Pulse control of multiple electromechanical devices

Abstract

To improve the energy conversion efficiency of multiple electromechanical machines (e.g., motors and generators), various methods, controllers, and electromechanical systems that facilitate pulse control of the machines are described. Under selected operating conditions, the electromechanical machine is driven intermittently (pulsed). Due to the pulsed operation, the output of the electromechanical machine switches between a first output level and a second output level that is lower than the first output level. The output levels are selected such that at least one of the electromechanical machine and the system including the electromechanical machine has an energy conversion efficiency higher than the energy conversion efficiency that the electromechanical machine would have if it were operated at a third output level required to continuously drive the electromechanical machine to supply a desired output during the pulsed operation. In some embodiments, the second output level is zero torque.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims priority based on U.S. Provisional Application No. 63 / 254,333, filed on October 11, 2021, and incorporates the said application by reference for all purposes into this application.

[0002] This application generally relates to multiple electric machine control. More specifically, it describes a control method and controller design that facilitate operating electric machines in a more energy - efficient form by pulsing the operation of two or more electric machines during selected operating conditions.

Background Art

[0003] As used herein, the term "electric machine" is intended to be broadly construed to mean both motors and generators. Motors and generators are very similar structurally. An electric machine converts electrical energy into mechanical energy when operating as a motor. An electric machine converts mechanical energy into electrical energy when operating as a generator.

[0004] Electric motors and generators are used in a very wide variety of applications and under a variety of operating conditions. Generally, many modern electrical machines have a relatively high energy conversion efficiency. However, the energy conversion efficiency of most electrical machines can vary greatly based on the operating load of the electrical machine. For systems using multiple electrical machines, considering their applications in range sensitive applications such as electric vehicles (EVs), drones, etc., the efficiency of the multi-motor drive often becomes very important. Furthermore, in many applications, it is required that the electrical machine operate under a variety of different operating load conditions. This means that the electrical machine often does not operate as efficiently as its capabilities would allow. Therefore, there is a need to operate electrical machines such as motors and generators at a higher level of efficiency.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Various methods, controllers, and electrical machine systems are described that facilitate pulse control of a multi-electrical machine (e.g., electric motor and generator) drive system and improve the energy conversion efficiency of the electrical machine when the operating conditions permit. More specifically, under selected operating conditions, one or more electrical machines in a multi-electrical machine drive system are driven in a pulsed (e.g., intermittent drive) mode or a continuous mode based on the optimization of the efficiency and performance of the drive system as a whole.

Means for Solving the Problems

[0006] One aspect is a multi - machine torque modulation method that can be incorporated into control algorithms for the operation of various electromechanical or motors. This method, based on a given input, evaluates which electromechanical machine, or combination of electromechanical machines, is operating, how much load they are sharing, and whether one or more of the electromechanical machines operate under torque modulation (pulsing) to maximize system efficiency. In one embodiment, such an evaluation or determination can be made based on one or more of the following: 1) operating speed and required torque, (2) loss characteristics of individual electromechanical machines, (3) noise, vibration, and harshness (NVH), temperature, thermal balancing, or other characteristics of the electromechanical machines.

[0007] In another embodiment, the pulsing of each motor in a multi - motor drive system is phase - adjusted in a way that increases the frequency of the pulsations to improve motor characteristics such as smoothness of torque supply and minimization of noise, vibration, and harshness (NVH). In such a configuration, individual motors pulse - operate at a lower frequency for better efficiency improvement, but as a result of the phase - adjustment of the motors, the overall system with multiple motors has higher - frequency excitation (low NVH) by phase - adjustment control.

[0008] Multi - machine torque modulation techniques can be implemented to achieve maximum system efficiency in a multi - motor drive system, significantly reduce rare - earth magnet composition, maintain thermal balance, and suppress NVH, torque ripple, or other characteristics of the electromechanical machines.

Brief Description of the Drawings

[0009] The technology and its advantages described herein can be best understood by referring to the following description in conjunction with the accompanying drawings.

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DETAILED DESCRIPTION OF THE INVENTION

[0019] In the drawings, like reference numerals may be used to indicate like structural elements. Also, it is to be understood that the depictions in the figures are schematic and not to scale.

[0020] The present disclosure generally relates to pulse control of a multi-electromechanical drive system (e.g., an electric motor and a generator) that operates continuously or, when operating conditions permit, pulsed to improve the energy conversion efficiency of the electromechanical device.

[0021] More specifically, under selected operating conditions, one or more of the electromechanical devices in the multi-electromechanical drive system are driven intermittently (i.e., pulsed). One such pulsed operation includes dynamic motor drive (DMD). The dynamic motor drive uses a pulse density control method that intermittently operates the electromechanical device at a torque having maximum efficiency considering the required motor torque demand. Exemplary DMD systems and methods, such as those disclosed in U.S. Patent No. 11,133,763, issued September 28, 2021, U.S. Patent No. 10,742,155, filed March 14, 2019, U.S. Patent No. 10,944,352, filed March 13, 2020, U.S. Patent Application No. 16 / 912,313, filed June 25, 2020, and U.S. Patent Application No. 17 / 166,646, filed February 3, 2021, may be implemented. The entire contents of all of these documents are incorporated herein by reference.

[0022] In one embodiment, by the pulsed operation of the electromechanical machine, the output of the electromechanical machine alternates between a first output level and a second output level lower than the first output level. The first and second output levels are selected such that at least one of the electromechanical machine and the system including the electromechanical machine has an energy conversion efficiency during the pulsed operation that is higher than the energy conversion efficiency that the electromechanical machine would have if operated at a third output level required to continuously drive the electromechanical machine to supply a desired output. In some embodiments, the second output level is zero torque (or substantially zero torque). In some embodiments, the pulsed operation may further include at least one intermediate output level between the first output level and the second output level. Here, alternating between the first output level and the second output level provides operation at at least one intermediate output level.

[0023] In some embodiments, the electromechanical machine is driven pulsedly when the desired output is less than the specified output level for a given motor operating speed, and is driven continuously when the desired motor output is greater than or equal to the specified output level.

[0024] The present disclosure generally relates to pulse control of electromechanical machines (e.g., motors and generators) that would otherwise operate continuously, to improve the energy conversion efficiency of the electromechanical machine when operating conditions permit. More specifically, under selected operating conditions, the electromechanical machine is driven intermittently (pulsed) at a more efficient energy conversion operating level to supply the desired average torque more energy-efficiently than achieved by conventional continuous motor control.

[0025] Many types of electric machines, such as mechanically rectified machines, electronically rectified machines, externally rectified asynchronous machines, and externally rectified synchronous machines, have conventionally been driven by a continuous (potentially varying) drive current when used as motors to supply a desired torque output. The drive current is often controlled by controlling the output voltage of a power converter (e.g., an inverter) that functions as a voltage input to the motor. Conversely, the power output of many types of generators is controlled by controlling the strength of the magnetic field. This can be achieved, for example, by controlling the excitation current supplied to the rotor coil by an exciter. (The exciter can be part of a rectifier or other suitable component.) Regardless of the type of machine, the drive current for a motor or the current output by a generator tends to be continuous.

[0026] Using pulse control, the output of the machine is intelligently and intermittently changed between a "torque on" state and a "zero torque (no torque)" state so as to (1) meet the operational requirements and (2) improve the overall efficiency. In other words, under selected operating conditions, the electric machine is intermittently driven at a more efficient energy conversion operating level (the "torque on" state) to supply the desired output. During the period between pulses, the machine ideally generates and consumes no torque (the "zero torque" state). Conceptually, this is considered to turn the electric machine "off". In some implementations, this can be achieved, for example, by substantially turning the electric machine "off" by interrupting the drive current to the motor or the excitation current for the generator. However, in other implementations, the electric machine can be controlled in a way that attempts to make the torque generated by the electric machine zero or as close to zero as may be practical or appropriate for a particular machine when in the "zero torque" state. In some embodiments, any power converter used in conjunction with the electric machine can also be substantially turned off during at least a portion of the "zero torque" period.

[0027] FIG. 1 illustrates a functional block diagram of a multi-electromechanical control system 10 according to a non-exclusive embodiment of the present technology. In this embodiment, system 10 includes a controller 20, a power source / sink 50, a power converter 30, and a plurality of electromechanical devices (e.g., machine 1 (40a), machine 2 (40b), 40b, ..., machine n (40n)). Controller 20 may include a machine controller, a pulse controller, or other control logic or circuitry, either as a single control unit or as a plurality of control modules.

[0028] When operating electromechanical devices 40a - 40n as motors, controller 20 functions as a motor controller and sends command 15 to power converter 30 to convert the power 26 received from power source 50 into a form suitable for driving electromechanical devices 40a - 40n. In such a configuration, power converter 30 (functioning as an inverter) provides input powers 32a, 32b - 32n to electromechanical devices 40a, 40b - 40n respectively. In some embodiments, electromechanical devices 40a - 40n include three-phase motors and power signals 32a, 32b - 32n include a conventional sinusoidal three-phase input. Command 15 is configured to drive electromechanical devices 40a - 40n to operate collectively or individually in a continuous mode or a pulse mode of operation, although further details will be described later. During the pulse operation mode, the output of the machine is turned on and off in pulses, and controller 20 may instruct the power converter to turn off for at least a portion of the time when the electromechanical device is pulsed off. Dedicated lines illustrating various possible power / control signals, e.g., 32a, 32b - 32n, are marked with arrows at both ends, indicating that when the machine is used as a motor, current can flow in both directions from power converter 30 to electromechanical devices 40a - 40n, and when the machine is used as a generator, current can flow from electromechanical devices 40a - 40n to power converter 30. When operating electromechanical devices 40a - 40n as generators, controller 20 functions as a generator controller and power converter 30 converts the power received from the generator into a form suitable for supplying to power sink 50.

[0029] It is understood that the control system 10 and the controller 20 can be implemented to control a plurality of electric machines. For example, for an embodiment employed in a motor vehicle, the control system 10 can be configured to operate two motors whose drive shafts (not shown) can be connected to wheels in various configurations. For example, in a dual (2) motor design, one motor can be dedicated to front-wheel drive and the other motor can be dedicated to the rear wheels. Alternatively, both motors can be connected to the same drive (e.g., both dedicated to rear-wheel drive or both dedicated to front-wheel drive). In another embodiment, each motor can be connected to a dedicated wheel (e.g., the left and right rear wheels in a dual motor drive, each of the four wheels of a vehicle in a four-motor configuration). Other applications (e.g., other than vehicles) are also conceivable. For example, the control system 10 and the controller 20 can be implemented to operate a drone in a state where each motor is designated to drive one or more (e.g., 4, 6, or 8 propeller configurations) of the drone propellers. The above embodiments are detailed for illustrative purposes only, and it is understood that the systems and methods of the presented technology can be applied across many different applications in addition to motors and drive configurations.

[0030] In an embodiment where the power source / sink 50 can directly supply or receive power in a form required by or output by the electric machines 40a - 40n, the power converter 30 can conceptually take the form of a switch or a logical multiplier that simply turns the motor on / off to facilitate the operation of the electric machines 40a - 40n.

[0031] The power source / sink 50 can take any suitable form. In some implementations, the power source / sink 50 can take the form of a battery or a capacitor. In other implementations, the power source / sink 50 can be a power grid (e.g., "wall power"), a photovoltaic system, or any other available source. Similarly, the sink can be an electrical load (a mechanically or electrically operated machine or appliance, a building, a factory, a home, etc.), a power grid, or any other system that uses or stores power.

[0032] The power converter 30 can also take a variety of different forms. If the power source / sink 50 is a DC power source and the electromechanical devices 40a - 40n include AC motors, the power converter 30 can take the form of an inverter. Conversely, if the power source / sink 50 is a DC power sink and the electromechanical devices 40a - 40n include AC generators, the power converter 30 can take the form of a rectifier. If both the power source / sink 50 and the electromechanical devices are AC components, the power converter 30 can include a bidirectional or four - quadrant power converter.

[0033] In FIG. 1, the required output or demand 24 (also referred to herein as "torque demand") is input to and / or provides feedback to the controller 20, along with the motor / generator operating speed 44, the supplied torque 42, and other inputs 46. In some embodiments, the controller 20 includes an application programming 22 stored in a memory (not shown) and executable on a processor (not shown) to provide pulse - operation adjustment, timing, and / or other signal processing of one or more aspects of the current / signal to each of the electromechanical devices 40a, 40b - 40n so that the electromechanical devices 40a, 40b - 40n operate with optimal efficiency and other performance characteristics or parameters.

[0034] As can be seen in FIG. 1, the controller 20 is configured to receive an input of torque supplied or received by the electromechanical devices 40a-40n in order to provide feedback to the system 10. This feedback can be in the form of the total cumulative torque 42 supplied to all of the electromechanical devices 40a-40n, and / or the individual torques 42a, 42b-42n supplied to each of the electromechanical devices 40a, 40b-40n. The feedback to the controller 20 can also be in the form of data from speed measurements (e.g., the rotor speeds 44 of all of the electromechanical devices 40a-40n, and / or the individual shaft speeds 44a, 44b-44n for each of the electromechanical devices 40a, 40b-40n). Further feedback 46 can include motor phase, current I, and / or voltage V. Further inputs can include one or more comparison devices such as a look-up table 34 that provides data regarding efficiency or other parameters / characteristics over a part or all of the operating range of the electromechanical devices 40a, 40b-40n. A look-up table will be described in detail below as one form of the input 34, but it is understood that such functionality can be achieved via non-tabular means such as equations, simulations, or other routines or algorithms available in the art. Also, in some embodiments, it is understood that the rotor speeds for the various motors can be different, and those motors can be coupled to gears having different gear ratios.

[0035] Figure 2 is a functional block diagram illustrating a specific embodiment of a control architecture or system 100 for a dual - motor drive system. The control system 100 includes a system controller 110 configured to transmit control commands 150 to operate a pair of electric motors, namely motor 1 (140a) and motor 2 (140b). In FIG. 2, a torque demand 24 is input to and / or provides feedback to the system controller 110 along with other inputs such as motor / generator speed 144, supplied torque 142, and a look - up table 134. In some embodiments, the system controller 110 includes application programming 122 stored in a memory (not shown) and executable on a processor (not shown) to provide pulse - operation adjustment, timing, and / or other signal processing of one or more aspects of the current / signal to each of the electric motors 140a, 140b such that the electric motors 140a, 140b operate with optimal efficiency and other performance characteristics or parameters. In the embodiment shown in FIG. 2, the system controller transmits commands 150 to dedicated motor controllers 1 (120a) and motor controllers 2 (120b) and corresponding inverters 1 (130a) and inverters 2 (130b). Inverters 1 (130a) and inverters 2 (130b) constitute one or more power converters connected to motors 1 (140a) and motors 2 (140b). The inverters 130a and 130b then send currents / voltages 132a and 132b to motors 140a and 140b respectively. The system controller 110 may be configured to operate any number of motors and may include logic and / or programming for integrating motor controllers 120a, 120b and the system controller 110 into a single controller or module. The command signal may include information and / or signals that determine whether to operate motors 140a, 140b continuously, in a pulse mode, or in other operating modes or signal characteristics (amplitude, phase, timing, etc.).It is also understood that a single inverter may be used instead of the dual inverter configuration of FIG. 2.

[0036] Also, as can be seen in FIG. 2, the controller 110 is configured to receive an input of torque supplied or received by the motors 140a and 140b in order to provide feedback to the system 100. This feedback can be in the form of the total cumulative torque 142 supplied to both of the motors 140a and 140b, and / or the individual torques 142a, 142b supplied to each of the motors 140a and 140b. Feedback to the system controller 110 can also be in the form of data from speed measurements (e.g., the cumulative or drive shaft speed 144 of all of the motors 140a and 140b, and / or the individual shaft speeds 144a, 144b for each of the motors 140a and 140b). Further inputs can include one or more look-up tables 134 that provide data regarding efficiency or other parameters / characteristics over a part or all of the operating ranges of the motors 140a and 140b. Feedback 146a and 146b (e.g., motor phase, current I, and / or voltage V) can be input to the motor controllers 120a and 120b, respectively, and / or provided to the system controller 110.

[0037] FIG. 3 shows a flowchart illustrating a multi-electromechanical control method 60 according to an embodiment. The method 60 can be implemented as application programming 22 of the controller 20 in FIG. 1 or application programming 122 of the system controller 110 for the operation of a multi-electromechanical / motor drive system. First, at step 62, an input is acquired. The input generally includes either the requested torque 24 or any of other feedback data (such as motor speed 44, output torque 42, etc.). Based on the input 24 and one or more look-up tables 34, at step 64, a determination is made to identify in which mode the electromechanical / motor is to operate. The exemplary look-up table 34 includes operation mode scenarios for mechanical / motor characteristics and / or conditions such as loss data, thermal data, noise, vibration and harshness (NVH) data, efficiency data, etc. In addition, the exemplary look-up table 34 includes operation mode scenarios for characteristics and / or conditions of other system components such as the power supply / sink 50 that affect the efficiency and / or losses of the entire drive system. The performance and / or losses of some system components such as the power supply / sink 50 depend on the combined output of all the electromechanicals 40a - 40n reflected in the total demand from the power converter 30. Table 3 shows an exemplary operation mode scheme for use in a dual-motor drive system similar to the control system 110 described in detail in FIG. 2. Table 3 shows four operation modes for two motors (motor 1 and motor 2). However, it is understood that the operation modes shown in Table 3 can include any number of operation modes and can be implemented similarly in the system of FIG. 1 and on various electromechanicals in addition to the configuration shown in FIG. 2. For example, a further configuration can include an operation mode 0 in which both motors are off. Similarly, a further mode of "motor 1 pulse output, motor 2 off" (i.e., mode 2a can be included).

[0038] Table 3 Operation Modes for Dual-Motor Drive Configuration

Table 1

[0039] In operation mode 1, normal operating conditions are implemented. That is, one or both of motor 1 and motor 2 operate in a continuous (non-pulse) mode. Neither motor 1 nor motor 2 operates in DMD (pulse) mode. This mode is generally selected when the input energy required for normal operation is less than the input energy required for DMD operation, or when the DMD mode produces an unacceptable performance level in comparison to one or both of the motors operating according to conventional or typical torque splitting techniques, depending on the operating characteristics of the motors (e.g., NVH level, thermal balancing, losses, etc.). In some embodiments, the input data for losses includes the total losses associated with one or more motors, converters, or batteries / power supplies.

[0040] In operation mode 2, motor 1 is operated in DMD (pulse) operation mode and motor 2 is operated in a conventional (continuous) operation mode or turned off. Similarly, in operation mode 3, motor 2 is operated in DMD (pulse) operation mode and motor 1 is operated in a conventional (continuous) operation mode or turned off. These modes are selected when the system losses for the above combinations are minimized (or are minimal) and the performance characteristics (such as NVH level) are acceptable, in any of operation mode 1, operation mode 2, or operation mode 3.

[0041] In operation mode 4, both motor 1 and motor 2 are operated in the DMD (pulse) operation mode. Similar to modes 2 and 3, operation mode 4 is selected when the system loss for the above combination is minimized and the performance characteristics (e.g., NVH level) are acceptable. In this mode, the timing or frequency of the pulse operation (e.g., modulation or on / off frequency) can be configured to operate the motor such that the phase of the on period or off period (or a part thereof) is shifted, or other complementary timing configurations are achieved. For example, when two motors are pulsed / operated at a modulation frequency of 10 hz, the timing of the motor pulsing can be adjusted (e.g., phase shifted) such that the frequencies are additive. That is, due to the combination of motors, the substantial fundamental or system frequency on the vehicle body becomes 20 Hz. This frequency can be a frequency that is difficult for the operator to perceive. Such phase timing is used to mitigate or reduce unacceptable vibrations and torque pulsations (torque ripples), and thus can provide torque smoothing for the operation of the motor. DMD pulsing at higher frequencies may be less efficient compared to pulsing at lower frequencies due to the transition losses associated with each pulse. However, the NVH of the vehicle is more sensitive to lower frequencies. The vehicle structure and the human body are very sensitive to frequencies in the range of 0.5 to 20 Hz. Therefore, by shifting the phase of the timing of multiple motors, it is possible to "take the best of both", that is, achieve the efficiency of 10 Hz DMD with the NVH of 20 Hz torque pulses. In some embodiments, phase timing is performed to minimize torque vibrations at 1 times, 2 times, and 3 times the fundamental frequency.

[0042] In another embodiment, for applications where a simple 180-degree phase difference may not achieve complete cancellation at the desired position (such as the driver's seat or other operator interfaces) due to the transfer function from the torque output of each motor to the vibration at the target position, a table of phase angles as a function of frequency for each motor is provided. For example, if the phase lag of motor 1 at the driver's seat at 20 Hz is 0 and the phase lag of motor 2 at the same location is 90 degrees, to minimize vibration, motor 2 is commanded to add 90 degrees of phase so that, including the transfer function, the total is 180 degrees. This is a function of the frequency characteristics of the vehicle / other applications.

[0043] Also, as detailed below, the phase command can be calculated from the identification of a system of vibration response OR real-time using the inverter as a shaker OR real-time feedback controller using the inverter with vibration / other sensors.

[0044] FIG. 6A shows an exemplary motor pulsing scheme 200 for operating a DMD at 10 Hz with motors that are phase shifted from each other, where the substantial fundamental frequency that excites the vehicle body is 20 Hz. When motor 1 is pulsed “off,” motor 2 is pulsed “on” to fill the center of the torque hole created by the stop of motor 1. In the examples shown in FIGS. 6A and 6B, motors 1 and 2 pulse individually at 10 Hz with equal amplitudes (signals 202 and 204 respectively), but the combined waveform 206 has a fundamental of 20 Hz (assuming both motors are identical and have the same duty cycle, a 50:50 torque split). This is an ideal scenario where the problematic 10 Hz excitation is canceled while each motor enjoys the maximum efficiency benefits of pulsing at 10 Hz. This effectively doubles the frequency of the excitation. FIG. 6B shows an embodiment where the amplitude of the pulses for motor 1 is different from the amplitude of motor 2, where the difference in amplitude is indicated by the dotted line 207. The difference in amplitude can be the result of differences between motor 1 and motor 2. In some embodiments, the duty cycle for motor 1 can be different from the duty cycle of motor 2. The difference in duty cycle can be the result of differences between motor 1 and motor 2.

[0045] Figures 7A - 7C illustrate various multi - motor drive configurations that can be used in accordance with the systems and methods of the presented technology. Figure 7A shows an exemplary two - motor drive train 300 comprising a motor 1 (304a) configured to operate a rear - wheel drive 308 (wheels 302a and 302b) and a motor 2 (304b) configured to operate a front - wheel drive 306 (wheels 302c and 302d). In one configuration, the motor pulsing scheme 200 can be implemented on the two - motor configuration 300 of Figure 7A. Figure 7B shows an exemplary three - motor drive train 310 comprising a motor 1 (314a) and a motor 2 (314b) configured to operate respective wheels 302a and 302b of a rear - wheel drive 318, and a motor 3 (314c) configured to operate a front - wheel drive 316 (wheels 302c and 302d). Figure 7C shows an exemplary four - motor drive train 320 comprising a motor 1 (324a) and a motor 2 (324b) configured to operate respective wheels 302a and 302b of a rear - wheel drive 328, and a motor 3 (324c) and a motor 4 (324d) configured to operate respective wheels 302c and 302d to operate a front - wheel drive 326.

[0046] The torque generated by each motor does not necessarily have to be the same. If there is a biased power split (by design) in torque generation between the front and rear motors, the system will still function, but the fundamental frequency is not completely canceled out, but is significantly attenuated. This is still good for NVH and allows operation at lower frequencies than in the absence of the system. Consequently, the DMD pulse duty cycle does not need to be matched between two (or more) motors for the damping effect.

[0047] The above phase timing principle can be further adopted to drive systems having three, four, or more motors. For example, the three-motor configuration 310 of FIG. 7B may have a phase timing such that torque pulses are staggered at a 120° phase difference from each other at the fundamental pulse frequency, thereby tripling the fundamental frequency. In another three-motor embodiment, the pulses of two of the three motors may be in-phase with each other, and the third motor may be 180° out of phase.

[0048] Furthermore, the four-motor configuration 320 of FIG. 7C may have a phase timing such that torque pulses are staggered at a 90° phase difference from the pulses of the preceding motor at the fundamental pulse frequency, thereby quadrupling the fundamental frequency. In such a configuration, the four motors can drive each wheel of the vehicle individually, achieving a 40 Hz torque supply to the vehicle even when each motor is pulsed at only 10 Hz. In another four-motor system, the four motors can be divided into two groups (e.g., 1 / 3 or 2 / 2). Here, the motors within the same group pulse in-phase with each other, but are 180° out of phase from the motors of the other group. In a further embodiment, the four motors are divided into three groups (e.g., 1 / 1 / 2). Here, the phasing follows the above three-motor system.

[0049] For three, four, or more motor systems, the decision of whether to group the motors for phase adjustment purposes can be determined by the physical layout of the motors in the application (e.g., grouping by front / rear motors in a vehicle), the frequency of pulsing of each motor, and the NVH response of the system, or other factors.

[0050] If the dynamic characteristics of the vehicle do not allow for left - right phase adjustment, the front motors and the rear motor can be grouped for the purpose of phase adjustment such that the two front motors operate synchronously in a pulsed manner and the rear motor operates with a phase shift relative to the front motors and pulsed, resulting in the fundamental frequency simply doubling. The determination of whether to group each motor or perform individual phase adjustment in a multi - motor configuration can depend on specific vehicle characteristics or drive modes.

[0051] The motors can also operate at the same pulse frequency or at different pulse frequencies. Assuming there are n motors, each can be controlled separately. In a broad sense, those motors can operate in a torque modulation mode or a pulse mode having n torque modulation frequencies. For example, the first motor can operate in zero - torque modulation (no - DMD, normal operation), the second motor can operate in DMD with a torque modulation frequency of f1, the third motor can operate at a frequency of f2, etc. However, in many cases, based on different factors such as NVH, beats, control complexity, etc., it may be ideal for there to be one DMD frequency at a certain operating time. Thus, some of the motors operate in the no - DMD mode and other motors operate in the DMD mode using a certain torque modulation frequency f1. In such embodiments, there can still be a phase shift between the modulation currents for the motors operating in the DMD mode.

[0052] Once the operating mode is determined in step 64 (Figure 3), in step 66, a control command or signal (e.g., command 15, 150) is sent to the motor to operate continuously or in a pulsed manner according to the selected mode.

[0053] It is understood that the motor 1 and motor 2, as well as any further motors used in the drive system, may specifically be configured similarly or differently according to different design considerations. For example, motor 1 may be configured to operate most efficiently in a higher torque or speed range than motor 2, or may belong to a different class. For example, motor 1 may be an interior permanent magnet motor, while motor 2 is a synchronous reluctance motor.

[0054] In some embodiments, the plurality of motors may not be completely out of phase or completely in phase with each other, but instead may have a phase difference that depends on the characteristics of the vehicle body and the different positions of the motors. To provide an example of the characteristics of the vehicle body, FIG. 8 illustrates a graph of the vibration response versus a given motor torque amplitude as a function of frequency used to illustrate the frequency response function (FRF). The seat X / torque curve 804 provides a graph of the seat vibration in the X direction versus the unit torque vibration versus frequency. The steering wheel X / torque curve 808 provides a graph of the steering wheel vibration in the X direction versus the unit torque vibration versus frequency. The steering wheel Y / torque curve 812 provides a graph of the steering wheel vibration in the Y direction versus the unit torque vibration versus frequency. The steering wheel Z / torque curve 816 provides a graph of the steering wheel vibration in the Z direction versus the unit torque vibration versus frequency. The peaks of the curves indicate the resonance frequencies at the corresponding positions and directions. The FRF is a function of the path (structure) connecting the vibration source (motor) and the vibration receiving side (driver / passenger interface). The FRF has both amplitude and phase, but FIG. 8 shows only the amplitude. Different motors in the same multi-motor vehicle may have different FRFs (both amplitude and phase) towards the receiving side because the motors are in different positions. In order to achieve complete phase cancellation at the receiving side, instead of simply shifting the two motors 180° out of phase with each other, it is necessary to adjust the phase of each source considering the effect of the phase delay of the FRF.

[0055] Figure 9A shows a graph of torque magnitude versus frequency used to illustrate the FRF to provide a further example of the above application. The curve 904 of motor 1 shows the magnitude of the vibration at the receiving side (driver / passenger interface) with respect to the unit torque vibration from motor 1 as a function of frequency. The curve 908 of motor 2 shows the magnitude of the vibration at the receiving side (driver / passenger interface) with respect to the unit torque vibration from motor 2 as a function of frequency. Figure 9B illustrates a graph of the phase (in radians) of the vibration with respect to the unit torque vibration versus frequency used to illustrate the FRF. The curve 912 of motor 1 shows the phase of the vibration at the receiving side (driver / passenger interface) with respect to the unit torque vibration versus frequency from motor 1 as the source. The curve 916 of motor 2 shows the phase of the vibration at the receiving side (driver / passenger interface) with respect to the unit torque vibration versus frequency from motor 2 as the source. Figures 9A and 9B illustrate that for different motors acting as sources, the phase at the receiving side position may be different. The illustrated FRF is an example. In some embodiments, the frequency range of the FRF is in the range from 1 hertz (Hz) to several thousand Hz. For example, at about 50 Hz, the phase difference between motor 1 and motor 2 is about 1 radian, which is about 60 degrees. When motors 1 and 2 are operated with a 180-degree phase shift, since the phase lag between motors 1 and 2 received by the receiving side is 60 degrees, motors 1 and 2 do not cancel each other out. Therefore, at 50 Hz, instead of operating motor 2 with a 180-degree phase-shifted pulse with respect to motor 1, by operating motor 2 with a pulse with a delay of about 120 degrees with respect to motor 1, the phase difference between the two sources is set to the target 180 degrees (120 degrees + 60 degrees), providing improved cancellation. A look-up table may be used to store the phase difference between motors at the receiving side for different frequencies and other parameters.

[0056] In some embodiments, the FRF is measured offline during vehicle development to create a phase adjustment table that provides phase adjustment as a function of frequency and possibly other factors. In some embodiments, the FRF is measured offline such that the phase adjustment is pre-calibrated to be completely canceled at the receiving side, such as the driver. In the case of multiple passengers, in some embodiments, the phase adjustment can be pre-calibrated to minimize NVH at a particular receiving side, or can provide an average minimum NVH for all passengers. In some embodiments, the FRF is used to minimize the NVH of one passenger in order to minimize the NVH of other passengers. In some embodiments, the controller can use the phase adjustment table to determine the phase adjustment between motor 1 and motor 2.

[0057] In some embodiments, since the FRF is measured online, the phase adjustment is calculated in real time by measuring the phase adjustment in each vehicle. For online measurement, signals can be generated from different motors and the phase lag at the receiving side is measured. Whether measured online or offline initially, the FRF can be continuously monitored to account for variations in vehicle response over time or under different load conditions and can be re-calibrated periodically as needed.

[0058] FIG. 4 shows a high-level flowchart illustrating a dual motor control method 170 according to one embodiment. The method 170 can be implemented within the application programming 122 of a system controller 110 (FIG. 2) for operation of a dual motor drive system, or in other controllers or logic devices within the drive system or vehicle. Using the acquired inputs (e.g., one or more of the requested torques 24, or any of the other feedback data (e.g., motor speed 144, output torque 142, etc.)), a plurality of more look-up tables 160a, 160b, and 160c are applied to obtain information on 1) the requested input energy, and 2) the performance characteristic tolerance (in this example, NVH) (step 164). As shown in FIG. 4, look-up table 1A (160a) shows the requested input energy over the full operating range (Op points (torque τ and operating speed ω from zero to the requested torque)) for motor drive 1 in continuous mode, motor drive 1 with DMD, motor drive 2 in continuous mode, and motor drive 2 with DMD. Look-up table 1B (160b) shows the NVH level information for operating a single motor over the full operating range (Op points (torque τ and operating speed ω from zero to the requested torque)) for motor drive 1 in continuous mode, motor drive 1 with DMD, motor drive 2 in continuous mode, and motor drive 2 with DMD. Look-up table 1C (160c) shows the NVH level information over the full operating range (Op points (torque τ and operating speed ω from zero to the requested torque)) for operating both motors for both motors in continuous mode, both motors in DMD mode, motor drive 1 with DMD when motor drive 2 is operating in continuous mode, and motor drive 2 with DMD when motor drive 1 is operating in continuous mode. Regarding the torque split of the dual motors, either motor can contribute zero to the requested torque to the axle, regardless of the presence or absence of DMD.Thus, the look-up tables 160a, 160b, and 160c preferably include data in the range from zero to the required torque level for both motor drives.

[0059] Next, in step 166, a desired combination of motor operations is selected for the required torque that consumes the minimum input energy while maintaining an acceptable performance (e.g., NVH) level. This combination can be any one of the motors in continuous mode only, both motors in continuous mode, one motor in continuous mode and another motor in DMD mode, or both in DMD mode, or only one of the motors operating in DMD mode.

[0060] Once the operation mode is determined in step 166, control commands or commands 150 (e.g., command 1 for motor 1 and command 2 for motor 2) are sent to the respective power converters / inverters to operate the respective motor(s) continuously or in pulses according to the selected operation mode.

[0061] FIG. 4 is shown in detail using dual motor operation, mainly considering the NVH level, but it is understood that the method 170 can be implemented for various operation mode scenarios for any number of machines / motors and corresponding characteristics and / or conditions (loss data, thermal data, etc.).

[0062] Figure 5 is a detailed flowchart illustrating an alternative dual motor control method 170a according to another embodiment. Method 170a can be implemented as application programming 122 of system controller 110 for the operation of a dual motor drive system, or in other controllers or logic devices within the drive system or vehicle. Using the acquired inputs (e.g., one or more of the requested torques 24, or any of the other feedback data (e.g., motor speed 144, output torque 142, etc.)), a specific look-up table 180 is applied to obtain information on 1) the requested input energy, and 2) the performance characteristic tolerance (in this example, NVH). As shown in Figure 5, look-up table 2 (180) shows the requested input energy over the full operating range (Op points (torque τ and operating speed ω from zero to the requested torque)) for motors 1 and 2. In this embodiment, look-up table 2 (180) already has information for selecting a motor operating mode or combination to reach minimum total energy consumption while maintaining acceptable performance characteristics (e.g., NVH level, temperature balance, etc.), including the characterization of one or more motors (e.g., via experimental analysis, simulation, or other characterization). The selected combination or mode can be either only one of the motors in continuous mode, both motors in continuous mode, one of the motors in continuous mode when the other motor is in DMD mode, or both in DMD mode, or only one of the motors operating in DMD mode. In embodiments using the NVH level, an NVH scenario for any combination of motor operations over the full operating range can be determined in advance and implemented in look-up table 180. In a further embodiment, each of the motor drive information columns in look-up table 180 includes values such as the torque level of the motor for which the continuous operation mode is selected, and the maximum efficiency torque, torque modulation frequency, duty cycle, etc. for which DMD operation is selected for the motor or combination of motors.

[0063] Next, in step 182, a desired combination of motor operations is selected for the required torque that consumes the minimum input energy while maintaining an acceptable performance (e.g., NVH) level. This combination can be any one motor in continuous mode, both motors in continuous mode, one motor in continuous mode and another motor in DMD mode, or both in DMD mode, or only one of the motors operating in DMD mode.

[0064] Once the operating mode is determined in step 182, control commands or commands 150 (e.g., command 1 for motor 1 and command 2 for motor 2) are sent to the respective power converters / inverters to operate the respective motor(s) / motors continuously or in pulses according to the selected operating mode.

[0065] As described above, one or more of the electromechanical devices are driven in pulses when the desired output is less than the specified output level for a given motor speed, and are driven continuously when the desired motor output is greater than or equal to the specified output level.

[0066] Regarding the pulse operation in the multi-motor configuration detailed in FIG. 2, the system controller 110 (and / or motor controllers 120a, 120b) instructs the inverters 103a, 130b to supply power to one or more of the motors 140a, 140b in a pulsed manner. During the "on" pulses, the inverters 103a, 130b are instructed to supply power at a preferred output level. Here, the preferred output level typically (but not necessarily) coincides with or is close to the maximum efficiency operating level for the current motor speed. During the "off" pulses, the motors 140a, 140b ideally output zero torque. In some embodiments, the timing of the pulsing is controlled by a separate pulse controller (not shown).

[0067] To facilitate the pulse operation, the system controller 110 determines a desired output level and a desired duty cycle for the pulse operation at the current motor speed (which preferably matches or is close to the maximum efficiency energy conversion output level of the system at the current motor speed, although other energy efficiency levels can be used as appropriate). The controllers 120a, 120b then instruct their respective inverters 130a, 130b to implement the desired duty cycle at the specified power level. Conceptually, this can be achieved by turning the power on and off at a relatively high frequency such that the proportion of time that power is supplied to the motor corresponds to the desired duty cycle and the power level corresponds to the preferred output level. In some embodiments, the "off" portion of the duty cycle can be implemented by instructing the controller / inverter to drive the motor to supply zero torque.

[0068] The frequency at which the power is pulsed is preferably determined by the system controller 110 or another controller such as a pulse controller (not shown). In some embodiments, the pulse frequency can be fixed for all operations of the motor, while in other embodiments, it can vary based on operating conditions such as motor speed, torque requirements, etc. For example, in some embodiments, the pulse frequency can be determined through the use of a look-up table. In such embodiments, appropriate metrics such as motor speed, torque requirements, etc. can be used to reference the appropriate pulse frequency for the current motor operating conditions. In other embodiments, the pulse frequency is not necessarily fixed for any given operating condition and can vary as determined by any of the controllers 110, 120a, 120b. This type of variation can be implemented using sigma-delta conversion in the determination of the electromechanical pulse, as discussed in U.S. Patent No. 10,742,155. In some specific embodiments, the pulse frequency can vary proportionally as a function of the motor speed, at least in some operating regions of the motor.

[0069] Once the desired duty cycle is determined, the duration and nature of the pulses used to drive the motor can be determined / generated in a variety of ways. One relatively simple method is to use a pulse width modulation (PWM) controller as a pulse controller (not shown).

[0070] The pulsed power considered and utilized herein is quite different. Specifically, the inverters 130a, 130b (or the power converter 30 in FIG. 1) are controlled to periodically switch between a state of generating high-efficiency torque output (e.g., peak efficiency torque) and a state of not generating torque in the electromechanical device. As a result, in the induction motor, the magnetic flux coupled to the motor winding substantially decreases to zero.

[0071] Conventional pulse width modulation functions in many applications, but has the potential drawback that pulses can generate undesirable vibrations or noise when the motor and / or power supply is turned on / off. Such vibrations are particularly likely to occur when the motor is operated in a steady state with the same pulse period for a certain period of time. There are several ways to reduce such risks, some of which will be described in more detail below. Another method is to add dither to the commanded pulse period.

[0072] As suggested above, the period of each cycle during pulsed operation (or inversely proportional to the pulse frequency) can vary widely, ranging from microseconds to several seconds or more, based on design requirements and the nature of the system being controlled. The selection of the cycle period is affected by various factors. These include factors such as the capabilities and characteristics of the motor, transient effects related to switching, potential NVH problems, and expected operating loads. Generally, the pulse frequency selected for any particular application is related to a trade-off that includes factors such as NVH considerations, the responsiveness required of the electromechanical device, and efficiency losses associated with pulsing. For example, in some automotive applications, pulse frequencies on the order of 10 Hz to 1000 Hz are considered to function well.

[0073] In most of the above examples, pulsing is achieved by modulating torque between a higher (more energy-efficient) torque output level and a zero torque output level. This is considered to be a preferred approach in most pulse control applications, but there may be situations (e.g., certain machines / machine operating regions) where it may be suitable to modulate between a higher torque output and a lower non-zero torque output rather than modulating between high torque and zero torque. For example, in some situations, high / low pulsing may have better noise, vibration, and harshness (NVH) characteristics than on / off pulsing. Thus, a more desirable trade-off between energy conversion efficiency and NVH characteristics may be achievable with high / low pulsing rather than on / off pulsing. In another example, for some operating regions of some motors, the high / low pulsing approach may provide better overall energy conversion efficiency than on / off pulsing. Motors incorporating permanent magnets that require weakening the magnetic field to generate zero torque are particularly good candidates for the use of high-low torque modulation.

[0074] Most motors have a specified maximum rated output level. Generally, the maximum rated output level is based on steady-state operation, and often a motor can be driven at a higher output level for a short period of time without adverse effects. In some embodiments, in a selected operating region, the output level of the motor can be pulsed with the "on" level higher than the maximum rated continuous output level for steady-state operation. For some motors in some potential operating regions, there are some potential advantages to using over-drive pulses. For example, in some specific operating situations, the energy conversion efficiency of a motor or system (e.g., a motor and an inverter) at a given motor speed can be higher in some over-drive regions than in the "normal" operating region. This means that pulsed operation at higher torque or power can be even more efficient.

[0075] Furthermore, more efficient operation typically results in less heating, which potentially facilitates an even higher net torque output. Thus, when motors that are conventionally driven with continuous power (such as induction motors and other AC motors, brushless DC motors, switched reluctance motors, etc.) are designed with pulsed operation in mind, it is thought that in some cases, using pulse control can optimize to achieve a higher net torque output than would be appropriate using more conventional steady / continuous drive power.

[0076] There are various factors that contribute to maximizing motor efficiency. One of these is the power factor, which is the cosine of the angle between the rotational voltage and the current vector. Ideally, the voltage and current should be in phase, or have a power factor of 1. However, for many types of electric motors / generators, this ideal does not necessarily represent the highest system efficiency point for any given load and speed. Considering the pulse control of the motors described herein and optimizing power factor correction taking into account the pulsed operating points, it is expected that the substantial power factor will be improved to be higher than that of conventional continuous motor operation.

[0077] Another factor contributing to the inefficiency of the motor is sometimes referred to as resistive loss or I2R loss. Resistive losses heat the motor windings (not shown), and as a result, the resistive losses further increase because the resistivity of the windings generally increases with temperature. Resistive losses are non-linear and increase at least with the square of the current. Therefore, resistive losses tend to have a greater impact on the overall motor efficiency at higher motor output levels, such as the levels used during pulsed operation. In the rule of thumb for motor design, the magnetic losses should be approximately equal to the resistive losses at the target set operating point. Since motor operating points below the most efficient operating point are not generally used, using the pulsed motor control method described herein can affect the appropriate motor design or selection. In other words, the motor is driven at its substantially most efficient operating point, or at a higher load. Low-load continuous operation need not be considered in motor design or selection, which also helps to further improve the overall efficiency of the system.

[0078] Another factor contributing to the efficiency (or inefficiency) of the motor is sometimes referred to as magnetic core loss, which relates to flux orientation loss. One loss mechanism is the leakage reactance of the motor windings, which refers to the flux lines that do not link between the magnetic elements of the rotor and stator. Another magnetic core loss mechanism relates to hysteresis in the magnetic iron core, often represented by the BH curve, where B is the magnetic flux density and H is the magnetic field strength. These are related by the magnetization of the material through which the magnetic field passes, which for some motors is the iron core present in the rotor or stator. Again, motors designed specifically for pulse control can be optimized to reduce core losses during pulsed motor operation.

[0079] As described above, the transient switching losses associated with the switching between motor "on" and motor "off" during pulsing are another factor that affects the efficiency of the motor during pulsed operation. As described above, one way to reduce these transient switching losses is to improve (shorten) the rise and fall times of the motor drive current associated with the on / off pulsing of the motor. Another way that helps manage transient switching losses is to manage the pulsing frequency. Generally, the lower the switching frequency, the lower the transient switching losses. However, there is a trade-off here when low-frequency switching induces noise, vibration, harshness (NVH) that may be undesirable or unacceptable in a particular application. Thus, the pulse frequency for any given motor is preferably selected appropriately taking into account both the efficiency of the motor and the NVH issues and / or requirements related to the intended use of the motor. Along this line, it should be noted that a pulsing controller having a noise shaping function such as a sigma-delta conversion-based pulsing controller can be very helpful in reducing the impact of NVH associated with pulsed motor control and thus can help support the use of a somewhat lower switching frequency.

[0080] It should be understood that the appropriate pulsing (torque modulation) frequency for different motors can vary widely based on the motor's structure, operating environment, and operating range. The most appropriate pulse frequency for any given motor depends on various factors including the motor size, on / off transient characteristics, NVH considerations, etc.

[0081] Also, the selection of a desired drive point for any given motor speed can affect the pulse frequency. More specifically, many motors have a relatively flat efficiency curve over a relatively wide operating range. Generally, pulse operation at a torque level slightly lower than the optimal efficiency point for continuous operation may facilitate switching at a slightly lower frequency, which, depending on the nature of the switching losses, can result in a higher overall motor efficiency during pulse operation. This emphasizes that the desired pulse operation drive point associated with any given motor speed does not necessarily coincide with the torque level that is most efficient for continuous motor operation. Rather, in some situations, the most energy-efficient point for pulse operation may be somewhat different from the most energy-efficient point for continuous operation. Additionally, NVH considerations and / or other operational or control considerations can influence the determination of the drive point considered appropriate for any given motor speed.

[0082] The above-described polyphase systems and methods can be equally beneficial in a number of vehicle and propulsion-related applications, including motors used in vehicles such as trucks, automobiles, carts, motorcycles, bicycles, drones, and other flying devices, as well as robots and other devices that autonomously move within an environment. Thus, the term "vehicle" should be broadly construed to include all of the above, as well as assemblies moved by any other type of motor, whether currently known or developed in the future.

[0083] Motors used in appliances such as washing machines, dryers, heating, ventilation, and air conditioning (HVAC) applications can provide further examples of applications that can benefit from multiple electromechanical systems using pulse control.

[0084] Only a few embodiments of the present technology have been described in detail, but it should be understood that the present technology can be implemented in many other forms without departing from the spirit and scope of the present technology. The various multi-machine controllers and related mechanical elements described above can be implemented, grouped, and configured in a variety of different architectures in different embodiments. For example, in some embodiments, the controller can be incorporated within a motor controller or an inverter controller, or provided as a separate component. Similarly, for a generator, the controller can be incorporated within a generator controller or a rectifier controller, and in a combined motor / generator, the controller can be incorporated within a combined motor / generator controller or a combined inverter / rectifier controller. In some embodiments, the above control functions can be implemented algorithmically in software or firmware executed on a processor. The processor can take any suitable form, including, for example, general-purpose processors and microprocessors, digital signal processors, and the like.

[0085] The system and / or motor controller can be part of a larger control system. For example, in a vehicle application, the above control can be part of a vehicle controller, a power train controller, a hybrid power train controller, or an ECU (engine control unit) that performs various functions related to vehicle control. In such applications, the vehicle or other related controllers, etc., can take the form of a single processor that executes all of the required control, or can include multiple processors located in the same place as part of a power train or vehicle control module, or distributed at various locations within the vehicle. The specific functions performed by any one of the processors or control units can be very diverse.

[0086] Generally, methods for multiphase motor control can be implemented digitally, algorithmically, using analog components, or using a hybrid approach. The motor controller can be implemented as code executed on a processor, on programmable logic such as an FPGA (Field Programmable Gate Array), within a circuit such as an ASIC (Application Specific Integrated Circuit), on a digital signal processor (DSP), using analog components or any other suitable hardware. In some implementations, the control method can be incorporated into object code to be executed on a digital signal processor (DSP) incorporated within an inverter controller (and / or, for a generator and / or combined inverter / rectifier controller, a rectifier controller).

[0087] Accordingly, this embodiment should be considered illustrative and not restrictive, and the present technology should not be limited to the details given herein, but may be modified within the scope of the appended claims and their equivalents.

Claims

1. A multi-electromechanical system, comprising: a first electromechanical machine; a second electromechanical machine; one or more power converters connected to the first electromechanical machine and the second electromechanical machine; a controller connected to the one or more power converters and arranged to receive one or more inputs related to the system; wherein the controller, in response to the one or more inputs: in a first operating mode, instructs the one or more power converters to produce continuous outputs of both the first electromechanical machine and the second electromechanical machine; in a second operating mode, instructs the one or more power converters to produce a pulsed output of the first electromechanical machine and a continuous output of the second electromechanical machine; in a third operating mode, instructs the one or more power converters to produce pulsed outputs of both the first electromechanical machine and the second electromechanical machine; and is configured such that during the pulsed output, the controller causes one or more outputs of the first electromechanical machine and the second electromechanical machine to switch between a first output level and a second output level, and the second output level is lower than the first output level. A multi-electromechanical system.

2. The multi-electromechanical system according to claim 1, wherein the second output level is zero or off.

3. The multi-electromechanical system according to claim 2, wherein the controller turns off the power to the one or more power converters for at least a part of the period during which the second output level is off.

4. The multi-electromechanical system according to claim 1, wherein the controller selects between the first, second, and third operating modes to optimize the energy conversion efficiency of the multi-electromechanical system.

5. The multi-electromechanical system according to claim 1, wherein the controller selects between the first, second, and third operating modes as a function of an input in one or more forms of an operating speed or a required torque related to the system.

6. ​ ​ ​ ​ ​ The controller selects among the first, second, and third operating modes based on the performance characteristics of the first and second electromechanical machines, and the performance characteristics include one of noise, vibration, and harshness (NVH) levels, thermal balancing, and total losses of the first and second electromechanical machines. The multi-electromechanical machine system according to claim 1.

7. In the third operating mode, the timing of the first electromechanical machine pulse is out of phase with the second electromechanical machine pulse. The multi-electromechanical machine system according to claim 1.

8. The first and second electromechanical machines include motors, and the one or more power converters include inverters. The multi-electromechanical machine system according to claim 1.

9. The multi-electromechanical machine system is configured to operate as a motor / generator. The multi-electromechanical machine system according to claim 1.

10. In the fourth operating mode, the controller is configured to instruct the one or more power converters to produce a continuous output of the first electromechanical machine and a pulsed output of the second electromechanical machine. The multi-electromechanical machine system according to claim 1.

11. The controller selects among the first, second, and third operating modes as a function of an input in one or more forms of operating speed or required torque related to the system. The multi-electromechanical machine system according to any one of claims 1 to 4.

12. The controller selects among the first, second, and third operating modes based on the performance characteristics of the first and second electromechanical machines, and the performance characteristics include one of noise, vibration, and harshness (NVH) levels, thermal balancing, and total losses of the first and second electromechanical machines. The multi-electromechanical machine system according to any one of claims 1 to 4 and 11.

13. In the third operating mode, the timing of the first electromechanical machine pulse is out of phase with the second electromechanical machine pulse. The multi-electromechanical machine system according to any one of claims 1 to 4 and 11 to 12.

14. The first and second electromechanical machines include motors, and the one or more power converters include inverters. The multi-electromechanical machine system according to any one of claims 1 to 4 and 11 to 13.

15. The multi-electromechanical system is configured to operate as a motor / generator. The multi-electromechanical system according to any one of claims 1 to 4 and 11 to 14.

16. In the fourth operating mode, the controller is configured to instruct the one or more power converters to produce a continuous output of the first electromechanical machine and a pulsed output of the second electromechanical machine. The multi-electromechanical system according to any one of claims 1 to 4 and 11 to 15.

17. A controller for a multi-electromechanical system including a first electromechanical machine and a second electromechanical machine, the controller receives one or more inputs related to the multi-electromechanical system, in response to the one or more inputs, variably switches one or more of the first electromechanical machine and the second electromechanical machine between operating modes in which the one or more outputs of the first electromechanical machine and the second electromechanical machine are pulsed or continuous. is configured to During the pulsed output, the output switches between a first output level and a second output level, and the second output level is lower than the first output level. Controller.

18. The multi-electromechanical system further includes a third electromechanical machine, and the controller in response to the one or more inputs, variably switches one or more of the first electromechanical machine, the second electromechanical machine, and the third electromechanical machine between operating modes in which the one or more outputs of the first electromechanical machine and the second electromechanical machine are pulsed or continuous. The controller according to claim 17.

19. The controller is configured to select between a first operating mode in which both the first electromechanical machine and the second electromechanical machine have a continuous output, a second operating mode in which the output of the first electromechanical machine is pulsed and the output of the second electromechanical machine is continuous, a third operating mode in which the output of the first electromechanical machine is continuous and the output of the second electromechanical machine is pulsed, and a fourth operating mode in which the outputs of both the first electromechanical machine and the second electromechanical machine are pulsed. The controller according to claim 17.

20. The second output level is zero or off. The controller according to claim 19.

21. The controller selects among the first, second, third, and fourth operating modes in order to optimize the energy conversion efficiency of the multi-electromechanical system. The controller according to claim 19.

22. The controller selects among the first, second, third, and fourth operating modes as a function of an input in one or more forms of an operating speed or a required torque related to the system. The controller according to claim 19.

23. The controller selects among the first, second, third, and fourth operating modes based on the performance characteristics of the first and second electromechanical machines, and the performance characteristics include one of noise, vibration, and harshness (NVH) levels, thermal balancing, and total losses of the first and second electromechanical machines. The controller according to claim 19.

24. During the fourth operating mode, the timing of the first electromechanical pulse is phase-shifted from the second electromechanical pulse. The controller according to claim 19.

25. The controller is configured to select among a first operating mode in which both the first electromechanical machine and the second electromechanical machine have continuous outputs, a second operating mode in which the output of the first electromechanical machine is pulsed and the output of the second electromechanical machine is continuous, a third operating mode in which the output of the first electromechanical machine is continuous and the output of the second electromechanical machine is pulsed, and a fourth operating mode in which the outputs of both the first electromechanical machine and the second electromechanical machine are pulsed. The controller according to any one of claims 17 to 18.

26. The second output level is zero or off. The controller according to any one of claims 17 to 18 and 25.

27. The controller selects among the first, second, and third operating modes in order to optimize the energy conversion efficiency of the multi-electromechanical system. The controller according to any one of claims 25 to 26.

28. The controller selects among the first, second, third, and fourth operating modes as a function of an input in one or more forms of an operating speed or a required torque related to the system. The controller according to any one of claims 25 to 27.

29. The controller selects among the first, second, third, and fourth operating modes based on the performance characteristics of the first and second electromechanical machines, where the performance characteristics include one of the noise, vibration, and harshness (NVH) levels, thermal balancing, and total losses of the first and second electromechanical machines. The controller according to any one of claims 25 to 28.

30. During the fourth operating mode, the timing of the first electromechanical pulse is phase-shifted from the second electromechanical pulse. The controller according to any one of claims 25 to 29.

31. A method for a multi-electromechanical system including a first electromechanical machine and a second electromechanical machine, the method comprising: Receiving one or more inputs related to the multi-electromechanical system; In response to the one or more inputs, variably switching one or more of the first electromechanical machine and the second electromechanical machine between operating modes in which the one or more outputs of the first electromechanical machine and the second electromechanical machine are pulsed or continuous; Including, During pulse output, the output switches between a first output level and a second output level, and the second output level is lower than the first output level. Method.

32. The multi-electromechanical system further includes a third electromechanical machine, and the method further includes: In response to the one or more inputs, variably switching one or more of the first electromechanical machine, the second electromechanical machine, and the third electromechanical machine between operating modes in which the one or more outputs of the first electromechanical machine and the second electromechanical machine are pulsed or continuous. The method according to claim 31.

33. Variably switching one or more of the first electromechanical machine and the second electromechanical machine between operating modes includes selecting between a first operating mode in which both the first electromechanical machine and the second electromechanical machine have continuous outputs, a second operating mode in which the output of the first electromechanical machine is pulsed and the output of the second electromechanical machine is continuous, a third operating mode in which the output of the first electromechanical machine is continuous and the output of the second electromechanical machine is pulsed, and a fourth operating mode in which the outputs of both the first electromechanical machine and the second electromechanical machine are pulsed. The method according to claim 31.

34. The second output level is zero or off. The method according to claim 33.

35. Selecting among the first, second, third, and fourth operating modes is performed to optimize the energy conversion efficiency of the multi-electromechanical system. The method according to claim 33.

36. Selecting among the first, second, third, and fourth operating modes is performed as a function of an input in one or more forms of an operating speed or a required torque related to the system. The method according to claim 33.

37. Selecting among the first, second, third, and fourth operating modes is a function of the performance characteristics of the first and second electromechanical machines, and the performance characteristics include one of the noise, vibration, and harshness (NVH) levels, thermal balancing, and total losses of the first and second electromechanical machines. The method according to claim 33.

38. In the third operating mode, the timing of the first electromechanical pulse is phase-shifted from the second electromechanical pulse. The method according to claim 33.

39. Variably switching one or more of the first electromechanical machine and the second electromechanical machine between operating modes includes selecting between a first operating mode in which both the first electromechanical machine and the second electromechanical machine have a continuous output, a second operating mode in which the output of the first electromechanical machine is pulsed and the output of the second electromechanical machine is continuous, a third operating mode in which the output of the first electromechanical machine is continuous and the output of the second electromechanical machine is pulsed, and a fourth operating mode in which the outputs of both the first electromechanical machine and the second electromechanical machine are pulsed. The method according to any one of claims 31 to 32.

40. The second output level is zero or off. The method according to any one of claims 31 to 32 and 39.

41. Selecting among the first, second, third, and fourth operating modes is performed to optimize the energy conversion efficiency of the multi-electromechanical system. The method according to any one of claims 31 to 32 and 39 to 40.

42. Selecting among the first, second, third, and fourth operating modes is performed as a function of an input in one or more forms of an operating speed or a required torque related to the system. The method according to any one of claims 31 to 32 and 39 to 41.

43. Selecting between the first, second, third, and fourth operating modes is a function of the performance characteristics of the first and second electromechanical machines, the performance characteristics including one of noise, vibration, and harshness (NVH) levels, thermal balancing, and total losses of the first and second electromechanical machines. The method according to any one of claims 31 to 32 and 39 to 42.

44. In the third operating mode, the timing of the first electromechanical pulse is phase-shifted from the second electromechanical pulse. The method according to any one of claims 31 to 32 and 39 to 43.

45. A controller for a multi-electromechanical system comprising a first electromechanical machine and a second electromechanical machine, the controller being configured to receive one or more inputs related to the multi-electromechanical system, and in response to the one or more inputs, operate the first electromechanical machine and the second electromechanical machine in a pulse operating mode in which the outputs of the first electromechanical machine and the second electromechanical machine switch between a first output level and a second output level lower than the first output level. configured as the timing of pulsing the first electromechanical machine and the second electromechanical machine is adjusted to minimize noise, vibration, and harshness of the multi-electromechanical system induced by the first electromechanical machine and the second electromechanical machine. controller.

46. The pulsing of the second electromechanical machine is adjusted in timing to be phase-shifted from the pulsing of the first electromechanical machine. The controller according to claim 45.

47. The first electromechanical machine and the second electromechanical machine are pulsed at a first frequency, and the pulsing of the first electromechanical machine and the second electromechanical machine is adjusted in timing to minimize noise, vibration, and harshness. The controller according to claim 46.

48. The pulsing of the second electromechanical machine is adjusted in timing to be 180° out of phase with the pulsing of the first electromechanical machine. The controller according to claim 46.

49. The pulsing of the second electromechanical machine is adjusted in timing to be phase-shifted from the pulsing of the first electromechanical machine. The controller according to claim 46.

50. The controller further includes a third electromechanical device, and the pulsing of the third electromechanical device is adjusted in timing so as to be out of phase with the pulsing of one or more of the first electromechanical device and the second electromechanical device. The controller according to claim 45.

51. The first electromechanical device, the second electromechanical device, and the third electromechanical device are pulsed at a first frequency, and the pulsing of the first electromechanical device, the second electromechanical device, and the third electromechanical device is adjusted in timing so as to minimize noise, vibration, and harshness. The controller according to claim 49.

52. The controller further includes a fourth electromechanical device, and the pulsing of the fourth electromechanical device is adjusted in timing so as to be out of phase with the pulsing of one or more of the first electromechanical device, the second electromechanical device, and the third electromechanical device. The controller according to claim 49.

53. The first electromechanical device, the second electromechanical device, the third electromechanical device, and the fourth electromechanical device are pulsed at a first frequency, and the pulsing of the first electromechanical device, the second electromechanical device, the third electromechanical device, and the fourth electromechanical device is adjusted in timing so as to minimize the noise, vibration, and harshness of the multi-electromechanical system. The controller according to claim 52.

54. In response to the one or more inputs, the controller is configured to variably switch between one or more of the first electromechanical device and the second electromechanical device between an operating mode in which one or more of the outputs of the first electromechanical device and the second electromechanical device are pulsed or continuous, and during pulse output, the output switches between a first output level and a second output level, and the second output level is lower than the first output level. The controller according to claim 45.

55. The first electromechanical device and the second electromechanical device are pulsed at a first frequency, and the pulsing of the first electromechanical device and the second electromechanical device is adjusted in timing so as to minimize noise, vibration, and harshness. The controller according to any one of claims 45 to 46.

56. The pulsing of the second electromechanical device is adjusted in timing so as to be 180° out of phase with the pulsing of the first electromechanical device. The controller according to any one of claims 45 to 46 and 55.

57. The pulsing of the second electromechanical machine is adjusted in timing so as to be out of phase with the pulsing of the first electromechanical machine. The controller according to any one of claims 45 to 46 and 55.

58. The controller further includes a third electromechanical machine. The pulsing of the third electromechanical machine is adjusted in timing so as to be out of phase with the pulsing of one or more of the first electromechanical machine and the second electromechanical machine. The controller according to any one of claims 45 to 46 and 55 to 57.

59. The first electromechanical machine, the second electromechanical machine, and the third electromechanical machine are pulsed at a first frequency. The pulsing of the first electromechanical machine, the second electromechanical machine, and the third electromechanical machine is adjusted in timing so as to minimize noise, vibration, and harshness. The controller according to claim 58.

60. The controller further includes a fourth electromechanical machine. The pulsing of the fourth electromechanical machine is adjusted in timing so as to be out of phase with the pulsing of one or more of the first electromechanical machine, the second electromechanical machine, and the third electromechanical machine. The controller according to any one of claims 58 to 59.

61. The first electromechanical machine, the second electromechanical machine, the third electromechanical machine, and the fourth electromechanical machine are pulsed at a first frequency. The pulsing of the first electromechanical machine, the second electromechanical machine, the third electromechanical machine, and the fourth electromechanical machine is adjusted in timing so as to minimize the noise, vibration, and harshness of the multi-electromechanical machine system. The controller according to claim 60.

62. The controller is configured to variably switch, in response to the one or more inputs, between one or more of the first electromechanical machine and the second electromechanical machine during an operating mode in which one or more of the outputs of the first electromechanical machine and the second electromechanical machine are pulsed or continuous. During pulse output, the output switches between a first output level and a second output level, and the second output level is lower than the first output level. The controller according to any one of claims 45 to 46 and 55 to 61. ​

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