Pulsed electrical machine control with soft start and soft end

Abstract

An electrical machine controller is provided that is arranged to direct a power converter to cause an electrical machine to pulse over a selected operating range to deliver a desired output and to cause the electrical machine to continuously operate over the selected operating range. A transition generator is provided to provide a transition between pulsed operation and continuous operation.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

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

[0002] The present application relates generally to electric machine control. More particularly, control schemes and controller designs are described that pulse the operation of an electric machine during selected operating conditions so that the electric machine operates in a more energy efficient manner and with reduced noise, vibration, and harshness (NVH) reduction. Summary of the invention

[0003] Various methods, controllers, and electric machine systems are described that facilitate pulse control of a multi-electric machine (e.g., electric motors and generators) drive system to improve the energy conversion efficiency of the electric machines when operating conditions permit. More specifically, an electric machine controller is provided that is arranged to direct a power converter to cause the electric machine to operate in pulses (pulsed operation) within a selected operating range to deliver a desired output and to cause the electric machine to operate continuously within the selected operating range. A transition generator (ramp generator) is arranged to provide a transition (ramp) between pulsed operation and continuous operation.

[0004] In another embodiment, a system is provided, wherein the system includes an electric machine, a power converter, and an electric machine controller. The electric machine controller is arranged to direct the power converter to cause the electric machine to operate in pulses within a selected operating range to deliver a desired output, and to cause the electric machine to operate continuously within the selected operating range, wherein the electric machine controller includes a transition generator configured to provide a transition between pulse operation and continuous operation.

[0005] In another embodiment, a method of controlling an electric machine by an electric machine controller is provided, the electric machine controller being arranged to command a power converter to cause the electric machine to operate in pulses within a selected operating range to deliver a desired output, and to cause the electric machine to operate continuously within the selected operating range. A transition between pulsed operation and continuous operation is provided.

[0006] These and other features of the present disclosure will be described in more detail in the detailed description of the disclosure and in conjunction with the following figures. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present invention and its advantages may be best understood by referring to the following description taken in conjunction with the accompanying drawings, in which:

[0008] Figure 1 is a representative torque / speed / efficiency graph illustrating the energy conversion efficiency of an electric motor under different operating conditions for a representative electric motor.

[0009] Figure 2A An example of continuous motor operation is illustrated.

[0010] Figure 2B An example of pulse motor operation is illustrated.

[0011] Figure 3 is a functional block diagram that graphically illustrates an electric machine controller according to one described embodiment.

[0012] Figure 4 is a flow chart illustrating a motor control scheme according to some implementations.

[0013] Figure 5 are illustrative examples of transitions used in some embodiments.

[0014] Figure 6 is an illustrative example of a transition generator that may be used in some implementations.

[0015] Figure 7 is another illustrative example of a transition used in some embodiments.

[0016] In the drawings, like reference numerals are sometimes used to denote like structural elements. It should also be understood that the depictions in the drawings are graphical and not to scale. DETAILED DESCRIPTION

[0017] The present application relates to pulse control of various electrical machines (e.g., electric motors and generators) that otherwise operate in a continuous manner. 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 (P200C), filed on June 25, 2020, describe pulse electrical machine control. Each of the above applications is incorporated herein by reference in its entirety. As described in the incorporated applications, pulse control of electrical machines provides the benefit of improving the operational energy conversion efficiency of the machine.

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

[0019] Electric motors and generators are used in a variety of applications and under a variety of operating conditions. In general, many modern electrical machines have relatively high energy conversion efficiencies, however, the energy conversion efficiency of most electrical machines can vary greatly based on their operating load. Many applications require electrical machines to operate under a variety of operating load conditions, which means that electrical machines are often not operated to the best of their capabilities. An example of the essence of this problem is Figure 1 , which is a motor efficiency map 10, graphically illustrates the efficiency of a representative motor under different operating conditions. More specifically, the graph plots the energy conversion efficiency of the motor as a function of the motor speed (X-axis) and the generated torque (Y-axis).

[0020] exist Figure 1 As can be seen in the diagram, the motor shown is generally most efficient when it operates within a specific speed range and generates torque within a defined range 12. For the specific motor shown, the most efficient region of its operating range is the operating region labeled 14, which is generally in the range of 4500-6000 revolutions per minute (RPM) and has a torque output in the range of about 40-70 Nm, with an energy conversion efficiency of about 96%. Region 14 is sometimes referred to herein as the "sweet spot," which is simply the region where the motor operates most efficiently.

[0021] exist Figure 1 As can be seen from the graph, at any particular motor speed, there will be a corresponding most efficient output torque, which is graphically illustrated by the maximum efficiency curve 16. For any given motor speed, the efficiency of the motor tends to drop somewhat as the load on the motor is above or below the most efficient load. In some regions, the efficiency of the motor tends to drop relatively quickly—for example, when the torque output drops below about 30 Nm in the example motor.

[0022] If the operating conditions can be controlled so that the motor is almost always operating at or near its optimal point, the energy conversion efficiency of the motor will be quite good. However, many applications require the motor to operate across a variety of load conditions, with widely varying torque requirements and widely varying motor speeds. One such application that is easily visualized is automotive and other vehicles or mobile applications, where the motor speed can vary between zero (when the vehicle is stopped) to relatively high RPMs (when traveling at highway speeds). The torque demand can also vary widely at any of those speeds - based on multiple factors such as whether the vehicle is accelerating or decelerating, going uphill, downhill, traveling on relatively flat terrain, etc., the weight of the vehicle, and many other factors. Of course, motors used in other applications may also encounter a variety of operating conditions.

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

[0024] The present disclosure generally relates to pulse control of electrical machines (e.g., electric motors and generators) that would otherwise operate in a continuous manner to improve the energy conversion efficiency of the electrical machines when operating conditions permit. More specifically, under selected operating conditions, the electrical machines are intermittently driven (pulsed) at more efficient energy conversion operating levels to deliver a desired average torque more energy efficiently than conventional continuous motor control.

[0025] Many types of electrical machines (including mechanically commutated machines, electronically commutated machines, externally commutated asynchronous machines, and externally commutated synchronous machines) are traditionally driven by a continuous (although possibly variable) drive current when the machine is used as a motor to deliver the 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). In contrast, the power output of many types of generators is controlled by controlling the magnetic field strength - this can be achieved, for example, by controlling the excitation current (excitation current) provided by an exciter to the rotor coils. (The exciter can be part of a rectifier or other suitable component). Regardless of the type of machine, the drive current of the motor or the current output of the generator is often continuous. The continuous drive current output can be continuous direct current (DC) or continuous alternating current (AC).

[0026] Under pulse control, the output of the machine is intelligently and intermittently adjusted between different torque levels in a manner that: (1) meets operating demands while (2) improving overall efficiency. In other words, within a selected operating range, the electric machine is intermittently driven at a more efficient energy conversion operating level (compared to the level that would be available if the electric machine were driven in a continuous and steady manner) to deliver the desired output.

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

[0028] exist Figure 1 As can be seen in FIG. 1 , at any particular motor speed, there is a corresponding most efficient output torque, which is graphically illustrated by the maximum efficiency curve 16. From a conceptual perspective, when 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 (operating) the motor. Conversely, when the desired motor torque is at or above the maximum efficiency curve 16, the motor can be operated in a conventional (continuous / non-pulsed) manner to deliver the desired torque.

[0029] Figure 2A An example of continuous motor operation is illustrated. In this specific example, the desired motor torque is 10 Nm, provided by a continuous output 18 of 10 Nm.

[0030] Figure 2B An example of pulse motor operation is illustrated. This example is described in U.S. Patent No. 10,742,155 granted to Adya S. Tripathi on August 11, 2020, which is incorporated herein by reference for all purposes. In this specific example, the desired motor torque is 10 Nm, but the most effective torque output for the current running motor speed is 50 Nm. Conceptually, the motor can be driven to deliver a net torque of 10 Nm (marked as 24) by causing the motor to deliver a torque of 50 Nm for 20% of the time and then not deliver torque (deliver zero torque) for the remaining 80% of the time. Since the operating efficiency of the motor when it delivers 50 Nm is higher than the operating efficiency when it delivers 10 Nm, the overall efficiency of the motor can be improved by pulsing the operation of the motor in the manner described. In the example shown in Figure 2, the motor generates a torque pulse mode 204 to provide a motor output of 50 Nm (marked as 24) for a period of 1 time unit in every 5 time units, and then the motor is controlled to produce zero torque during an interval of 4 time units.

[0031] As long as the desired motor output does not exceed 50Nm, the desired motor output can theoretically be met simply by changing the duty cycle of the motor operation at 50Nm. For example, if the desired motor output becomes 20Nm, the duty cycle of the motor operation at 50Nm can be increased to 40%; if the desired motor output becomes 40Nm, the duty cycle can be increased to 80%; if the desired motor output becomes 5Nm, the duty cycle can be reduced to 10%, and so on. More generally, the pulses of the motor can potentially be used to advantage at any time when the desired motor torque is below the maximum efficiency curve 16.

[0032] The scale of the time units used may vary widely based on the size, properties, and design requirements of any particular system. In practice, when the motor switches relatively quickly from a "torque" state to a "zero torque" state to achieve a specified duty cycle, the fact that the motor switches back and forth between these states may not substantially degrade the performance of the motor from an operational perspective. In some embodiments, the scale of the period for each on / off cycle is expected to be on the order of 100 μsec to 0.10 seconds (i.e., pulsed at a frequency in the range of 10 to 10,000 Hz), such as, for example, 20 to 1000 Hz, or 20 to 100 Hz, as discussed in more detail below.

[0033] The zero torque portion of the pulse cycle can be conceptually viewed as shutting down the motor - although in many cases the motor may not be shut down during those periods, or may be shut down for only part of the "zero torque" interval.

[0034] Figure 3 is a block diagram of an example system having an electric machine controller 50 that can be used in some embodiments to enable pulsed operation of an electric machine 52. The electric machine 52 can 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 example electric machine 52 is a three-phase electric machine, but it should be understood that the electric machine can be designed to use any desired number of phases, including only a single phase.

[0035] The electric machine controller 50 includes a power converter 54, a pulse controller 30 and a torque control decision module 62. The pulse controller 30 has a transition 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 electrical machine 52 is operated as a motor, the power converter 54 is responsible for generating three-phase AC power (A, B and C phases are named 18A, 18B and 18C respectively) from the DC power source / sink 56. The three-phase AC power in this example is provided by three power signals having the same amplitude and frequency but 120o phase difference from each other. The three-phase input power is applied to the windings of the stator of the electrical 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 causes a rotor magnetic field. The interaction of the rotor and stator magnetic fields generates an electromagnetic force (EMF), causing the rotor to rotate, which in turn causes the motor shaft to rotate. The rotating shaft provides the output torque of the motor. For the most common permanent magnet motors, the rotor magnetic field is the magnetic field of the permanent magnets.

[0037] The three phases 18A-18C are each depicted by a line with arrows at both ends, indicating that current can flow in either direction. When used as a motor, current flows from the power supply / transducer 56 through the power converter 54 to the electrical machine 52. When used as a generator, current flows from the electrical machine 52 through the power converter 54 to the power supply / transducer 56. When operating as a generator, the power converter 54 essentially operates as a power rectifier, and the AC power from the electrical machine 52 is converted to DC power, which is stored in a DC power source such as a battery or capacitor.

[0038] The pulse controller 30 is responsible for selectively pulsing the three-phase input current 18A-18C to the electric machine 52. During normal (i.e., continuous) operation, the three-phase input current provided to the electric machine 52 is a continuous sinusoidal current signal, each signal being 120° out of phase with one another. In this example, when the electric machine 52 is synchronized with the three-phase AC power, the frequency of each signal of the three-phase AC power is equal to the rotational frequency of the motor shaft, and the amplitude of the signal of the three-phase AC power is related to the torque provided by the motor shaft.

[0039] Figure 4 The control flow that can be performed by the pulse controller 30 to effectively deliver the electric machine output desired according to the torque demand of the electric machine 52 is illustrated. To simplify the discussion, an embodiment is described in which the electric machine 52 is used as a motor. In this arrangement, the power supply / transducer 56 acts as a power source and the pulse controller 30 acts as a motor controller.

[0040] Initially, the pulse controller 30 determines the output demand (torque demand) and any required motor state information such as the current motor speed, as shown in box 171. The pulse controller 30 then determines whether the desired desired electrical machine output (torque demand) is within the pulse control range, as shown in decision box 172. This determination can be made in any desired manner. For example, in some embodiments, a query table or other suitable data structure can be used to determine whether pulse control is appropriate. In some embodiments, a simple query table can identify the maximum efficiency torque level that pulse control is suitable for various motor speeds. The maximum efficiency torque level can be an energy conversion effective output level. In one embodiment, the maximum efficiency torque level can be a specified output level. In such an embodiment, the current motor speed can be used as an index to the query table to obtain the maximum efficiency torque level that is suitable for pulse control under the current operating conditions. The specified output level can then be compared with the required torque to determine whether the required output is within the pulse control range.

[0041] If for any reason the desired torque / current operating conditions are outside the pulse control range, conventional (i.e., continuous / non-pulsed) motor control is employed, as indicated by the "no" branch flowing out of decision box 172. Thus, pulsing is not employed, and power converter 54 is directed to deliver power to electric machine 52 at a level suitable for driving the motor to deliver the desired output in a conventional manner, as indicated by box 174. Conversely, when the desired torque / current operating conditions are within the pulse control range, pulse control is employed, as indicated by the "yes" branch flowing out of box 172. In such an embodiment, pulse controller 30 will direct power converter 54 to deliver power to the motor using a pulse mode. The pulse mode provides power at a first torque level and a second torque level.

[0042] To facilitate pulsed operation, the pulse controller 30 determines the desired output level (block 175). The pulse pattern is determined based on the current motor speed and the desired output level (block 176). The pulse controller 30 then directs the power converter 54 to implement the desired pulse pattern at the specified power level. Conceptually, this can be achieved by adjusting the amplitude of the AC power signal.

[0043] The pulse controller 30 preferably determines the duty cycle and frequency of the pulse pattern. In some embodiments, the pulse frequency may be fixed for all operating conditions of the motor, while in other embodiments it may vary based on operating conditions (such as motor speed, torque demand, etc.). For example, in some embodiments, the pulse pattern and frequency may be determined by using a lookup table. In such an embodiment, appropriate indicators (such as motor speed, torque demand, etc.) may be used to query the pulse pattern and frequency suitable for the current motor operating conditions. In other embodiments, the pulse pattern and frequency are not necessarily fixed for any given operating condition and may vary as indicated by the pulse controller 30. This type of variation is common when Σ-Δ conversion is used for pulse determination.

[0044] Although Figure 4 Some steps are illustrated in sequence to facilitate a clear understanding of the functions provided, but it should be understood that many of the steps can be combined and / or reordered in practice. For example, entries in a multidimensional lookup table using the desired output and current motor speed as indicators can indicate a preferred output level and a duty cycle suitable for the desired operation.

[0045] Figure 4 The electric machine 52 is shown to be able to go from continuous mode to pulse mode and then back to continuous mode. It has been found that switching from continuous mode to pulse mode and vice versa results in increased noise, vibration and harshness (NVH). It is believed that the abrupt transition from continuous mode to pulse mode or vice versa introduces noise over a wide frequency range, which can sometimes produce noticeable drive train "clunk". Therefore, various embodiments provide for transitions in one or more of frequency, period, duty cycle and amplitude when switching from continuous mode to pulse mode or vice versa.

[0046] Various embodiments provide for a transient pulse transition from continuous mode to pulse mode and / or from pulse mode to continuous mode to reduce NVH. Figure 5 is a graph of torque vs. time that may be used in some embodiments. Figure 5 In the example of curve 504, first, the curve from t 0 to 1 506. In this example, at 10 Nm, the system is 1Transition from continuous torque to pulsed torque. In this example, the 40% pulse mode has a duty cycle of about 40%. The region of the curve 504 with constant pulses 508 provides pulses of 40% duty cycle, 50 Hz frequency, 20 millisecond (ms) period. In addition, the region of the curve 504 with constant pulses 508 has a 25 Nm amplitude from 0 Nm to 25 Nm, wherein the 40% duty cycle provides an average torque of 10 Nm.

[0047] In this example, curve 504 has a first ramping pulse period 520 having a period of about 6.7 ms and a range of about 9.4 Nm to 11 Nm, with a 40% duty cycle such that the pulse is at about 11 Nm about 40% of the time and at about 9.4 Nm about 60% of the time. Figure 5 As shown, torque varies constantly, therefore torques are approximate and values ​​are provided as examples.

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

[0049] After the transition from the continuous torque 506 to the constant pulse 508, the constant pulse 508 is provided. After the constant pulse 508 is provided, a transition region 560 may be provided that transitions from the constant pulse 508 to the continuous torque 510. In some embodiments, the transition region 560 from the constant pulse 508 to the continuous torque 501 may be the inverse of the transition from the continuous torque 506 to the constant pulse 508.

[0050] In some embodiments, the torque magnitude is transitioned linearly with respect to time, such as Figure 5 In some embodiments, the duty cycle does not change during the transition period, but the frequency, period, and amplitude are transitioned. Figure 5In some embodiments, the transition pulse period increases during the transition. Some embodiments may have a nonlinear transition. In some embodiments, the transition may be one or two pulses slightly less than the maximum torque of the constant pulse and slightly greater than the minimum torque of the constant pulse. For example, in some embodiments, the transition may consist of two pulses whose maximum torque is between 75% and 95% of the maximum torque of the constant pulse. Some embodiments have a short transition time because the transition causes inefficiencies, and shortening the transition time reduces inefficiencies. In some embodiments, the frequency of the transition 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 frequency of the transition pulse may be a multiple of 20 Hz. For example, the frequency of the first transition pulse may be 100 Hz, and the subsequent transition pulse provides a transition from 100 Hz to 20 Hz as a multiple of 20 Hz. In some embodiments, the transition time from the continuous torque 506 to the constant pulse 508 may be different (or unequal) from the transition time from the constant pulse 508 to the continuous torque 510. For example, the transition time from the continuous torque 506 to the constant pulse 508 may be greater than the transition time from the constant pulse 508 to the continuous torque 510 .

[0051] There are multiple possibilities for transition profiles. In some embodiments, the transition is at least one of an asymptotic function, a quadratic function, or a square root function with an initial sharp rise time followed by a slower rise time. In some embodiments, in order to provide a transition pulse from continuous torque to a constant pulse, the amplitude of the transition is monotonically "non-decreasing". In some embodiments, in order to provide a transition pulse from a constant pulse to a continuous torque, the transition is monotonically "non-increasing". In some embodiments, for the transition from continuous torque to a constant pulse, the amplitude of the transition is monotonically increasing. In some embodiments, for the transition from a constant pulse to a continuous torque, the transition is monotonically decreasing.

[0052] For transition region 560, the maximum torque transitions down and the minimum torque transitions up to a continuous torque. In some embodiments, during the transition, the transition pulse period can be reduced. In some embodiments, the frequency and amplitude transition over the same duration (time, duration). In some embodiments, only one of the frequency or amplitude transitions. In some embodiments, both the amplitude and the frequency transition, wherein the transition has a duration that is at least partially non-overlapping. In some embodiments, the pulse period can transition. In some embodiments, the transition can start at a non-zero value. For example, the torque can be adapted to or end at a non-zero value. In some embodiments, the frequency transitions through (multiple) values ​​with lower transfer rates over the transition duration. In some embodiments, the transition is not continuous, so that pulses within the frequency range that may excite system resonance are excluded from the transition.

[0053] In some embodiments, the period of transition is related to the resonance period of the system. In some embodiments, the resonant frequency of the system is less than 20 Hz. In some embodiments, the transition length is between 100 ms and 500 ms. For systems with fast time constants, the transition may be over a shorter period. For systems with slow time constants, the transition may be over a longer period. In some embodiments, the transition length is between 1 microsecond and 2 seconds. In some embodiments, the duration of the transition is about 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 these embodiments, the transition 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, wherein a lower duty cycle does not cause the vehicle to shake much. In some embodiments, the fundamental amplitude depends on the amplitude and duty cycle. In some implementations, a one-dimensional lookup table may utilize functional amplitudes to specify multiples of nominal frequencies, linear transitions, transition frequencies, amplitudes, and / or periods.

[0054] In some embodiments, the increase in torque modulation frequency may be used to change the torque frequency to a frequency range with lower noise vibration harshness (NVH). Some embodiments provide for a transition that reduces NVH.

[0055] Figure 6is a schematic example of a transition generator that may be used in some embodiments. In some embodiments, DmdEnbl switches from 0 to 1 when the system goes from constant torque to continuous pulsing. RampedEnbl begins to increase linearly from 0 to 1 according to the rise rate specified in the rate limiter. In some embodiments, the pulse amplitude is equal to RampedEnbl so that the pulse amplitude starts at zero, that is, both OnTqSoft and OffTqsoft start at the current value of TqRqst (constant torque), then OnTqSoft increases linearly to OnTqNom, while OffTqSoft decreases to zero. FreqScale starts at InitFreqScale, which is greater than 1 in some embodiments, and decreases to 1, so that the on / off time is initially reduced, but then transitions to its nominal value. When the system goes from continuous pulsing to constant torque, the output transitions back to the constant torque value according to the fall rate specified by the rate limiter.

[0056] The pulse controller described herein may be implemented in a variety of different ways, including using software or firmware executed on a processing unit such as a microprocessor, using programmable logic, using an application-specific integrated circuit (ASIC), using discrete logic, etc., and / or using any combination of the foregoing.

[0057] The energy conversion efficiency of a power converter will also generally vary within the operating range of the power converter. In some embodiments, when optimizing the control of a generator as part of a rectifier / generator system, it may be desirable to consider the energy conversion efficiency of the overall rectifier / generator system rather than the energy conversion efficiency of the generator alone.

[0058] Preferably, the pulse control of the electric machine will be modeled to take into account the efficiency of any / all components that affect the energy conversion during the pulse. For example, when the power for the AC electric motor comes from a battery, in addition to the converter and motor efficiencies, the power delivery efficiency of the battery, cabling losses between components, and any other loss factors may also be considered when determining the motor drive signal that delivers the best energy conversion efficiency.

[0059] In general, the overall energy conversion efficiency of the power converter / electric machine system is a function of the product of the converter conversion efficiency times the electric machine conversion efficiency times the delivery efficiency of the other components. Therefore, it should be understood that the parameters of the shaped pulse drive signal with the maximum system energy conversion efficiency may be different from the parameters that provide the best energy conversion efficiency for the motor itself.

[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 the AC induction motor is powered by a battery (which provides DC power), a power converter such as an inverter can be used to facilitate the conversion of DC power to AC power. In such embodiments, the amplitude of the AC signal generated by the converter can be used to provide shaped pulses.

[0061] In some embodiments, a ΣΔ series pulse controller can be used to control the timing of the pulses. Those familiar with ΣΔ control will understand that the characteristics of ΣΔ control are that it facilitates noise shaping and tends to reduce / eliminate idle tones, as well as push noise to higher frequencies. When noise is randomized and / or diffused to frequencies beyond the limits of human perception, there are fewer concerns because any such noise and / or vibration does not cause trouble to the motor user. Therefore, in the context of automotive electric motor applications, the use of ΣΔ control tends to reduce the likelihood that the vehicle user will perceive noise or vibration caused by pulse motor control. Various embodiments can be combined with ΣΔ control to further reduce NVH. U.S. Patent No. 10,742,155 (incorporated herein by reference in its entirety) describes a variety of representative ΣΔ converter designs.

[0062] Figure 7 is a torque vs. time graph that may be used for another transition in some embodiments. Figure 7 In the example of , the graph 704 provides a transition where the maximum amplitude transitions up and then transitions down, but where the minimum value of each pulse is constant at zero torque. In other embodiments, the minimum value of each pulse can be constant at a torque that is not equal to zero. The benefit of this pulse method is that the inverter can be turned off during all off pulses, even during the soft start and end phases. Depending on the motor type, intermittently turning off the inverter can be a primary source of energy savings in dynamic motor drives. Motor Types and Applications

[0063] As will be apparent from the foregoing description, the pulse machine control described can be used in a variety of different applications to improve the energy conversion efficiency of various different types of electric motors and generators. These include both AC and DC motor / generators.

[0064] Several representative types of electrical machines that can benefit from the described pulses include asynchronous and synchronous AC electrical machines - including: Induction machines (IM); switched reluctance machines (SMR); Synchronous reluctance machines (SynRM); Permanent Magnet Synchronous Reluctance machines (PMaSynRM); Hybrid PMaSynRMs; Externally Excited AC Synchronous machines (SyncAC); Wound field Synchronous machines, Permanent Magnet Synchronous machines (PMSM); Eddy current machines; AC linear machines; AC and DC mechanically commutated machines; Axial flux motors; etc. Representative DC electrical machines include brushless, electrically excited, permanent magnet, series wound, shunt, brushed, compound, etc. In some embodiments, the electrical machine can be a hybrid permanent magnet synchronous reluctance machine.

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

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

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

[0068] Although the present disclosure has been described with respect to several preferred embodiments, there are a variety of changes, modifications, arrangements and various alternative equivalent forms that fall within the scope of the present disclosure. It should also be noted that there are a variety of alternative ways to implement the method and apparatus of the present disclosure. Therefore, the appended claims should be interpreted as including all such changes, modifications, arrangements and various alternative equivalent forms that fall within the actual spirit and scope of the present disclosure.

Claims

1. An electric machine controller arranged to command a power converter to cause an electric machine to operate in pulses within a selected operating range to deliver a desired output, and to cause the electric machine to operate continuously within the selected operating range, wherein the electric machine controller includes a transition generator arranged to provide a transition between the pulse operation and the continuous operation.

2. The electric machine controller of claim 1, wherein the transition is a transition from the continuous operation to the pulsed operation and from the pulsed operation to the continuous operation.

3. The electric machine controller of claim 1, wherein the transition is a transition in at least one of magnitude, frequency, and period.

4. The electric machine controller of claim 1 wherein the transition transitions both magnitude and frequency.

5. The electric machine controller of claim 1 wherein the transition generator is configured to reduce noise, vibration, and harshness when transitioning between pulsed operation and continuous operation.

6. The electric machine controller of claim 1, wherein the transition is at least one of a linear transition, an asymptotic function transition, a quadratic function transition, and a square root function transition.

7. The electric machine controller of claim 1, wherein the transitioning includes providing at least two transition pulses between continuous operation and pulsed operation.

8. The electric machine controller of claim 1, wherein the transition occurs over a duration between 100 ms and 500 ms.

9. The electric machine controller of claim 1, wherein the transition generator is configured to provide the transition between the pulsed operation and the continuous operation, wherein a period of transition from the continuous operation to the pulsed operation is not equal to a period of transition from the pulsed operation to the continuous operation.

10. An electrical machine controller according to any one of claims 1-2, wherein the transition is a transition in at least one of magnitude, frequency and period.

11. An electric machine controller according to any one of claims 1-2, wherein the transition transitions both magnitude and frequency.

12. An electric machine controller according to any one of claims 1-2 and 10-11, wherein the transition generator is arranged to reduce noise, vibration and harshness when transitioning between pulsed operation and continuous operation.

13. The electric machine controller of any one of claims 1-2 and 10-12, wherein the transition is at least one of a linear transition, an asymptotic function transition, a quadratic function transition, and a square root function transition.

14. An electric machine controller according to any one of claims 1-2 and 10-13, wherein the transitioning comprises providing at least two transition pulses between continuous operation and pulsed operation.

15. An electric machine controller as claimed in any one of claims 1-2 and 10-14, wherein the transition is over a duration of 100 ms to 500 ms.

16. An electrical machine controller according to any one of claims 1-2 and 10-15, wherein the transition generator is configured to provide the transition between the pulsed operation and the continuous operation, wherein a period of transition from the continuous operation to the pulsed operation is not equal to a period of transition from the pulsed operation to the continuous operation.

17. A system comprising: electrical machinery; Power converters; and An electric machine controller is arranged to command a power converter to cause the electric machine to operate in pulses within a selected operating range to deliver a desired output and to cause the electric machine to operate continuously within the selected operating range, wherein the electric machine controller includes a transition generator arranged to provide a transition between the pulsed operation and the continuous operation.

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

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

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

21. The system of claim 17, wherein the transition 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 transition is a transition in at least one of magnitude, frequency, and period.

23. The system of claim 17, wherein the transition transitions magnitude and frequency.

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

25. The system of claim 17, wherein the transition is at least one of a linear transition, an asymptotic function transition, a quadratic function transition, and a square root function transition.

26. The system of claim 17, wherein the transitioning comprises providing at least two transition pulses between continuous operation and pulsed operation.

27. The system of claim 17, wherein the transition occurs over a duration between 100 ms and 500 ms.

28. The system of claim 17, wherein the transition generator is configured to provide the transition between the pulsed operation and the continuous operation, wherein a period of transition from the continuous operation to the pulsed operation is not equal to a period of transition from the pulsed operation to the continuous operation.

29. The system of any one of claims 17-20, wherein the transition 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 17-20 and 29, wherein the transition is a transition in at least one of magnitude, frequency, and period.

31. The system of any one of claims 17-20 and 29, wherein the transition transitions magnitude and frequency.

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

33. The system of any one of claims 17-20 and 29-32, wherein the transition is at least one of a linear transition, an asymptotic function transition, a quadratic function transition, and a square root function transition.

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

35. The system of any one of claims 17-20 and 20-34, wherein the transition takes place over a duration between 100 ms and 500 ms.

36. A system according to any one of claims 17-20 and 20-35, wherein the transition generator is configured to provide the transition between the pulsed operation and the continuous operation, wherein a period of transition from the continuous operation to the pulsed operation is not equal to a period of transition from the pulsed operation to the continuous operation.

37. A method of controlling an electric machine by an electric machine controller, the electric machine controller being arranged to command a power converter to cause the electric machine to operate in pulses within a selected operating range to deliver a desired output and to cause the electric machine to operate continuously within a selected operating range, the method comprising providing a transition between the pulsed operation and the continuous operation.

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

39. The method of claim 37, wherein the providing transition provides a transition in at least one of magnitude, frequency, and duration.

40. The method of claim 37, wherein said providing a transition transitions magnitude and frequency.

41. The method of claim 37, wherein said providing a transition is configured to reduce noise, vibration and harshness when transitioning between pulsed operation and continuous operation.

42. The method of claim 37, wherein the providing a transition provides at least one of a linear transition, an asymptotic function transition, a quadratic function transition, and a square root function transition.

43. The method of claim 37, wherein providing a transition comprises providing at least two transition pulses between continuous operation and pulsed operation.

44. The method of claim 37, wherein the transition occurs over a duration between 100 ms and 500 ms.

45. The method of claim 37, wherein a period of transition from the continuous operation to the pulse operation is not equal to a period of transition from the pulse operation to the continuous operation.

46. ​​The method of any one of claims 37-38, wherein the providing a transition provides a transition in at least one of magnitude, frequency, and period.

47. The method of any one of claims 37-38, wherein said providing a transition transitions magnitude and frequency.

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

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

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

51. A method according to any one of claims 45-48 and 46-50, wherein the transition takes place over a duration between 100 ms and 500 ms.

52. The method according to any one of claims 45-48 and 46-51, wherein a period of transition from the continuous operation to the pulse operation is not equal to a period of transition from the pulse operation to the continuous operation.

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