SYNCHRONIZED TORQUE PULSATIONS FOR ELECTRIC DRIVE SYSTEMS

Abstract

Systems and methods for commanding an electric propulsion system for an electric or hybrid vehicle are described. In one example, the propulsion system is commanded by a controller that provides synchronized pulsed torque commands whose magnitude and / or phase vary depending on the timing of a vehicle operator requesting constant driver demand torque.

Description

field of technology

[0001] The present description relates to methods and a system for controlling a torque of two electric machines in an electric drive system. background

[0002] Some electric drive systems may be equipped with two electric machines. For example, a four-wheel-drive electric vehicle may include a first electric machine that selectively provides torque to a vehicle's front wheels and a second electric machine that selectively provides torque to the vehicle's rear wheels. Two electric machines in an electric drive system can offer the potential to increase the vehicle's driving dynamics and performance. However, operating two electric machines in an electric drive system can result in increased losses, reducing a vehicle's driving range.

[0003] The foregoing background is provided to introduce, in simplified form, a selection of concepts that are described in more detail in the Detailed Description. It is not intended to identify important features of the claimed subject matter, the scope of which is defined solely by the claims that follow the Detailed Description. Furthermore, the claimed subject matter is not limited to implementations that overcome any of the disadvantages noted above or in any part of this disclosure. Brief description

[0004] The disclosure provides a description of an electric drive system comprising: an electric drive system including a first inverter, a first electric machine, a second inverter, a second electric machine; and one or more controllers including executable instructions stored in non-transitory memory that cause the one or more controllers to generate synchronized pulsed torque commands for the first electric machine and the second electric machine, and other possible modifications and variations.

[0005] It further describes that by generating synchronized pulsed torque commands for a first electric machine and a second electric machine, it may be possible to reduce losses of an electric drive system while maintaining a lower noise and vibration level compared to operating the first and second electric machines according to asynchronous torque pulse commands. Furthermore, the loss reduction of the electric drive system may be further reduced if the asynchronous torque pulses are generated based on a loss allocation for an electric drive system that includes two electric machines instead of a single electric machine.

[0006] The disclosure also provides a description of a method for an electric drive system, comprising: generating synchronized pulsed torque commands for a first electric machine and a second electric machine, wherein the synchronized pulsed torque commands for the first electric machine have a first frequency and wherein the synchronized pulsed torque commands for the second electric machine have the first frequency and other possible modifications and variations. Short description of the drawings

[0007] The advantages described herein will become more fully apparent from reading an example of an embodiment, referred to herein as the detailed description, when read alone or with reference to the drawings, in which: Fig. Figure 1 is a schematic diagram of a vehicle incorporating two electric machines for propulsion; Fig. 2 is a block diagram of a controller that provides a pulsed torque signal to an electric drive system including an electric machine; Fig. 3 and Fig. 4 show the operating ranges of an electrical machine in which losses of an electrical machine can be reduced; Fig. 5 shows a block diagram of a method for synchronizing pulsed operation of two electrical machines; Fig. 6-12 show sequences of ways in which synchronized torque pulsation commands can be set; Fig. Figure 13 shows a method that synchronizes torque pulsations at a pulsating event level; Fig. 14-17 show graphs of additional ways in which synchronized torque pulsation commands can be set; Fig. 18 shows a block diagram of a method for synchronizing torque pulsations according to vehicle operating conditions; and Fig. Figure 19 shows a detailed view of an example pulsed torque command. Detailed description

[0008] The present description relates to the efficiency of an electric drive system that includes two electric machines. The efficiency of the electric drive system can be increased by issuing commands to the electric drive systems via synchronized pulsed torque command signals. The pulsed torque command signals can be output by a controller when the electric machines are operating within a range of predetermined operating conditions to increase the efficiency of the electric drive system. The pulsed torque command signals can be used in a vehicle of the type described in Fig. 1. The pulsed torque command signals can be generated via a controller and input into an electric drive system as shown in the block diagram of Fig. 2. The pulsed torque commands can provide the efficiencies required in Fig. 3 and Fig. 4 are shown. The Fig. 5, Fig. 13 and Fig. 18 show methods for generating and delivering synchronized torque pulsations to two electric machines of an electric drive system. Fig. Figures 6-12 and 14-17 show how torque pulsations can be synchronized to increase the efficiency of the electric drive. Finally, Fig. 19 a detailed view of a portion of a pulsed torque request.

[0009] An electric drive system including two electric machines may disable pulsed torque commands to the two electric machines according to a mapping describing electric drive system losses for each of the electric machines to increase the efficiency of the electric drive system.

[0010] Furthermore, one of the two electric machines may be turned off at lower electric machine speeds and loads, under the assumption that turning off one of the electric machines would increase the efficiency of the electric drive system. However, the present inventors have determined that turning off one of the electric machines according to a mapping describing electric drive losses for each of the electric machines may increase the losses of the electric drive system. Furthermore, during some operating conditions, providing asynchronous torque pulsations to two electric machines may generate more noise and vibration than may be desired.

[0011] The inventors of the present invention have recognized the aforementioned problems and developed an electric drive system comprising: an electric drive system including a first inverter, a first electric machine, a second inverter, a second electric machine; and one or more controllers including executable instructions stored in non-transitory memory that cause the one or more controllers to generate synchronized pulsed torque commands for the first electric machine and the second electric machine.

[0012] By generating synchronized pulsed torque commands for a first electric machine and a second electric machine, it may be possible to reduce losses of an electric drive system while maintaining a lower noise and vibration level compared to operating the first and second electric machines according to asynchronous torque pulse commands. Furthermore, the loss reduction of the electric drive system may be further reduced if the asynchronous torque pulses are generated based on a loss allocation for an electric drive system that includes two electric machines instead of a single electric machine.

[0013] The present description can provide several advantages. In particular, the approach can be useful for extending a vehicle's driving range. Furthermore, the approach can reduce the likelihood of generating noise and vibration harmonics that may be unpleasant for vehicle occupants. Furthermore, the approach can provide smoother torque generation and reduced losses of the electric drive system.

[0014] The above advantages, as well as other advantages and features of the present description, will be readily apparent from the following detailed description when read alone or in conjunction with the accompanying drawings.

[0015] Fig. 1 illustrates an exemplary vehicle propulsion system 100 for a vehicle 121. A front portion of the vehicle 121 is indicated at 110 and a rear portion of the vehicle 121 is indicated at 111. The vehicle propulsion system 100 includes two power sources, including a front electric machine 125 and a rear electric machine 126. The electric machines 125 and 126 may consume or generate electrical power depending on their operating mode. Fig. 1, mechanical connections between different components are illustrated as solid lines, whereas electrical connections between different components are illustrated as dashed lines.

[0016] The vehicle propulsion system 100 includes a front axle 133 and a rear axle 122. In some examples, the rear axle may include two half-shafts, for example, a first half-shaft 122a and a second half-shaft 122b. Likewise, the front axle 133 may include a first half-shaft 133a and a second half-shaft 133b. The vehicle propulsion system 100 further includes front wheels 130 and rear wheels 131. In this example, the front wheels 130 may be selectively driven via the electric machine 125. The rear wheels 131 may be driven via the electric machine 126.

[0017] The rear axle 122 is coupled to the electric machine 126. A rear drive unit 136 may transfer power from the electric machine 126 to the axle 122, resulting in rotation of the drive wheels 131. The rear drive unit 136 may include a set of 175 small gears and a large gear 177 coupled to the electric machine 126 via an output shaft 126a of the rear electric machine 126. The set of 175 small gears may be engaged via a full closure of a clutch 176 of the small gears. The large gear 177 may be engaged via a full closure of a clutch 178 of a large gear. The large gear clutch 177 and the small gear clutch 178 may be opened and closed via instructions received from the rear drive unit 136 via a CAN 299.Alternatively, the large gear clutch 177 and the small gear clutch 178 may be opened and closed via digital outputs or pulse widths provided via the control system 14. The rear drive unit 136 may include a differential 128 so that torque can be provided to the axle 122a and the axle 122b. In some examples, an electrically controlled differential clutch (not shown) may be included in the rear drive unit 136.

[0018] The front axle 133 is coupled to the electric machine 125. A front drive unit 137 can transfer power from the electric machine 125 to the axle 133, resulting in rotation of the drive wheels 130. The front drive unit 137 can include a set of 170 small gears and a large gear 173 coupled to the electric machine 125 via an output shaft 125a of the front electric machine 125. The set of 170 small gears can be engaged via a full closure of a clutch 171 of the small gears. The large gear 173 can be engaged via a full closure of a clutch 174 of a large gear. The large gear clutch 174 and the small gear clutch 171 can be opened and closed via commands received by the front drive unit 137 via the CAN 299.Alternatively, the large gear clutch 174 and the small gear clutch 171 may be opened and closed via digital outputs or pulse widths provided via the control system 14. The front drive unit 137 may include a differential 127 so that torque may be provided to the axles 133a and 133b. In some examples, an electrically controlled differential clutch (not shown) may be included in the rear drive unit 137.

[0019] The electric machines 125 and 126 can receive electrical power from the on-vehicle electrical energy storage device 132. Furthermore, the electric machines 125 and 126 can provide a generator function to convert the vehicle's kinetic energy into electrical energy, which electrical energy can be stored in the electrical energy storage device 132 for later use by the electric machine 125 and / or the electric machine 126. A first inverter system controller (ISC1) 134 can convert alternating current generated by the rear electric machine 126 to direct current for storage in the electrical energy storage device 132, and vice versa. The first inverter system controller 134 can include a processor 134a, memory 134b (e.g., random access memory, exclusive read memory), input / output circuits 134c (e.g.,digital inputs / outputs, analog inputs / outputs, transistors, etc.). A second inverter system controller (ISC2) 147 may convert alternating current generated by the front electric machine 125 to direct current for storage in the electrical energy storage device 132, and vice versa. The second inverter system controller may include a processor 147a, memory 147b (e.g., random access memory, exclusive read memory), input / output circuits 147c (e.g., digital inputs / outputs, analog inputs / outputs, transistors, etc.). The electrical energy storage device 132 may be a battery, a capacitor, an inductor, or other electrical energy storage device.

[0020] In some examples, the electrical energy storage device 132 may be configured to store electrical energy that may be supplied to other electrical loads onboard the vehicle (other than the engine), including the interior heating and air conditioning, engine starting, headlights, interior audio and video systems, etc.

[0021] A control system 14 may communicate with one or more of the electric machine 125, the electric machine 126, the energy storage device 132, etc. The control system 14 may receive sensory feedback information from one or more of the electric machine 125, the electric machine 126, the energy storage device 132, etc. Further, the control system 14 may send control signals (e.g., torque commands) to the inverter controllers 147 and 134 to operate the electric machine 125 and the electric machine 126. The control system 14 may also issue control commands to the energy storage device 132, etc. in response to this sensory feedback. The control system 14 may receive an indication of an operator-requested output of the vehicle propulsion system from a human operator 102 or an autonomous controller.For example, control system 14 may receive sensory feedback from a pedal position sensor 194 that communicates with a pedal 192. Pedal 192 may schematically refer to a driver demand pedal. Likewise, control system 14 may receive an indication of an operator-requested vehicle deceleration via a human operator 102 or an autonomous controller. For example, control system 14 may receive sensory feedback from a pedal position sensor 157 that communicates with a brake caliper application pedal 156.

[0022] Energy storage device 132 may periodically receive electrical energy from a power source, such as a stationary power grid (not shown), that is external to the vehicle (e.g., not part of the vehicle). As a non-limiting example, vehicle propulsion system 100 may be configured as a plug-in electric vehicle (EV), whereby electrical energy may be supplied to energy storage device 132 via the power grid (not shown).

[0023] The electrical energy storage device 132 includes an electrical energy storage device controller 139 and a power distribution module 138. The electrical energy storage device controller 139 can provide charge balancing between energy storage elements (e.g., battery cells) and communication with other vehicle controllers (e.g., controller 12). The power distribution module 138 controls the flow of power into and out of the electrical energy storage device 132.

[0024] One or more wheel speed sensors (WSS) 195 may be coupled to one or more wheels of the vehicle propulsion system 100. The wheel speed sensors may detect the rotational speed of each wheel. One such example of a WSS may include a permanent magnet sensor.

[0025] The vehicle propulsion system 100 may further include a motor electronics coolant pump (MECP) 146. The MECP 146 may be used to circulate a coolant to dissipate heat generated by at least one electric machine 120 of the vehicle propulsion system 100 and the electronics system. As one example, the MECP may receive electrical power from the onboard energy storage device 132.

[0026] The controller 12 may comprise a portion of a control system 14. In some examples, the controller 12 may be a single controller of the vehicle. The control system 14 is shown receiving information from a plurality of sensors 16 (various examples of which are described herein) and sending control signals to a plurality of actuators 81 (various examples of which are described herein). As one example, the sensors 16 may include wheel pressure sensor(s) (not shown), wheel speed sensor(s) 195, etc. In some examples, sensors associated with the electric machine 125, the electric machine 126, the wheel speed sensor 195, etc. may communicate information to the controller 12 regarding various states of electric machine operation. The controller 12 includes a non-transitory (e.g.,Read-only memory) 165, a random access memory 166, digital inputs / outputs 168 and a microcontroller 167.

[0027] The vehicle propulsion system 100 may also include an on-board navigation system 17 (e.g., a global positioning system) on an instrument panel 19 with which a vehicle operator can interact. The navigation system 17 may include one or more location sensors to assist in estimating a location (e.g., geographic coordinates) of the vehicle. For example, the on-board navigation system 17 may receive signals from GPS satellites (not shown) and identify the geographic location of the vehicle based on the signal. In some examples, the geographic location coordinates may be communicated to the controller 12.

[0028] The instrument panel 19 may further include a display system 18 configured to display information to the vehicle operator. The display system 18 may include, as a non-limiting example, a touchscreen or a human-machine interface (HMI) display that allows the vehicle operator to view graphical information as well as input commands. In some examples, the display system 18 may be wirelessly connected to the internet (not shown) via a controller (e.g., 12). Accordingly, in some examples, the vehicle operator may communicate with a website or a software application (app) via the display system 18.

[0029] The instrument panel 19 may further include an operator interface 15 through which the operator can adjust the operating status of the vehicle. Specifically, the operator interface 15 may be configured to initiate and / or terminate operation of the vehicle's powertrain (e.g., the electric machine 125 and the electric machine 126) based on an operator input. Various examples of the operator interface 15 may include interfaces that utilize a physical device, such as an active key that can be inserted into the operator interface 15 to start the electric machines 125 and 126 and turn on the vehicle, or removed to turn off the electric machines 125 and 126 and turn off the vehicle. Other examples may include a passive key communicatively coupled to the operator interface 15.The passive key may be configured as an electronic remote key or a smart key that does not need to be inserted into or removed from the interface 15 to operate the vehicle's electric machines 125 and 126. Instead, the passive key may be located in or near the vehicle (e.g., within a threshold distance from the vehicle). Still other examples may additionally or optionally utilize a start / stop button manually pressed by the operator to start or stop the electric machines 125 and 126 and to turn the vehicle on or off.In other examples, a remote start of the electric machine may be initiated via a remote computing device (not shown), for example, a mobile phone or a smartphone-based system, where a user's mobile phone sends data to a server and the server communicates with the vehicle controller 12 to start the electric machines.

[0030] Referring to Fig. 2, a block diagram 200 of a controller 112 is shown that provides a synchronized pulsed torque signal or synchronized pulsed torque commands to two electric drive systems, each including an electric machine. The controller 112 includes a torque pulsation algorithm that implements one or more of the methods of Fig. 5, Fig. 13 and Fig. 18. The controller 112 may be configured as executable instructions executable in the controller 12 of the Fig. 1 are stored. Alternatively, two controllers similar to controller 112, but each outputting a single pulsed torque signal or a single pulsed torque command, may be provided to generate torque signals or commands for each of the inverter system controllers 147 and 134. Controller 112 includes a torque pulsation algorithm 208 and a continuous torque algorithm 205. Torque pulsation algorithm 208 may be activated under selected operating conditions, such as those described in Fig. 4. The continuous torque algorithm 205 may be activated during other operating conditions. The continuous torque algorithm outputs a torque demand that is continuous rather than pulsed. In some examples, the Fig. 1, a controller 112 may be provided within each of the inverter system controller 147 and the inverter system controller 134. For such embodiments, the controllers 112 may communicate torque pulsation information (e.g., signal or command timing, amplitudes, frequencies, duty cycles, etc.) with each other.

[0031] The torque pulsation algorithm module 208 generates the synchronized pulsed torque requests or commands according to one or more of the methods of Fig. 5, Fig. 13 and Fig. 18. The synchronized pulsed torque requests or commands are input to the first inverter system controller 134 and the second inverter system controller 147. In Fig. 2, a detailed view of the first inverter system controller 134 is shown, while a less detailed view of the second inverter system controller 147 is shown; however, it should be understood that the second inverter system controller 147 has the same shape as the first inverter system controller 134.

[0032] One of the synchronized pulsed torque request or command (e.g., a signal that moves between the two limits without moving to intermediate values ​​when switching between the two values, as in Fig. 16) may be output to a space vector pulse width modulation motor controller 209 that operates the electric machine 126. The space vector pulse width modulation motor controller 209 may be included in the first inverter system controller 134 or the controller 112.

[0033] In this example, the electric machine 126 is a three-phase electric machine to which electrical power is supplied via a power inverter 224. The amounts of electrical current supplied in each of the three phases are input to block 226, where Park and Clark transformations convert the electrical currents from each of the three phases into a measured torque current i q and a measured flow current i d The measured flow current i d is controlled by the commanded river current i d subtracted at the junction 214 (e.g. the summing point). The measured torque current i q is determined by the commanded torque current i qat the junction 212 (e.g., the summing point). One of the synchronized pulsed torque request or command signals is input to a current reference generator 210, and the current reference generator 210 decomposes the synchronized pulsed torque request and outputs a commanded flux current i d and a commanded torque current i qto generate the commands that cause the electric machine 126 to generate the average pulsed torque request corresponding to the requested driver demand torque. The synchronized pulsed torque request or command is generated to request or command a predetermined fraction of the driver demand torque (e.g., half the driver demand torque) from the first electric machine. The synchronized pulsed torque command or command for the second electric machine issues a request for a remaining fraction of the driver demand torque, such that the synchronized pulsed torque commands or requests cause the driver demand torque to be generated across the first and second electric machines.It should be noted that the requested driver demand torque may correspond to an electric machine torque output, a wheel torque, or an intermediate torque between the electric machine torque and the wheel torque. If the driver demand torque corresponds to a torque different from the electric machine output torque, the commanded electric machine output torque may be compensated or adjusted for any gear ratio that may exist between the electric machines and the location in the vehicle propulsion system that corresponds to the driver demand torque.

[0034] A torque current proportional / integral controller 216 receives a torque current error from the junction 212 and issues a torque voltage command v qSimilarly, a flux current proportional / integral controller 218 receives a flux current error from junction 214 and issues a flux voltage command v d The command for the torque voltage v d and the command for the forward voltage v d are converted via an inverse Park transformation at block 220 to a torque voltage in a rotating reference frame v d and a flux voltage in the rotating reference frame v β processed. At block 222, the torque voltage in the rotating reference frame v α and the flux voltage in the rotating reference frame v βconverted into phase pulses via space vector pulse width modulation. The pulses drive the transistors or switches in the power inverter 224. The power inverter 224 outputs voltages for each of the phase windings of the electric machine 126. The position of the electric machine 126 is converted into an angle, and the angle is fed to blocks 220 and 226 for the inverse Park transform and the Park and Clark transform.

[0035] Thus, a synchronized pulsed torque request can be converted into two electric current commands, and the two electric current commands are converted into pulse-width-modulated pulses. The pulse-width-modulated pulses control the voltage supplied to the electric machine 126. The other synchronized pulsed torque request or command issued by the controller 112 can be processed in a similar manner via the second inverter system controller 147 to operate the second electric machine 125.

[0036] The system of Fig. 1 and Fig. 2 provides an electric drive system comprising: a first inverter, a first electric machine, a second inverter, a second electric machine; and one or more controllers including executable instructions stored in non-transitory memory that cause the one or more controllers to generate synchronized pulsed torque commands for the first electric machine and the second electric machine. In a first example, the electric drive system includes the synchronized pulsed torque commands alternating between a first range of torque values ​​and a second value, the second value being less than the first range of torque values.In a second example, which may include the first example, the electric drive system includes where the synchronized pulsed torque commands for the first electric machine and the second electric machine have a same frequency. In a third example, which may include one or both of the first and second examples, the electric drive system includes where the synchronized pulsed torque commands for the first electric machine and the second electric machine have different duty cycles. In a fourth example, which may include one or more of the first through third examples, the electric drive system includes where the synchronized pulsed torque commands for the first electric machine and the second electric machine have the same duty cycles.In a fifth example, which may include one or more of the first to fourth examples, the electric drive system includes where the synchronized torque pulse commands for the first electric machine and the second electric machine include a timing of the torque pulses for the first electric machine that overlaps a timing of the torque pulses for the second electric machine. In a sixth example, which may include one or more of the first to fifth examples, the electric drive system includes where the synchronized pulsed torque commands for the first electric machine and the second electric machine include a timing of the torque pulses for the first electric machine that does not overlap a timing of the torque pulses for the second electric machine.In a seventh example, which may include one or more of the first to sixth examples, the electric drive system includes where the synchronized pulsed torque commands include pulsed torque commands for the first electric machine and pulsed torque commands for the second electric machine that synchronize at a pulse event level of the pulsed torque commands for the electric machine.

[0037] The system of Fig. 1 and Fig. 2 further provides an electric drive system comprising: a first inverter, a first electric machine, a second inverter, a second electric machine; and one or more controllers including executable instructions stored in non-transitory memory that cause the one or more controllers to generate synchronized pulsed torque commands for the first electric machine and the second electric machine, wherein the synchronized pulsed torque commands for the first electric machine and the second electric machine are generated based on a loss profile. In a first example, the electric drive system includes where the loss profile describes a relationship between losses of the electric drive system and torque generated via the first electric machine and the second electric machine.In a second example, which may include the first example, the electric drive system includes where the synchronized pulsed torque commands alternate between a first range of torque values ​​and a second torque value, where the second torque value is lower than the first range of torque values. In a third example, which may include one or both of the first and second examples, the electric drive system includes where the first range of torque values ​​are equal constant values ​​or values ​​that have a range that varies by less than five percent of the full torque range for the first electric machine.In a fourth example, which may include one or more of the first through third examples, the electric drive system includes adjusting magnitudes of the synchronized pulsed torque commands in response to speeds and torques of the first electric machine and the second electric machine.

[0038] Referring to Fig. 3, a plot 300 of electric machine losses for a single electric machine versus electric machine torque is shown. Plot 300 includes a vertical axis representing electric machine losses, and the magnitude of the losses increases in the direction of the vertical axis arrow. The larger the loss value, the lower the efficiency of the electric machine. The horizontal axis represents the torque output of the electric machine, and the torque output increases in the direction of the horizontal axis arrow. A solid line plot 302 represents electric machine losses when a torque request for the electric machine is not pulsed. A dashed line 304 represents losses of the same electric machine when the torque request for the electric machine is pulsed.It can be observed that torque losses for the electric machine are lower when the torque demand is pulsed. Accordingly, there may be advantages to providing a pulsed torque demand to an electric drive system.

[0039] Further to Fig. 4, a plot 400 of electric machine losses for a single electric machine and two electric machines versus electric machine torque is shown. Plot 400 includes a vertical axis representing total electric machine losses, and the magnitude of the total losses increases in the direction of the vertical axis arrow. The horizontal axis represents total driveline torque output of the electric machine, and the total torque output increases in the direction of the horizontal axis arrow. A solid line plot 402 represents losses of the two electric machine drives when a torque request for the electric machine is not pulsed. The dashed line 404 represents losses of a single electric drive when the torque request for the single electric drive (e.g.,The dotted line 406 represents losses for two electric drives (e.g., two electric machines are turned on and providing torque to the driveline) when the torque demand for two electric drives is pulsed. It can be observed that the torque losses for the single electric drive are higher than for the two electric drives when the torque demand is between torque t1 and torque t2. Consequently, the driveline is more efficient when two electric drives are commanded with torque pulses when the total driveline torque is pulsed between torque t1 and torque t2.Additionally, for the total driveline torque between torque t0 and torque t1, operating two electric drives is as efficient as operating a single electric drive. Accordingly, there may be advantages to providing synchronized pulsed torque requests to two different electric drives to generate a requested driver demand torque.

[0040] Referring to Fig. Figure 5 shows a block diagram of a first method for providing synchronized torque pulsations to two different electric drives. The method of Fig. 5 may be included as executable instructions in a non-transitory memory of one or more controllers. Furthermore, the method of Fig. 5 on the system of Fig. 1 and Fig. 2. In addition, the procedure of Fig. 5 together with the procedures of Fig. 13 and Fig. 18. The procedure of Fig. 5 may also include actions taken in the physical world to determine the operating states of the system of Fig. 1 and Fig. 2. The procedure of Fig. 5 may be executed when a vehicle is operated under predetermined conditions (e.g., a specific speed and driver demand torque range).

[0041] At 502, vehicle operating conditions are determined. The vehicle operating conditions may include, among other things, a driver demand torque, a vehicle speed, an electric machine speed, and a vehicle drive mode (e.g., two-wheel drive, four-wheel drive, etc.). Method 500 proceeds to 504.

[0042] At 504, method 500 assesses whether synchronized torque pulsation (e.g., delivering torque pulses to two electric machines) is enabled or not. Synchronized torque pulsation may be enabled if it is determined that the vehicle is operating under conditions where synchronized torque pulsations may increase electric propulsion efficiency. In one example, method 500 may make such a determination based on a relationship between propulsion losses and total driveline torque, as described in Fig. 4. For example, if the driver demand torque and the driveline torque are between torque t0 and torque t2, as in Fig. As shown in Figure 4, method 500 may judge that synchronized torque pulsations should be generated and enabled. If method 500 judges that synchronized torque pulsations should be enabled, the answer is yes, and method 500 proceeds to 508. Otherwise, the answer is no, and method 500 proceeds to 506.

[0043] At 506, method 500 operates one or two electric drives in a continuous mode where no torque pulsations are provided. While operating in a continuous mode, torque commands or requests may be supplied to the two electric drives based on the driver demand torque and the vehicle speed or electric machine speed. Method 500 persists after entering the continuous torque mode.

[0044] At 508, method 500 determines a frequency for generating synchronized torque pulsation. Generating synchronized torque pulsation may enable noise and vibration from two electric drive systems to be reduced when the two electric machines respond to pulsed torque commands or requests to achieve increased powertrain efficiency. The two electric drive systems are to be commanded with torque pulses that have a similar frequency. In one example, the frequency may be determined by indexing a table or function that outputs a frequency in response to vehicle operating conditions (e.g., vehicle speed, driver demand torque, electric machine speed, electric machine temperature, battery temperature, etc.).The frequency values ​​in the tables or functions can be determined by operating a vehicle on a dynamometer and adjusting the frequency values ​​until desired vehicle operating characteristics (e.g., higher efficiency, lower noise, lower vibration, etc.) are achieved. Synchronizing the torque pulsations to a single frequency at a specific set of vehicle operating conditions can provide for the generation of synchronized pulses. Method 500 proceeds to 510 and 512.

[0045] At 510, method 500 determines a magnitude of the torque pulsations to be generated for the first electric drive, a duty cycle of the torque pulsations to be generated for the first electric drive, and phase adjustments to the torque pulsations to be generated for the first electric drive. Method 500 may look up values ​​of these parameters using tables or functions in a similar manner to how the frequency values ​​were determined. Further, values ​​for the magnitude, phase, and duty cycle may be determined empirically via a dynamometer, as mentioned for the frequency determination. Method 500 proceeds to 512.

[0046] At 512, the method 500 generates pulsed torque commands for the first electric drive system and the first electric machine. In one example, the method 500 may generate the pulsed torque commands via a pulse generation algorithm that may be executed at a fixed time interval. Alternatively, the method 500 may follow a predetermined pulse profile stored in the controller memory. The method 500 issues a command to the first electric drive with a pulsed torque command, such as in Fig. 6-12. Method 500 ends.

[0047] At 514, method 500 determines a magnitude of the torque pulsations to be generated for the second electric drive, a duty cycle of the torque pulsations to be generated for the second electric drive, and phase adjustments to the torque pulsations to be generated for the second electric drive. Method 500 may look up values ​​of these parameters using tables or functions in a similar manner to how the frequency values ​​were determined. Method 500 proceeds to 516.

[0048] At 516, the method 500 generates pulsed torque commands for the second electric drive system and the second electric machine. In one example, the method 500 may generate the pulsed torque commands via a pulse generation algorithm that may be executed at a fixed time interval. Alternatively, the method 500 may follow a predetermined pulse profile stored in the controller memory. The method 500 issues a command to the second electric drive with a pulsed torque command, such as in Fig. 6-12. Method 500 ends.

[0049] In examples where a single controller generates the synchronized torque pulses for the first and second electric drives, the controller may adjust the timing between the torque pulses for the first electric drive and the second electric drive, as in Fig. 6-12. Since the single controller controls both torque pulse trains, the single controller knows the relative timing between the two torque pulse trains.

[0050] In examples where two or more controllers generate the synchronized torque pulses for the first and second electric drives, one controller may operate as the master controller and the other controller may operate as the slave controller, with the slave controller outputting pulses according to an output of the master controller. The pulsed torque commands generated in Fig. 6-12 and 14-17 can be generated via data values ​​(e.g. digital signals) or as analog signals and delivered to the electric drive for the first electric machine and the electric drive for the second electric machine.

[0051] Referring to Fig. 6 shows a curve 600, how pulsed torque commands or requests are processed by the method of Fig. 5 can be generated. In this example, there are zero torque periods between the torque pulse commands for the first electric drive and the first electric machine and the torque pulse commands for the second electric drive and the second electric machine. Furthermore, the magnitudes of the torque pulses for the first electric drive and the first electric machine differ from the magnitudes of the torque pulses for the second electric drive and the second electric machine.

[0052] In this example, the pulsed torque commands or requests are generated in response to a request for constant driver demand torque. The trace 600 includes a vertical axis representing a torque command or request value of the synchronized pulsed torque commands, and the torque command value of the pulsed torque commands increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases in the direction of the horizontal axis arrow. The solid trace 602 represents pulsed torque commands for the first electric drive and the first electric machine. The dashed trace 604 represents pulsed torque commands for the second electric drive and the second electric machine. The torque value on the horizontal axis plane in Fig. 6-12 and 14-17 is zero.

[0053] In this example, for the first electric drive and the first electric machine, the period of the pulsed torque command is indicated at 610, the duty cycle is indicated at 612, and the magnitude is indicated at 614. The rising edge of the pulsed torque command for the first electric drive and the first electric machine is indicated at 616, and its falling edge is indicated at 618. The pulsed torque command for the second electric drive and the second electric machine has a period that is the same as the period for the pulsed torque command for the first electric drive and the first electric machine. However, there is a phase difference, as indicated at 620, between the rising edges of the pulsed torque command for the first electric drive and the first electric machine and the rising edges for the second electric drive and the second electric machine.Furthermore, there are zero torque periods, as indicated at 622, in which zero torque is requested for both the first and second electric drives and electric machines. Both signals have the same frequency, so they are synchronized in time because they have the same period. Such torque pulsations can reduce electric drive losses and reduce noise and vibration of the electric drive and electric machine. In this example, the timing of the rising edges and falling edges of the pulsed torque commands for the first electric drive and the second electric drive is such that there is no overlap between the pulsed torque commands.

[0054] The duty cycle of the first electric drive and the first electric machine is 602 is shorter than the duty cycle of the second electric drive and the second machine, the period of the pulsed torque command 604. However, the magnitude of the first electric drive and the first electric machine by which the torque command is 602 is greater than the magnitude of the second electric drive and the second electric machine, so that both the first electric machine and the second electric machine produce an equal average torque, as indicated at line 650.

[0055] It should be noted that although the rising and falling edges of the pulsed torque command signals 602 and 604 extend between the lower limit torque value (e.g., zero) and the peak values ​​of the individual torque pulses, intermediate torque values ​​between the lower limit and the peak values ​​are not included as values ​​in the pulsed torque request. The pulsed torque commands or requests contain values ​​that only include a lower value and peak values ​​for each torque pulse. The rising and falling edges shown between the lower limit and the upper limit of the torque pulse command values ​​are shown simply so that the curve can be followed more easily. The same applies throughout the disclosure, except where indicated. Furthermore, the upper limits (e.g.,high side of the pulsed torque command) of the pulsed torque commands cover a range of values, in that it is understood that the pulsed torque commands disclosed herein contemplate range-bound upper torque command values ​​(high side).

[0056] Referring to Fig. 7 shows a curve 700 of how pulsed torque commands or requests are processed by the method of Fig. 5 can be generated. In this example, there is an overlap between the torque pulse commands for the first electric drive and the first electric machine and the torque pulse commands for the second electric drive and the second electric machine. Furthermore, the magnitudes of the torque pulses for the first electric drive and the first electric machine differ from the magnitudes of the torque pulses for the second electric drive and the second electric machine.

[0057] In this example, the pulsed torque commands or requests are generated in response to a request for constant driver demand torque. Trace 700 includes a vertical axis representing a torque command or request value of the synchronized pulsed torque commands, and the torque command value of the pulsed torque commands increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases in the direction of the horizontal axis arrow. Solid trace 702 represents pulsed torque commands for the first electric drive and the first electric machine. Dashed trace 704 represents pulsed torque commands for the second electric drive and the second electric machine.

[0058] In this example, the pulsed torque command for the second electric drive and the second electric machine has a period that is the same as the period for the pulsed torque command for the first electric drive and the first electric machine. However, the timing of the two signals is different, so there are overlap periods, as indicated at 710, in which the pulsed torque command for the second electric drive is at a higher level while the pulsed torque command for the first electric drive and the first electric machine is at a higher level. Both signals have the same frequency, so they are synchronized in time because they have the same period. The overlap periods can help reduce noise and vibration of the electric drive and the electric machine.

[0059] Referring to Fig. 8 shows a curve 800, how pulsed torque commands or requests are processed by the method of Fig. 5 can be generated. In this specific example, the pulsed torque commands are complementary because the pulsed torque command for the second electric drive and the second electric machine is at a higher torque level when the pulsed torque command for the first electric drive and the first electric machine is zero. As a result, the torque output to the vehicle powertrain is continuous. Additionally, the magnitudes of the torque pulses for the first electric drive and the first electric machine differ from the magnitudes of the torque pulses for the second electric drive and the second electric machine.

[0060] In this example, the pulsed torque commands or requests are generated in response to a request for constant driver demand torque. Trace 800 includes a vertical axis representing a torque command or request value of the synchronized pulsed torque commands, and the torque command value of the pulsed torque commands increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases in the direction of the horizontal axis arrow. Solid trace 802 represents pulsed torque commands for the first electric drive and the first electric machine. Dashed trace 804 represents pulsed torque commands for the second electric drive and the second electric machine.

[0061] In this example, the pulsed torque command for the second electric drive and the second electric machine has a period that is the same as the period for the pulsed torque command for the first electric drive and the first electric machine. However, the timing of the two signals is different, so there is no overlap. Instead, the timing of the rising edges of the pulsed torque commands for the first electric drive and the first electric machine is the same as the timing of the falling edges for pulsed torque commands for the second electric drive and the second electric machine. Both signals have the same frequency, so they are synchronized in time because they have the same period.The non-overlapping periods can help provide a sense of continuous torque delivery to the driveline to reduce the likelihood of vehicle speed fluctuation during pulsed torque operation.

[0062] Referring to Fig. 9 shows a curve 900, how pulsed torque commands or requests are processed by the method of Fig. 5 can be generated. In this example, the pulsed torque commands occur simultaneously because they occur simultaneously and are delivered to the first and second electric drives. Additionally, the magnitudes of the torque pulses for the first electric drive and the first electric machine differ from the magnitudes of the torque pulses for the second electric drive and the second electric machine.

[0063] In this example, the pulsed torque commands or requests are generated in response to a request for constant driver demand torque. Trace 900 includes a vertical axis representing a torque command or request value of the synchronized pulsed torque commands, and the torque command value of the pulsed torque commands increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases in the direction of the horizontal axis arrow. Solid trace 902 represents pulsed torque commands for the first electric drive and the first electric machine. Dashed trace 904 represents pulsed torque commands for the second electric drive and the second electric machine.

[0064] In this example, the pulsed torque command for the second electric drive and the second electric machine has a period that is the same as the period for the pulsed torque command for the first electric drive and the first electric machine. Furthermore, the timing of the two signals is the same, so there is an overlap between the timing of the pulsed torque commands. Both signals have the same frequency, so they are synchronized in time because they have the same period. The overlapping periods may provide some noise and / or vibration reduction during some vehicle operating conditions.

[0065] Fig. Figures 10-11 show synchronized pulsed torque commands for the first electric drive and the first electric machine, and the second electric drive and the second electric machine, adjusted for phase, magnitude, and duty cycle, respectively. The settings can be applied to each individual torque pulse command or a sequence of torque pulse commands together, and all settings can be either fixed, randomized, or dependent on settings of other electric drives.

[0066] Further to Fig. 10 shows a curve 1000 of how pulsed torque commands or requests are processed by the method of Fig. 5 can be generated. In this example, the pulsed torque commands are synchronous in time, but the pulsed torque commands for the second electric drive and the second electric machine are out of phase with the pulsed torque commands for the first electric drive and the first electric machine. Additionally, the magnitudes of the torque pulses for the first electric drive and the first electric machine differ from the magnitudes of the torque pulses for the second electric drive and the second electric machine.

[0067] In this example, the pulsed torque commands or requests are generated in response to a request for constant driver demand torque. Trace 1000 includes a vertical axis representing a torque command or request value of the synchronized pulsed torque commands, and the torque command value of the pulsed torque commands increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases in the direction of the horizontal axis arrow. Solid trace 1002 represents pulsed torque commands for the first electric drive and the first electric machine. Dashed trace 1004 represents pulsed torque commands for the second electric drive and the second electric machine.

[0068] Here, the pulsed torque command for the second electric drive and the second electric machine has a phase that is adjusted with respect to the timing of the high or non-zero portion of the pulsed torque command for the first electric drive and the first electric machine. In this example, the phase between the high side or non-zero portion of the pulsed torque command for the second electric drive and the second electric machine has a phase that is adjusted with respect to the timing of the high or non-zero portion of the pulsed torque command for the first electric drive and the first electric machine. Both signals have the same frequency, so they are synchronized in time because they have the same period.By randomly adjusting the phase of the pulsed torque commands, it may be possible to overcome the possibility of generating resonant vibrations within the electric drive system and electrical machines.

[0069] Further to Fig. 11 shows a curve 1100 of how pulsed torque commands or requests are processed by the method of Fig. 5 can be generated. In this example, the pulsed torque commands are synchronous, but the pulsed torque commands for the second electric drive and the second electric machine are out of phase with the pulsed torque commands for the first electric drive and the first electric machine. Additionally, the magnitudes of the torque pulses for the first electric drive and the first electric machine differ from the magnitudes of the torque pulses for the second electric drive and the second electric machine.

[0070] In this example, the pulsed torque commands or requests are also generated in response to a request for constant driver demand torque. Trace 1100 includes a vertical axis representing a torque command or request value of the synchronized pulsed torque commands, and the torque command value of the pulsed torque commands increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases in the direction of the horizontal axis arrow. Solid trace 1102 represents pulsed torque commands for the first electric drive and the first electric machine. Dashed trace 1104 represents pulsed torque commands for the second electric drive and the second electric machine.

[0071] For this setting, the magnitudes of the pulsed torque commands for the second electric drive and the second electric machine are adjusted with respect to time. Both signals have the same frequency, so they are synchronized with respect to time because they have the same period. By randomly adjusting the magnitude of the pulsed torque commands, it may be possible to overcome the possibility of generating resonant oscillations within the electric drive system and the electric machines.

[0072] Referring to Fig. 12 shows a curve 1200 of how pulsed torque commands or requests are processed by the method of Fig. 5 can be generated. In this example, the pulsed torque commands occur simultaneously, but the duty cycle of the pulsed torque commands for the second electric drive and the second electric machine are adjusted, while the duty cycle for the pulsed torque commands for the first electric drive and the first electric machine remains constant.

[0073] In this example, the pulsed torque commands or requests are also generated in response to a request for constant driver demand torque. Trace 1200 includes a vertical axis representing a torque command or request value of the synchronized pulsed torque commands, and the torque command value of the pulsed torque commands increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases in the direction of the horizontal axis arrow. Solid trace 1202 represents pulsed torque commands for the first electric drive and the first electric machine. Dashed trace 1204 represents pulsed torque commands for the second electric drive and the second electric machine.

[0074] For this adjustment, the duty cycle of the non-zero portion of the pulsed torque commands for the second electric drive and the second electric machine is adjusted with respect to time. Both signals have the same frequency, so they are synchronized with respect to time because they have the same period. By randomly adjusting the duty cycle of the pulsed torque commands, it may be possible to overcome the possibility of generating resonant oscillations within the electric drive system and the electric machines.

[0075] Referring to Fig. 13 shows a block diagram of a second method for providing synchronized torque pulsations to two different electric drives. The method of Fig. 13 may be included as executable instructions in a non-transitory memory of one or more controllers. Furthermore, the method of Fig. 13 on the system of Fig. 1 and Fig. 2. In addition, the procedure of Fig. 13 together with the procedures of Fig. 5 and Fig. 18. The procedure of Fig. 13 may also include actions taken in the physical world to determine the operating states of the system of Fig. 1 and Fig. 2. The procedure of Fig. 13 may be performed when a vehicle is operating under predetermined conditions (e.g., a specific speed and driver-demand torque range). Method 1300 may be applied when controllers in the respective electric drives generate the pulsed torque commands. A first controller may send a synchronization signal to the other controller so that the second controller can issue pulsed torque commands synchronously with the first controller.

[0076] At 1302, vehicle operating conditions are determined. The vehicle operating conditions may include, among other things, a driver demand torque, a vehicle speed, an electric machine speed, and a vehicle drive mode (e.g., two-wheel drive, four-wheel drive, etc.). Method 1300 proceeds to 1304.

[0077] At 1304, method 1300 assesses whether synchronized torque pulsation (e.g., delivering torque pulses to two electric machines) is enabled or not. Synchronized torque pulsation may be enabled if it is determined that the vehicle is operating under conditions where synchronized torque pulsations may increase electric propulsion efficiency. In one example, method 1300 may make such a determination based on a relationship between propulsion losses and total driveline torque, as described in Fig. 4. For example, if the driver demand torque and the driveline torque are between torque t0 and torque t2, as in Fig. As shown in Figure 4, method 1300 may judge that synchronized torque pulsations should be generated and enabled. If method 1300 judges that synchronized torque pulsations should be enabled, the answer is yes, and method 1300 proceeds to 1308. Otherwise, the answer is no, and method 1300 proceeds to 1306.

[0078] At 1306, method 1300 operates one or two electric drives in a continuous mode in which no torque pulsations are provided. While operating in a continuous mode, torque commands or requests may be supplied to the two electric drives based on the driver demand torque and the vehicle speed or electric machine speed. Method 1300 persists after entering the continuous torque mode.

[0079] At 1308, method 1300 judges whether or not a torque pulse transient is present. If so, the answer is yes, and method 1300 proceeds to 1316.

[0080] Otherwise, the answer is no, and method 1300 proceeds to 1314. In one example, the torque pulse transient may be a change in a pulsed torque command, such as a rising or falling edge of a signal, an increase of more than a threshold amount in a variable, or another signal characteristic. Thus, method 1300 may synchronize pulsed torque commands at an event level.

[0081] At 1314, method 1300 commands no change to the pulsed torque commands of the second electric drive and the second electric machine. Method 1300 proceeds to exit.

[0082] At 1316, the method 1300 performs adjustments to the pulsed torque commands of the second electric drive system and the second electric machine. The adjustments may include adjustments to the torque pulse command magnitude, the torque pulse command duty cycle, and the torque pulse command phase, as described in Fig. 14-17. The settings may be based on vehicle operating conditions, including, but not limited to, electric machine speed, vehicle speed, electric machine temperature, and driver demand torque. Method 1300 proceeds to 1318.

[0083] At 1318, method 1300 commands the second electric drive and the second electric machine with the adjusted torque pulse commands. Method 1300 proceeds to exit.

[0084] In this way, even if the first electric machine generates random torque pulsation commands, the operation of the second electric machine can be synchronized with the operation of the first electric machine. Consequently, control can be distributed while maintaining synchronization between electric machines.

[0085] Referring to Fig. 14 shows a curve 1400, how pulsed torque commands or requests are processed by the method of Fig. 13 can be generated. In this example, the pulsed torque commands for the second electric drive and the second electric machine are complementary and event-synchronous with the pulsed torque commands of the first electric drive and the first electric machine.

[0086] In this example, the pulsed torque commands or requests are also generated in response to a request for constant driver demand torque. Trace 1400 includes a vertical axis representing a torque command or request value of the synchronized pulsed torque commands, and the torque command value of the pulsed torque commands increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases in the direction of the horizontal axis arrow. Solid trace 1402 represents pulsed torque commands for the first electric drive and the first electric machine. Dashed trace 1404 represents pulsed torque commands for the second electric drive and the second electric machine.

[0087] In this example, the pulsed torque commands for the first electric drive and the first electric machine are randomly generated via a first controller. A second controller may generate pulsed torque commands for the second electric drive and the second electric machine according to the pulsed torque values ​​or another signal from the first controller. Here, the pulsed torque commands for the second electric machine are at a higher non-zero value when the pulsed torque commands for the first electric machine are zero or near zero. Thus, the pulsed torque commands for the second electric machine and the second electric drive are complementary to those of the first electric drive and the first electric machine.

[0088] Referring to Fig. 15 shows a curve 1500, how pulsed torque commands or requests are processed by the method of Fig. 13 can be generated. In this example, the pulsed torque commands for the second electric drive and the second electric machine are simultaneous and event-synchronous with those of the first electric drive and the first electric machine.

[0089] In this example, the pulsed torque commands or requests are also generated in response to a request for constant driver demand torque. Trace 1500 includes a vertical axis representing a torque command or request value of the synchronized pulsed torque commands, and the torque command value of the pulsed torque commands increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases in the direction of the horizontal axis arrow. Solid trace 1502 represents pulsed torque commands for the first electric drive and the first electric machine.

[0090] The dashed trace 1504 represents pulsed torque commands for the second electric drive and the second electric machine.

[0091] Here, the pulsed torque commands for the first electric drive and the first electric machine are again randomly generated via a first controller. A second controller can generate pulsed torque commands for the second electric drive and the second electric machine according to the pulsed torque values ​​or another signal from the first controller. In this example, when the pulsed torque commands for the first electric machine are at a higher non-zero level, the pulsed torque commands for the second electric machine are at a higher non-zero level. Thus, the pulsed torque commands of the second electric drive and the second electric machine are mimicked in frequency, phase, or duty cycle with the pulsed torque commands of the first electric drive and the first electric machine.

[0092] Referring to Fig. 16 shows a curve 1600 of how pulsed torque commands or requests are processed by the method of Fig. 13 can be generated. In this example, the pulsed torque commands for the second electric drive and the second electric machine are delayed and event-synchronous with those of the first electric drive and the first electric machine.

[0093] In this example, the pulsed torque commands or requests are also generated in response to a request for constant driver demand torque. Trace 1600 includes a vertical axis representing a torque command or request value of the synchronized pulsed torque commands, and the torque command value of the pulsed torque commands increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases in the direction of the horizontal axis arrow. Solid trace 1602 represents pulsed torque commands for the first electric drive and the first electric machine. Dashed trace 1604 represents pulsed torque commands for the second electric drive and the second electric machine.

[0094] In Fig. 16, the pulsed torque commands for the first electric drive and the first electric machine are randomly generated via a first controller. A second controller may generate pulsed torque commands for the second electric drive and the second electric machine according to the pulsed torque values ​​or another signal from the first controller. In this example, the pulsed torque commands for the second electric machine are time-delayed with respect to the pulsed torque commands of the first electric drive and the first electric machine.

[0095] Referring to Fig. 17 shows a curve 1700, how pulsed torque commands or requests are processed by the method of Fig. 13 can be generated. In this example, the pulsed torque commands for the second electric drive and the second electric machine are set with transient synchronous modifications.

[0096] In Fig. 17, the pulsed torque commands or requests are also generated in response to a request for constant driver demand torque. Trace 1700 includes a vertical axis representing a torque command or request value of the synchronized pulsed torque commands, and the torque command value of the pulsed torque commands increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases in the direction of the horizontal axis arrow. Solid trace 1702 represents pulsed torque commands for the first electric drive and the first electric machine. Dashed trace 1704 represents pulsed torque commands for the second electric drive and the second electric machine.

[0097] In this example, the pulsed torque commands for the first electric drive and the first electric machine are adjusted to change the time required to transition from a lower pulse value to a higher pulse value and vice versa. A second controller can generate pulsed torque commands for the second electric drive and the second electric machine according to the pulsed torque values ​​or another signal from the first controller. Fig. 17, the pulsed torque commands for the second electric machine change the time duration for a transition from a low pulse level to a high pulse level and vice versa in response to similar adjustments made to the pulsed torque commands for the first electric drive and the first electric machine.

[0098] Referring to Fig. Figure 18 shows a block diagram of a third method for providing synchronized torque pulsations to two different electric drives. The method of Fig. 18 may be included as executable instructions in a non-transitory memory of one or more controllers. Furthermore, the method of Fig. 18 on the system of Fig. 1 and Fig. 2. In addition, the procedure of Fig. 18 together with the procedures of Fig. 5 and Fig. 13. The procedure of Fig. 18 may also include actions taken in the physical world to determine the operating states of the system of Fig. 1 and Fig. 2. The procedure of Fig. 18 may be executed when a vehicle is operated under predetermined conditions (e.g., a specific speed and driver demand torque range).

[0099] At 1802, vehicle operating conditions are determined. The vehicle operating conditions may include, among other things, a driver demand torque, a vehicle speed, an electric machine speed, and a vehicle drive mode (e.g., two-wheel drive, four-wheel drive, etc.). Method 1800 proceeds to 1804.

[0100] At 1806, method 1800 assesses whether or not pulsed torque commands reduce electric drive system losses at current vehicle operating conditions. In one example, method 1800 may determine a response according to a relationship as shown in Fig. 4. If method 1800 judges that the pulsed torque commands reduce electric drive system losses under the current operating conditions, the answer is yes and method 1800 proceeds to 1804. Otherwise, the answer is no and method 1800 proceeds to 1806.

[0101] At 1806, method 1800 operates one or two electric drives in a continuous mode in which no torque pulsations are provided. While operating in a continuous mode, torque commands or requests may be supplied to the two electric drives based on the driver demand torque and the vehicle speed or electric machine speed. Method 1800 persists after entering the continuous torque mode.

[0102] At 1808, method 1800 assesses whether synchronized torque pulsation (e.g., delivering torque pulses to two electric machines) is enabled or not. Synchronized torque pulsation may be enabled if it is determined that the vehicle is operating under conditions where synchronized torque pulsations may increase electric propulsion efficiency. In one example, method 1800 may make such a determination based on a relationship between propulsion losses and total driveline torque, as described in Fig. 4. For example, if the driver demand torque and the driveline torque are between torque t0 and torque t2, as in Fig. As shown in Figure 4, method 1800 may judge that synchronized torque pulsations should be generated and enabled. If method 1800 judges that synchronized torque pulsations should be enabled, the answer is yes, and method 1800 proceeds to 1812. Otherwise, the answer is no, and method 1800 proceeds to 1810.

[0103] At 1810, method 1800 issues pulsed torque commands that are independent and unsynchronized to two electric drives and two electric machines. Method 1800 may operate two electric drives and two electric machines with pulsed torque commands that have different frequencies, magnitudes, duty cycles, and / or phases. Method 1800 proceeds to exit.

[0104] At 1812, method 1800 indexes or references tables and / or functions that output pulsed torque signal attributes, which may include, but are not limited to, frequency, duty cycle, phase, and magnitude. The tables and / or functions may be referenced based on average torque requirements of the individual electric machine, as determined at 1810. In one example, method 1800 may determine driver demand torque and vehicle speed and determine an average torque to be requested or commanded for each electric drive and electric machine. The driver demand torque may be divided between the two electric machines according to a predetermined ratio. Additionally, the tables and / or functions may be referenced or indexed by noise and vibration characteristics and loss profiles (e.g., as in the relationship of Fig. 4), as indicated at 1816. The tables or functions return attributes for pulsed torque commands. The procedure 1800 proceeds to 1820.

[0105] At 1820, the method 1800 generates synchronized pulsed torque commands for the first electric drive, the first electric machine, the second electric drive, and the second electric machine according to the attributes determined at 1812. In one example, the method 1800 may generate the synchronized pulsed torque commands via a pulse generation algorithm that may be executed at a fixed time interval. Alternatively, the method 1800 may generate the pulsed torque commands by following one or more predetermined pulse profiles stored in the controller memory. The method 1800 issues a command to the first electric drive and the second electric drive with pulsed torque commands, such as in Fig. 6-12. The 1800 procedure ends.

[0106] In this way, synchronized torque commands can be optimized to reduce noise and vibration. Settings can be varied according to vehicle operating conditions.

[0107] Referring to Fig. Figure 19 shows an example of how a pulsed torque command or pulsed torque request can be generated. The graph 1900 includes a vertical axis and a horizontal axis. The vertical axis represents a torque request value (e.g., 0-600 Newton meters), and the torque request value increases in the direction of the upward arrow on the vertical axis. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph.

[0108] In this example, the pulsed torque request is one of two values. Namely, the pulsed torque request value is the lower limit (e.g., zero) or the upper limit (e.g., Thigh). The average torque is equal to Tdes, which is equal to a constant driver demand torque being requested. The pulsed torque request consists of individual values ​​specified via points similar to point 1902 and point 1904. The line connecting the points is provided to visually enhance the plot, not to indicate that arbitrary intermediate torque values ​​between 0 and Thigh exist, since none exist. These individual values ​​can be updated at a predetermined rate via the controller to enable the generation of a pulsed torque request at a desired frequency.The torque pulse demand traces shown herein depict a line between the lower limit values ​​and values ​​within the pulses (e.g., non-lower limit values). The line should not be understood to depict intermediate torque values ​​between lower limit values ​​and values ​​within the respective torque pulses. It is understood that the lower limit values ​​described herein may be non-zero.

[0109] The methods described herein provide a method for an electric drive system, comprising: generating synchronized pulsed torque commands for a first electric machine and a second electric machine, wherein the synchronized pulsed torque commands for the first electric machine have a first frequency and wherein the synchronized pulsed torque commands for the second electric machine have the first frequency. In a second example, which may include the first example, the method includes where the synchronized pulsed torque commands for the first electric machine have a first magnitude, the synchronized pulsed torque commands for the second electric machine have a second magnitude, the second magnitude being greater than the first magnitude.In a third example, which may include one or both of the first and second examples, the method includes where the synchronized pulsed torque commands for the first electric machine have a first duty cycle and the synchronized pulsed torque commands for the second electric machine have a second duty cycle, wherein the second duty cycle is different from the first duty cycle. In a fourth example, which may include one or more of the first to third examples, the method includes where a timing of the synchronized pulsed torque commands for the first electric machine overlaps a timing of the synchronized pulsed torque commands for the second electric machine.In a fifth example, which may include one or more of the first through fourth examples, the method includes where a timing of the synchronized pulsed torque commands for the first electric machine does not overlap a timing of the synchronized pulsed torque commands for the second electric machine. In a sixth example, which may include one or more of the first through fifth examples, the method includes where the synchronized pulsed torque commands for the first electric machine and the second electric machine vary according to a driver demand torque. In a seventh example, which may include one or more of the first through sixth examples, the method includes where the synchronized pulsed torque commands for the first electric machine and the second electric machine vary according to a loss profile for the electric drive system.

[0110] It should be noted that the example control and estimation routines included herein may be used with various internal combustion engine and / or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions on non-transitory memory and may be executed by the control system including the controller in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Therefore, various illustrated acts, operations, and / or functions may be performed in the illustrated sequence or in parallel, or in some cases, may be omitted.Likewise, the processing order is not critical to achieving the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts, operations, and / or functions may be performed repeatedly depending on the particular strategy employed. Furthermore, at least a portion of the described acts, operations, and / or functions may graphically represent code to be programmed into a non-transitory memory of the computer-readable storage medium in the control system.The control actions may also transform the operating state of one or more sensors or actuators in the physical world when the described actions are performed by executing the instructions in a system that includes the various engine hardware components in combination with one or more controllers.

[0111] This concludes the description. If read by a person skilled in the art, many changes and modifications would become apparent without departing from the spirit and scope of the description. For example, various types of electrical machines may advantageously utilize the present description.

[0112] According to the present invention, an electric drive system is provided, comprising: a first inverter, a first electric machine, a second inverter, a second electric machine; and one or more controllers including executable instructions stored in non-transitory memory that cause the one or more controllers to generate synchronized pulsed torque commands for the first electric machine and the second electric machine.

[0113] According to one embodiment, the synchronized pulsed torque commands alternate between a first range of torque values ​​and a second value, wherein the second value is less than the first range of torque values.

[0114] According to one embodiment, the synchronized pulsed torque commands for the first electric machine and the second electric machine have a same frequency.

[0115] According to one embodiment, the synchronized pulsed torque commands for the first electric machine and the second electric machine have different duty cycles.

[0116] According to one embodiment, the synchronized pulsed torque commands for the first electric machine and the second electric machine have equal duty cycles.

[0117] According to one embodiment, the synchronized pulsed torque commands for the first electric machine and the second electric machine include a timing of the torque pulses for the first electric machine that overlaps a timing of the torque pulses for the second electric machine.

[0118] According to one embodiment, the synchronized pulsed torque commands for the first electric machine and the second electric machine include a timing of the torque pulses for the first electric machine that does not overlap a timing of the torque pulses for the second electric machine.

[0119] According to one embodiment, the synchronized pulsed torque commands include pulsed torque commands for the first electric machine and pulsed torque commands for the second electric machine that synchronize at a pulse event level of the pulsed torque commands for the electric machine.

[0120] According to the present invention, a method is provided for an electric drive system, comprising: generating synchronized pulsed torque commands for a first electric machine and a second electric machine, wherein the synchronized pulsed torque commands for the first electric machine have a first frequency and wherein the synchronized pulsed torque commands for the second electric machine have the first frequency.

[0121] In one aspect of the invention, the synchronized pulsed torque commands for the first electric machine have a first magnitude, wherein the synchronized pulsed torque commands for the second electric machine have a second magnitude, wherein the second magnitude is greater than the first magnitude.

[0122] In one aspect of the invention, the synchronized pulsed torque commands for the first electric machine have a first duty cycle, and wherein the synchronized pulsed torque commands for the second electric machine have a second duty cycle, wherein the second duty cycle is different from the first duty cycle.

[0123] In one aspect of the invention, a timing of the synchronized pulsed torque commands for the first electric machine overlaps a timing of the synchronized pulsed torque commands for the second electric machine.

[0124] In one aspect of the invention, a timing of the synchronized pulsed torque commands for the first electric machine does not overlap a timing of the synchronized pulsed torque commands for the second electric machine.

[0125] In one aspect of the invention, the synchronized pulsed torque commands for the first electric machine and the second electric machine vary according to a driver demand torque.

[0126] In one aspect of the invention, the synchronized pulsed torque commands for the first electric machine and the second electric machine vary according to a loss profile for the electric drive system.

[0127] According to the present invention, there is provided an electric drive system comprising: a first inverter, a first electric machine, a second inverter, a second electric machine; and one or more controllers including executable instructions stored in non-transitory memory that cause the one or more controllers to generate synchronized pulsed torque commands for the first electric machine and the second electric machine, wherein the synchronized pulsed torque commands for the first electric machine and the second electric machine are generated based on a loss profile.

[0128] According to one embodiment, the loss profile describes a relationship between losses of the electric drive system and torque generated via the first electric machine and the second electric machine.

[0129] According to one embodiment, the synchronized pulsed torque commands alternate between a first range of torque values ​​and a second torque value, wherein the second torque value is less than the first range of torque values.

[0130] According to one embodiment, the first range of torque values ​​are equal constant values ​​or values ​​having a range that varies by less than five percent of a full torque for the first electric machine.

[0131] According to one embodiment, magnitudes of the synchronized pulsed torque commands are adjusted in response to speeds and torques of the first electric machine and the second electric machine.

Claims

[1] Electric propulsion system comprising: a first inverter, a first electrical machine, a second inverter, a second electrical machine; and one or more controllers including executable instructions stored in non-transitory memory that cause the one or more controllers to generate synchronized pulsed torque commands for the first electric machine and the second electric machine. [2] The electric drive system of claim 1, wherein the synchronized pulsed torque commands alternate between a first range of torque values ​​and a second value, the second value being less than the first range of torque values. [3] The electric drive system of claim 2, wherein the synchronized pulsed torque commands for the first electric machine and the second electric machine have a same frequency. [4] The electric drive system of claim 3, wherein the synchronized pulsed torque commands for the first electric machine and the second electric machine have different duty cycles. [5] The electric drive system of claim 3, wherein the synchronized pulsed torque commands for the first electric machine and the second electric machine have equal duty cycles. [6] The electric drive system of claim 3, wherein the synchronized pulsed torque commands for the first electric machine and the second electric machine include a timing of the torque pulses for the first electric machine that overlaps a timing of the torque pulses for the second electric machine. [7] The electric drive system of claim 3, wherein the synchronized pulsed torque commands for the first electric machine and the second electric machine include a timing of the torque pulses for the first electric machine that does not overlap a timing of the torque pulses for the second electric machine. [8] The electric drive system of claim 3, wherein the synchronized pulsed torque commands include pulsed torque commands for the first electric machine and pulsed torque commands for the second electric machine that synchronize at a pulse event level of the pulsed torque commands for the electric machine. [9] Method for an electric drive system comprising: Generating synchronized pulsed torque commands for a first electric machine and a second electric machine, wherein the synchronized pulsed torque commands for the first electric machine have a first frequency and wherein the synchronized pulsed torque commands for the second electric machine have the first frequency. [10] The method of claim 9, wherein the synchronized pulsed torque commands for the first electric machine have a first magnitude, the synchronized pulsed torque commands for the second electric machine have a second magnitude, the second magnitude being greater than the first magnitude. [11] The method of claim 9, wherein the synchronized pulsed torque commands for the first electric machine have a first duty cycle and wherein the synchronized pulsed torque commands for the second electric machine have a second duty cycle, the second duty cycle being different from the first duty cycle. [12] The method of claim 9, wherein a timing of the synchronized pulsed torque commands for the first electric machine overlaps a timing of the synchronized pulsed torque commands for the second electric machine. [13] The method of claim 9, wherein a timing of the synchronized pulsed torque commands for the first electric machine does not overlap a timing of the synchronized pulsed torque commands for the second electric machine. [14] The method of claim 9, wherein the synchronized pulsed torque commands for the first electric machine and the second electric machine vary according to a driver demand torque. [15] The method of claim 9, wherein the synchronized pulsed torque commands for the first electric machine and the second electric machine vary according to a loss profile for the electric drive system.

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