one or more of the features described herein, the first section and the second section are selected to reduce or minimize current ripple and torque errors.

[0019] In addition to one or more of the features described herein, the method includes correcting an offset error of the reference currents based on applying a low-pass filter to the reference currents.

[0020] In yet another exemplary embodiment, a vehicle system includes a memory having computer-readable instructions and a processing device for executing the computer-readable instructions, the computer-readable instructions controlling the processing device to perform a method. The method includes receiving, from a current sensor, measurements of three-phase alternating current (AC) signals applied to a three-phase electrical device, the measurements including a first measurement of a first phase current, a second measurement of a second phase current, and a third measurement of a third phase current.The method further includes applying a transformation to the measurements to generate a plurality of reference currents, each reference current in the plurality of reference currents being represented as a current vector rotating in a two-dimensional reference frame, calculating a current angle between the plurality of reference currents, relating the current angle to a second order harmonic function, and determining a gain error associated with the measurements based on the relating.

[0021] In addition to one or more of the features described here, the second-order harmonic function is a rotating second-order complex vector having a real part and an imaginary part.

[0022] In addition to one or more of the features described herein, determining the gain error includes estimating a first gain error associated with the first measurement based on the real part and determining a combined gain error associated with the second measurement and the third measurement based on the imaginary part.

[0023] In addition to one or more of the features described herein, the method includes applying a gain correction to each of the first measurement, the second measurement, and the third measurement, wherein applying the gain correction includes distributing the combined gain error, correcting the second measurement based on a first portion of the combined gain error, and correcting the third measurement based on a second portion of the combined gain error.

[0024] In addition to one or more of the features described herein, the method includes correcting an offset error of the plurality of reference streams based on applying a low-pass filter to the plurality of reference streams.

[0025] The above-described features and advantages and other features and advantages of the invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Further features, advantages and details appear only as examples in the following detailed description, which refers to the drawings; they show: Fig. 1 is a schematic plan view of a motor vehicle according to an exemplary embodiment; Fig. 2 schematically illustrates components of an inverter module including a current measurement and / or control system according to an exemplary embodiment; Fig. 3 illustrates a control system for controlling a three-phase current introduced into an electrical device or electronic system including fault detection and / or fault compensation components, according to an exemplary embodiment; Fig. 4 Aspects of sensor error detection and compensation according to an exemplary embodiment; Fig. 5 is a flowchart illustrating a method for detecting and learning current sensor errors and / or correcting current sensor measurements according to an exemplary embodiment; Fig. 6 a normalized graphic vector representation of three-phase currents represented in an αβ reference frame; Fig. 7 a graph illustrating sensor angles and showing effects of sensor errors; and Fig. 8 a computer system according to an exemplary embodiment. DETAILED DESCRIPTION

[0027] The following description is merely exemplary in nature. It should be understood that throughout the drawings, corresponding reference numerals designate similar or corresponding portions and features.

[0028] According to an exemplary embodiment, methods, apparatus, and systems for current sensing, fault detection, and / or current sensor measurement correction are provided. One embodiment of a current sensing system includes one or more current sensors configured to detect current supplied to a vehicle motor or other three-phase electrical system, and a processing device configured to detect and learn sensor faults. The current sensing system may be included as part of a control system (e.g., a motor controller) for controlling a power conversion device, such as a vehicle inverter, connected to an electric motor.

[0029] One embodiment of a method includes acquiring three-phase current measurements (also referred to as "measured currents" or "current measurements") and applying a transformation to generate reference currents. In one embodiment, the reference currents are transformed to rotational phase vectors in a two-dimensional reference frame (e.g., an αβγ transformation). Offset errors may be corrected using a low-pass filter.

[0030] Gain errors associated with each measured phase current are learned by relating a current angle (an angle between the reference currents, such as α and β currents) to a second-order harmonic function. For example, the reference currents are related to a second-order complex vector, and real and imaginary components are separately integrated to zero to derive the gain errors.

[0031] Embodiments described herein present numerous advantages and technical effects. The embodiments provide effective correction of current sensor errors that can occur due to various conditions. For example, automotive current sensors experience offset and gain errors due to temperature variation and aging, leading to torque ripple and torque offset problems. The embodiments provide effective and efficient error correction because the methods can be performed using existing components and require only current measurements and signal processing. Additionally, error learning can be adapted to a variety of operating conditions (e.g., different vehicle speeds and torque conditions). Furthermore, errors can be learned and compensated in real time and used in highly dynamic environments such as traction motors.

[0032] The embodiments may be applicable to various contexts. For example, embodiments may be used with automobiles, trucks, aircraft, construction equipment, agricultural equipment, automated factory equipment, and / or any other device or system for which additional thermal control may be desired to facilitate the existing thermal control capabilities or features of a device or system.

[0033] Fig. 1 shows an embodiment of a motor vehicle 10 including a vehicle body 12 that at least partially defines a passenger compartment 14. The vehicle body 12 also supports various vehicle subsystems, including a propulsion system 16 and other subsystems to support functions of the propulsion system 16, and other vehicle components such as a braking subsystem, a suspension system, a steering subsystem, a fuel injection subsystem, an exhaust subsystem, and others.

[0034] The vehicle 10 may be an internal combustion engine vehicle, an electric vehicle (EV), or a hybrid vehicle. In one embodiment, the vehicle 10 is a hybrid vehicle that includes an internal combustion engine assembly 18 and at least one electric motor assembly. In this embodiment, the propulsion system 16 includes an electric motor 20 and may include one or more additional motors positioned at various locations.

[0035] The vehicle 10 includes a battery system 22 that may be electrically connected to the engine 20 and / or other components, such as the vehicle's electronics. The battery system 22 may be configured as a rechargeable energy storage system (RESS).

[0036] In one embodiment, the battery system 22 includes a battery assembly, such as a high-voltage battery pack 24, having a plurality of battery modules 26. Each of the battery modules 26 includes a plurality of individual cells (not shown). The battery system 22 may also include a monitoring unit 28 configured to receive measurements from sensors 30.

[0037] The battery system 22 is electrically connected to a direct current (DC) converter module 32 and an inverter module 34. The inverter module 34 (e.g., a traction power inverter unit or TPIM) converts DC power from the battery system 22 to three-phase alternating current (AC) power to drive the motor 20. In one embodiment, the inverter module 34 includes an inverter 36 connected to the DC-DC converter module 34 for receiving DC power and connected to the motor 20 for supplying three-phase AC power.

[0038] One or more processing devices are included to control the operation of the propulsion system. In one embodiment, the vehicle 10 includes a motor control unit (MCU) 38 configured to control the operation of the motor 20 by controlling a three-phase current output from the inverter 36. Other control units, such as an engine controller (not shown), may be included.

[0039] The vehicle 10 also includes a computer system 40 that includes one or more processing devices 42 and a user interface 43. The various processing devices and processing units may communicate with each other via a communication device or system, such as a controller area network (CAN) or a transmission control protocol (TCP) bus.

[0040] Fig. Figure 2 schematically illustrates components of one embodiment of the propulsion system 16, including the inverter module 34, the motor 20, and the MCU 38. The inverter module 34 includes a three-phase inverter circuit (an inverter 36). The inverter module 34 may be incorporated into the vehicle 10, another vehicle, or another system.

[0041] The MCU 38 is configured to perform functions including sensor correction described herein. The MCU 38 may also control functions of the inverter 36 and / or the motor 20. The MCU 38 may be part of an electronic control unit (ECU), a motor controller, a TPIM controller, or may be a separate, dedicated controller.

[0042] The inverter 36 includes three sets of switches connected in parallel to a positive DC bus 50 and a negative DC bus 52. Each set of switches is in a half-bridge configuration. A first set of switches 54 and 56 is connected to a first motor phase (Phase A), a second set of switches 58 and 60 is connected to a second motor phase (Phase B), and a third set of switches 62 and 64 is connected to a third motor phase (Phase C). In one embodiment, the sets of switches are incorporated into one or more switching modules. The inverter module 34 also includes various capacitors for stabilizing operation, such as a bulk DC capacitor 66 and bypass capacitors 68 and 70.

[0043] Each set of switches is connected by a conductor to a phase of motor 20. For example, the first set of switches 54 and 56 is connected by a conductor 80 to a first phase (phase A) of motor 20. The second set of switches 58 and 60 is connected by a conductor 82 to a second phase (phase B). The third set of switches 62 and 64 is connected by a conductor 84 to a third phase (phase C).

[0044] Various sensors (e.g., voltmeters, current sensors, etc.) are arranged relative to components of the inverter module 34. For example, a first current sensor 90 is configured to measure the phase A current, a second current sensor 92 is configured to measure the phase B current, and a third current sensor 94 is configured to measure the phase C current.

[0045] Fig. 3 illustrates one embodiment of a control system 100, which may be embodied as the MCU 38 or other suitable processing device or controller. The control system 100 receives a torque command to apply an amount of torque T e and also receives a DC voltage V dc a power supply (e.g. a vehicle battery system) and an engine speed ω e . A torque-to-current conversion module 102 converts the inputs to current command signals I dq for inphase and quadrature (dq). The current command signals I dq are supplied to a current regulator 104, which supplies dq voltage instructions V dq calculated.

[0046] The dq voltage instructions and motor position θ e , (e.g. from a position sensor 105) are input to a converter 106 and the dq voltage commands are converted into a three-phase voltage V abcimplemented. The voltage V abc is modulated by a modulator 108 to generate modulated voltage pulses that are applied to the inverter 36. In one embodiment, the voltage V abc modulated using pulse width modulation (PWM).

[0047] Current measurement is critical for accurate torque control in the vehicle system. Any current measurement errors (e.g., due to sensor faults and / or analog-to-digital conversion errors) can result in undesirable torque ripple, causing noise, vibration, and harshness, and DC torque errors.

[0048] To determine current sensor errors and compensate for such errors, the control system includes a sensor error compensation module 110 configured to calculate measured currents of phases A, B, and C (I abc,measured) and motor position, learn sensor errors, and correct current measurements before delivering such measurements to the control system. For example, as in Fig. 3, the sensor error compensation module 110 converts the measured phase currents to dq currents while correcting sensor errors (e.g., gain and offset errors). The result is corrected dq currents (I dq,correc-ted ), which are fed into the current regulator 104 together with dynamic engine position and / or engine speed information (represented by block 109).

[0049] In one embodiment, the compensation module (or further processing device) is configured to learn and diagnose sensor errors in real time (e.g., during vehicle operation).

[0050] Fig. Figure 4 is a block diagram illustrating aspects of current sensor fault detection and compensation performed by the sensor fault compensation module 110. Although aspects of fault detection and compensation methods are described in connection with the module 110, embodiments are not so limited, as the methods may be performed by any suitable controller, module, processing device, or processing system.

[0051] In a typical three-phase system, measured currents can be modeled as sinusoidal components spatially separated by 120 degrees. The errors from the current sensor can be modeled as: Ia,measured=Ka*I*sin θ+Ao; Ib,measured=Kb*I*sin θ−2π / 3+Bo; Ic,measured=Kc*I*sin θ+2π / 3+Co where K a , K b and Kc amplification errors are. A o , B o and C o are three-phase offset errors. Gain and offset errors are typically caused by temperature variation, aging of sensors, and ADCs. Errors can also be inherent properties of the sensing technologies. The methods described here can be used to determine the gain errors and can also be used to determine the offset errors.

[0052] Fig. Figure 5 illustrates embodiments of a method 160 for measuring current, detecting current sensor errors, and correcting or compensating for such errors. The method 160 may be performed in conjunction with a vehicle conversion device, such as the inverter module 34. However, the method 160 is not so limited and may be used with any suitable electrical device or system.

[0053] Aspects of the method 160 may be performed by a suitable processing device. For example, the method 160 is performed in conjunction with the error compensation module of Fig. 4 discussed.

[0054] The method 160 includes a plurality of steps or stages represented by blocks 161-170. The method 160 is not limited to the number or order of steps therein, as some steps represented by blocks 161-170 may be performed in an order different from that described below, or fewer than all of the steps may be performed.

[0055] In block 161, the inverter module 34 is operated and a three-phase current is supplied to the motor 20. Current (AC signals) through each of the conductors 80, 82, and 84 (referred to as "phase currents") is measured, resulting in current measurements for each phase. The current measurements may also be referred to as measured phase currents I abc,measured (e.g. measured current of phase A, measured current of phase B and measured current of phase C).

[0056] In block 162, a transformation is applied to the measured phase currents to generate reference currents ( Fig. 4, block 180). The reference currents are represented as a current vector rotating in a two-dimensional reference frame.

[0057] For example, the measured phase currents are processed using an αβγ transformation. The gamma term is set to zero, so that the transformation is scale-invariant.

[0058] The αβγ transformation is applied to equations (1), which gives the following measured α-current (I α,measured ) and measured β-current (I β,measured ), which are collectively known as I αβ,measured results in: [Iα,measuredIβ,measured]=13[2−1−103−3][Ia,measuredIb,measuredIc,measured]; Iα,measured=13(2Ka+Kb2+Kc2)∗I∗sin θ+123(Kb−Kc)∗cos θ+Iα,offset; Iβ,measured=(Kb2+Kc2)∗I∗cos θ+123(Kb−Kc)∗sin θ+Iβ,offset

[0059] Iα,Offset and I β, Offset are offsets that are a function of the offset errors, where Iα,Offset=2Ao−Bo−Co and Iβ,Offset=Bo−Co.

[0060] In block 163 the measured αβ currents I α,measured and I β,measured using a low-pass filter 182 ( Fig. 4) filtered to remove offset errors. The low-pass filter parameters (e.g., the cutoff frequency) are chosen to isolate the offset errors. Filtering also allows the system to learn the offset errors.

[0061] In one embodiment, offset error learning is triggered based on thresholds related to motor speed, cycles, and / or current magnitude. For example, a minimum motor speed and current magnitude are selected, and offset error learning is performed if the motor speed, voltage, and current magnitude are at or above the minimum values. A low-pass filter may be used that includes a z-transform function (K o T s / (1 - z (-1) ) which has a pulse width parameter T s and a filter parameter K o , which is chosen to set the filter cutoff frequency. For example, the filter frequency can be set low (e.g., in the range of 0.1 to 1 Hz) to provide relatively slow learning.

[0062] The learned offset errors may be diagnosed by comparing the offset errors to one or more thresholds associated with different error conditions (block 169) and / or stored for later analysis and / or used in subsequent error detection and compensation procedures.

[0063] In block 164, gain errors are compensated by relating an error signature to a second-order harmonic function. For example, errors are related to a complex current angle vector to learn the gain errors. Gain error determination can be triggered by a sufficiently high voltage and motor speed.

[0064] Gain errors due to measuring a phase A current are called K a Gain errors due to measuring a phase B current are called K band measuring a current of phase C are called K c The gain errors can be represented in the following equations: Iα,measured=13(2Ka+Kb2+Kc2)∗I∗sin θ+123(Kb−Kc)∗cos θ; Iβ,measured=(Kb2+Kc2)∗I∗cos θ+123(Kb−Kc)∗sin θ

[0065] As further discussed here (see discussion with reference to Fig. 6 and Fig. 7), gain errors can result in second-order harmonics. As a result, it can be assumed that the current angle (the angle between α and β currents) would exhibit second-order harmonics. The current angle Φ can be defined as: ϕ=atan2(Iβ,measured,Iα,measured)

[0066] In one embodiment, the error present in the current angle is related to a second-order rotating complex vector defined as: ej∗2∗Φ=cos(2∗Φ)+sin(2∗Φ), where the cosine term is the real part and is associated with gain errors of phase A. The sine term is the imaginary part and is associated with a combination of a phase B and phase C error. The correlation is in Fig. 4 as determining a current angle in block 184 (atan2 function), performing a complex vector correlation in block 186 and integrating using an integrator 188.

[0067] In block 165, the phase A gain error is estimated by integrating the complex vector to drive the real part of the complex vector to zero.

[0068] In block 166, the complex vector is integrated to drive the imaginary part of the complex vector to zero to obtain a combined gain error of phase B and phase C. The learned values may be constrained as a function of an operating point based on torque, motor speed, Vdc (a DC bus voltage), and rationalized and diagnosed (block 169) and stored in memory (block 170).

[0069] In one embodiment, as in Fig. 4, the complex vector is integrated by an integrator 188 to drive the second-order content of the current angle to zero and separate the real part (phase A gain error, block 190) and the imaginary part (phase B and C gain errors, block 192). For example, the integration is performed by relating a current angle (from block 184) to a rotating second-order complex harmonic vector (block 186) and is integrated by the integrator 188. The real and imaginary parts are taken, and the gain errors are extracted.

[0070] In block 167, the gain errors are dynamically limited based on operating conditions. Dynamically limiting each phase gain error and distributing the errors among three phases ensures that the occurrence of torque ripple and DC torque error is reduced or eliminated. For example, the motor speed and voltage are determined, and a limit is applied to each gain error before correction.

[0071] An example of gain error limitation is shown in Fig. 4 as block 196a for a phase A gain error limit, as block 196b for a phase B gain error limit, and as block 196c for a phase C gain error limit. These limits are dynamic and can thus be changed as operating conditions change.

[0072] In block 168, the learned gain errors are used to correct the measured currents. The measured currents are controlled to adjust the current measurements such that the gain errors are minimized. For example, the real part is compared with an ideal case (K a = 1) and the difference is provided to correct the measured current of phase A (block 194a, Fig. 4), optionally with dynamic limitation.

[0073] The combined gain errors of phase B and phase C are distributed among the measured currents of phase B and phase C. The distribution is chosen to reduce or eliminate torque ripple and DC torque offsets and results in a first portion of the combined errors being applied to correct phase B current measurements (block 194b, Fig. 4), and a second portion of the combined errors is applied to correct phase C measurements (block 194c).

[0074] In one example, the gain error compensation technique is analogous to modeling a reference adaptive control (MRAC), forcing a plant or system to behave similarly to a reference model. Additionally, if a detected gain error is too high, a warning can be generated and / or a mitigating action (e.g., a shutdown or torque reduction) can be performed.

[0075] The extraction of gain errors and the correction of current measurements in one embodiment are performed iteratively in a closed-loop manner, and over time, the gain errors converge to real values. The integrator 188 can thus learn the gain error values in real time. The integrator 188 also ensures that any change within a certain bandwidth can be reliably learned. For example, the integrator uses a function (K g T s / (1 - z (-1) ), which has a K g parameter chosen to set the bandwidth. Kg can also be changed as a function of an operating point (e.g., torque / speed) at various adaptive learning rates.

[0076] Fig. Figure 6 illustrates an example of gain errors and illustrates the second-order harmonic content determined according to the methods described herein. In this example, the measured alpha and beta currents are normalized and plotted as a function of each other on a graph 200.

[0077] As can be seen, there is a deviation between a graphical representation of an ideal vector 202 and a graphical representation of a measured vector 204. This deviation, or "jitter," indicates the second-order harmonic content due to gain errors.

[0078] The second order harmonic content is also present in the current angle. Fig. Figure 7 shows a graph 210 of a current angle of an ideal current versus a current angle with gain errors corresponding to the second-order harmonic content. Curve 212 shows an ideal current angle curve, and curve 214 shows a current angle curve corresponding to a measured current angle with gain errors.

[0079] Fig. Figure 8 illustrates aspects of an embodiment of a computer system 240 that can perform various aspects of embodiments described herein. Computer system 240 includes at least one processing device 242, generally including one or more processors for performing aspects of image acquisition and analysis methods described herein.

[0080] Components of computer system 240 include processing device 242 (such as one or more processors or processing units), memory 244, and a bus 246 that couples various system components, including system memory 244, to processing device 242. System memory 244 may be a non-transitory computer-readable medium and may include a variety of computer-system-readable media. Such media may be any available media accessible by processing device 242 and include both volatile and non-volatile media, and removable and non-removable media.

[0081] For example, system memory 244 includes non-volatile memory 248, such as a hard disk, and may also include volatile memory 250, such as random access memory (RAM) and / or cache. Computer system 240 may further include other removable / non-removable volatile / non-volatile computer system storage media.

[0082] System memory 244 may include at least one program product having a set (e.g., at least one) of program modules configured to perform functions of the embodiments described herein. For example, system memory 244 stores various program modules that generally perform the functions and / or methodologies of embodiments described herein. A module 252 may be included to perform functions related to motor control and / or current regulation, and a module 254 may be included to perform functions related to error detection and correction of current measurements, as discussed herein. System 240 is not so limited, as other modules may be included.As used herein, the term "module" refers to processing circuitry that may include an application-specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) with memory executing one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality.

[0083] Processing device 242 may also communicate with one or more external devices 256, such as a keyboard, a pointing device, and / or any device (e.g., a network card, a modem, etc.) that enables processing device 242 to communicate with one or more other computing devices. Communication with various devices may occur via input / output (I / O) interfaces 264 and 265.

[0084] The processing device 242 may also communicate with one or more networks 266, such as a local area network (LAN), a general area network (WAN), a bus network, and / or a public network (e.g., the Internet) via a network adapter 268. It should be understood that other hardware and / or software components may be used in connection with the computer system 40, although not shown. Examples include, but are not limited to, microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, and data archival storage systems, etc.

Claims

[1] System for evaluating current sensor measurements, comprising: a current sensor configured to measure three-phase alternating current (AC) signals applied to a three-phase electrical device, the measured AC signals including a first measurement of a first phase current, a second measurement of a second phase current, and a third measurement of a third phase current; and a fault detection module configured to receive the measured AC signals and perform: Applying a transformation to the measured AC signals to generate a plurality of reference currents, each reference current of the plurality of reference currents being represented as a current vector rotating in a two-dimensional reference frame; Calculating a current angle between the plurality of reference currents; relating the current angle to a second-order harmonic function and Determining a gain error associated with the measured AC signals based on the correlation. [2] The system of claim 1, wherein the three-phase electrical device includes an electric motor configured to drive a vehicle. [3] The system of claim 1, wherein the second-order harmonic function is a second-order rotating complex vector having a real part and an imaginary part. [4] The system of claim 3, wherein determining the gain error comprises estimating a first gain error associated with the first measurement based on the real part and determining a combined gain error associated with the second measurement and the third measurement based on the imaginary part. [5] The system of claim 4, wherein the error detection module is configured to apply a gain correction to each of the first measurement, the second measurement, and the third measurement. [6] The system of claim 5, wherein applying the gain correction comprises distributing the combined gain error, correcting the second measurement based on a first portion of the combined gain error, and correcting the third measurement based on a second portion of the combined gain error. [7] The system of claim 6, wherein the first section and the second section are selected to reduce or minimize current ripple and torque errors. [8] The system of claim 1, wherein the error detection module is configured to correct an offset error of the plurality of reference streams based on applying a low-pass filter to the plurality of reference streams. [9] Method for evaluating current sensor measurements, comprising: Measuring, by a current sensor, three-phase alternating current (AC) signals applied to a three-phase electrical device, the measured AC signals including a first measurement of a first phase current, a second measurement of a second phase current, and a third measurement of a third phase current; Applying a transformation to the measured AC signals to generate a plurality of reference currents, each reference current of the plurality of reference currents being represented as a current vector rotating in a two-dimensional reference frame; Calculating a current angle between the plurality of reference currents; relating the current angle to a second-order harmonic function and Determining a gain error associated with the measured AC signals based on the correlation. [10] The method of claim 9, wherein the second order harmonic function is a rotating second order complex vector having a real part and an imaginary part, and determining the gain error comprises estimating a first gain error associated with the first measurement based on the real part and determining a combined gain error associated with the second measurement and the third measurement based on the imaginary part.

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