Power management in drives with synchronous permanent magnet motors

Abstract

System comprising: a synchronous permanent magnet motor (PMSM) (46; 160); and a motor control system (100; 200) configured to limit a supply current and a regenerative current, wherein the motor control system (100; 200) is configured to: receive a torque command and generate a corresponding current command to produce a torque amount based on the torque command; determine an estimated battery current drawn according to the current command; and, in response to the estimated battery current exceeding a threshold: generate a modified torque command; generate a modified current command corresponding to the modified torque command; and send the modified current command to cause the PMSM (46; 160) to produce a modified torque amount.

Description

BACKGROUND The present application relates generally to motor control systems and in particular to power management in synchronous permanent magnet machines. Synchronous permanent magnet machines (PMSMs) are widely used in electric drive applications due to their high power density, superior control behavior, and reliability. Torque control of PMSMs is typically implemented indirectly through current feedback control, which usually employs current and position measurements. Field-oriented control (FOC) is the most common current control technique, in which all AC signals are transformed into DC signals via a reference frame transformation. The control system is then implemented within the synchronously rotating, or d / q, reference frame. DE 10 2014 104 488 A1 relates to a method for controlling a permanent magnet synchronous motor in an auxiliary power steering system, in which the battery current and power losses are limited by speed-dependent torque limit curves. A first curve for a first torque limit and a second curve for a second torque limit are calculated as a function of speed, maximum available electrical power, and power losses, which describe the permissible operating conditions of the motor. At high speeds above a speed threshold, the motor is limited based on the first curve, while at low speeds below this threshold, a third curve is used, which, starting from a torque limit at standstill, forms an approximately linear transition to the first curve and thus stabilizes the control in the lower speed range. US Patent 2008 / 0265808A1 describes a drive system for permanent magnet AC motors in which the usable speed and power range is extended and battery current consumption is limited by combined control of phase shift and DC link voltage boost. The control system adjusts the phase shift angle between current and rotor flux, as well as the level of the DC link voltage provided by a boost converter, depending on the speed and torque requirements. This ensures that, given a current limit, the highest possible motor efficiency and output power are achieved while adhering to a maximum battery current value. From US patent 2014 / 0111129A1, a device is known consisting of an electrical power source with at least two elements of different technologies, such as a battery and resistor or supercapacitors, and an inverter that controls a multi-phase traction motor so that a predetermined maximum source current is not exceeded. The inverter regulates the motor's phase currents based on a torque setpoint. The inverter measures both the DC supply current and the motor phase currents and calculates an internally used control torque setpoint from the vehicle's specified torque setpoint. This control torque setpoint is reduced as soon as the measured supply current approaches the predetermined current limits of the source, thus adjusting the motor current and, consequently, the torque generated by the motor according to the DC current limit. The object of the present invention is to provide technical solutions for power management in synchronous permanent magnet machines. This problem is solved by a system having the features of claim 1 and a method having the features of claim 9. Advantageous embodiments are specified in the dependent claims. An exemplary system includes a permanent magnet synchronous motor (PMSM) and a motor control system that limits the supply current and the regenerative current of the PMSM. The limiting process involves receiving a torque command and generating a corresponding current command to produce a torque quantity based on the torque command. Furthermore, the limiting process involves determining an estimated battery current, which is drawn from the battery according to the current command. In response to the estimated battery current exceeding a threshold, a modified torque command is generated, and a modified current command corresponding to the modified torque command is also generated. The modified current command is used to cause the PMSM to produce the specified torque quantity. In accordance with one or more embodiments, a method for limiting a supply current and a regenerative current in a motor control system comprises receiving a torque command and generating a corresponding current command to produce a torque quantity in accordance with the torque command. The method further comprises determining an estimated battery current, which is drawn from the battery in accordance with the current command. In response to the estimated battery current exceeding a threshold, the method comprises generating a modified torque command and generating a modified current command corresponding to the modified torque command. The method further comprises sending the modified current command to cause a motor to produce the torque quantity. In accordance with one or more embodiments, a motor control system comprises a current generation module that receives a torque command and generates a corresponding current command to produce a torque quantity according to the torque command. Furthermore, a battery current estimation and comparison module determines an estimated battery current to be drawn from a power supply to apply the current command. The battery current estimation and comparison module further compares the estimated battery current to a maximum battery current threshold.In response to the estimated battery current exceeding the maximum battery current threshold, the battery current estimation and comparison module sends a feedback factor to modify the torque command. Conversely, in response to the estimated battery current remaining within the maximum battery current threshold, the current command to generate torque is sent. A battery current pre-limiting module further modifies the torque command using the feedback factor and sends the modified torque command to the current generation module. These and other advantages and features will become clearer from the following description when read in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS The subject matter, which is considered to be the invention, is specifically disclosed and claimed separately in the claims at the end of the description. The foregoing and further features and advantages of the invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: Fig. 1 represents an EPS system in accordance with one or more embodiments; Fig. 2 represents a block diagram of an exemplary torque control algorithm for PMSMs; Fig. 3 represents a power flow of a motor control system; Fig. 4 represents a flowchart for an exemplary method for limiting supply currents and regenerative currents in accordance with one or more embodiments; Fig.Figure 5 shows a block diagram of a module for pre-limiting a supply current and a regenerative current and a feedback circuit in accordance with one or more embodiments; Figure 6 shows a block diagram of an exemplary module for estimating and comparing supply currents and regenerative currents in accordance with one or more embodiments; Figure 7 shows exemplary results for an exemplary motor control system implementing the supply current and regenerative current limitation described herein; and Figure 8 shows exemplary results for the exemplary motor control system without implementing the supply current and regenerative current limitation described herein. DETAILED DESCRIPTION The terms module and submodule, as used here, refer to one or more processing circuits, such as an application-specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or grouped) with memory that executes one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality. As can be seen, the submodules described below can be combined and / or further subdivided. Now, with reference to the figures, in which the technical solutions are described with reference to specific embodiments without limiting them, Fig. 1 is an exemplary embodiment of an electric power steering system (EPS system) 40 suitable for implementing the disclosed embodiments. The steering mechanism 36 is a rack and pinion system and includes a (not shown) toothed rack in a housing 50 and a (also not shown) pinion arranged under a gearbox housing 52. When the operator input, hereafter referred to as the steering wheel 26 (e.g., a handwheel and the like), is turned, the upper steering shaft 29 rotates, and the lower steering shaft 51, which is connected to the upper steering shaft 29 by a universal joint 34, rotates the pinion.The rotation of the pinion gear moves the rack, which moves tie rods 38 (only one is shown), which in turn move the steering knuckles 39 (only one is shown), which rotate or turn one or more steerable wheels 44 (only one is shown). Assistance by the electric power steering is provided by the control device, generally designated by reference numeral 24, which includes the controller 16 and an electric machine 46, which can be a synchronous permanent magnet motor and is referred to below as motor 46. The controller 16 is supplied with power from the vehicle power supply 10 via a line 12. The controller 16 receives a vehicle speed signal 14, representing the vehicle speed, from a vehicle speed sensor 17. A steering angle is measured by a position sensor 32, which can be an optically coded sensor, a variable resistance sensor, or another suitable type of position sensor, and this provides a position signal 20 to the controller 16.Motor speed can be measured with a tachometer or other device and transmitted to the controller 16 as a motor speed signal 21. A motor speed, denoted as ωm, can be measured, calculated, or determined by a combination of these methods. For example, the motor speed can be calculated ω times the change in the motor position θ, measured by a position sensor 32, over a given time interval. For instance, the motor speed ω times the derivative of the motor position θ from the equation ωm = Δθ / Δt, where Δt is the sampling time and Δθ is the change in position during the sampling interval. Alternatively, the motor speed can be derived from the motor position as the rate of change of the position over time. It should be noted that there are numerous well-known methods for performing the derivative function. When the steering wheel 26 is turned, a torque sensor 28 detects the torque applied to the steering wheel 26 by the vehicle operator. The torque sensor 28 can include a torsion bar (not shown) and a variable resistance sensor (also not shown), which outputs a variable torque signal 18 to the controller 16 in relation to the amount of rotation of the torsion bar. While this is one type of torque sensor, any other suitable torque sensing device using known signal processing techniques can suffice. In response to the various inputs, the controller sends a command 22 to the electric motor 46, which provides torque assistance to the steering system via a worm gear 47 and a worm wheel 48, thus providing torque assistance for vehicle control. It should be noted that the disclosed embodiments are described by reference to a motor control system for electric power steering applications; however, it should be emphasized that these references are for illustrative purposes only and that the disclosed embodiments can be applied to any motor control application that uses an electric motor, e.g., steering, valve control, and the like. Furthermore, the references and descriptions herein can apply to many types of parameter sensors, including, without limitation, torque, position, speed, and the like. It should also be noted that, for the sake of brevity and simplicity, electrical machines, including, without limitation, motors, will henceforth be referred to simply as "motors." In the depicted control system, the controller 16 uses torque, position, speed, and similar data to calculate one or more commands for delivering the requested output power. The controller 16 communicates with the various systems and sensors of the motor control system. It receives signals from each of the system sensors, quantifies the received information, and, in response, provides one or more output command signals, in this case, for example, for the motor 46. The controller 16 is designed to generate the corresponding voltages from a converter (not shown), which can optionally be integrated into the controller 16 and is referred to here as the controller 16. When applied to the motor 46, these voltages produce the desired torque or position.In one or more examples, the controller 24 operates in a feedback mode as a current controller to generate command 22. Alternatively, in one or more examples, the controller 24 operates in a feedforward mode to generate command 22. Since these voltages are related to the position and speed of the motor 46 and the desired torque, the position and / or speed of the rotor and the torque applied by an operator are determined. A position encoder is connected to the steering shaft 51 to detect the angular position θ. The encoder can detect the rotational position based on optical detection, fluctuations in a magnetic field, or other methods. Typical position sensors include potentiometers, resolvers, synchros, encoders, and the like, as well as combinations comprising at least one of the above.The position encoder outputs a position signal 20, which indicates the angular position of the steering shaft 51 and thus that of the motor 46. A desired torque can be determined by one or more torque sensors 28, which transmit torque signals 18 indicating an applied torque. One or more exemplary embodiments comprise such a torque sensor 28 and the torque signal(s) 18 from it, which respond to a compliant torsion bar, T-bar, spring, or similar device (not shown) configured to provide a response indicating the applied torque. In one or more examples, one or more temperature sensors 23 are arranged on the electric machine 46. Preferably, the temperature sensor 23 is configured to directly measure the temperature of the sensing section of the motor 46. The temperature sensor 23 transmits a temperature signal 25 to the controller 16 to enable the processing and compensation described herein. Typical temperature sensors include thermocouples, thermistors, thermostats, and the like, as well as combinations comprising at least one of the aforementioned sensors, which, when suitably positioned, provide a calibratable signal proportional to the specific temperature. The position signal 20, the speed signal 21, and one or more torque signals 18, among others, are applied to the controller 16. The controller 16 processes all input signals to generate values ​​corresponding to each signal, resulting in a rotor position value, a motor speed value, and a torque value, which are available for processing in the algorithms described here. Measurement signals such as those mentioned above are often linearized, compensated, and, if desired, filtered to improve their characteristics or eliminate undesired characteristics of the acquired signal. For example, the signals can be linearized to improve processing speed or to address a large dynamic range of the signal. Furthermore, frequency- or time-based compensation and filtering can be applied to eliminate noise and avoid undesired spectral characteristics. To perform the functions and processing described above, as well as the necessary calculations (e.g., the detection of motor parameters, control algorithms, and the like), the controller 16 can, without restriction, include one or more processors, computers, DSPs, main memory, mass storage, registers, timers, interrupts, communication interfaces, and input / output signal interfaces, and the like, as well as combinations thereof that include at least one of the above. For example, the controller 16 can include the processing and filtering of input signals to enable accurate sampling and conversion or the acquisition of such signals from communication interfaces. Additional features of the controller 16 and specific processes within it will be discussed in detail later. In one or more examples, the technical solutions described here enable power management of the electric drive section of the EPS system, i.e., the motor control system. It should be noted that although the technical solutions are described here using embodiments of a steering system, they are applicable to any other motor control system used in a different PMSM. To protect a power source in an electric drive system (motor control system), the motor control system typically specifies a voltage limit across a supply and / or regenerative current. These limits can be in the form of an offline calibrated table or a continuously changing online limit sent to the motor control system. When this supply and / or regenerative current limit is in place, the motor current command is modified to ensure the system does not draw more supply current or supply more regenerative current than specified, thus protecting the power source. In specific examples of motor control systems used in automotive applications, such as a steering system, the power supply is a vehicle battery. The technical solutions described here address the technical challenge of limiting supply or regenerative currents in the motor control system. In one or more examples, these solutions enable the active limitation of both the supply and regenerative currents flowing between the power supply and the PMSM (Power Metering System). This limitation restricts the draw of supply and regenerative current by actively modifying torque commands and, in turn, ensures full voltage utilization.The limitation of the supply and regenerative current is translated into an equivalent torque limitation of the PMSM by solving the power equations of the power flow circuit based on the principle of conservation of power in the motor control system. This is implemented through an online modification of torque commands according to the maximum permissible torque determined by the battery current limit. The technical solutions described here therefore protect the power supply, such as a battery, from excessive discharge or charge current under all operating conditions of the PMSM drive system. Furthermore, the technical solutions described here are applicable to all electric drive systems that use PMSMs and are not limited to any specific application. Fig. 2 shows a block diagram of an exemplary torque control algorithm for PMSMs. The block diagram represents a motor control system 100 in which, for a given DC coupling voltage VDC, supplied by a battery 110, and for a (mechanical) motor speed ωm, the maximum torque Te,max is calculated and then compared with a given torque command to generate a final torque command within the system capacity by a torque limiting module 120. Consequently, the motor control system 100 enables motor torque control and motor current control. A signal is sent to a maximum torque per ampere (MTPA) module 130 to calculate current commands, which are then sent to a maximum torque per volt (MTPV) module 140 to check whether the corresponding PMSM voltage vm exceeds the maximum possible value vm,max, which is limited by the DC coupling voltage.If the PMSM voltage does not exceed vmvm,max, the current commands calculated by the MTPA module 130 are used as final commands for PMSM control; otherwise, the MTPV block 140 generates other commands to comply with the PMSM voltage limit. The final current commands are then sent to a current controller 150, which ensures current tracking and thus torque tracking. Here, "tracking" refers to how closely the output current (or output torque) is to the desired current (or torque) as requested by the current command (torque command). To protect battery 110 from excessive discharge or charge due to excessive currents, and thus extend its service life, battery current limiting is implemented during PMSM 110 operation. PMSM 160 can be motor 26 used in steering system 40, or any other application. As described above, lookup tables (LUTs) are typically used to adjust the torque and current commands so that the battery current does not exceed the maximum value. A technical challenge with this approach is the need for offline calibration for different motors, which is time-consuming. Furthermore, due to the offline nature of these techniques, the current and torque commands are not optimal, as dynamically changing operating conditions of PMSM 160 are not taken into account.The technical solutions described here enable battery current limiting capable of simultaneously limiting both supply and regenerative currents. This limiting can be implemented with at least one threshold accuracy across all operating regions of the PMSM 160 when the PMSM 160 is online, and furthermore ensures full utilization of the DC coupling voltage. The technical solutions are described in more detail below. Fig. 3 illustrates the power flow of a motor control system. The motor control system shown originates from the steering system 40 with the control module 16 and the motor 46, which define a voltage circuit that includes the voltage across the (not shown) battery 110 and the voltage at the input of the (not shown) inverter, which is then connected to the motor 46. For a given battery voltage (VBATT) and a measurement of the voltage input (VDC) to system 16, the power equations can be solved to obtain motor current limits. A supply current Is is related to the regenerative current IB as follows: Furthermore, the voltage circuit model that incorporates the battery can be expressed mathematically as follows: where RBH represents the battery cable string resistance. The power balance equation of this system can be written as follows: where RC is the input resistance of the controller and Pe is the electrical power input to (or output from) the motor control system. The expression for Pe is further described here. Again with reference to Fig. 3, when the PMSM is operated as motor 46, the battery current ib is the supply current drawn from battery 110 and is considered a positive value; otherwise, when the PMSM is operated as a generator, the battery current i is regenerative current fed back to battery 110 and is considered negative.If the power equations for a given battery current limit Ib,max are solved according to the principle of conservation of power to obtain the PMSM torque limit, the power equilibrium equation of the system can be written as where Pin, Pe and RC are respectively the input power of the DC coupling, the electrical input power of the PMSM drive system and the input resistance of the DC coupling. The voltages of the DC coupling and the battery 110 are related as follows: where VBATT and RBH are the battery voltage and the battery cable string resistance, respectively. Furthermore, Pin and Pewie can be derived as follows: where Teω and Ploss are the electrical output power and the losses of the PMSM, respectively. The electrical losses include inverter losses, winding losses, core losses, and stray losses in the PMSM. The dominant component of all loss components is the winding loss. Consequently, the electromagnetic torque can be written as follows: If battery current limits need to be considered in the typical PMSM control algorithm, the torque command must be modified accordingly. Specifically, if a maximum battery supply current or a renewable current Ib,max of the PMSM is added as a control limit for the PMSM, the maximum permissible torque will be: The technical challenge here lies in the fact that the loss component Plossin in this calculation formula for Tb,max is influenced by the motor current, which in turn affects the torque Tb,max sent to the motor control algorithm. The technical solutions described here address this challenge by combining a torque command pre-limitation with an iterative update procedure to eliminate or minimize the coupled interaction between torque and motor current. Fig. 4 presents a flowchart for an exemplary method for limiting supply and regenerative currents in accordance with one or more embodiments. In one or more examples, the technical solutions described herein are integrated into the PMSM control algorithm shown in Fig. 4 to generate current commands to ensure that supply and regenerative currents remain within predefined limits. As shown, the method includes pre-limiting the input current (supply or regenerative) ib, as shown in Figure 420, and further estimating and comparing ib, as shown in Figure 440. The method includes receiving input parameters, as shown in Figure 410. The input parameters include at least VDC, ω, and Ib,max. Pre-limiting ib involves conditioning parameters and modifying torque instructions, as shown in Figures 422 and 424. The processed parameters and the modified torque instruction are used together to calculate the current instructions, as shown in Figure 430. Furthermore, the procedure includes estimating the battery current ib based on the current commands and checking whether the estimated ib is within specified limits (one value each for supply and regenerative current limits), as shown in Figures 442 and 444. The procedure further includes providing feedback update information for the previous torque command modification step and iterating the procedure until the estimated ib meets the predefined limits, as shown in Figure 446. There are several ways to implement the ib prelimiting and feedback loop to allow ib to be limited by a torque command modification and iterative update. The current commands that meet the predefined limits are held for transmission to the current controller 150 as the commands and , as shown in Figure 450. Fig. 5 shows a block diagram of a module for pre-limiting supply and regenerative currents and part of the feedback circuit according to one or more embodiments. The module 520 for pre-limiting supply and regenerative currents implements parameter conditioning and torque instruction modification. In one or more examples, the module for pre-limiting supply and regenerative currents is part of the control module 16, is implemented by the control module 16, or is a separate electronic circuit included in the motor control system 200. Furthermore, in one or more examples, the module 520 for pre-limiting supply and regenerative currents comprises separate modules—including a parameter conditioning module 522 and a torque instruction modification module 524. Module 520, used for pre-limiting supply and regenerative currents, detects the operating mode of the PMSM 160 in one or more examples as part of parameter conditioning, using the product of Ib and ωm, as shown in Figure 530. Based on the operating mode, the maximum supply current Ib,max1 and the maximum regenerative current Ib,max2 are dynamically used to condition the parameters. If the product is greater than zero, the PMSM operating mode is determined to be (initially) in motor mode, and the procedure involves setting Ib,max = Ib,max1, as shown in Figure 532. If the product is less than zero, the system is operating in regenerative (or generation) mode, and Ib,max = Ib,max2 is set, as shown in Figure 534. Furthermore, a scaling factor k is used based on whether the product is greater than (or equal to) or less than zero.The scaling factor k is a torque factor used to reduce the dependence of the torque calculation on the loss, where the torque calculation is. Taking into account the maximum battery current limits, the maximum torque that ensures supply and regenerative currents remain within the limits can be calculated as in 542 as After the calculation of Tb,max, the original torque command is updated and replaced by the smaller value of Tb,max, as shown in Figure 544. Since the mechanical power of the PMSM in motor mode comes from battery 110, k is less than 1 in this mode (532). In regenerative mode, however, k is greater than 1 in this mode (534) because the power flows from the PMSM 160 to battery 110. The torque factor k is continuously updated by the feedback circuit until the limits for supply and regenerative currents are met, as shown in Figure 550. It should be noted that the constant values ​​shown in the preceding example and / or in Fig. 5 or in any other example / drawing herein are examples and may vary depending on system parameters and specific operating conditions in other examples. In one or more examples, a parameter adaptation scheme is used to achieve faster convergence of the value of k during the implementation of the preceding procedure. Furthermore, the torque modification can alternatively be implemented as Tb,max = Tb,max - ΔT, where ΔT is a torque update step. In other examples, alternative methods for updating the torque within the feedback loop may be used. In one or more examples, PMSM operation exhibits a critical region at low engine speeds (rotational speeds or velocities below a predetermined threshold) where the product is zero, yet battery 110 still supplies power to the system. In such a critical region, the battery current limit specified in the ib prelimit is incorrect because it assumes battery 110 is being charged by a renewable current, yet it is still supplying power. To avoid this error, the procedure described above is modified in one or more examples. Fig. 6 shows a block diagram of an exemplary module for estimating and comparing ib in accordance with one or more embodiments. In one or more examples, the module for estimating and comparing ib is part of the control module 16, it is implemented by the control module 16, or it is a separate electronic circuit included in the motor control system 200. Furthermore, the module 620 for estimating and comparing supply and regenerative currents in one or more examples includes separate modules—among others, a battery current estimation module 622 and a battery current comparison module 624. Module 620 for estimating and comparing supply and regenerative currents performs one or more operations to estimate the battery current Ib using the final current commands from the prelimiting operations 520, as shown in Figure 622. Module 620 for estimating and comparing supply and regenerative currents further performs one or more operations to check whether the system is currently operating in the critical region, as shown in Figure 630. Based on the result of the comparison, the battery current limits are dynamically adjusted. For example, in the critical region, the current limit is corrected to Ib,max = -Ib,max1, ensuring that the supply current remains within the given limit Ib,max1, as shown in Figure 632. If the system is not currently operating in the critical region, the value of Ib,max is not adjusted, as shown in Figure 634.Furthermore, the estimated battery current ib is compared with the battery current limit Ib,max using a modulo operator at the values, as shown in 636. The battery current ib (during one or more iterations) can be estimated using the power equations given above. The power equation can be solved to obtain ib as follows, where the electrical power Peaus input into the motor control system is obtained from the electromagnetic torque, the machine currents, the voltage, and motor parameters. The power Pe can be expressed using the electromagnetic torque Te as follows, where Pmisc is the loss component, which includes the motor core losses as well as one or more stray losses in the motor control system, Rm is the motor circuit resistance, which includes the resistances of the motor and the power circuit, and Id and Iq are the d-axis and q-axis motor currents, respectively. Furthermore, the torque can be represented using the motor currents as follows.where Ke is the constant of the motor voltage or motor torque, Np is the number of rotor poles, and Ld and Lq are the d-axis and q-axis inductances, respectively. Consequently, Pe can be obtained using the motor currents and the torque expression. Alternatively, the power Pe can be expressed using Vd and Vq, which are the d-axis and q-axis motor voltages, respectively, by utilizing the motor's voltage-current relationships as follows. If the limit is observed, the current commands are held to be forwarded to the current controller 150 as the commands shown in Figure 450. If the limit is exceeded, the current commands are recalculated using the feedback circuit as described here to adjust the torque factor k, as shown in Figure 550. Figure 7 presents exemplary results for an exemplary motor control system that implements a limitation of supply and regenerative currents as described herein. In the exemplary case for which the results are shown, the limits for the supply and regenerative currents are set to Ib,max1 = 50 A and Ib,max2 = -40 A, respectively. Furthermore, Figure 8 presents exemplary results for the exemplary motor control system without implementing the limitation of supply and regenerative currents described herein. Figure 7 shows that both supply and regenerative currents are successfully limited within their maximum values. In comparison to the final torque command in Figure 8 (without battery current limiting), Figure 7 (with the limiting) is modified to generate new current commands when the limiting of the supply and regenerative currents is integrated into the PMSM control algorithm. This modified torque command is calculated in accordance with given battery current limits based on the conservation of power principle and is iteratively updated by the feedback loop until the current limit is met, as described here. Due to the modified torque command, both the motor current and the motor voltage, which are also shown in Figures 7 and 8, are changed. The results demonstrate the effectiveness of the limiting for both supply and regenerative currents.It should be mentioned that these results are an example, and that in one or more examples using other case-specific parameters and factors, the results may vary. The technical solutions described here therefore enable power management (power limitation) of a motor, specifically by limiting supply and regenerative currents when various constraints and requirements exist. These solutions can be used to apply supply and regenerative current limitations to PMSM machines regardless of operating conditions, and are not limited to specific operating conditions such as only regenerative currents or only non-pronounced poles. Furthermore, these solutions allow the supply and regenerative current limitations to be applied dynamically by dynamically adjusting the limits, rather than calibrating them offline.Furthermore, the technical solutions described here ensure maximum voltage utilization across all PMSM operating regions, given battery current limiting restrictions. The technical solutions presented here can be a system, a process, and / or a computer program product at any possible level of technical detail of integration. The computer program product can include one or more computer-readable storage media containing computer-readable program instructions to cause a processor to execute aspects of the technical solutions presented here. Aspects of the present technical solutions are described here with reference to flowchart illustrations and / or block diagrams of processes, devices (systems), and computer program products in accordance with embodiments of the technical solutions. It is understood that each block of the flowchart illustrations and / or block diagrams and / or combinations of blocks in the flowchart illustrations and / or block diagrams can be implemented by computer-readable program instructions. The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, procedures, and computer program products in accordance with various embodiments of the presented technical solutions. In this regard, each block in the flowcharts or block diagrams can represent a module, segment, or part of instructions, comprising one or more executable instructions for implementing the described logical functions. In some alternative implementations, the functions described in the blocks may occur out of the order shown in the figures. For example, two blocks shown sequentially may actually be executed essentially simultaneously, or the blocks may sometimes be executed in reverse order, depending on the functionality involved.It should also be mentioned that each block of the block diagrams and / or flowchart illustration and combinations of blocks in the block diagrams and / or flowchart illustration can be implemented by special hardware-based systems that perform the described functions or actions, or execute combinations of special hardware and computer instructions. Furthermore, it should be noted that all modules, units, components, servers, computers, terminals, or devices described herein as examples, which execute instructions, contain or can otherwise access computer-readable media such as storage media, computer storage media, or data storage devices (removable and / or non-removable), such as magnetic disks, optical disks, or tapes. Computer storage media can include volatile and non-volatile, removable and non-removable media implemented by any method or technology for storing information, such as computer-readable instructions, data structures, program modules, or other data. These computer storage media can be part of the device, accessible to it, or connectable to it.All applications or modules described herein can be implemented using computer-readable / computer-executable instructions that can be stored on these computer-readable media or otherwise maintained.

Claims

System comprising: a synchronous permanent magnet motor (PMSM) (46; 160); and a motor control system (100; 200) configured to limit a supply current and a regenerative current, wherein the motor control system (100; 200) is configured to: receive a torque command and generate a corresponding current command to produce a torque amount based on the torque command; determine an estimated battery current drawn according to the current command; and, in response to the estimated battery current exceeding a threshold: generate a modified torque command; generate a modified current command corresponding to the modified torque command; and send the modified current command to cause the PMSM (46; 160) to produce a modified torque amount. System according to claim 1, further comprising a current regulator (150) with feedback, which converts the modified current command into a voltage command for application to the PMSM (46; 160). System according to claim 1, wherein generating the modified torque command comprises iteratively modifying the torque command and determining the estimated battery current drawn until the estimated battery current meets the threshold. System according to claim 3, wherein modifying the torque command comprises modifying a torque factor k which is used to calculate the torque command. System according to claim 4, wherein the torque command is calculated as T e = k ( VDC ib − ib 2 RC ) ω m , T e where T e The torque command is k, the torque factor is V DC a DC coupling voltage, Rc is an input resistance of the motor control system, ω m a motor speed is and i b The battery power is. System according to claim 3, wherein modifying the torque command comprises decrementing the torque command by a predetermined amount. System according to claim 1, wherein the threshold used to compare the estimated battery current is dynamically determined based on an operating mode of the motor control system (100; 200). System according to claim 1, further comprising a feedforward current controller (24) which converts the modified current command into a voltage command for application to the PMSM (46; 160). Method for limiting a supply current and a regenerative current in a motor control system (100; 200), the method comprising: receiving a torque command and generating a corresponding current command to produce a torque quantity in accordance with the torque command; determining an estimated battery current drawn (ib) corresponding to the current command; and, in response to the estimated battery current exceeding a threshold: generating a modified torque command; generating a modified current command corresponding to the modified torque command; and sending the modified current command to cause a motor to produce a modified torque quantity. The method of claim 9, wherein generating the modified torque command comprises iteratively modifying the torque command and determining the estimated battery current drawn until the estimated battery current exceeds the threshold. The method of claim 10, wherein modifying the torque command comprises modifying a torque factor k which is used to calculate the torque command in each iteration. Method according to claim 11, wherein the torque command is calculated as T e = k ( VDC ib − ib 2 RC ) ω m , where T e The torque command is k, the torque factor is V DC a DC coupling voltage, Rc is an input resistance of the motor control system (100; 200), ω m a motor speed is and i b The battery power is. The method of claim 10, wherein modifying the torque command comprises decrementing the torque command by a predetermined amount in each iteration. Method according to claim 9, wherein the threshold used to compare the estimated battery current is dynamically determined on the basis of an operating mode of the motor control system (100; 200). Method according to claim 14, wherein the operating mode of the motor control system (100; 200) is determined on the basis of the torque command and a speed of the motor (46; 160).

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