Pulsed electromechanical control with soft start and soft end

Abstract

An electric machine controller is provided that is configured to provide a desired output by causing pulsed operation of an electric machine in a selected operating range and to direct a power converter to cause continuous operation of the electric machine in the selected operating range, and a ramp generator is adapted to provide ramping between the pulsed operation and the continuous operation.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Application No. 63 / 390,196, filed July 18, 2022, and U.S. Application No. 18 / 305,776, filed April 24, 2023, which are incorporated herein by reference for all purposes. [Background technology]

[0002] The present invention relates generally to electric machine control and, more particularly, to a control scheme and controller design that pulses the operation of an electric machine under selected operating conditions to facilitate reduced noise, vibration, and harshness (NVH) and more energy-efficient operation of the electric machine. Summary of the Invention

[0003] Various methods, controllers, and electromechanical systems are described that facilitate pulsed control of multiple electric machine (e.g., electric motors and generators) drive systems to improve the energy conversion efficiency of the electric machines when operating conditions permit. More specifically, an electromechanical controller is provided that is configured to provide a desired output by causing pulsed operation of the electric machine in a selected operating range and to direct a power converter to cause continuous operation of the electric machine in the selected operating range. A ramp generator is adapted to provide ramping between the pulsed operation and the continuous operation.

[0004] In another embodiment, a system is provided that includes an electric machine, a power converter, and an electric machine controller configured to provide a desired output by causing pulsed operation of the electric machine in a selected operating range and direct the power converter to cause continuous operation of the electric machine in the selected operating range, the electric machine controller including a ramp generator adapted to provide ramping between the pulsed operation and the continuous operation.

[0005] In another embodiment, a method is provided for controlling an electric machine by an electric machine controller configured to provide a desired output by causing pulsed operation of the electric machine in a selected operating range and direct a power converter to cause continuous operation of the electric machine in the selected operating range, with ramping provided between the pulsed operation and the continuous operation.

[0006] These and other features of the present disclosure are described in more detail below in the detailed description of the present disclosure and in connection with the following figures. [Brief explanation of the drawings]

[0007] The present invention and its advantages are best understood by referring to the following description taken in conjunction with the accompanying drawings.

[0008] FIG. 1 is a typical torque / speed / efficiency graph showing the energy conversion efficiency of a typical electric motor under different operating conditions.

[0009] FIG. 2A is a diagram illustrating an example of continuous motor operation.

[0010] FIG. 2B is a diagram illustrating an example of pulsed motor operation.

[0011] FIG. 3 is a functional block diagram that illustrates a schematic of an electromechanical controller according to one described embodiment.

[0012] FIG. 4 is a flow chart illustrating a motor control strategy according to some embodiments.

[0013] FIG. 5 is a schematic diagram of ramping used in some embodiments.

[0014] FIG. 6 is a schematic diagram of a ramp generator that may be used in some embodiments.

[0015] FIG. 7 is another schematic diagram of ramping used in some embodiments.

[0016] In the drawings, like reference numerals may be used to designate like structural elements, and it should be understood that the depictions in the figures are schematic and not to scale. DETAILED DESCRIPTION OF THE INVENTION

[0017] This application relates to pulsed control of a wide variety of electric machines (e.g., electric motors and generators) that are normally continuously operated. Pulsed electric machine control is described in U.S. Patent Nos. 10,742,155 (P200B); 10,944,352 (P201); 11,077,759 (P208C1); 11,088,644 (P207C1); 11,133,767 (P204X1); 11,167,648 (P205); and U.S. Patent Application No. 16 / 912,313, filed June 25, 2020 (P200C). Each of the aforementioned applications is incorporated herein by reference in its entirety. As described in the incorporated applications, pulsed control of electric machines provides the advantage of improving the machine's operating energy conversion efficiency.

[0018] As used herein, the phrase "electric machine" is intended to be broadly interpreted to mean both electric motors and generators. Electric motors and generators are very similar in construction. When an electric machine operates as a motor, it converts electrical energy into mechanical energy. When it operates as a generator, it converts mechanical energy into electrical energy.

[0019] Electric motors and generators are used in a wide variety of applications and under a wide variety of operating conditions. In general, many modern electric machines have relatively high energy conversion efficiencies. However, the energy conversion efficiency of most electric machines varies significantly with operating load. Many applications require electric machines to operate under a wide variety of operating load conditions, often resulting in machines not operating to the fullest extent of their capacity. The essence of this problem is illustrated in Figure 1, which is a motor efficiency map 10 that graphically illustrates the efficiency of a typical motor under different operating conditions. More specifically, the figure plots the motor's energy conversion efficiency as a function of motor speed (X-axis) and generated torque (Y-axis).

[0020] As can be seen from FIG. 1, the illustrated motor is generally most efficient when operating within a particular speed range and producing torque within a defined range 12. For the particular motor illustrated, the most efficient region of its operating range is the operating region labeled 14. This is generally in the range of 4500-6000 revolutions per minute (RPM), with torque output in the range of approximately 40-70 Nm, where the energy conversion efficiency is approximately 96%. Region 14 is sometimes referred to herein as the "sweet spot," which is simply the motor's most efficient operating region.

[0021] As can be seen from Figure 1, at any particular motor speed, there is a corresponding most efficient output torque, represented generally by maximum efficiency curve 16. At any given motor speed, if the motor load is higher or lower than the most efficient load, the motor's efficiency tends to decrease somewhat. In some regions, motor efficiency tends to decrease relatively quickly, for example, once the torque output for the illustrated motor drops below approximately 30 Nm.

[0022] Motors can be much more efficient at converting energy if their operating conditions can be controlled so that they operate almost always at or near their sweet spot. However, many applications require motors to operate under a variety of load conditions that result in widely varying torque requirements and therefore motor speeds. One such application is easily imagined: an automobile or other vehicle or mobility application. In such applications, motor speed can vary from zero RPM when the vehicle is stationary to relatively high RPMs when cruising at highway speeds. Furthermore, torque requirements can vary widely at any of these speeds based on factors such as whether the vehicle is accelerating or decelerating, climbing an incline or descending a incline, or traveling on relatively flat terrain, the vehicle's weight, and many other factors. Of course, motors used in other applications can be subject to a similarly wide variety of operating conditions.

[0023] Although the energy conversion efficiency of conventional electric machines is generally good, efforts are ongoing to further improve energy conversion efficiency over a wider range of operating conditions.

[0024] This disclosure relates generally to pulsing control of otherwise continuously operating electric machines (e.g., electric motors and generators) to improve the energy conversion efficiency of the electric machines when operating conditions permit. More specifically, under selected operating conditions, the electric machines are intermittently driven (pulsed) at more efficient energy conversion operating levels to provide a desired average torque more energy efficiently than can be achieved by conventional continuous motor control.

[0025] Many types of electric machines, including mechanically commutated machines, electronically commutated machines, externally commutated asynchronous machines, and externally commutated synchronous machines, are conventionally driven by a continuous (albeit potentially variable) drive current when the machine is used as a motor to provide a desired torque output. The drive current is often controlled by controlling the output voltage of a power converter (e.g., an inverter), which serves as the voltage input to the motor. Conversely, the output of many types of generators is controlled by controlling the strength of the magnetic field. This is accomplished, for example, by controlling the excitation current supplied to the rotor coils by an exciter. (The exciter may be part of a rectifier or other suitable component.) Regardless of the type of machine, the drive current of a motor and the current output by a generator tend to be continuous. A continuous drive current output may be continuous direct current (DC) or continuous alternating current (AC).

[0026] With pulsation control, the machine's output power is intelligently and intermittently modulated between different torque levels in a manner that (1) meets operational demands and (2) improves overall efficiency. In other words, within a selected operating range, the electric machine is intermittently driven at a more efficient energy conversion operating level than would be achieved if the electric machine were driven continuously and steadily to provide the desired output power.

[0027] As mentioned above, Figure 1 illustrates the energy conversion efficiency of a typical motor. The map shown in Figure 1 is an efficiency map for the interior permanent magnet synchronous motor used in the 2010 Toyota Prius. It should be understood that this map is merely exemplary. Similar efficiency maps can be generated for any electric machine, although the characteristics of the map will vary depending on the specific machine being characterized.

[0028] As can be seen from Figure 1, at any particular motor speed, there exists a corresponding most efficient output torque, shown schematically by maximum efficiency curve 16. From a conceptual standpoint, if the desired motor torque is below the most efficient output torque for the current motor speed, the overall efficiency of the motor can be improved by pulsing the motor. Conversely, if the desired motor torque is above or equal to maximum efficiency curve 16, the motor can be operated in a conventional manner (continuous / non-pulsed) to deliver the desired torque.

[0029] Figure 2A shows an example of continuous motor operation. In this particular example, the desired motor torque is 10 Nm and is provided by a continuous output 18 of 10 Nm.

[0030] FIG. 2B illustrates an example of pulsed motor operation. This example is described in U.S. Patent No. 10,742,155, issued to Adya S. Tripathi on August 11, 2020, and is incorporated herein by reference for all purposes. In this particular example, the desired motor torque is 10 Nm, but the most efficient torque output for the current operating motor speed is 50 Nm. Conceptually, the motor can be driven to deliver a net torque of 10 Nm (labeled 24) by having the motor deliver 50 Nm of torque 20% of the time and no torque (zero) for the remaining 80% of the time. Because the motor operates more efficiently when delivering 50 Nm than when delivering 10 Nm, pulsing the motor's operation in the manner described above can improve the motor's overall efficiency. In the example shown in FIG. 2, the motor generates torque pulse pattern 204 to produce 50 Nm of motor power (labeled 24) for one time unit out of each five time units, after which the motor is controlled to produce zero torque for the four intervening time units.

[0031] As long as the desired motor output does not exceed 50 Nm, the desired motor output can theoretically be met simply by changing the duty cycle of a motor operating at 50 Nm. For example, if the desired motor output changes to 20 Nm, the duty cycle of a motor operating at 50 Nm can be increased to 40%, if the desired motor output changes to 40 Nm, the duty cycle can be increased to 80%, and if the desired motor output changes to 5 Nm, the duty cycle can be decreased to 10%. More generally, motor pulsing can potentially be used advantageously whenever the desired motor torque falls below the maximum efficiency curve 16.

[0032] The time scale used can vary widely based on the size, nature, and design needs of a particular system. In practice, when a motor is switched relatively rapidly from a "torque-on" state to a "zero torque" state to achieve a specified duty cycle, the fact that the motor is switched back and forth between these states may not substantially degrade the motor's performance from an operational standpoint. In some embodiments, the duration scale of each on / off cycle is expected to be on the order of 100 μs to 0.10 s (i.e., pulsing at frequencies in the range of 10 to 10,000 Hz). For example, it is expected to be in the range of 20 to 1000 Hz, or 20 to 100 Hz, as described in more detail below.

[0033] The zero torque portion of the pulse cycle can be conceptually considered to be turning the motor off, although in many cases the motor may not be turned off during that period or may only be turned off for a portion of the "zero torque" interval.

[0034] 3 is a block diagram illustrating a system having an electric machine controller 50 that enables pulsed operation of an electric machine 52 that may be used in some embodiments. The electric machine 52 may be any type of electric machine, including an induction motor / machine, a permanent magnet assisted synchronous reluctance machine, an interior permanent magnet (IPM) machine, etc. The electric machine 52 shown is a three-phase electric machine, but it should be understood that the electric machine may be designed to utilize any desired number of phases (including single phase).

[0035] The electromachine controller 50 includes a power converter 54, a pulse controller 30, and a torque control decision module 62. The pulsing controller 30 has a ramp generator. The power converter 54 can operate as a power inverter or a power rectifier, depending on the direction of energy flow through the system.

[0036] When the electric machine 52 operates as a motor, the power converter 54 is responsible for generating three-phase AC power (phases A, B, and C, designated 18A, 18B, and 18C, respectively) from a DC source / sink 56. In this example, the three-phase AC power is provided by three power signals of equal amplitude and frequency, but 120° out of phase with each other. The three-phase input power is applied to the stator windings of the electric machine 52 to generate a rotating magnetic force (RMF). In an induction motor, this rotating magnetic field causes current to flow in the rotor windings, which in turn induces a rotor magnetic field. The interaction of the rotor field with the stator magnetic field generates an electromagnetic force (EMF), which causes rotor rotation, which in turn rotates the motor shaft. The shaft rotation produces the motor's output torque. In a typical permanent magnet motor, the rotor field is the magnetic field of the permanent magnet.

[0037] Each of the three phases 18A-18C is depicted as a line with an arrowhead at each end, indicating that current can flow in either direction. When used as a motor, current flows from source / sink 56 through power converter 54 to electric machine 52. When used as a generator, current flows from electric machine 52 through power converter 54 to source / sink 56. When operating as a generator, power converter 54 essentially acts as a power rectifier, converting AC power coming from electric machine 52 to DC power that can be stored in a DC power source, such as a battery or capacitor.

[0038] Pulse controller 30 is responsible for selectively pulsing three-phase input current 18A-18C to electric machine 52. During conventional (i.e., continuous) operation, the three-phase input current supplied to electric machine 52 is a continuous sinusoidal current signal, with each signal being 120 degrees out of phase with respect to each other. In this example, when electric machine 52 is synchronized with the three-phase AC power, the frequency of each of the three-phase AC power signals is equal to the frequency of rotation of the motor shaft, and the amplitude of the three-phase AC power signals is related to the torque provided by the motor shaft.

[0039] 4 illustrates a control flow that may be executed by pulse controller 30 to cause electric machine 52 to efficiently provide the desired electric machine output as a torque demand. For ease of discussion, an embodiment will be described in which electric machine 52 functions as a motor. In this configuration, source / sink 56 functions as the power source, and pulse controller 30 functions as the motor controller.

[0040] Initially, the pulse controller 30 receives the power demand (torque demand) and necessary motor state information, such as the current motor speed, as represented by block 171. Next, the pulse controller 30 determines whether the requested desired electromechanical output (torque demand) is within the pulse control range, as represented by decision block 172. This determination can be made in any desired manner. By way of example, in some embodiments, a lookup table or other suitable data structure can be used to determine whether pulsing control is appropriate. In some aspects, a simple lookup table can identify the maximum efficiency torque level at which pulsing control is appropriate for various motor speeds. The maximum efficiency torque level can be an output level at which energy conversion is efficient. In one embodiment, the maximum efficiency torque level can be a specified output level. In such an implementation, the current motor speed can be used as an index into the lookup table to obtain the maximum efficiency torque level at which pulsing control is appropriate under the current operating conditions. The specified output level can be compared to the requested torque to determine whether the requested output is within the pulse control range.

[0041] If the desired torque / current operating conditions are outside the pulsing control range for any reason, conventional (i.e., continuous / non-pulsed) motor control is used, as represented by the “no” branch off decision block 172. In this manner, pulsing is not used and power converter 54 is directed to supply power to electric machine 52 at a level appropriate to drive the motor to provide the desired output in a conventional manner, as represented by block 174. Conversely, if the desired torque / current operating conditions are within the pulsing control range, pulsing control is utilized, as represented by the “yes” branch off block 172. In such an embodiment, pulse controller 30 directs power converter 54 to supply power to the motor using a pulse pattern. The pulse pattern provides power at a first torque level and a second torque level.

[0042] To facilitate the pulse operation, the pulse controller 30 determines a desired power level (block 175). A pulse pattern is determined (block 176) depending on the current motor speed and the desired power level. The pulse controller 30 then instructs the power converter 54 to implement the desired pulse pattern at the specified power level. Conceptually, this can be accomplished by modulating the amplitude of the AC power signal.

[0043] Pulse controller 30 preferably determines the duty cycle and frequency of the pulse pattern. In some embodiments, the pulsing frequency may be fixed for all motor operating conditions, while in other embodiments, it may vary based on operating conditions such as motor speed, torque requirements, etc. For example, in some embodiments, the pulse pattern and frequency may be determined using a look-up table. In such embodiments, the pulse pattern and frequency appropriate for the current motor operating condition may be looked up using an appropriate index, such as motor speed, torque requirements, etc. In other embodiments, the pulse pattern and frequency may not necessarily be fixed for all operating conditions but may vary as directed by pulse controller 30. This type of variation is common when using sigma-delta conversion in determining the pulses.

[0044] 4 illustrates several steps sequentially to facilitate a clear understanding of the functionality provided, it should be understood that many of the steps may in fact be combined and / or reordered. For example, entries in a multi-dimensional lookup table using the desired power and current electric motor speed as indices may indicate both the preferred power level and the appropriate duty cycle for the desired operation.

[0045] 4 illustrates that the electric machine 52 can transition from continuous mode to pulsed mode and then back to continuous mode. Switching from continuous mode to pulsed mode and from pulsed mode to continuous mode has been found to cause increased noise, vibration, and harshness (NVH). Abrupt transitions from continuous mode to pulsed mode or from pulsed mode to continuous mode are believed to introduce noise across a wide frequency range and sometimes cause noticeable driveline clunk. As a result, various embodiments provide ramping of one or more of the frequency, period, duty cycle, and amplitude when transitioning from continuous mode to pulsed mode or from pulsed mode to continuous mode.

[0046] Various embodiments provide ramped pulse transitions from continuous mode to pulsed mode and / or from pulsed mode to continuous mode to reduce NVH. FIG. 5 is a torque versus time graph that may be used in some embodiments. In the example of FIG. 5, curve 504 first provides a continuous torque 506 of 10 Nm from time t0 to time t1. In this example, at 10 Nm, the system transitions from continuous torque to pulsed torque at time t1. In this example, the pulsed mode has an approximately 40% duty cycle. The region of curve 504 with constant pulses 508 provides pulses with a 40% duty cycle, a frequency of 50 Hz, and a period of 20 milliseconds (ms). Furthermore, the region of curve 504 with constant pulses 508 has an amplitude of 25 Nm, going from 0 Nm to 25 Nm, with the 40% duty cycle resulting in an average torque of 10 Nm.

[0047] In this example, curve 504 has a period of approximately 6.7 ms and a first ramping pulse period 520 having a range of approximately 9.4 Nm to 11 Nm, with a duty cycle of 40% so that the pulse is at approximately 11 Nm about 40% of the time and at approximately 9.4 Nm about 60% of the time. As shown in Figure 5, torque is constantly changing, so the torque is an approximation and the values are provided as an example.

[0048] The second ramping pulse period 524 has a period of approximately 7.3 ms and a range of approximately 8.6 Nm to 12 Nm with an approximate 40% duty cycle. The third ramping pulse period 528 has a period of approximately 8 ms and a range of approximately 7.9 to 13.2 Nm. The fourth ramping pulse period 532 has a period of approximately 9.3 ms and a range of approximately 7 to 14.5 Nm. The fifth ramping pulse period 536 has a period of approximately 10.7 ms and a range of approximately 5.9 to 16.1 Nm. The sixth ramping pulse period 540 has a period of approximately 12.7 ms and a range of approximately 4.7 to 17.9 Nm. The seventh ramping pulse period 544 has a period of approximately 14 ms and a range of approximately 3.4 to 20 Nm. The eighth ramping pulse period 548 has a period of approximately 16 ms and a range of approximately 1.8 to 22.3 Nm. The ninth ramping pulse period 552 has a period of approximately 18.7 ms and a range of approximately 0 to 25 Nm.

[0049] After ramping from continuous torque 506 to constant pulse 508, constant pulse 508 is provided. After constant pulse 508 is provided, a ramping region 560 may be provided that ramps from constant pulse 508 to continuous torque 510. In some embodiments, ramping region 560 from constant pulse 508 to continuous torque 510 may be the inverse of the ramping from continuous torque 506 to constant pulse 508.

[0050] In some embodiments, the torque magnitude is ramped linearly with respect to time, as shown in FIG. 5. In some embodiments, the duty cycle does not change during ramping, but the frequency, period, and amplitude are ramped. For example, in FIG. 5, the ramp pulse period increases during ramping. Some embodiments can have a non-linear ramp. In some embodiments, the ramp may be one or two pulses slightly less than the maximum torque and slightly greater than the minimum torque of the constant pulse. For example, in some embodiments, the ramp may consist of two pulses with a maximum torque between 75% and 95% of the maximum torque of the constant pulse. Some embodiments have a short ramp time because ramping causes inefficiencies and shortening the ramp time reduces the inefficiencies. In some embodiments, the frequency of the ramp pulse period may be a multiple of the frequency of the constant pulse 508. For example, if the constant pulse frequency is 20 Hz, the ramp pulse may have a frequency that is a multiple of 20 Hz. For example, the first ramping pulse may have a frequency of 100 Hz, while subsequent ramping pulses provide ramps from 100 Hz to 20 Hz that are multiples of 20 Hz. In some embodiments, the ramp time for ramping from continuous torque 506 to constant pulse 508 may be different (i.e., not equal) than the ramp time from constant pulse 508 to continuous torque 510. For example, the ramp time for ramping from continuous torque 506 to constant pulse 508 may be greater than the ramp time from constant pulse 508 to continuous torque 510.

[0051] There are many possibilities for the ramp profile. In some embodiments, the ramp is at least one of an asymptotic, quadratic, or square root function with an initial steep rise time and then a slower rise time. In some embodiments, to provide a ramped pulse for ramping from continuous torque to a constant pulse, the ramp amplitude is monotonically "non-decreasing." In some embodiments, to provide a ramped pulse for ramping from a constant pulse to continuous torque, the ramp is monotonically "non-increasing." In some embodiments, to ramp from continuous torque to a constant pulse, the ramp amplitude is monotonically increasing. In some embodiments, to ramp from a constant pulse to continuous torque, the ramp is monotonically decreasing.

[0052] In the ramping region 560, the maximum torque is ramped down and the minimum torque is ramped up to a continuous torque. In some embodiments, the ramping pulse duration may decrease during the ramping. In some embodiments, the frequency and amplitude are ramped over the same duration. In some embodiments, only the frequency or the amplitude is ramped. In some embodiments, both the amplitude and the frequency are ramped, and the ramping has at least partially non-overlapping durations. In some embodiments, the pulse duration may be ramped. In some embodiments, the ramping may start from a non-zero value. For example, the torque may start or end from a non-zero value. In some embodiments, the frequency is transitioned through values with lower transmissibility over the ramp duration. In some embodiments, the ramping is not continuous, such that pulses in frequency ranges that may excite system resonances are excluded from the ramp.

[0053] In some embodiments, the ramping is for a period related to the resonant period of the system. In some embodiments, the resonant frequency of the system is less than 20 Hz. In some embodiments, the ramping is 100 ms to 500 ms long. For systems with fast time constants, the ramping can occur over a shorter period. For systems with slow time constants, the ramping can occur over a longer period. In some embodiments, the ramping is 1 microsecond to 2 seconds long. In some embodiments, the ramping duration is approximately 200 ms. In some embodiments, if the resonant frequency of the system is less than 1 Hz, the resonant period is greater than 1000 ms. In such embodiments, the ramp time will be significantly longer than 1000 ms. In some embodiments, the system resonant frequency is a function of at least one of the rotor revolutions per minute (RPM), torque, and duty cycle, with lower duty cycles causing less vehicle sway. In some embodiments, the fundamental amplitude depends on the amplitude and duty cycle. In some embodiments, a one-dimensional lookup table can use functional amplitude to specify multiples of a nominal frequency, a linear ramp, a ramp frequency, an amplitude, and / or a period.

[0054] In some embodiments, increasing the torque modulation frequency may be used to shift the torque frequency to a frequency range with lower noise vibration harshness (NVH). The ramping provided by some embodiments reduces NVH.

[0055] FIG. 6 is a schematic diagram of a ramp generator that may be used in some embodiments. In some embodiments, when the system goes from constant torque to continuous pulses, DmdEnbl switches from 0 to 1. RampedEnbl begins to increase linearly from 0 to 1 according to the ramp rate specified by the rate limiter. In some embodiments, the pulsing amplitude is equal to RampedEnbl, so the pulse amplitude starts at zero; that is, OnTqSoft and OffTqsoft both start from the current value of TqRqst (constant torque), then OnTqSoft increases linearly to OnTqNom, while OffTqSoft decreases to zero. FreqScale, in some embodiments, starts at InitFreqScale, which is greater than 1, and decreases to 1, thereby allowing the on / off times to initially decrease but transition to their respective nominal values. As the system goes from continuous pulses to constant torque, the output ramps back to the constant torque value according to the ramp rate specified by the rate limiter.

[0056] The pulse controllers described herein can be implemented in a wide variety of different ways, including using software or firmware running on a processing unit such as a microprocessor, using programmable logic, using application specific integrated circuits (ASICs), using discrete logic, etc., and / or using any combination of the foregoing.

[0057] The energy conversion efficiency of a power converter also typically varies over the operating range of the power converter. In some embodiments, when optimizing the control of a generator that is part of a rectifier / generator system, it is desirable to consider the energy conversion efficiency of the entire rectifier / generator system, rather than the energy conversion efficiency of the generator alone.

[0058] Preferably, the pulse control of the electric machine is modeled taking into account the efficiency of any / all components that affect energy conversion during pulsing. For example, if power for an AC electric motor is drawn from a battery, the converter and motor efficiency, as well as the battery power supply efficiency, wiring losses between components, and other loss factors, can be considered in determining the motor drive signal that provides the best energy conversion efficiency.

[0059] In general, the overall energy conversion efficiency of a power converter / electromechanical system is a function of the product of the converter's conversion efficiency, the electric machine's conversion efficiency, and the transmission efficiency of the other components. Therefore, it should be understood that the parameters of the shaped pulse drive signal that maximize the system's energy conversion efficiency may differ from the parameters that maximize the motor's own energy conversion efficiency.

[0060] In various embodiments, pulse control can be used for different types of motor control, including AC electric motor control and DC brushless motor control. When an AC induction motor is powered by a battery (which provides DC power), a power converter such as an inverter may be used to facilitate the conversion of the DC power to AC power. In such embodiments, the amplitude of the AC signal generated by the converter may be used to provide a shaped pulse.

[0061] In some embodiments, a sigma-delta type pulse controller can be used to control the timing of the pulses. As those familiar with sigma-delta control will appreciate, features of sigma-delta control tend to facilitate noise shaping, reduce / eliminate idle tones, and push noise to higher frequencies. If the noise is randomized and / or spread to frequencies above the limits of human perception, such noise and / or vibrations are less of a concern because they are not annoying to motor users. Thus, in the context of automotive electric motor applications, the use of sigma-delta control tends to reduce the likelihood that vehicle occupants will perceive noise and vibrations due to pulsed motor control. Various embodiments may be combined with sigma-delta control to further reduce NVH. U.S. Pat. No. 10,742,155, incorporated herein by reference in its entirety, describes a number of representative sigma-delta converter designs.

[0062] FIG. 7 is a torque versus time graph for another ramping technique that may be used in some embodiments. In the example of FIG. 7, graph 704 provides ramping such that the maximum amplitude is ramped up and then down, but the minimum value of each pulse is constant at zero torque. In other embodiments, the minimum value of each pulse may be constant at a torque that is not equal to zero. An advantage of this pulsing method is that the inverter can be shut off during all off-pulses, even during the soft start and soft end phases. Depending on the motor type, intermittently shutting off the inverter can be a major source of energy savings in dynamic motor drives.

[0063] Motor types and applications As is apparent from the foregoing discussion, the described pulsed machine control can be utilized in a wide variety of different applications to improve the energy conversion efficiency of a wide variety of different types of electric motors and generators. This includes both AC and DC motor / generators.

[0064] Some typical electric machines that benefit from pulsing include asynchronous and AC synchronous electric machines, such as induction machines (IMs), switched reluctance machines (SMRs), synchronous reluctance machines (SynRMs), permanent magnet synchronous reluctance machines (PMaSynRMs), hybrid PMaSynRMs, externally excited AC synchronous machines (SyncACs), wound field synchronous machines, permanent magnet synchronous machines (PMSMs), eddy current machines, AC linear machines, AC or DC mechanically commutated machines, and axial flux motors. Typical DC electric machines include brushless, electrically excited, permanent magnet, series-wound, shunt, brushed, and compound. In some embodiments, the electric machine may be a hybrid permanent magnet synchronous reluctance machine.

[0065] While only a few embodiments of the present invention have been described in detail, it should be understood that the present invention may be embodied in many other forms without departing from the spirit or scope of the present invention. The variously described pulse controllers and other control elements may be implemented, grouped, and configured in a wide variety of different architectures in different embodiments. For example, in some embodiments, the pulse controller may be incorporated into a motor controller or converter controller, or may be provided as a separate component. Similarly, in a generator, the pulse controller may be incorporated into a generator controller or rectifier controller, and in a combined motor / generator, the pulse controller may be incorporated into a combined motor / generator controller or combined converter / rectifier controller. In some embodiments, the described control functions may be implemented algorithmically in software or firmware running on a processor. The processor may take any suitable form, including, for example, a general-purpose processor, a microprocessor, a digital signal processor (DSP), or the like.

[0066] The pulse controller may be part of a larger control system. For example, in a vehicle application, the described control may be part of a vehicle controller, powertrain controller, hybrid powertrain controller, or ECU (engine control unit) that performs various functions related to vehicle control. In such applications, the vehicle or other related controller may take the form of a single processor that performs all of the necessary controls, or may include multiple processors that are collocated as part of a powertrain or vehicle control module, or distributed at various locations within the vehicle. The specific functions performed by any processor or control unit may vary widely.

[0067] In some embodiments, the ramp generator is a separate physical device from the pulse controller. In some embodiments, the ramp generator is a physical device that is part of the pulse controller. In some embodiments, the ramp generator is computer readable code executed by the pulse controller.

[0068] While the present disclosure has been described in terms of several preferred embodiments, there are alterations, modifications, permutations, and various substitute equivalents that fall within the scope of the present disclosure. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present disclosure. It is therefore intended that the following appended claims be interpreted as including all such alterations, modifications, permutations, and various substitute equivalents that fall within the true spirit and scope of the present disclosure.

Claims

1. 1. An electric machine controller configured to provide a desired output by causing pulsed operation of an electric machine in a selected operating range and to direct a power converter to cause continuous operation of the electric machine in the selected operating range, the electric machine controller comprising a ramp generator adapted to provide ramping between the pulsed operation and the continuous operation.

2. The electromechanical controller of claim 1 , wherein the ramping is from the continuous operation to the pulsed operation and from the pulsed operation to the continuous operation.

3. The electromachine controller of claim 1 , wherein the ramping is a ramping of at least one of magnitude, frequency, and period.

4. The electromachine controller of claim 1 , wherein the ramping ramps both magnitude and frequency.

5. The electromachine controller of claim 1 , wherein the ramp generator is adapted to reduce noise, vibration, and harshness when transitioning between pulsed and continuous operation.

6. The electromachine controller of claim 1 , wherein the ramping is at least one of linear ramping, asymptotic ramping, quadratic ramping, and square root ramping.

7. The electromachine controller of claim 1 , wherein the ramping includes providing at least two ramp-like pulses between continuous and pulsed operation.

8. The electromachine controller of claim 1 , wherein the ramping is for a duration of between 100 ms and 500 ms.

9. 2. The electromachine controller of claim 1, wherein the ramp generator is adapted to provide the ramping between the pulsed operation and the continuous operation, and wherein a duration of the ramping from the continuous operation to the pulsed operation is not equal to a duration of the ramping from the pulsed operation to the continuous operation.

10. The electromachine controller according to any one of claims 1 to 2, wherein the ramping is at least one of ramping of magnitude, frequency, and period.

11. An electromachine controller as claimed in any preceding claim, wherein the ramping ramps both magnitude and frequency.

12. 12. The electromachine controller of claim 1, wherein the ramp generator is adapted to reduce noise, vibration, and harshness when transitioning between pulsed and continuous operation.

13. 13. The electromachine controller of claim 1, wherein the ramping is at least one of linear ramping, asymptotic ramping, quadratic ramping, and square root ramping.

14. 14. The electromachine controller of any of claims 1-2 and 10-13, wherein the ramping comprises providing at least two ramp-like pulses between continuous and pulsed operation.

15. An electromachine controller as claimed in any of claims 1-2 and 10-14, wherein the ramping is for a duration of between 100ms and 500ms.

16. 16. An electromachine controller as claimed in any one of claims 1 to 2 and 10 to 15, wherein the ramp generator is adapted to provide the ramping between the pulsed operation and the continuous operation, and wherein a duration of the ramping from the continuous operation to the pulsed operation is not equal to a duration of the ramping from the pulsed operation to the continuous operation.

17. Electrical machinery and a power converter; an electric machine controller configured to provide a desired output by causing pulsed operation of the electric machine in a selected operating range and to direct a power converter to cause continuous operation of the electric machine in a selected operating range; the electromechanical controller comprising a ramp generator adapted to provide ramping between the pulsed operation and the continuous operation; A system comprising:

18. The system of claim 17 , wherein the electric machine is a motor and the power converter comprises an inverter.

19. The system of claim 17 , wherein the electric machine is a generator and the power converter includes a rectifier.

20. The system of claim 17 , wherein the electric machine is configured to operate as a motor / generator.

21. 20. The system of claim 17, wherein the ramping is from the continuous operation to the pulsed operation and from the pulsed operation to the continuous operation.

22. The system of claim 17 , wherein the ramping is at least one of ramping magnitude, frequency, and period.

23. 20. The system of claim 17, wherein the ramping ramps both magnitude and frequency.

24. 20. The system of claim 17, wherein the ramp generator is adapted to reduce noise, vibration, and harshness when transitioning between pulsed and continuous operation.

25. 20. The system of claim 17, wherein the ramping is at least one of linear ramping, asymptotic ramping, quadratic ramping, and square root ramping.

26. 20. The system of claim 17, wherein the ramping comprises providing at least two ramp-like pulses between continuous operation and pulsed operation.

27. 20. The system of claim 17, wherein the ramping is for a duration between 100 ms and 500 ms.

28. 18. The system of claim 17, wherein the ramp generator is adapted to provide the ramping between the pulsed operation and the continuous operation, and wherein a duration of the ramping from the continuous operation to the pulsed operation is not equal to a duration of the ramping from the pulsed operation to the continuous operation.

29. The system of any of claims 17 to 20, wherein the ramping is from the continuous operation to the pulsed operation and from the pulsed operation to the continuous operation.

30. The system of any one of claims 17 to 20 and 29, wherein the ramping is ramping of at least one of magnitude, frequency, and period.

31. The system of any of claims 17 to 20 and 29, wherein the ramping ramps both magnitude and frequency.

32. 32. The system of any of claims 17-20 and 29-31, wherein the ramp generator is adapted to reduce noise, vibration, and harshness when transitioning between pulsed and continuous operation.

33. The system of any of claims 17 to 20 and 29 to 32, wherein the ramping is at least one of linear ramping, asymptotic ramping, quadratic ramping, and square root ramping.

34. The system of any of claims 17-20 and 29-33, wherein the ramping comprises providing at least two ramp-like pulses between continuous operation and pulsed operation.

35. A system according to any of claims 17 to 20 and 20 to 34, wherein the ramping is for a duration between 100ms and 500ms.

36. 36. The system of any of claims 17 to 20 and 20 to 35, wherein the ramp generator is adapted to provide the ramping between the pulsed operation and the continuous operation, and wherein a duration of the ramping from the continuous operation to the pulsed operation is not equal to a duration of the ramping from the pulsed operation to the continuous operation.

37. 1. A method of controlling an electric machine by an electric machine controller configured to provide a desired output by causing pulsed operation of the electric machine in a selected operating range and to direct a power converter to cause continuous operation of the electric machine in the selected operating range, the method including providing ramping between the pulsed operation and the continuous operation.

38. 38. The method of claim 37, wherein providing the ramping provides ramping from the continuous operation to the pulsed operation and from the pulsed operation to the continuous operation.

39. 38. The method of claim 37, wherein providing the ramping provides ramping of at least one of magnitude, frequency, and period.

40. 38. The method of claim 37, wherein the providing ramping ramps both magnitude and frequency.

41. 38. The method of claim 37, wherein providing the ramping is adapted to reduce noise, vibration, and harshness when transitioning between pulsed and continuous operation.

42. 38. The method of claim 37, wherein providing ramping provides at least one of linear ramping, asymptotic ramping, quadratic ramping, and square root ramping.

43. 38. The method of claim 37, wherein providing the ramping comprises providing at least two ramp-like pulses between a continuous operation and a pulsed operation.

44. 38. The method of claim 37, wherein the ramping is for a duration between 100 ms and 500 ms.

45. 38. The method of claim 37, wherein a duration of the ramping from the continuous operation to the pulsed operation is not equal to a duration of the ramping from the pulsed operation to the continuous operation.

46. The method of any of claims 37 to 38, wherein providing ramping provides ramping of at least one of magnitude, frequency, and period.

47. The method of any of claims 37-38, wherein providing ramping ramps both magnitude and frequency.

48. 48. The method of any of claims 37-38 and 46-47, wherein providing ramping is adapted to reduce noise, vibration, and harshness when transitioning between pulsed and continuous operation.

49. The method of any of claims 37-38 and 46-48, wherein providing ramping provides at least one of linear ramping, asymptotic ramping, quadratic ramping, and square root ramping.

50. The method of any of claims 45-48 and 46-49, wherein providing ramping comprises providing at least two ramp-like pulses between continuous operation and pulsed operation.

51. A method according to any of claims 45 to 48 and 46 to 50, wherein the ramping is for a duration between 100ms and 500ms.

52. A method according to any of claims 45 to 48 and 46 to 51, wherein the duration of the ramping from the continuous operation to the pulsed operation is not equal to the duration of the ramping from the pulsed operation to the continuous operation.

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