Optimization of torque capability with active limitation of regenerative current in synchronous motor drives

Abstract

The present application discloses an optimization of torque capacity under regenerative current in an actively limited synchronous motor drive. A method of controlling the operation of an electric motor includes: determining a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus that supplies power to an inverter to power the electric motor; determining a motor current-based torque limit based on a motor current limit; determining a final torque limit based on: a voltage-based torque limit and a motor current-based torque limit; determining a limited command torque based on a torque command and a final torque limit; determining an initial current command corresponding to an inverter that satisfies the regenerative current limit of the DC bus; and calculating a final current command based on at least the limited command torque and the initial current command. The method includes a final current command that exceeds the initial current command so that the electric motor produces a torque corresponding to the limited torque command.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. Provisional Patent Application Serial No. 63 / 088,581 filed on October 7, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to electric machines, and in particular to using a motor drive to control the operation of an electric machine. Background Art

[0004] Vehicles such as automobiles, trucks, sport utility vehicles, crossovers, minivans, boats, aircraft, all-terrain vehicles, recreational vehicles, or other suitable vehicles often include one or more electric machines, such as electric motors, etc. For example, a vehicle may include one or more multi-phase electric machines that are driven by corresponding motor drivers and configured to control various aspects of a steering system of the vehicle.

[0005] Power management is an important consideration when controlling an electric motor drive to regulate the power delivered to and recovered from the electric motor. Active power management involves considering multiple constraints simultaneously to determine the achievable torque. Constraints include supply voltage, supply (regeneration) current, and inverter (motor) current. Nonlinearities exist in the equations representing the different constraints, which require additional algorithms to additionally arbitrate between solutions from two independent constraints.

[0006] Constraints to consider in active power management include: voltage constraints; inverter (motor) current limits; supply current limits and regeneration current limits; and torque commands. Such voltage constraints can be based on the physical capabilities of the machine, including voltage limits of the inverter, motor, and / or other components such as interconnect wiring. Voltage constraints can also include the capabilities of the power source (e.g., battery). Current limits can protect the drive system from damage. Supply current limits and regeneration current limits may include externally imposed constraints (typically for vehicle power management and protection of the battery or vehicle electrical microgrid). Typically, the torque command is independent of the constraints and attempts to ensure that the limited torque command is as close to the original command as possible.

[0007] The priority of different constraints may be relatively important for the best performance of such motors. The priority of constraints depends largely on the application and use case in which the motor drive is employed. Summary of the invention

[0008] The present disclosure generally relates to using a motor drive to control the operation of an electric machine.

[0009] One aspect of the disclosed embodiment includes a method of controlling the operation of an electric motor. The method includes: determining a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus that supplies power to an inverter to power the electric motor; determining a motor current-based torque limit based on a motor current limit; determining a final torque limit based on: a voltage-based torque limit and a motor current-based torque limit; determining a limited command torque based on a torque command and a final torque limit; determining an initial current command corresponding to an inverter that satisfies a regenerative current limit of the DC bus; and calculating a final current command based on at least the limited command torque and the initial current command. The method includes a final current command that exceeds the initial current command to cause the electric motor to produce a torque corresponding to the limited torque command.

[0010] One aspect of the disclosed embodiment includes a control system for controlling the operation of an electric motor. The control system includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: determine a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus that supplies power to an inverter to power the electric motor; determine a motor current-based torque limit based on a motor current limit; determine a final torque limit based on: a voltage-based torque limit and a motor current-based torque limit; determine a limited command torque based on a torque command and a final torque limit; determine an initial current command for the inverter that satisfies a regenerative current limit of the DC bus; and calculate a final current command based on at least the limited command torque and the initial current command. The final current command exceeds the initial current command to cause the electric motor to produce a torque corresponding to the limited torque command.

[0011] One aspect of the disclosed embodiment includes a control system for controlling the operation of an electric motor. The control system includes an inverter and a controller, the inverter including a plurality of switches operable to supply alternating current to the electric motor. The controller is operable to: determine a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus that supplies power to the inverter to power the electric motor; determine a motor current-based torque limit based on a motor current limit; determine a final torque limit based on: a voltage-based torque limit and a motor current-based torque limit; determine a limited command torque based on a torque command and a final torque limit; determine an initial current command corresponding to an inverter that satisfies a regenerative current limit of the DC bus; and calculate a final current command based on at least the limited command torque and the initial current command. The final current command exceeds the initial current command to cause the electric motor to produce a torque corresponding to the limited torque command.

[0012] These and other aspects of the disclosure are disclosed in the following detailed description of the embodiments, the appended claims and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present disclosure is best understood by the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not drawn to scale. Instead, the sizes of the various features are arbitrarily expanded or reduced for clarity.

[0014] Figure 1 A schematic diagram of an electric power steering system in accordance with the principles of the present disclosure is generally shown.

[0015] Figure 2 A controller according to the principles of the present disclosure is generally shown.

[0016] Figure 3 A block diagram of a motor controller in accordance with the principles of the present disclosure is generally shown.

[0017] Figure 4 A block diagram generally illustrates an example algorithm for controlling an electric motor in accordance with aspects of the present disclosure.

[0018] Figures 5A-5D FIG. 1 shows a graph generally illustrating four different I values ​​for searching for maximum torque that satisfies DC bus voltage and motor current limit constraints according to the principles of the present disclosure. d ,I q Trajectory.

[0019] Figure 6 A graph generally illustrates applied torque versus speed for a motor control system in accordance with aspects of the present disclosure.

[0020] Figure 7 A block diagram of a regeneration seek control algorithm in accordance with the principles of the present disclosure is generally shown.

[0021] Figure 8 A block diagram of an algorithm for adjusting maximum d-axis current based on quadrant of operation in accordance with the principles of the present disclosure is generally shown.

[0022] Fig. 9 A graph is shown generally illustrating the principles of a regeneration seek control algorithm in accordance with the principles of the present disclosure.

[0023] Fig.10 A flow chart is shown generally illustrating a method of controlling operation of an electric machine according to the principles of the present disclosure. DETAILED DESCRIPTION

[0024] The following discussion is directed to various embodiments of the present disclosure. Although one or more of these embodiments may be preferred, the disclosed embodiments should not be interpreted or otherwise used as limiting the scope of the present disclosure, including the claims. In addition, it will be understood by those skilled in the art that the following description has a wide range of applications, and the discussion of any embodiment is intended only to be an exemplary discussion of that embodiment, and is not intended to imply that the scope of the present disclosure, including the claims, is limited to that embodiment.

[0025] As discussed above, vehicles such as automobiles, trucks, sport utility vehicles, crossovers, minivans, boats, aircraft, all-terrain vehicles, recreational vehicles, or other suitable vehicles often include one or more electric machines, such as electric motors, etc. For example, a vehicle may include one or more multi-phase electric machines configured to control various aspects of a steering system of the vehicle.

[0026] Power management is an important consideration when controlling an electric motor drive to regulate the power delivered to and recovered from the electric motor. Active power management involves considering multiple constraints simultaneously to determine the achievable torque. Constraints include supply voltage, supply (regeneration) current, and inverter (motor) current. Nonlinearities exist in the equations representing the different constraints, which require additional algorithms to additionally arbitrate between solutions from two independent constraints.

[0027] Constraints to consider in active power management include: voltage constraints; inverter (motor) current limits; supply current limits and regeneration current limits; and torque commands. Such voltage constraints can be based on the physical capabilities of the machine, including voltage limits of the inverter, motor, and / or other components such as interconnect wiring. Voltage constraints may also include the capabilities of the power source (e.g., battery). Current limits can protect the drive system from damage. Supply current limits and regeneration current limits may include externally imposed constraints (typically for vehicle power management and protection of the battery or vehicle electrical microgrid). Typically, the torque command is independent of the constraints and attempts to ensure that the limited torque command is as close to the original command as possible.

[0028] The priority of different constraints may be relatively important for optimal performance of such motors. The priority of constraints depends largely on the application and use case in which the motor drive is employed.

[0029] According to one aspect of the present disclosure, a number of different constraints are considered simultaneously, and torque maximization takes precedence over satisfying regenerative current constraints.

[0030] Figure 1A schematic diagram of an electric power steering system (EPS) 40 suitable for implementing the disclosed technology is generally shown. The EPS includes a steering mechanism 36 that includes a rack-and-pinion type mechanism having a toothed rack (not shown) within a housing 50 and a pinion (also not shown) located below a gear housing 52. When the operator input, hereinafter represented as the steering wheel 26 (e.g., hand wheel, etc.), is rotated, the upper steering shaft 29 is rotated, and the lower steering shaft 51 connected to the upper steering shaft 29 by a universal joint 34 causes the pinion to rotate. The rotation of the pinion causes the rack to move, which moves the tie rods 38 (only one shown), which in turn moves the steering knuckles 39 (only one shown), which rotate the steerable wheel(s) 44 (only one shown).

[0031] Electric power steering assistance is provided by a control system 24, which includes a controller 16 and a motor 19, which may be a permanent magnet synchronous motor (PMSM). The controller 16 is powered by a vehicle power supply 10 via line 12. The controller 16 receives a vehicle speed signal 14 representing the vehicle speed from a vehicle speed sensor 17. The steering angle is measured by a position sensor 32, which may be an optically encoded sensor, a variable resistor sensor, or any other suitable type of position sensor, and which provides a position signal 20 to the controller 16. The motor speed may be measured using a tachometer or any other device and transmitted to the controller 16 as a speed signal 21. The position sensor 32 may be represented as ω. m The motor speed is measured, calculated, or a combination of measurement and calculation. For example, the motor speed ω m is calculated as the change in motor position θ measured by the position sensor 32 over a specified time interval. For example, it can be calculated according to the equation ω m =Δθ / ΔtThe motor speed ω m Determined as the derivative of the motor position θ, 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 based on the rate of change of position with respect to time. It will be appreciated that there are many well-known methods for performing the function of the derivative.

[0032] As the steering wheel 26 is turned, the torque sensor 28 senses the torque applied to the steering wheel 26 by the vehicle operator. The torque sensor 28 may include a torsion bar (not shown) and a variable resistor type sensor (also not shown) that outputs a variable torque signal 18 to the controller 16 that is related to the amount of twist on the torsion bar. Although this is one type of torque sensor, any other suitable torque sensing device used with known signal processing techniques will suffice. In response to various inputs, the controller sends a command 22 to the motor 19, which provides torque assistance to the steering system through the worm 47 and worm gear 48, thereby providing torque assistance for vehicle steering.

[0033] It should be noted that while the disclosed embodiments are described with reference to motor control for electric steering applications, it will be understood that such references are illustrative only, and the disclosed embodiments may be applied to any motor control application employing an electric motor, e.g., steering, valve control, etc. In addition, the references and descriptions herein may be applicable to various forms of parameter sensors, including but not limited to torque, position, speed, etc. It should also be noted that hereinafter, for the sake of brevity and simplicity, references herein to electric machines, including but not limited to motors, will only refer to motors without limitation.

[0034] In the control system 24 as depicted, the controller 16 uses torque, position, speed, etc. to calculate (one or more) commands to deliver the required output power. The controller 16 is arranged to communicate with various systems and sensors of the motor control system. The controller 16 receives signals from each system sensor, quantifies the received information, and provides (one or more) output command signals in response thereto, in this case, for example, to the motor 19. The controller 16 is configured to develop (one or more) corresponding voltages output from an inverter (not shown), which can be optionally combined with the controller 16 and will be referred to as the controller 16 herein, so that when (one or more) corresponding voltages are applied to the motor 19, the desired torque or position is generated. In one or more examples, the controller 16 operates as a current regulator in a feedback control mode to generate the command 22. Alternatively, in one or more examples, the controller 16 operates in a feedforward control mode to generate the command 22. Because these voltages are related to the position and speed of the motor 19 and the desired torque, the position and / or speed of the rotor and the torque applied by the operator are determined. A position encoder is connected to the steering shaft 51 to detect the angular position θ. The encoder can sense the rotational position based on optical detection, magnetic field changes, or other methods. Typical position sensors include potentiometers, resolvers, synchronizers, encoders, etc. The position encoder outputs a position signal 20, which indicates the angular position of the steering shaft 51 and thereby indicates the angular position of the motor 19.

[0035] The desired torque may be determined by one or more torque sensors 28 transmitting a torque signal 18 indicative of the applied torque. Such torque sensors 28 and the torque signal(s) 18 therefrom may be responsive to a flexible torsion bar, T-bar, spring, or similar device (not shown) configured to provide a response indicative of the applied torque.

[0036] Position signal 20, speed signal 21, and (one or more) torque signal 18 are applied to controller 16. Controller 16 processes all input signals to generate values ​​corresponding to each signal, thereby obtaining rotor position values, motor speed values, and torque values ​​that can be used for processing in the algorithm specified in this article. It is usually also desirable to linearize, compensate, and filter the measurement signals such as those described above to enhance the characteristics of the acquired signal or eliminate undesirable characteristics of the acquired signal. For example, the signal can be linearized to increase the processing speed or to solve the large dynamic range of the signal. In addition, frequency or time-based compensation and filtering can be used to eliminate noise or avoid undesirable spectral characteristics.

[0037] In order to perform the specified functions and the desired processing, and the calculations therefor (e.g., identification of motor parameters, (one or more) control algorithms, etc.), the controller 16 may include, but is not limited to, (one or more) processors, (one or more) computers, (one or more) DSPs, memories, storage devices, (one or more) registers, timing, (one or more) interrupts, (one or more) communication interfaces, and input / output signal interfaces, etc., and combinations including at least one of the foregoing. For example, the controller 16 may include input signal processing and filtering to enable accurate sampling and conversion or acquisition of such signals from the vehicle's communication interface.

[0038] like Figure 2 Controller 16 may include any suitable controller as generally shown in FIG. 1 . Controller 16 may be configured to control, for example, various aspects of the vehicle (e.g., various aspects of the electric power steering system and / or other suitable features or components of the vehicle). Controller 16 may include a processor 60 and a memory 62.

[0039] The processor 60 may include any suitable processor, such as those described herein. Additionally or alternatively, the controller 16 may include any suitable number of processors in addition to or in addition to the processor 60. The memory 62 may include a single disk or multiple disks (e.g., a hard drive) and include a storage management module that manages one or more partitions within the memory 62. In some embodiments, the memory 62 may include flash memory, semiconductor (solid-state) memory, etc. The memory 62 may include random access memory (RAM), read-only memory (ROM), or a combination thereof. The memory 62 may include instructions that, when executed by the processor 60, cause the processor 60 to at least control various functions of the vehicle.

[0040] In some embodiments, the controller 16 can be configured to control various aspects of the motor (eg, the motor control system 200), such as Figure 3 . In some embodiments, as generally shown, the motor control system 200 may include a three-phase PMSM controller. However, the motor control system 200 may include any suitable number of phases. Additionally or alternatively, although the motor control system 200 is generally shown and described as being associated with a vehicle and its systems, the motor control system 200 may be configured to control any suitable application or be operatively associated with any suitable application in addition to (or in addition to) controlling the vehicle (e.g., the motor 19 may be used in any suitable application other than a vehicle, and the principles of the present disclosure may apply accordingly).

[0041] The present disclosure provides a motor control system 200 for controlling the operation of an electric machine (e.g., motor 19). However, the principles of the present disclosure may be applied to control other types of synchronous machines. The principles of the present disclosure may be used to control salient pole machines and / or non-salient pole machines. The principles of the present disclosure may be used to control wound rotor synchronous machines.

[0042] The current reference calculator 202 converts the torque command T c Converted into d / q current reference I dqc , the d / q current reference I dqc It is then sent to the current controller 206. The current controller 206 can be a feedback regulator that uses the current measurement, or a feed-forward compensator. The temperature T can be fed to the parameter compensator 204 to adjust the PMSM electrical parameters as needed. The current controller 206 then generates a d / q voltage command, which is equivalent to the commanded modulation index m i and phase advance angle δ. m i and δ are converted into equivalent duty cycle signals d for each of the three phases a, b, c by the duty cycle generator 210 of the power converter switching module 208. a db d c .

[0043] Once the equivalent duty cycle signal d is generated for each phase a d b d c , the pulse width modulator 212 generates corresponding on-times t for different switches (eg, FETs) in the phase arms of the power converter (eg, the inverter 216). a ,t b ,t c . Duty cycle signal d a d b d c Can be collectively labeled as d a,b,c , and the conduction time t a ,t b ,t c Can be collectively labeled as t a,b,c The inverter 216 powered by the power supply 214 then supplies the desired voltage to the motor (eg, motor 19), which generates a phase current I a ,I b ,I c and electromagnetic torque T e The inverter 216 is connected to the power supply 214 via a direct current (DC) bus 215. The position θ is then measured. r and phase current I a ,I b ,I c The current is fed back to the position sensor 220 and the current sensor 222 of the control system to close the control loop. a ,I b ,I c Can be collectively labeled as I a,b,c The measured position θ m Used together with the phase current to calculate the measured d / q current I dqm , which is used for closed-loop current control. Voltage source inverters (VSI) are commonly used as power converters in PMSM-based electric drives. Each phase of the motor 19 is connected to a corresponding phase arm of the inverter 216, and each phase arm may have two or more switches.

[0044] Although the actual machine design and construction are different for three-phase PMSM and multi-phase (greater than three-phase) PMSM, for all these machines the same principles of vector control in a synchronous or d / q reference frame are possible by using appropriate transformation matrices to convert the phase currents and voltages into equivalent DC quantities in the synchronous coordinate frame.

[0045] Figure 41 is a block diagram of an example algorithm 300 for controlling an electric machine according to aspects of the present disclosure. Specifically, the example algorithm 300 includes a torque arbitration block 302 configured to determine an arbitrated torque limit T based on several inputs. Arb , the input may include one or more of the following: voltage-based torque limit T Vltg ; Torque limit based on motor current T MotCurr ; Torque limit based on supply current T CurSply ; Torque limit T based on voltage and supply current VltgSply ; and torque limit T based on voltage and motor current VltgMotCurr .

[0046] The example algorithm 300 includes a voltage-based torque block 304 that is configured to constrain the voltage V of the DC bus 215 based on the voltage V DC To determine the voltage-based torque limit T Vltg . Voltage Constraint V DC The voltage constraint V DC The voltage at which the DC bus 215 is rated to operate may be included. The DC bus 215 is constrained by a voltage V DC Operating at voltages other than 200V may have adverse consequences, such as equipment failure and / or damage to hardware connected to the DC bus 215. In some embodiments, the voltage-based torque block 304 may use the following equation (1) (also referred to as the voltage equation) to determine the voltage-based torque limit T Vltg and / or voltage-based direct-axis current I dVltg Either or both of .

[0047]

[0048] The example algorithm 300 includes a motor current based torque block 306 configured to determine a torque limit T based on the motor current. MotCurr , the torque limit based on the motor current T MotCurr Corresponding to satisfying the motor current limit The motor current I supplied by the inverter 216 to the motor 19 m . Motor current limit This may include current limiting of the motor 19 and / or current limiting of the inverter 216. Motor Current Limiting The current limit of the motor 19 and the current limit of the inverter 216 may be the smaller one. In some embodiments, the motor current based torque block 306 may determine the motor current based torque limit T using the following equation (2) (also referred to as the motor current equation): MotCurr .

[0049]

[0050] The example algorithm 300 includes a torque based on supply current block 308 configured to determine a torque limit T based on supply current. CurSply , the torque limit based on the supply current T CurSply Corresponding to satisfying the supply current limit I slim The supply current I supplied from the DC bus 215 to the inverter 216 s In some embodiments, the torque based on supply current block 308 may determine the torque limit T based on supply current using the following equation (3) (also referred to as the power equation): CurSply .

[0051]

[0052] Among them, V d and I d are the d-axis voltage and d-axis current, V q and I q are the q-axis voltage and q-axis current, V dc is the bus voltage of the DC bus 215, I s is the supply current supplied from the DC bus 215 to the inverter 216, and R dc is the effective resistance of the DC bus 215 .

[0053] The example algorithm 300 also includes a voltage and supply current based torque block 310 configured to determine a torque that satisfies the voltage constraint V of the DC bus 215. DC Torque limit T based on voltage and supply current VltgSply , and wherein the supply current I supplied from the DC bus 215 to the inverter 216 s Meet the supply current limit I slim In some embodiments, the voltage and supply current based torque block 310 may determine a voltage constraint V that satisfies the DC bus 215 based on the intersection of the d-axis current and the q-axis current. DC and supply current limit I slim The torque limit T of each of the VltgSply .

[0054] The example algorithm 300 also includes a voltage and motor current based torque block 312 configured to determine a torque that satisfies the voltage constraint V of the DC bus 215. DC Torque limit T based on voltage and motor current VltgMotCurr , and wherein the motor current I between the inverter 216 and the motor 19 m Meet the motor current limit In some embodiments, the torque block 312 based on voltage and motor current can determine the D voltage constraint V that satisfies the DC bus 215 based on the intersection of the d-axis current and the q-axis current. DC and motor current limit The torque limit T based on the voltage and motor current of each VltgMotCurr .

[0055] The example algorithm 300 also includes a torque limit block 320 that is based on the commanded torque T Cmd and the arbitrated torque limit T from the torque arbitration block 302 Arb Determine the limited command torque T CmdLmtd The torque limit block 320 may be configured to limit the command torque T CmdLmtd Set to the commanded torque T Cmd and arbitration torque limit T Arb The smaller one.

[0056] The example algorithm 300 also includes a regenerative maximum d-axis current search block 321 configured to determine the maximum d-axis current I dmax and the d-axis current I used to generate peak torque dpeakTq , each of which satisfies the requirement for the regenerative current. The regenerative maximum d-axis current search block 321 can use the limited command torque T CmdLmtd To determine the maximum d-axis current I dmax and / or the d-axis current I used to generate peak torque dpeakTq One or both of them, each of which meets the requirement for regenerative current. The requirement for regenerative current may include a regenerative current limit I Regen , which is the maximum amount of current that the DC bus 215 can receive from the inverter 216. Exceeding the regenerative current limit I Regen Problems may result, such as overcharging a battery connected to the DC bus 215 .

[0057] In some embodiments, the regenerative maximum d-axis current search block 321 may determine the maximum d-axis current I using the following equation (4) (also referred to as the power equation): dmax and / or the d-axis current I used to generate peak torque dpeakTq One or both of them, each of which meets the requirement for regenerative current.

[0058]

[0059] Among them, I r is the regenerative current supplied from the inverter 216 to the DC bus 215. The regenerative current I r is the supply current I s The inverse of .

[0060] The example algorithm 300 also includes a maximum torque per ampere block 322 , which may be based on the limited command torque T CmdLmtd Determine the preliminary motor current value I′ dq . Preliminary motor current value I′ dq The optimization may be performed based on the maximum torque per ampere determination, which may include performing one or more calculations and / or other methods. The optimized motor current value I′ dq The preliminary d-axis current I′ may be included d and the preliminary q-axis current I′ q .

[0061] The example algorithm 300 also includes a d-axis current boost block 324, which may be configured to determine a minimum d-axis current I based on one or more of the following: dmin : Preliminary motor current value I′ dq , limited command torque T CmdLmtd , Maximum d-axis current I dmax and / or the d-axis current I used to generate peak torque dpeakTq .

[0062] The example algorithm 300 also includes a regeneration current search block 326, which may be configured to determine a modified motor current I″ dq , the modified motor current I″ dq Including the modified d-axis current I″ d and the modified q-axis current I″ q , which correspond to satisfying the regenerative current limit I of the DC bus 215 Regen The regenerative current search block 326 may determine the modified motor current I″ based on one or more of the following: dq : Minimum d-axis current I dmin , Regenerative current limit I Regen , limited command torque T CmdLmtd , Maximum d-axis current I dmax and / or the d-axis current I used to generate peak torque dpeakTq .

[0063] The example algorithm 300 also includes a maximum torque per voltage block 328, which may be configured to determine the d-axis current command I dCmd and q-axis current command I qCmd , the d-axis current command I dCmd and q-axis current command I qCmd The motor 19 can generate a command torque T that also satisfies the constraints CmdLmtd The maximum torque per voltage block 328 may determine the d-axis current command I based on one or more of the following: dCmdand / or q-axis current command I qCmd : Modified motor current I″ dq , limited command torque T CmdLmtd , Maximum d-axis current I dmax and / or the d-axis current I used to generate peak torque dpeakTq .

[0064] Figures 5A-5D A graph is shown which generally illustrates a method for searching for a voltage that satisfies a DC bus voltage constraint V according to the principles of the present disclosure. DC and motor current limit constraints Four different I d ,I q Trajectory.

[0065] Specifically, Figure 5A A first plot 350 is included which shows the calculated current limit to meet the motor current limit. The d-axis current I d and q-axis current I q The first plot line 350 is in the d-axis current I d The first q-axis current I based on the motor current equals to the predetermined minimum value qi1 With the d-axis current I d The second q-axis current I based on the motor current is equal to the predetermined maximum value. qi2 The predetermined minimum value may be, for example, zero or a positive or negative value that is less than the predetermined maximum value. Figure 5A Also included is a second plot line 352 that shows the calculated voltage V that satisfies the DC bus 215. DC The d-axis current I d and q-axis current I q The second plot line 352 is the d-axis current I d The first voltage-limited q-axis current I qv1 With the d-axis current I d The second voltage-limited q-axis current I qv2 Extend between.

[0066] Figure 5A The plot lines 350, 352 are shown for all d-axis currents I d The values ​​all have positive q-axis current I q The first plotted line 350 always has a corresponding q-axis current I smaller than the second plotted line 352. q The value of the q-axis current I q Therefore, in this case, the torque block 312 based on voltage and motor current can set the torque limit T based on voltage and motor current toVltgMotCurr Set equal to the torque limit based on motor current

[0067] Figure 5B A first plot line 354 is included which shows the calculated current limit to meet the motor current limit. The d-axis current I d and q-axis current I q The first plotted line 354 is in the d-axis current I d The first q-axis current I based on the motor current equals to the predetermined minimum value qi1 With the d-axis current I d The second q-axis current I based on the motor current is equal to the predetermined maximum value. qi2 Extend between. Figure 5B Also included is a second plot line 356 which shows the calculated voltage V that satisfies the DC bus 215. DC The d-axis current I d and q-axis current I q The second plot line 356 is the d-axis current I d The first voltage-limited q-axis current I qv1 With the d-axis current I d The second voltage-limited q-axis current I qv2 Extend between.

[0068] Figure 5B It is shown that both plot lines 354 and 356 are plotted for all d-axis currents I d The values ​​all have positive q-axis current I q The second plot line 356 always has a corresponding q-axis current I smaller than the first plot line 354. q The value of the q-axis current I q Therefore, in this case, the torque block 312 based on voltage and motor current can set the torque limit T based on voltage and motor current to VltgMotCurr Set equal to the voltage-based torque limit T Vltg .

[0069] Figure 5C A first plot line 358 is included which shows the calculated current limit to meet the motor current limit. The d-axis current I d and q-axis current I q The first plot line 358 is the d-axis current I d The first q-axis current I based on the motor current equals to the predetermined minimum value qi1 With the d-axis current I d The second q-axis current I based on the motor current is equal to the predetermined maximum value.qi2 Extend between. Figure 5C Also included is a second plot line 360 ​​that shows the calculated voltage constraint V of the DC bus 215 being satisfied. DC The d-axis current I d and q-axis current I q The second plot line 60 is the d-axis current I d The first voltage-limited q-axis current I qv1 With the d-axis current I d The second voltage-limited q-axis current I qv2 Extend between.

[0070] Figure 5C The depiction lines 358, 360 are shown in the region (I d ,I q Therefore, when the current-based curve and the voltage-based curve intersect, the final torque limit T pk The determination should be based on the intersection of the curves represented by the plot lines 358, 360. For example, the controller 16 may determine that the current limit corresponding to the motor current is The q-axis current is equal to the voltage constraint V corresponding to the DC bus 215 DC In the case of a q-axis current of (i.e., in the case where the plotted lines 358 and 360 intersect), the d-axis intersection current value I d_int The controller 16 can be based on the d-axis intersection current value I d_int To determine the final torque limit T pk For example, the controller 16 may determine the corresponding q-axis intersection current value I that satisfies the following two equations: q_int : used to meet the voltage constraint V of the DC bus 215 DC The voltage equation and the current limit for the motor The voltage equation may include the above equation (1); and the current equation may include the above equation (2). The corresponding q-axis intersection current value I q_int exist Figure 5C The controller 16 can then determine the d-axis intersection current value I based on the d-axis intersection current value I d_int The current value I intersecting the q axis q_int To determine the final torque limit T pk For example, the controller 16 can calculate the d-axis intersection current value I d_int The current value I intersecting the q axis q_int Substituting into the torque equation for calculating torque based on the d-axis current and the q-axis current to calculate the final torque limit T pk The torque equation may include the following equation (5),

[0071]

[0072] Among them, T e is the torque generated by motor 19, K e is the motor voltage constant, N p is the number of poles of motor 19, L d and L q are the d-axis inductance and q-axis inductance of the motor 19, and I d and I q They are the d-axis current and the q-axis current respectively.

[0073] Figure 5D A first plot line 362 is included which shows the calculated current limit to meet the motor current limit. The d-axis current I d and q-axis current I q The first plotted line 362 is at the d-axis current I d The first q-axis current I based on the motor current equals to the predetermined minimum value qi1 With the d-axis current I d The second negative q-axis current (not shown) based on the motor current extends between 0 and 100° and is equal to the predetermined maximum value. Figure 5D Also included is a second plot line 364 which shows the calculated voltage V that satisfies the DC bus 215. DC The d-axis current I d and q-axis current I q The second plot line 364 is the d-axis current I d The first voltage-limited q-axis current equal to the predetermined minimum value and the d-axis current I d The second voltage-limited q-axis current I qv2 The first voltage-limited q-axis current has a negative value and is not shown in the figure.

[0074] Figure 5D It is shown that for any d-axis current I d There is no q-axis current I less than or equal to each of the plot lines 362 and 364. q The value of the q-axis current I q Therefore, in this case, the torque block 312 based on voltage and motor current can set the torque limit T based on voltage and motor current to VltgMotCurr In other words, in the absence of a direct relationship between the two curves represented by the plotted lines 362, 364, the final torque limit T pk Can be set to zero.

[0075] Figure 6 A graph of applied torque and speed for a motor control system according to aspects of the present disclosure is depicted. Specifically, Figure 6 A diagram including four quadrants is depicted, wherein quadrants II and IV are each associated with the motor control system being in a regeneration mode.

[0076] Figure 7 A block diagram generally illustrates a regenerative current search algorithm 400 , which may be implemented in the regenerative maximum d-axis current search block 321 , in accordance with the principles of the present disclosure.

[0077] The regenerative current search algorithm 400 includes a voltage and torque intersection block 402 configured to use the limited command torque T CmdLmtd Determine the maximum d-axis current I based on voltage dmax(Vltg) The voltage and torque intersection block 402 may determine the voltage-based maximum d-axis current I based on known voltage characteristics of the motor 19 (eg, a PMSM). dmax(Vltg) , which corresponds to the limited command torque T at a given motor speed CmdLmtd The voltage and torque intersection block 402 can directly calculate the maximum d-axis current I based on the voltage using the formula or other numerical methods. dmax(Vltg) The voltage and torque intersection block 402 may determine the maximum d-axis current I based on the voltage using other methods (eg, using a lookup table, an estimation method, and / or using iterative modeling). dmax(Vltg) . As referenced below Fig. 9 As described, the voltage and torque intersection block 402 may be based on the command torque T corresponding to the limited CmdLmtd The maximum d-axis current I based on the voltage is determined by the intersection of the constant torque line of the motor and the set of d-axis current values ​​and q-axis current values ​​corresponding to the motor that satisfies the motor voltage constraint. dmax(Vltg) . Corresponding to the limited command torque T CmdLmtd The constant torque line is Fig. 9 The third depiction line 434 is shown and corresponds to satisfying the voltage constraint V of the DC bus 215. DC The d-axis current value and the q-axis current value of the inverter 216 are shown in Fig. 9 In the second drawing line 432.

[0078] The regeneration current search algorithm 400 also includes a motor current and torque intersection block 404, which is configured to use the limited command torque T CmdLmtd Determine the maximum d-axis current I based on the motor current dmax(MotCurr) The motor current and torque intersection block 404 may determine the maximum d-axis current I based on the motor current based on known characteristics of the motor 19 (eg, a PMSM). dmax(MotCurr) , which corresponds to the limited command torque T at a given motor speed CmdLmtdThe motor current and torque intersection block 404 can directly calculate the maximum d-axis current I based on the motor current using a formula or other numerical methods. dmax(MotCurr) The motor current and torque intersection block 404 may determine the maximum d-axis current I based on the motor current using other methods (eg, using a lookup table, an estimation method, and / or using iterative modeling). dmax(MotCurr) . As referenced below Fig. 9 As described, the motor current and torque intersection block 404 may be based on the command torque T corresponding to the limited CmdLmtd The maximum d-axis current I based on the motor current is determined by the intersection of the constant torque line of the motor and the set of d-axis current values ​​and q-axis current values ​​corresponding to the motor that satisfies the motor current constraint. dmax(MotCurr) .

[0079] The regeneration current search algorithm 400 also includes a comparison block 406 that compares the voltage-based maximum d-axis current I from the voltage and torque intersection block 402 to the maximum d-axis current I dmax(Vltg) The maximum d-axis current I based on the motor current from the motor current and torque intersection block 404 dmax(MotCurr) Compare to determine the maximum d-axis current intersection point I dmax(Interscn) value, which is the maximum d-axis current I based on the voltage dmax(Vltg) and the maximum d-axis current I based on the motor current dmax(MotCurr) The smaller one.

[0080] Figure 8 FIG. 1 is a schematic diagram generally showing a method for adjusting the maximum d-axis current I based on the quadrant of operation according to the principles of the present disclosure. dmax A block diagram of the algorithm 420. The maximum d-axis current I dmax It can also be written as I d(max) . Figure 8 The algorithm 420 includes a quadrant determination block 422 that determines the current quadrant of operation of the motor 19 (e.g., PMSM). For details on the four quadrants of operation, see the discussion above. Figure 6 .

[0081] Figure 8 The algorithm 420 also includes a motoring control block 424 configured to, in response to the quadrant determination block 422 determining that the motor 19 (e.g., PMSM) is operating in one of quadrants 1 or 3 (I or III), set the maximum d-axis current I dmax Set equal to the maximum d-axis current I based on the voltage dmax(Vltg) , indicating that the motor is operating in mechanical power generation mode, which may also be referred to as "motor drive".

[0082] Figure 8The algorithm 420 also includes a generating control block 426 configured to, in response to the quadrant determination block 422 determining that the motor 19 (eg, PMSM) is operating in one of quadrants 2 or 4 (II or IV), set the maximum d-axis current I dmax Set to be equal to the maximum d-axis current intersection point I dmax(Interscn) , indicating that the motor is operating in a mechanical power reduction mode, which can also be called "generation".

[0083] Fig. 9 A graph is shown generally illustrating the principles of a regeneration seek control algorithm in accordance with the principles of the present disclosure. Fig. 9 The graph includes the q-axis current I q (in amperes, A) and the d-axis current I d (in amperes, A). Specifically, Fig. 9 The graph shows a first plot line 430 of the motor current constraint, which corresponds to the motor current limit The combination of the d-axis current and the q-axis current. Fig. 9 A second plot line 432 of the motor voltage constraint is also shown, which is the voltage constraint V of the DC bus 215 that the inverter 216 satisfies when supplied to the motor. DC The combination of the d-axis current and the q-axis current. Fig. 9 Also shown is a third depiction of a constant torque line 434, which may represent the limited command torque T CmdLmtd The intersection of the first plot line 430 of the motor current constraint and the third plot line 434 of the constant torque line represents the x-axis (representing the d-axis current I d ) based on the maximum d-axis current I of the motor current dmax(MotCurr) Similarly, the intersection between the second plot line 432 of the motor voltage constraint and the third plot line 434 of the constant torque line represents the x-axis (representing the d-axis current I d ) based on the maximum d-axis current I dmax(Vltg) .

[0084] The systems and methods of the present disclosure may consider all constraints simultaneously and prioritize maximizing torque over regenerating current.

[0085] Fig.10 1 shows a flow chart generally illustrating a method 500 for controlling operation of an electric machine. The method 500 may prioritize implementation of a torque command over a regenerative current limit of the DC bus 215. At 502, the method 500 determines a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus that supplies power to an inverter to power the electric machine. For example, the processor 102 may execute instructions of the voltage-based torque block 304 to determine a voltage-based torque limit TVltg .

[0086] At 504, method 500 determines a motor current based torque limit based on the motor current limit. For example, processor 60 may execute instructions implementing motor current based torque block 306 to determine a torque limit corresponding to satisfying the motor current limit. The motor current I supplied by the inverter 216 to the motor 19 m Torque limit based on motor current T MotCurr .

[0087] At 506, method 500 determines a final torque limit based on: a voltage-based torque limit and a motor current-based torque limit. For example, processor 60 may execute instructions implementing torque arbitration block 302 to determine the final torque limit as the arbitrated torque limit T Arb .

[0088] At 508, method 500 determines a limited command torque based on the torque command and the final torque limit. For example, processor 60 may execute instructions implementing torque limit block 320 to limit the torque based on the commanded torque T c and arbitration torque limit T Arb Determine the limited command torque T CmdLmtd More specifically, the torque limit block 320 can limit the command torque T CmdLmtd Set to be limited not to exceed the arbitration torque limit T Arb The command torque T c .

[0089] At 510, the method 500 determines an initial current command for the inverter that corresponds to satisfying the regenerative current limit of the DC bus. For example, the processor 60 may execute instructions implementing the regenerative current search block 326 to determine an initial current command that includes, for example, a modified d-axis current I″ d and the modified q-axis current I″ q , which together correspond to satisfying the regenerative current limit I of the DC bus 215 Regen Inverter 216.

[0090] At 512 , method 500 calculates a final current command based on at least the limited command torque and the initial current command. For example, processor 60 may execute instructions to implement maximum torque per voltage block 328 to determine the d-axis current command I dCmd and q-axis current command I qCmd To make the motor 19 generate a command torque T that also satisfies the limitation CmdLmtdmaximum torque. Thus, the system and method may prioritize torque maximization over satisfying regenerative current constraints. This may be useful or necessary in safety critical applications, such as in EPS systems where satisfying peak torque demands (particularly over short time periods) may provide benefits that outweigh potential problems that may result from supplying regenerative current from the inverter to the DC bus in excess of the regenerative current limit of the DC bus. For example, such problems may include battery degradation. Potential problems caused by exceeding the regenerative current limit of the DC bus may be mitigated by operating characteristics of the system, which may include exceeding the regenerative current limit of the DC bus only for short time periods and / or exceeding the regenerative current limit of the DC bus only in rare circumstances that are unlikely to occur during normal operation.

[0091] A method for controlling the operation of an electric motor includes: determining a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus that supplies power to an inverter to power the electric motor; determining a motor current-based torque limit based on a motor current limit; determining a final torque limit based on: a voltage-based torque limit and a motor current-based torque limit; determining a limited command torque based on a torque command and a final torque limit; determining an initial current command for the inverter that corresponds to a regenerative current limit that satisfies the DC bus; and calculating a final current command based at least on the limited command torque and the initial current command, the final current command exceeding the initial current command to cause the electric motor to generate a torque corresponding to the limited torque command.

[0092] In some embodiments, the method of controlling operation of an electric machine further includes selectively controlling a plurality of switches within the inverter based on the final current command so that the inverter supplies current to the electric machine.

[0093] In some embodiments, the motor current limit includes a current limit of an inverter.

[0094] In some embodiments, the method of controlling operation of an electric machine further comprises: calculating a supply current based torque limit based on a supply current limit supplied to an inverter rated by the DC bus; and determining a final torque limit further comprises: determining the final torque limit based on the supply current based torque limit.

[0095] In some embodiments, determining the final torque limit includes arbitrating between a voltage-based torque limit and a motor current-based torque limit.

[0096] In some embodiments, arbitrating between the voltage-based torque limit and the motor-current-based torque limit further includes: determining a first motor-current-based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to the motor current limit; determining a second motor-current-based q-axis current corresponding to a d-axis current having a predetermined maximum value and corresponding to the motor current limit; determining a first voltage-limit-based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to a voltage constraint of a DC bus; determining a second voltage-limit-based q-axis current corresponding to a d-axis current having a predetermined maximum value and corresponding to a voltage constraint of the DC bus; determining one of the first motor-current-based q-axis current and the first voltage-limit-based q-axis current as a smaller value; determining one of the second motor-current-based q-axis current and the second voltage-limit-based q-axis current as a smaller value; and selecting one of the motor-current-based torque limit and the voltage-based torque limit based on one of the first motor-current-based q-axis current and the first voltage-limit-based q-axis current as a smaller value and based on one of the second motor-current-based q-axis current and the second voltage-limit-based q-axis current as a smaller value.

[0097] In some embodiments, selecting one of a motor current-based torque limit and a voltage-based torque limit further includes: selecting the motor current-based torque limit as the final torque limit in response to determining that a first motor current-based q-axis current is less than a first voltage-limited q-axis current and a second motor current-based q-axis current is less than a second voltage-limited q-axis current; and selecting the voltage-based torque limit as the final torque limit in response to determining that the first voltage-limited q-axis current is less than the first motor current-based q-axis current and the second voltage-limited q-axis current is less than the second motor current-based q-axis current.

[0098] In some embodiments, arbitrating between the voltage-based torque limit and the motor current-based torque limit further includes: determining a first motor current-based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to the motor current limit; determining a second motor current-based q-axis current corresponding to a d-axis current having a predetermined maximum value and corresponding to the motor current limit; determining a first voltage-limited q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to a voltage constraint of a DC bus; determining a second voltage-limited q-axis current corresponding to a d-axis current having a predetermined maximum value and corresponding to a voltage constraint of a DC bus; determining the first motor current-based q-axis current and the first voltage-limited q-axis current. flow as a smaller value; determining a second motor current-based q-axis current and a second voltage limit-based q-axis current as a smaller value; determining that the second motor current-based q-axis current and the second voltage limit-based q-axis current as a smaller value correspond to a different constraint than the first motor current-based q-axis current and the first voltage limit-based q-axis current as a smaller value; determining a d-axis intersection current value at which the q-axis current corresponding to the motor current limit is equal to the q-axis current corresponding to the voltage constraint of the DC bus; and determining a final torque limit based on the d-axis intersection current value and based on the q-axis current corresponding to each of the motor current limit and the voltage constraint of the DC bus.

[0099] A control system for controlling operation of an electric motor includes a processor and a memory including instructions. The instructions, when executed by the processor, cause the processor to: determine a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus that supplies power to an inverter to power the electric motor; determine a motor current-based torque limit based on a motor current limit; determine a final torque limit based on: the voltage-based torque limit and the motor current-based torque limit; determine a limited command torque based on a torque command and the final torque limit; calculate an initial current command for the inverter that corresponds to a regenerative current limit of the DC bus; and calculate a final current command based on at least the limited command torque and the initial current command, the final current command exceeding the initial current command to cause the electric motor to produce a torque corresponding to the limited torque command.

[0100] In some embodiments, the instructions further cause the processor to: selectively control a plurality of switches within the inverter based on the final current command to cause the inverter to supply current to the motor.

[0101] In some embodiments, the motor current limit includes a current limit of an inverter.

[0102] In some embodiments, the instructions further cause the processor to: calculate a supply current based torque limit based on a supply current limit that the DC bus is rated to supply to the inverter; and determining the final torque limit further comprises: determining the final torque limit based on the supply current based torque limit.

[0103] In some embodiments, determining the final torque limit includes the processor arbitrating between a voltage-based torque limit and a motor current-based torque limit.

[0104] In some embodiments, arbitrating between a voltage-based torque limit and a motor-current-based torque limit further includes instructions causing the processor to: determine a first motor-current-based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to a motor current limit; determine a second motor-current-based q-axis current corresponding to a d-axis current having a predetermined maximum value and corresponding to the motor current limit; determine a first voltage-limit-based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to a voltage constraint of a DC bus; determine a second voltage-limit-based q-axis current corresponding to a d-axis current having a predetermined maximum value and corresponding to a voltage constraint of the DC bus; determine one of the first motor-current-based q-axis current and the first voltage-limit-based q-axis current as a smaller value; determine one of the second motor-current-based q-axis current and the second voltage-limit-based q-axis current as a smaller value; and select one of the motor-current-based torque limit and the voltage-based torque limit based on one of the first motor-current-based q-axis current and the first voltage-limit-based q-axis current as a smaller value and based on one of the second motor-current-based q-axis current and the second voltage-limit-based q-axis current as a smaller value.

[0105] In some embodiments, selecting one of a motor current-based torque limit and a voltage-based torque limit also includes instructions causing the processor to: select the motor current-based torque limit as the final torque limit in response to determining that a first motor current-based q-axis current is less than a first voltage-limited q-axis current and a second motor current-based q-axis current is less than a second voltage-limited q-axis current, and select the voltage-based torque limit as the final torque limit in response to determining that the first voltage-limited q-axis current is less than the first motor current-based q-axis current and the second voltage-limited q-axis current is less than the second motor current-based q-axis current.

[0106] In some embodiments, arbitrating between a voltage-based torque limit and a motor current-based torque limit further includes instructions causing the processor to: determine a first motor current-based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to the motor current limit; determine a second motor current-based q-axis current corresponding to a d-axis current having a predetermined maximum value and corresponding to the motor current limit; determine a first voltage-limited q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to a voltage constraint of a DC bus; determine a second voltage-limited q-axis current corresponding to a d-axis current having a predetermined maximum value and corresponding to a voltage constraint of a DC bus; determine a first motor current-based q-axis current and a first voltage-limited q-axis current corresponding to a d-axis current having a predetermined maximum value and corresponding to a voltage constraint of a DC bus; determine a first motor current-based q-axis current and a first voltage-limited q-axis current corresponding to a d-axis current having a predetermined maximum value and corresponding to a voltage constraint of a DC bus; determine a first motor current-based q-axis current and a first voltage-limited q-axis current corresponding to a d-axis current having a predetermined maximum value and corresponding to a voltage constraint of a DC bus; determine a first motor current-based q-axis current and a second motor current-based ... determining one of the second motor-current-based q-axis current and the second voltage-limit-based q-axis current as the smaller value; determining one of the second motor-current-based q-axis current and the second voltage-limit-based q-axis current as the smaller value to correspond to a different constraint than the first motor-current-based q-axis current and the first voltage-limit-based q-axis current as the smaller value; determining a d-axis intersection current value at which the q-axis current corresponding to the motor current limit is equal to the q-axis current corresponding to the voltage constraint of the DC bus; and determining a final torque limit based on the d-axis intersection current value and based on the q-axis current corresponding to each of the motor current limit and the voltage constraint of the DC bus.

[0107] A control system for controlling the operation of an electric motor includes an inverter and a controller. The inverter includes a plurality of switches operable to supply alternating current to the electric motor. The controller is operable to: determine a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus that supplies power to the inverter to power the electric motor; determine a motor current-based torque limit based on a motor current limit; determine a final torque limit based on: a voltage-based torque limit and a motor current-based torque limit; determine a limited command torque based on a torque command and a final torque limit; determine an initial current command of the inverter corresponding to a regenerative current limit of the DC bus; and calculate a final current command based on at least the limited command torque and the initial current command, the final current command exceeding the initial current command to cause the electric motor to produce a torque corresponding to the limited torque command.

[0108] In some embodiments, the motor current limit includes a current limit of an inverter.

[0109] In some embodiments, the controller is further operable to: calculate a supply current based torque limit based on a supply current limit of the DC bus rated to supply the inverter; and determining the final torque limit further comprises: the controller determining the final torque limit based on the supply current based torque limit.

[0110] In some embodiments, determining the final torque limit includes the controller arbitrating between a voltage-based torque limit and a motor current-based torque limit.

[0111] The above discussion is intended to illustrate the principles and various embodiments of the present disclosure. Once the above disclosure is fully understood, many changes and modifications will become apparent to those skilled in the art. It is intended that the following claims be interpreted to include all such changes and modifications.

[0112] The word "example" is used herein to mean used as an example, instance or illustration. Any aspect or design described herein as an "example" is not necessarily to be interpreted as being more preferred or advantageous than other aspects or designs. On the contrary, the use of the word "example" is intended to present the concept in a specific way. As used in this application, the term "or" is intended to represent an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clearly seen from the context, "X includes A or B" is intended to represent any natural inclusive arrangement. That is, if X includes A; X includes B; or X includes both A and B, then "X includes A or B" is satisfied in any of the foregoing cases. In addition, the article "a / an" used in this application and the appended claims should generally be interpreted as meaning "one or more", unless otherwise specified or clearly pointed to the singular form from the context. In addition, unless so described, the use of the term "embodiment" or "one embodiment" throughout the text is not intended to represent the same embodiment or embodiment.

[0113] The implementation of the systems, algorithms, methods, instructions, etc. described herein may be implemented in hardware, software, or any combination thereof. The hardware may include, for example, a computer, an intellectual property (IP) core, an application specific integrated circuit (ASIC), a programmable logic array, an optical processor, a programmable logic controller, microcode, a microcontroller, a server, a microprocessor, a digital signal processor, or any other suitable circuit. In the claims, the term "processor" shall be understood to include any of the foregoing hardware, alone or in combination. The terms "signal" and "data" are used interchangeably.

[0114] As used herein, the term module may include a packaged functional hardware unit designed for use with other components, a set of instructions executable by a controller (e.g., a processor executing software or firmware), a processing circuit configured to perform a specific function, and a self-contained hardware or software component that interfaces with a larger system. For example, a module may include an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), an electrical circuit, a digital logic circuit, an analog circuit, a combination of discrete circuits, gate circuits, and other types of hardware, or a combination thereof. In other embodiments, a module may include a memory that stores instructions executable by a controller to implement the features of the module.

[0115] Furthermore, in one aspect, for example, the systems described herein may be implemented using a general purpose computer or general purpose processor with a computer program that, when executed, performs any corresponding method, algorithm, and / or instruction described herein. Additionally or alternatively, for example, a special purpose computer / processor may be utilized that may include other hardware for performing any method, algorithm, or instruction described herein.

[0116] In addition, all or part of the implementation of the present disclosure may take the form of a computer program product accessible from, for example, a computer usable or computer readable medium. A computer usable or computer readable medium may be, for example, any device that can tangibly contain, store, communicate, or transport a program for use by or in conjunction with any processor. The medium may be, for example, an electronic, magnetic, optical, electromagnetic device, or a semiconductor device. Other suitable media may also be used.

[0117] The above embodiments, implementations and aspects have been described to allow easy understanding of the present disclosure and are not intended to limit the present disclosure. On the contrary, the present disclosure is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope should be given the broadest interpretation to cover all such modifications and equivalent structures permitted by law.

Claims

1. A method of controlling the operation of a motor, comprising: determining a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus supplying power to an inverter for powering the motor; determining a motor current-based torque limit based on the motor current limit; determining a final torque limit based on: the voltage-based torque limit and the motor current-based torque limit; determining a limited command torque based on the torque command and the final torque limit; determining an initial current command for the inverter corresponding to satisfying a regenerative current limit of the DC bus; as well as A final current command is calculated based on at least the limited command torque and the initial current command, the final current command exceeding the initial current command to cause the electric machine to generate a torque corresponding to the limited command torque.

2. The method according to claim 1, further comprising: A plurality of switches within the inverter are selectively controlled based on the final current command to cause the inverter to supply current to the motor.

3. The method according to claim 1, wherein: The motor current limit includes a current limit of the inverter.

4. The method according to claim 1, further comprising: calculating a supply current based torque limit based on a supply current limit that the DC bus is rated to supply to the inverter; as well as Wherein, determining the final torque limit further comprises: determining the final torque limit based on the torque limit based on the supply current.

5. The method according to claim 1, wherein: Determining the final torque limit includes arbitrating between the voltage-based torque limit and the motor current-based torque limit.

6. The method according to claim 5, wherein: Arbitrating between the voltage-based torque limit and the motor current-based torque limit further includes: determining a first motor-current-based q-axis current corresponding to the d-axis current having a predetermined minimum value and corresponding to the motor current limit; determining a second motor-current-based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to the motor current limit; determining a first voltage-limited based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to a voltage constraint of the DC bus; determining a second voltage-limited based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to a voltage constraint of the DC bus; determining one of the first motor current-based q-axis current and the first voltage limit-based q-axis current as a smaller value; determining one of the second motor current-based q-axis current and the second voltage limit-based q-axis current as a smaller value; and One of the motor current-based torque limit and the voltage-based torque limit is selected based on the smaller one of the first motor current-based q-axis current and the first voltage-limit-based q-axis current and based on the smaller one of the second motor current-based q-axis current and the second voltage-limit-based q-axis current.

7. The method according to claim 6, wherein: Selecting one of the motor current based torque limit and the voltage based torque limit further comprises: selecting the motor current-based torque limit as the final torque limit in response to determining that the first motor current-based q-axis current is less than the first voltage-limit-based q-axis current and the second motor current-based q-axis current is less than the second voltage-limit-based q-axis current; and In response to determining that the first voltage-limited q-axis current is less than the first motor-current-based q-axis current and the second voltage-limited q-axis current is less than the second motor-current-based q-axis current, the voltage-based torque limit is selected as the final torque limit.

8. The method according to claim 5, wherein: Arbitrating between the voltage-based torque limit and the motor current-based torque limit further includes: determining a first motor-current-based q-axis current corresponding to the d-axis current having a predetermined minimum value and corresponding to the motor current limit; determining a second motor-current-based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to the motor current limit; determining a first voltage-limited based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to a voltage constraint of the DC bus; determining a second voltage-limited based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to a voltage constraint of the DC bus; determining one of the first motor current-based q-axis current and the first voltage limit-based q-axis current as a smaller value; determining one of the second motor current-based q-axis current and the second voltage limit-based q-axis current as a smaller value; determining that the smaller one of the second motor current-based q-axis current and the second voltage limit-based q-axis current corresponds to a different constraint than the smaller one of the first motor current-based q-axis current and the first voltage limit-based q-axis current; determining a d-axis intersection current value at which a q-axis current corresponding to the motor current limit is equal to a q-axis current corresponding to a voltage constraint of the DC bus; and The final torque limit is determined based on the d-axis intersecting current value and based on a q-axis current corresponding to each of a motor current limit and a voltage constraint of a DC bus.

9. A control system for controlling the operation of a motor, comprising: processor; as well as a memory comprising instructions which, when executed by the processor, cause the processor to: determining a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus supplying power to an inverter for powering the motor; determining a motor current-based torque limit based on the motor current limit; determining a final torque limit based on: the voltage-based torque limit and the motor current-based torque limit; determining a limited command torque based on the torque command and the final torque limit; calculating an initial current command for the inverter corresponding to satisfying a regenerative current limit of the DC bus; as well as A final current command is calculated based on at least the limited command torque and the initial current command, the final current command exceeding the initial current command to cause the electric machine to generate a torque corresponding to the limited command torque.

10. The control system according to claim 9, wherein: The instructions further cause the processor to selectively control a plurality of switches within the inverter based on the final current command to cause the inverter to supply current to the motor.

11. The control system according to claim 9, wherein: The motor current limit includes a current limit of the inverter.

12. The control system according to claim 9, wherein: The instructions further cause the processor to: calculate a supply current based torque limit based on a supply current limit of the DC bus rated to supply the inverter; as well as Wherein, determining the final torque limit further comprises: the processor determining the final torque limit based on the supply current based torque limit.

13. The control system according to claim 9, wherein: Determining the final torque limit includes the processor arbitrating between the voltage-based torque limit and the motor current-based torque limit.

14. The control system according to claim 13, wherein: Arbitrating between the voltage-based torque limit and the motor current-based torque limit further comprises the instructions causing the processor to: determining a first motor-current-based q-axis current corresponding to the d-axis current having a predetermined minimum value and corresponding to the motor current limit; determining a second motor-current-based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to the motor current limit; determining a first voltage-limited based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to a voltage constraint of the DC bus; determining a second voltage-limited based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to a voltage constraint of the DC bus; determining one of the first motor current-based q-axis current and the first voltage limit-based q-axis current as a smaller value; determining one of the second motor current-based q-axis current and the second voltage limit-based q-axis current as a smaller value; as well as One of the motor current-based torque limit and the voltage-based torque limit is selected based on the smaller one of the first motor current-based q-axis current and the first voltage-limit-based q-axis current and based on the smaller one of the second motor current-based q-axis current and the second voltage-limit-based q-axis current.

15. The control system according to claim 14, wherein: Selecting one of the motor current based torque limit and the voltage based torque limit further comprises the instructions causing the processor to: selecting the motor current-based torque limit as the final torque limit in response to determining that the first motor current-based q-axis current is less than the first voltage-limit-based q-axis current and the second motor current-based q-axis current is less than the second voltage-limit-based q-axis current; as well as In response to determining that the first voltage-limited q-axis current is less than the first motor-current-based q-axis current and the second voltage-limited q-axis current is less than the second motor-current-based q-axis current, the voltage-based torque limit is selected as the final torque limit.

16. The control system according to claim 13, wherein: Arbitrating between the voltage-based torque limit and the motor current-based torque limit further comprises the instructions causing the processor to: determining a first motor-current-based q-axis current corresponding to the d-axis current having a predetermined minimum value and corresponding to the motor current limit; determining a second motor-current-based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to the motor current limit; determining a first voltage-limited based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to a voltage constraint of the DC bus; determining a second voltage-limited based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to a voltage constraint of the DC bus; determining one of the first motor current-based q-axis current and the first voltage limit-based q-axis current as a smaller value; determining one of the second motor current-based q-axis current and the second voltage limit-based q-axis current as a smaller value; determining that the smaller one of the second motor current-based q-axis current and the second voltage limit-based q-axis current corresponds to a different constraint than the smaller one of the first motor current-based q-axis current and the first voltage limit-based q-axis current; determining a d-axis intersection current value at which a q-axis current corresponding to the motor current limit is equal to a q-axis current corresponding to a voltage constraint of the DC bus; as well as The final torque limit is determined based on the d-axis intersecting current value and based on a q-axis current corresponding to each of a motor current limit and a voltage constraint of a DC bus.

17. A control system for controlling the operation of a motor, comprising an inverter including a plurality of switches operable to supply alternating current to the motor; as well as A controller operable to: determining a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus supplying power to an inverter for powering the motor; determining a motor current-based torque limit based on the motor current limit; determining a final torque limit based on: the voltage-based torque limit and the motor current-based torque limit; determining a limited command torque based on the torque command and the final torque limit; determining an initial current command for the inverter corresponding to satisfying a regenerative current limit of the DC bus; as well as A final current command is calculated based on at least the limited command torque and the initial current command, the final current command exceeding the initial current command to cause the electric machine to generate a torque corresponding to the limited command torque.

18. The control system according to claim 17, wherein: The motor current limit includes a current limit of the inverter.

19. The control system according to claim 17, wherein: The controller is further operable to: calculate a supply current based torque limit based on a supply current limit of the DC bus rated to supply the inverter; as well as Wherein, determining the final torque limit further comprises: the controller determining the final torque limit based on the supply current-based torque limit.

20. The control system of claim 17, wherein: Determining a final torque limit includes the controller arbitrating between the voltage-based torque limit and the motor current-based torque limit.

Images