DESC:SYSTEM AND METHOD OF DETERMINING SHAFT TORQUE OF A MOTOR
CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims priority from Indian Provisional Patent Application No. 202421042510 filed on 31/05/2025, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
The present disclosure generally relates to a shaft torque of an electric motor. Particularly, the present disclosure relates to a system for determining shaft torque of an electric motor. Furthermore, the present disclosure relates to a method for determining shaft torque of an electric motor.
BACKGROUND
Recently, electric motors have seen rapid advancements in recent years due to their growing adoption across various industries. In the automotive sector, electric motors play a crucial role in propulsion systems. Primarily, the motors used for traction purposes to drive the vehicle. This has led to increased focus on improving motor efficiency and control.
Electric traction motors form the core of modern electric and hybrid vehicle propulsion systems, requiring precise and real-time control of operational parameters such as torque and speed to deliver efficient and responsive performance. Typically, traction motor control strategies are implemented through torque control or speed control mechanisms. In torque control strategy, the motor controller regulates the power output of the motor based on a calculated or estimated torque demand, offering fast, precise, and smooth response during vehicle operation. While such strategies provide effective control which relies heavily on the assumption that the torque generated by the motor is accurately translated to the output shaft. However, the actual shaft torque may differ from the commanded or estimated torque due to several physical factors. These include drivetrain losses, mechanical friction, torsional vibrations, elasticity in the shaft, load dynamics, and transient disturbances. As a result, the motor's actual contribution to vehicle propulsion may not accurately reflect the intended control input, leading to inefficiencies, suboptimal traction, and degraded control performance. To address this, direct measurement of the shaft torque using torque sensors has been proposed and implemented in certain applications. Torque sensors, such as strain gauge-based systems or magnetoelastic sensors which may provide the real-time shaft torque data. However, integrating such torque sensors into automotive drivetrains presents significant challenges. These sensors add mechanical and electrical complexity, increase system cost, and may compromise the robustness and durability of the vehicle, particularly in harsh operating conditions. Additionally, space constraints, long-term reliability, and calibration issues make these solutions impractical for mass-market automotive applications.
Therefore, there exists a need for improved technique to determine shaft torque that overcomes the one or more problems associated as set forth above.
SUMMARY
An object of the present disclosure is to provide a system for determining shaft torque of an electric motor.
Another object of the present disclosure is to provide a method for determining shaft torque of an electric motor.
In accordance with first aspect of the present disclosure, there is provided a system for determining shaft torque of an electric motor. The system comprises a sensor arrangement configured to sense real-time motor parameters including motor phase currents and DC link voltage, a memory module configured to store efficiency data of a powertrain and a processing unit communicably coupled to the sensor arrangement and the memory module. The processing unit is configured to convert the sensed motor phase currents into synchronously rotating reference frame currents comprising d-axis and q-axis currents, determine input shaft power based on the d-axis and q-axis currents and the DC link voltage, determine output power based on the input shaft power and the efficiency data of the powertrain and determine the shaft torque based on the output power and motor revolutions per minute (rpm).
The present disclosure provides system for determining shaft torque of an electric motor. The system as disclosed by present disclosure is advantageous over conventional torque sensing methods used in electric motor systems, particularly in traction applications. Beneficially, the system reduces mechanical complexity, cost, and potential reliability issues associated with sensor integration in automotive environments. Beneficially, the system leverages existing motor parameters such as phase currents and DC link voltage, along with stored powertrain efficiency data, to compute shaft torque accurately in real time. Furthermore, the system results in a more robust and compact solution that is easier to integrate into electric vehicle architectures. Additionally, the system enhances safety and control by enabling real-time comparison between the computed shaft torque and the driver’s torque demand, thereby allows for detection and mitigation of unintended acceleration or deceleration events. Beneficially, the system improves the vehicle responsiveness, drivability and also contributes to overall operational safety. Furthermore, the system ensures the high precision in electrical signal processing, ultimately leads to more accurate torque estimation.
In accordance with second aspect of the present disclosure, there is provided a method for determining shaft torque of an electric motor. The method comprises sensing real-time motor parameters including motor phase currents and DC link voltage using a sensor arrangement, retrieving efficiency data of a powertrain from a memory module, converting the sensed motor phase currents into synchronously rotating reference frame currents comprising d-axis and q-axis currents, determining, by a processing unit, input shaft power based on the d-axis and q-axis currents and the DC link voltage, determining, by the processing unit, output power based on the input shaft power and the efficiency data of the powertrain and determining, by the processing unit, the shaft torque based on the output power and motor revolutions per minute (rpm).
Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
FIG. 1 illustrates a block diagram of a system for determining shaft torque of an electric motor, in accordance with an aspect of the present disclosure.
FIG. 2 illustrates a flow chart of a method for determining shaft torque of an electric motor, in accordance with another aspect of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognise that other embodiments for carrying out or practising the present disclosure are also possible.
The description set forth below in connection with the appended drawings is intended as a description of certain embodiments of a system and a method for determining shaft torque of an electric motor and is not intended to represent the only forms that may be developed or utilised. The description sets forth the various structures and/or functions in connection with the illustrated embodiments; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimised to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.
The terms “comprise”, “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, system that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system. In other words, one or more elements in a system or apparatus preceded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings and which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
The present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.
As used herein, the terms “electric vehicle”, “EV”, and “EVs” are used interchangeably and refer to any vehicle having stored electrical energy, including the vehicle capable of being charged from an external electrical power source. This may include vehicles having batteries which are exclusively charged from an external power source, as well as hybrid-vehicles which may include batteries capable of being at least partially recharged via an external power source. Additionally, it is to be understood that the ‘electric vehicle’ as used herein includes electric two-wheeler, electric three-wheeler, electric four-wheeler, electric pickup trucks, electric trucks and so forth.
As used herein, the term “shaft torque” refers to a rotational force available or exerted at the output shaft of an electric motor. The shaft torque represents the mechanical torque transmitted by the motor to drive a connected load, such as a vehicle drivetrain in traction applications. The shaft torque is typically expressed in Newton-meters (Nm) and is a function of the output power of the motor and the rotational speed (revolutions per minute, RPM).
As used herein, the term “electric motor” and “motor” are used interchangeably and refer to an electromechanical device configured to convert electrical energy into mechanical energy, typically in the form of rotational motion. The electric motor includes, but is not limited to, components such as a stator, a rotor, windings, and a housing. The motor operates based on the interaction between magnetic fields generated by the stator and the rotor, and may be of various types including, but not limited to, induction motors, permanent magnet synchronous motors (PMSM), brushless DC (BLDC) motors, and switched reluctance motors (SRM).
As used herein, the term “sensor arrangement” refers to a combination of one or more sensing devices configured to monitor and acquire real-time electrical or physical parameters relevant to the operation of an electric motor system. The sensor arrangement may include, but is not limited to, current sensors for detecting motor phase currents, voltage sensors for measuring DC link voltage, and optionally other sensors such as temperature or position sensors, depending on the application.
As used herein, the term "real-time motor parameter” and “motor parameter” are used interchangeably and refer to any electrical or physical quantity associated with the operation of an electric motor that is measured, sensed, or computed continuously or at short, periodic intervals during motor operation to reflect the instantaneous or near-instantaneous state of the motor. Such parameters may include, but are not limited to, motor phase currents, voltages (such as DC link voltage), motor temperature, rotor position, motor speed (RPM), and magnetic flux components.
As used herein, the term “motor phase currents” and “phase currents” are used interchangeably and refer to the electrical currents flowing through the individual stator windings (phases) of a multi-phase electric motor, typically in a three-phase configuration. The motor phase currents are responsible for generating the rotating magnetic field within the motor that interacts with the rotor to produce torque.
As used herein, the term “DC link voltage” refers to the direct current (DC) voltage present across the DC bus or intermediate circuit that connects the output of a power conversion stage (such as a rectifier or a battery pack) to the input of an inverter. The DC link voltage serves as the primary power supply for the inverter, which then converts the DC link voltage into controlled alternating current (AC) voltages to drive the motor.
As used herein, the term “memory module” refers to any suitable non-transitory computer-readable storage medium capable of storing data and executable instructions. The memory module may include, but is not limited to, volatile memory such as Random Access Memory (RAM), and non-volatile memory such as Read-Only Memory (ROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), flash memory, hard drives, solid-state drives, or other forms of magnetic, optical, or semiconductor-based storage. The memory module may be configured to store operational parameters, lookup tables, software programs, algorithms, powertrain efficiency data, calibration data, and other information necessary for the operation of the system.
As used herein, the term “efficiency data” refers to pre-characterized information representing the energy conversion efficiency of the powertrain system of a vehicle, including but not limited to the electric motor, inverter, transmission, and associated drivetrain components. The efficiency data may be expressed as a function of one or more operating parameters such as input power, output power, motor speed (rpm), torque, temperature, or load conditions.
As used herein, the term “powertrain” refers to the collective system of components in a vehicle that are responsible for generating and delivering mechanical power to propel the vehicle. In the case of electric vehicles, the powertrain typically includes the electric motor, motor controller or inverter, transmission (if present), drive shafts, differential, and the associated electronic control units. The powertrain facilitates the conversion of electrical energy into mechanical energy and its transmission to the wheels for vehicle movement.
As used herein, the term "processing unit” refers to any suitable computing device, microcontroller, microprocessor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or a combination thereof, configured to execute instructions or algorithms for performing one or more functions as described herein. The processing unit may include memory or may be operatively coupled to memory for storing instructions, data, lookup tables, or other relevant information required for operation. The processing unit may operate based on software, firmware, hardware logic, or a combination thereof to process input signals, perform calculations, control system behavior, and generate output signals.
As used herein, the term “communicably coupled” refers to a bi-directional connection between the various components of the system. The bi-directional connection between the various components of the system enables exchange of data between two or more components of the system. Similarly, bi-directional connection between the system and other elements/modules enables exchange of data between system and the other elements/modules.
As used herein, the term “synchronously rotating reference frame currents” and “reference frame currents” are used interchangeably and refers to the representation of three-phase motor currents transformed from the stationary reference frame (three phase currents) into a two-axis coordinate system (d-axis and q-axis) that rotates synchronously with the rotor magnetic field. This transformation, commonly known as the park or dq0 transformation, converts the time-varying sinusoidal phase currents into steady or slowly varying direct (d-axis) and quadrature (q-axis) components. The d-axis current typically represents the magnetizing component, while the q-axis current corresponds to the torque-producing component of the motor current.
As used herein, the term “input power shaft” refers to the rotating shaft of an electric motor or powertrain component through which mechanical power is transmitted into the system. The input power shaft is the shaft at which the motor delivers torque and rotational speed before any power transmission losses occur due to drivetrain components or mechanical inefficiencies. The input power shaft serves as the interface between the motor’s electrical energy conversion and the mechanical output that drives the load or downstream components.
As used herein, the term “output power” refers to the mechanical power delivered by the electric motor’s output shaft to the load or drivetrain. The output power represents the effective power available for performing useful work after accounting for losses within the motor and the connected powertrain components. The output power is typically expressed in watts (W) or kilowatts (kW) and is calculated based on the input electrical power adjusted by the efficiency of the motor and powertrain system.
As used herein, the term “proportional-integral controller” and “PI controller” are used interchangeably and refer to a feedback control mechanism widely used in control systems to regulate process variables by minimizing the error between a desired setpoint and the measured process value. The PI controller combines two control actions: the proportional action, which produces an output proportional to the current error, and the integral action, which accounts for the accumulation of past errors over time. The proportional term provides an immediate corrective response to reduce the error, while the integral term eliminates steady-state error by adjusting the output based on the integral of the error signal. Together, these actions enable the PI controller to provide stable and accurate control with reduced steady-state error and improved system responsiveness.
As used herein, the term “at least one current sensor” and “current sensor” are used interchangeably and refer to one or more devices configured to measure the electrical current flowing through one or more phases of the electric motor. The current sensor may include, but is not limited to, Hall-effect sensors, shunt resistors, current transformers, or any other suitable sensing element capable of providing real-time current measurements.
As used herein, the term “at least one voltage sensor” and “voltage sensor” are used interchangeably and refer to one or more devices configured to measure or detect the electrical voltage within the system, specifically the DC link voltage in the electric motor. The voltage sensor may be any suitable type of sensor, such as a voltage divider circuit, Hall-effect voltage sensor, or isolated voltage transducer, capable of providing real-time voltage measurements to the processing unit for control and monitoring purposes.
As used herein, the term “unintended acceleration” and “acceleration” are used interchangeably and refer to a condition in a vehicle where the actual acceleration or increase in speed occurs without a corresponding or intentional input from the driver. The unintended acceleration is a situation where the vehicle’s propulsion system generates torque or power that causes the vehicle to accelerate unexpectedly, beyond or contrary to the driver’s commanded torque or speed demand.
As used herein, the term “unintended deceleration” and “deceleration” are used interchangeably and refer to a decrease in the rotational speed or torque output of the electric motor’s shaft that occurs unexpectedly or without a corresponding command or input from the vehicle operator. The unintended deceleration phenomenon arises when the actual shaft torque or vehicle speed falls below the user-defined or desired torque demand, resulting in a reduction of vehicle acceleration or speed that is not intentionally initiated by the driver.
As used herein, the term “alert signal” refers to a notification output generated by the system to indicate the occurrence of a specific event or condition that requires attention. The alert signal may be in various forms, including but not limited to, an audible alarm, visual indicator (such as a warning light or display message), haptic feedback (such as vibration), or an electronic communication sent to a connected control unit or external device.
Figure 1, in accordance with an embodiment describes a system 100 for determining shaft torque of an electric motor. The system 100 comprises a sensor arrangement 102 configured to sense real-time motor parameters including motor phase currents and DC link voltage, a memory module 104 configured to store efficiency data of a powertrain and a processing unit 106 communicably coupled to the sensor arrangement 102 and the memory module 104. The processing unit 106 is configured to convert the sensed motor phase currents into synchronously rotating reference frame currents comprising d-axis and q-axis currents, determine input shaft power based on the d-axis and q-axis currents and the DC link voltage, determine output power based on the input shaft power and the efficiency data of the powertrain and determine the shaft torque based on the output power and motor revolutions per minute (rpm).
The present disclosure provides system 100 for determining shaft torque of an electric motor. The system 100 as disclosed by present disclosure is advantageous in terms of accurately determining the shaft torque of an electric motor without the need for physical torque sensors. Beneficially, by utilizing real-time motor parameters such as phase currents and DC link voltage via the sensor arrangement 102, along with stored efficiency data of the powertrain, the system 100 enables precise calculation of input shaft power and output power, thereby allows the accurate estimation of shaft torque. Moreover, the sensor-less approach of shaft torque determination reduces the complexity, cost, and reliability concerns associated with conventional torque sensor implementations in automotive applications. Furthermore, the use of the memory module 104 to store powertrain efficiency data allows for adaptive and condition-specific output power estimation, thereby improves the accuracy of shaft torque determination across various load and speed condition. Furthermore, the integration of a proportional-integral (PI) controller for processing motor currents significantly enhances the accuracy and responsiveness of torque estimation under varying operating conditions. Furthermore, the system 100 also enables real-time monitoring and comparison of the estimated shaft torque with user-defined demand torque which facilitates the early detection of unintended acceleration or deceleration events. The capability of early detection enhances the vehicle safety by allowing timely generation of alerts and automated adjustment of motor operation to mitigate such anomalies. Additionally, the use of powertrain efficiency data in the form of a lookup table ensures adaptability and precision across a wide range of operating scenarios.
In an embodiment, the processing unit 106 employs a proportional-integral (PI) controller to compute d-axis and q-axis voltages based on the DC link voltage for determining the input shaft power. The PI controller receives current control references corresponding to the desired torque and flux and regulates the d-axis and q-axis current components accordingly. By utilizing the PI controller, the processing unit 106 ensures the accurate voltage estimation under dynamic operating conditions, thereby enables the precise computation of the input shaft power. Beneficially, the approach enhances the stability and responsiveness of the system 100 during transient events, thereby contributing to improved accuracy in shaft torque determination.
In an embodiment, the sensor arrangement 102 comprises at least one current sensor 108 configured to sense the motor phase currents and at least one voltage sensor 110 configured to sense the DC link voltage. The current sensor 108 may be configured to sense the motor phase currents in real-time which provides the essential input data for further processing and transformation into d-axis and q-axis current components. Simultaneously, the voltage sensor 110 may be configured to measure the DC link voltage across the inverter supplying the electric motor. The sensed electrical parameters may be critical for accurately computing the input shaft power, which in turn is used for estimating the output shaft torque. Beneficially, the integration of the at least one current sensor 108 and the at least one voltage sensor 110 within the system 100 allows for non-intrusive, real-time data acquisition necessary for precise torque estimation, without requiring additional mechanical torque sensing components.
In an embodiment, the processing unit 106 is configured to compare the determined shaft torque with a user-defined demand torque and detect unintended acceleration or deceleration based on the comparison. Furthermore, upon detecting unintended acceleration or deceleration, the processing unit 106 is configured to generate an alert signal. Based on the comparison, the processing unit 106 may be capable of detecting any unintended acceleration or deceleration that may occur due to discrepancies between the demanded and actual torque. Such deviations may indicate faults, unexpected load changes, or control errors, and their detection which enables the system 100 to take corrective actions or generate alerts to maintain safe and stable vehicle performance. Beneficially, the system 100 enhances both safety and operational reliability in electric vehicle applications.
In an embodiment, upon detecting unintended acceleration or deceleration, the processing unit 106 is configured to adjust motor operation to mitigate the unintended acceleration or deceleration. Specifically, upon detecting a deviation indicative of unintended vehicle behavior such as a higher or lower actual torque than what is demanded, the processing unit 106 dynamically adjusts the motor operation to mitigate the anomaly. The adjustment may involve modifying the torque command, altering the control signals to the inverter, or recalibrating the motor control loop to bring the actual torque output back in line with the intended demand. By adjusting the motor operation, the system 100 enhances the vehicle safety and ride quality by preventing erratic torque delivery which ensures the smoother acceleration or deceleration and maintaining desired vehicle dynamics without the need for external intervention.
In an embodiment, the efficiency data of the powertrain includes a lookup table mapping input power to output power across a range of operating conditions. The lookup table may be configured to map input power to corresponding output power across a range of operating conditions, such as varying motor speeds, load levels, and thermal states. By referencing the lookup table, the processing unit 106 is able to determine the output power of the powertrain with high accuracy based on the real-time computed input shaft power. Beneficially, the approach allows for rapid and computationally efficient estimation of powertrain output performance without relying on complex mathematical modeling or iterative calculations, thereby enabling real-time shaft torque determination under dynamically changing conditions.
In an embodiment, the system 100 comprises the sensor arrangement 102 configured to sense real-time motor parameters including motor phase currents and DC link voltage, the memory module 104 configured to store efficiency data of the powertrain and the processing unit 106 communicably coupled to the sensor arrangement 102 and the memory module 104. The processing unit 106 is configured to convert the sensed motor phase currents into synchronously rotating reference frame currents comprising d-axis and q-axis currents, determine input shaft power based on the d-axis and q-axis currents and the DC link voltage, determine output power based on the input shaft power and the efficiency data of the powertrain and determine the shaft torque based on the output power and motor revolutions per minute (rpm). Furthermore, the processing unit 106 employs the proportional-integral (PI) controller to compute d-axis and q-axis voltages based on the DC link voltage for determining the input shaft power. Furthermore, the sensor arrangement 102 comprises the at least one current sensor 108 configured to sense the motor phase currents and the at least one voltage sensor 110 configured to sense the DC link voltage. Furthermore, the processing unit 106 is configured to compare the determined shaft torque with the user-defined demand torque and detect unintended acceleration or deceleration based on the comparison. Furthermore, upon detecting unintended acceleration or deceleration, the processing unit 106 is configured to generate the alert signal. Furthermore, upon detecting unintended acceleration or deceleration, the processing unit 106 is configured to adjust motor operation to mitigate the unintended acceleration or deceleration. Furthermore, the efficiency data of the powertrain includes the lookup table mapping input power to output power across the range of operating conditions. Furthermore,
Figure 2, describes a method 200 for determining shaft torque of an electric motor. The method 200 starts at step 202 and completes at step 212. At step 202, the method 200 comprises sensing real-time motor parameters including motor phase currents and DC link voltage using a sensor arrangement 102. At step 204, the method 200 comprises retrieving efficiency data of a powertrain from a memory module 104. At step 206, the method 200 comprises converting the sensed motor phase currents into synchronously rotating reference frame currents comprising d-axis and q-axis currents. At step 208, the method 200 comprises determining, by a processing unit 106, input shaft power based on the d-axis and q-axis currents and the DC link voltage. At step 210, the method 200 comprises determining, by the processing unit 106, output power based on the input shaft power and the efficiency data of the powertrain. At step 212, the method 200 comprises determining, by the processing unit 106, the shaft torque based on the output power and motor revolutions per minute (rpm).
In an embodiment, determining the input shaft power includes employing a proportional-integral (PI) controller to compute d-axis and q-axis voltages based on the DC link voltage.
In an embodiment, the method 200 comprising monitoring the shaft torque in real-time and storing the determined shaft torque in the memory module 104 for performance analysis.
In an embodiment, the method 200 comprising comparing the determined shaft torque with a user-defined demand torque and detecting unintended acceleration or deceleration based on the comparison of the determined shaft torque and the demand torque.
In an embodiment, the method 200 comprising generating an alert signal upon detecting unintended acceleration or deceleration and adjusting motor operation to correct the unintended acceleration or deceleration upon detection.
In an embodiment, sensing the real-time motor parameters comprises using current sensors for the motor phase currents and a voltage sensor for the DC link voltage.
It would be appreciated that all the explanations and embodiments of the portable device 100 also applies mutatis-mutandis to the method 200.
In the description of the present invention, it is also to be noted that, unless otherwise explicitly specified or limited, the terms “disposed,” “mounted,” and “connected” are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected, either mechanically or electrically. They may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Modifications to embodiments and combination of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non- exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.
,CLAIMS:We Claim:
1. A system (100) for determining shaft torque of an electric motor, wherein the system (100) comprises:
- a sensor arrangement (102) configured to sense real-time motor parameters including motor phase currents and DC link voltage;
- a memory module (104) configured to store efficiency data of a powertrain; and
- a processing unit (106) communicably coupled to the sensor arrangement (102) and the memory module (104), wherein the processing unit (106) is configured to:
- convert the sensed motor phase currents into synchronously rotating reference frame currents comprising d-axis and q-axis currents;
- determine input shaft power based on the d-axis and q-axis currents and the DC link voltage;
- determine output power based on the input shaft power and the efficiency data of the powertrain; and
- determine the shaft torque based on the output power and motor revolutions per minute (rpm).
2. The system (100) as claimed in claim 1, wherein the processing unit (106) employs a proportional-integral (PI) controller to compute d-axis and q-axis voltages based on the DC link voltage for determining the input shaft power.
3. The system (100) as claimed in claim 1, wherein the sensor arrangement (102) comprises:
- at least one current sensor (108) configured to sense the motor phase currents; and
- at least one voltage sensor (110) configured to sense the DC link voltage.
4. The system (100) as claimed in claim 1, wherein the processing unit (106) is configured to:
- compare the determined shaft torque with a user-defined demand torque; and
- detect unintended acceleration or deceleration based on the comparison.
5. The system (100) as claimed in claim 4, wherein, upon detecting unintended acceleration or deceleration, the processing unit (106) is configured to generate an alert signal.
6. The system (100) as claimed in claim 4, wherein, upon detecting unintended acceleration or deceleration, the processing unit (106) is configured to adjust motor operation to mitigate the unintended acceleration or deceleration.
7. The system (100) as claimed in claim 1, wherein the efficiency data of the powertrain includes a lookup table mapping input power to output power across a range of operating conditions.
8. A method (200) for determining shaft torque of an electric motor, wherein the method (200) comprises:
- sensing real-time motor parameters including motor phase currents and DC link voltage using a sensor arrangement (102);
- retrieving efficiency data of a powertrain from a memory module (104);
- converting the sensed motor phase currents into synchronously rotating reference frame currents comprising d-axis and q-axis currents;
- determining, by a processing unit (106), input shaft power based on the d-axis and q-axis currents and the DC link voltage;
- determining, by the processing unit (106), output power based on the input shaft power and the efficiency data of the powertrain; and
- determining, by the processing unit (106), the shaft torque based on the output power and motor revolutions per minute (rpm).
11. The method (200) as claimed in claim 10, wherein determining the input shaft power includes employing a proportional-integral (PI) controller to compute d-axis and q-axis voltages based on the DC link voltage.
12. The method (200) as claimed in claim 10, comprising:
- monitoring the shaft torque in real-time; and
- storing the determined shaft torque in the memory module (104) for performance analysis.
13. The method (200) as claimed in claim 10, comprising:
- comparing the determined shaft torque with a user-defined demand torque; and
- detecting unintended acceleration or deceleration based on the comparison of the determined shaft torque and the demand torque.
14. The method (200) as claimed in claim 13, comprising generating an alert signal upon detecting unintended acceleration or deceleration and adjusting motor operation to correct the unintended acceleration or deceleration upon detection.
15. The method (200) as claimed in claim 10, wherein sensing the real-time motor parameters comprises using current sensors for the motor phase currents and a voltage sensor for the DC link voltage.