Electric machine with high efficiency torque conversion

Abstract

A motor is provided. A multiphase motor is provided. A power inverter is electrically connected to the multiphase motor. A controller is electrically connected to the power inverter, wherein the controller provides switching signals to the power inverter, wherein the controller includes a trajectory calculator that provides an optimized trajectory for transitioning the multiphase motor from a first torque to a second torque.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of priority to U.S. Application No. 63 / 210,345, filed June 14, 2021, which is incorporated herein by reference for all purposes. Background Technology

[0003] This application generally relates to electric motors.

[0004] As used in this article, the term "electric motor" is intended to be broadly understood to refer to both electric motors and generators. Electric motors and generators are very similar in structure. Both include a rotor and a stator with multiple poles. When operating as an electric motor, it converts electrical energy into mechanical energy. When operating as a generator, it converts mechanical energy into electrical energy. Summary of the Invention

[0005] To achieve the foregoing objectives and in accordance with the purposes of this disclosure, an electric motor is provided. A multiphase motor is provided. A power inverter is electrically connected to the multiphase motor. A controller is electrically connected to the power inverter, wherein the controller provides switching signals to the power inverter, and wherein the controller includes a trajectory calculator that provides an optimized trajectory for converting the multiphase motor from a first torque to a second torque.

[0006] In another embodiment, a method is provided for switching a multiphase motor from a first torque level to a second torque level, wherein the multiphase motor is controlled by a controller. An optimized trajectory from the controller is provided to the multiphase motor, wherein the optimized trajectory provides an optimized path for switching the multiphase motor from the first torque level to the second torque level.

[0007] These and other features of this disclosure will now be described in more detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0008] The invention and its advantages are best understood by referring to the following description taken in conjunction with the accompanying drawings, in which:

[0009] Figure 1 This is a schematic diagram of a motor according to some embodiments.

[0010] Figure 2 This is a high-level flowchart used in some embodiments.

[0011] Figure 3 This is a schematic diagram of a motor with pulse torque according to some embodiments.

[0012] Figure 4 The graphs show some of the improvements provided by the embodiments.

[0013] In the drawings, like reference numerals will be used to designate like structural elements. It is also to be understood that the depiction in the drawings is illustrative and not to scale. DETAILED DESCRIPTION

[0014] Modern electric machines have relatively high energy conversion efficiency. However, the energy conversion efficiency of most electric machines can vary significantly based on their operating load. In many applications, electric machines need to operate under a variety of different operating load conditions. Additionally, the torque provided by the electric machine can vary with operation that requires a change from a first torque to a second torque. The first torque can be a first torque level and the second torque can be a second torque level.

[0015] Most electric machines (motors and generators) are controlled to provide the highest efficiency under steady state conditions, regardless of transient time periods. Furthermore, for high bandwidth torque controllers, the smallest transient time period is desired, which often results in less than ideal control due to controller output saturation.

[0016] Research into torque conversion has shown that most, if not all, motor control laws simply attempt to convert torque as quickly as possible. Most multi-input multi-output (MIMO) torque controllers for multi-phase electric machines either underutilize bus voltages or saturate the controller outputs resulting in less than ideal control during transients. Underutilization of bus voltages results in slow torque response, while uncontrolled controller saturation results in fast but inefficient response. Therefore, a solution is needed that maximizes controller output to ensure the fastest conversion time while maximizing efficiency during that conversion time.

[0017] Typically, for MIMO systems such as multi-phase electric machines, controller gains are adjusted to keep the controller outputs within the range of system capabilities (e.g., bus voltage and current limits of an inverter). In this scenario, if the controller is linear, the bus voltages are underutilized. However, over-adjusted torque controllers and many other high bandwidth controllers, including nonlinear controllers, tend to saturate the outputs, thereby fully utilizing the bus voltages during transients. However, the trajectory of power applied to the electric machine does not follow the optimal relationship defined by a maximum torque per ampere (MTPA), maximum torque per loss (MTPL), maximum torque per flux (MTPF), or maximum torque per volt (MTPV) control strategy during such saturation. In essence, most techniques currently used trade off torque performance for transient efficiency to a large extent.

[0018] Some embodiments are directed to maximizing transient efficiency with possibly small transient time by maximizing bus voltage utilization and ensuring that the torque trajectory stays on at least one of the MTPA, MTPL, MTPF, or MTPV paths during the torque transient of any polyphase motor. Various embodiments use different methods / techniques that can achieve such performance. In some examples, three of the many possible techniques are described to demonstrate some embodiments of the invention, where the three techniques are described as follows:

[0019] 1) Optimal torque rate limit for maximum bus voltage utilization.

[0020] 2) Optimal I d / Iq rate limit / voltage angle for maximum bus voltage utilization.

[0021] 3) Open loop I q feedback as I d reference when Q-axis time constant is greater than D-axis time constant. q control. Open loop I d feedback as I q reference when D-axis time constant is greater than Q-axis time constant. d control.

[0022] All three methods make full use of the bus voltage used during the torque transient and optimally share the bus voltage between the D-axis and Q-axis to achieve maximum efficiency. In some embodiments, a computer optimization algorithm can be used to determine the path optimized trajectory.

[0023] The first method relies on calculating the maximum torque achievable in the next sampling period (i.e., T[k+1]). This controller requires a high-bandwidth inverse model controller, such as a deadbeat controller. It can utilize either a direct torque flux control loop or an I d / I q current vector control operation.

[0024] Consider the case of a synchronous reluctance motor. The voltages Vd, Vq, and the vector magnitude Vs can be calculated as follows.

[0025]

[0026]

[0027]

[0028] where [k] is the sampling instance k th , I d is the direct axis stator current, I q is the quadrature axis stator current, L dis direct axis stator inductance, L q is quadrature axis stator inductance, V d is direct axis stator voltage, V q是 quadrature axis stator voltage, V s is stator voltage vector magnitude, ω e is rotor electrical frequency (rad / s), and R s is per phase stator resistance (ohms).

[0029] Id / Iq references can be calculated from torque (rpm) and bus voltage can be derived using MTPA, MTPL, or MTPV equations or look up tables (LUTs) that satisfy these equations.

[0030] I d [k] = f1(rpm[k], V bus [k], τ[k]);

[0031] I q [k] = f2(rpm[k], V bus [k], τ[k]);

[0032] I d [k+1] = f1(rpm[k+1], V bus [k+1], τ[k+1]);

[0033] I q [k+1] = f2(rpm[k+1], V bus [k+1], τ[k+1]);

[0034] where [k+1] is the sample instance (k+1) th , V bus is the DC bus voltage available to the power inverter,

[0035] Since revolutions per minute (RPM) and Vbus do not change significantly over one sample time, torque [k+1] can be made to move quickly between minimum torque and maximum torque, from which Id[k], Iq[k], Id[k+1], Iq[k+1] can be used to derive Vs[k]. The value of torque [k+1] that satisfies Vs[k] = Vmax must be selected for the controller. In this way, using the f1() and f2() functions above, Vs is maximized while satisfying the MTPA, MTPL, or MTPV conditions. Torque [k+1] can then be used to rate limit the torque command.

[0036] This optimal torque [k+1] selection can use real-time manual scanning and search algorithms (such as binary search) or use a look up table (LUT) that satisfies the MTPA, MTPL, or MTPV conditions at rpm[k], V busThe process is completed using a 3-D LUT with [k] and τ[k] as inputs.

[0037] The second method relies on calculating the optimal voltage angle and the voltage amplitude that satisfies MTPA, MTPL, or MTPV when Vs = Vmax. When Vs is set to Vmax, the voltage equations of the synchronous reluctance motor in discrete state-space form are considered.

[0038]

[0039]

[0040] Where, φ v It is the stator voltage vector angle referenced to the direct axis, and V max It is the maximum permissible stator voltage vector amplitude.

[0041] If φ v Rapid movement between 0° and 360°, then targeting φ v To draw I d [k+1] and I q [k+1]. In I d [k+1] and I q If [k+1] satisfies the conditions MTPA, MTPL, or MTPV, then φ is chosen. v The value of I. At this time, I d [k+1] and I q Any of the terms in [k+1] can be used to rate limit the commands of the deadbeat controller, or φ v It can be used directly to calculate V d [k] and V q [k] retrieves the controller output during the transient period.

[0042] If the time constant of the D-axis is higher than that of the Q-axis, the third method uses a proportional-integral controller and takes advantage of this fact. Therefore, the full voltage is initially applied to the slower time constant axis, allowing I... d The ramp-up is limited only by the motor time constant. Then, using the optimal MTPA, MTPV, or MTPL table, I... d Feedback to generate I q Reference. Then, the output disturbance voltage angle of the Q-axis control loop is moved away from the D-axis so that the voltage is optimally shared between the two axes. If the time constant of the Q-axis is higher than that of the D-axis, a third method uses a proportional-integral controller and takes advantage of the fact that the time constant of the Q-axis is higher than that of the D-axis, thus initially applying the full voltage to the slower time constant axis and allowing I... qRamps up only limited by motor time constants. Then, using the optimal MTPA, MTPV, or MTPL table, I q is generated using feedback to generate I d ref. Then, the output disturbance voltage angle of the D-axis control loop is made to move away from the Q-axis so that the voltage achieves optimal sharing between the two axes.

[0043] Computer optimization algorithms can be used to help define the optimal path of I d and I q for any desired trajectory, including MTPA, MTPV, and MTPL. The result can be a look-up table (LUT) or a mathematical equation that can be processed in real-time in the controller. In some embodiments, the computer optimization algorithm can be at least one of numerical optimization, dynamic programming, and model predictive control. In various embodiments, the computer optimization algorithm can be used online or offline. When used offline, a LUT can be generated by the computer optimization algorithm.

[0044] In some embodiments using numerical optimization, an ordinary differential equation (ODE) solver is used with a differential equation formulation of the motor model to provide an estimate of how the model state will change over time when a control input is applied at each step. With each ODE solution, a cost can be computed to penalize or reward some objective, such as following a torque target, while also limiting signals or states within ranges. If such an optimization cannot be done in real-time, the optimization can be computed ahead of time and stored in a LUT. In an example of numerical optimization, a cost function is provided that targets are to be met over a specified time period. An initial value is specified for the control input, such as a voltage. In some embodiments, the control input can be two or more of V d , V q , voltage magnitude, and voltage angle. In this example, the ODE is solved assuming that the voltage input is applied each time. In this example, a cost is computed from the ODE results. In some embodiments, the cost (J) can be a single function or an arbitrary sum of multiple costs. The actual cost function can reward the ability to follow a torque trajectory, or reward increasing valuable statistics such as torque per unit current, or be a barrier function that penalizes violating constraints such as bus voltage or armature current limits. The cost function can vary over time or over multiple iterations, which is an important aspect of using barrier functions. The values of the voltage input are iterated over time and terminated under some condition, resulting in a cost-optimal vector of control inputs. In some embodiments, the ODE is solved and optimized over one time step, then the ODE is solved and optimized over the next time step, and so on. When finished, all of the trajectories can be concatenated together to arrive at the optimal long-term cost.

[0045] In some embodiments, dynamic programming can also be used to derive the cost optimal trajectory. The differential equation problem will be converted from a problem of numerical integration to one of choosing transitions between states in a timely manner, where each transition has a certain cost associated with it. By representing the problem as a series of paths from the desired final state to the beginning, dynamic programming can be used to choose the cost optimal path, and thus the cost optimal trajectory of states and inputs. This method takes advantage of the optimality principle due to its structure.

[0046] Economic model predictive control can use part of the direct optimization method to set up. The "economic" aspect will be an arbitrary cost function to solve this problem, not one of the ODE states such as current or flux. The ODE problem will still be solved, and the cost with possible constraints will still be computed from the ODE results, but the number of elements optimized against this problem will be limited to the first few time steps, while holding the last input constant for the remainder of the time. This ensures that the long term trajectory is cost optimal and constrained, but the problem is small enough to be solved quickly. By solving the model predictive control problem and saving the first control input for each time step, a larger offline solution can be constructed.

[0047] Current techniques either provide torque response performance with poor transient efficiency, or limit the rate of change of torque demand so that the control remains within voltage limits. Some embodiments optimize the torque transient period. Some embodiments provide high efficiency during the transient period with as small a transient period as possible. Since the time constant is longer than the sampling time, some embodiments assume quasi-steady state behavior during the transient, and force the system to transition through an optimal state trajectory to ensure efficiency maximization.

[0048] Some embodiments have the potential to improve the efficiency of any motor control, not just torque controlled motors used in the traction industry, and thus are a complement to existing control strategies employed.

[0049] Figure 1 is a block diagram of a motor system 100 that can be used in some embodiments. The motor system 100 includes a multiphase motor 104, a power inverter 108, a power source 112, and an inverter controller 116. In the specification and claims, the multiphase motor 104 can be a multiphase motor or a multiphase generator. Thus, in the specification and claims, the power inverter 108 is a power converter for a multiphase motor or a multiphase generator. Such a power inverter 108 can also be referred to as a power rectifier. In some embodiments, the power source 112 is a DC power source. One or more feedback signals are provided from the multiphase motor 104 to the inverter controller 116.

[0050] In some embodiments, the inverter controller 116 can be located within the power inverter 108. In some embodiments, the inverter controller 116 can be external to or separate from the power inverter 108. In some embodiments, a portion of the inverter controller 116 can be within the power inverter 108 and a portion of the inverter controller 116 can be external to or separate from the power inverter 108. In some embodiments, the inverter controller 116 includes a torque controller 120, a ramp rate limiter 122, a trajectory calculator 124, and a torque-to-current reference converter 128. In some embodiments, the inverter controller 116 does not have a torque-to-current reference converter 128. In such embodiments, the user torque command 136 can be provided directly to the ramp rate limiter 122. In some embodiments, the inverter controller 116 provides a switching signal to the power inverter 108. In some embodiments, the switching signal controls motor excitation such that the motor follows an optimized trajectory, thereby minimizing losses from a first torque to a second torque.

[0051] In some embodiments, when the multiphase motor 104 is operated as a 3-phase motor, the power inverter 108 is responsible for generating three-phase AC power from the DC power source 112 to drive the multiphase motor 104. Three-phase input power, denoted as phase A 137a, phase B 137b, and phase C 137c, is applied to the stator windings of the multiphase motor 104 to generate a rotating magnetic field. The lines depicting each phase 137a, 137b, and 137c are depicted with arrows on both ends, indicating that current can flow from the power inverter 108 to the multiphase motor 104 when the motor is used as a 3-phase motor, and from the multiphase motor 104 to the power inverter 108 when the multiphase motor 104 is used as a generator. When the multiphase motor 104 is operated as a generator, the power inverter 108 operates as a power rectifier, and AC power from the multiphase motor 104 is converted to DC and stored in the DC power source 112.

[0052] Figure 2is a flowchart of a process that can be used in some embodiments. In some embodiments, the inverter controller 116 receives a user torque command (step 204). In an example, the user torque command requests a transition of torque provided by the multi-phase electric machine 104 from a first torque to a second torque. In some embodiments, the trajectory calculator 124 provides an optimized trajectory from the first torque to the second torque (step 208). In some embodiments, the optimized torque trajectory is expressed by a series of voltage or current commands to provide a voltage or current path. The optimized torque trajectory information is provided to the slope rate limiter 122 (step 212). The slope rate limiter provides rate limit information to the torque controller 120 (step 216). The controlled torque input is provided to the power inverter 108 (step 220) to provide the optimized trajectory for the multi-phase electric machine 104.

[0053] In some embodiments, the trajectory calculator 124 uses at least one of the MTPA, MTPL, MTPF, or MTPV control strategies to calculate the optimized trajectory. In some embodiments, the optimized trajectory is determined using at least one of: 1) optimal torque rate limit for maximum bus voltage utilization, optimal I d / I q rate limit / voltage angle, and open loop Iq control with Iq feedback as Id reference. In some embodiments, some of the above methods are used to create a lookup table (LUT). The lookup table can provide the first torque and the second torque as inputs, and then provide from the lookup table a stored value in the lookup table identified by the first torque and the second torque. In some embodiments, computer optimization using optimization algorithms can be used to determine the optimized trajectory.

[0054] Figure 3 is Figure 1The schematic diagram of the motor system 100 is shown, but with the addition of a pulse torque controller used in a pulse motor system. Examples of such pulse torque motors are described in U.S. Patent No. 10,742,155, filed March 14, 2019, U.S. Patent Application No. 16 / 353,159, filed March 14, 2019, and U.S. Provisional Patent Application Nos. 62 / 644,912, 62 / 658,739, and 62 / 810,861, filed March 19, 2018, April 17, 2018, and February 26, 2019, respectively. Each of the above-mentioned applications is incorporated by reference herein in its entirety for all purposes. In such applications, the torque level transitions very frequently (possibly many times per second), and efficient transition control can enable more efficient operation. In some embodiments, the pulse torque controller 340 provides pulse torque commands to the trajectory calculator 124. In some embodiments, the first and second torque levels and the periodic pulses provide an overall average output that has a higher energy conversion efficiency than when the system is operated in a continuous manner to provide the same average output. Additionally, in some embodiments, the pulse period can be selected to minimize or reduce noise, vibration, and harshness.

[0055] Figure 4 is a plot of torque or current versus time, illustrating a current trajectory that can be used in some embodiments that use pulse periodic torque operation. In this example, the torque pulses between a first torque T1 to a second torque T2, with a period of t p In some embodiments, the pulse torque is provided by a pulse torque command or signal from the pulse torque controller 340. In some embodiments, the amplitude of the first torque T1 is zero. In this example, the trajectory calculator 124 provides an optimized trajectory of optimal torque from the first torque T1 to the second torque T2, as shown by Figure 3 . The trajectory provides I q ramp 412 and I d ramp 416 to provide a torque ramp 420 from the first torque T1 to the second torque T2 over a time period tl. The torque can remain at the second torque T2 for a period of time. Then, the torque command can request a ramp down of the torque from the second torque T2 to the first torque T1. The trajectory provides I q ramp 422 and I d ramp 424 to provide an optimal torque ramp 428 from the second torque T2 to the first torque T1 over a time period t2. The torque can remain at the first torque T1 for a period of time until the pulse period t p is complete.

[0056] In some embodiments, I q ramp 412 and I dThe trajectory of the ramp 416 improves efficiency. Some prior art systems attempt to provide a vertical current ramp in order to attempt to provide a vertical torque ramp from the first torque T1 to the second torque T2. In such prior art embodiments, the controller output is an uncontrolled saturated output which results in a low efficiency fast response. In other prior art devices, a very slow ramping process can be provided resulting in underutilization of the bus voltage leads resulting in low efficiency and slow torque response. Thus, the optimized trajectory avoids output saturation as well as underutilization of the bus voltage resulting in improved efficiency.

[0057] In some embodiments, the pulse period t p is half a second so that the torque can be converted between the first torque T1 and the second torque T2 several times per second. In some embodiments, the pulse period t p is less than one second. In some embodiments, the use of a pulsed torque provides improved efficiency multiple times per second.

[0058] By providing an optimized trajectory, the conversion from the first torque to the second torque is achieved more efficiently with less power consumption. Some embodiments provide maximum efficiency between torque conversions. Additionally, some embodiments ensure that the power delivered to the motor shaft is maximized during torque conversions. Some embodiments optimize torque performance by fully utilizing the available voltage and current during the conversion between the first torque and the second torque. The reduction in power consumption in the motor as an electric motor increases the range of the electric motor for a given power supply capacity. The reduction in power consumption in the motor as a generator allows more power to be provided to the DC power supply 112.

[0059] In various embodiments, the multi-phase electric machine can include, but is not limited to, a brushless DC (BLDC) electric machine, a permanent magnet synchronous electric machine (PMSM), an interior permanent magnet (IPM) electric machine, a wound rotor synchronous electric machine, an induction electric machine, and a synchronous reluctance electric machine. In some embodiments, the multi-phase electric machine can have two or more phases. As described above, the multi-phase electric machine can be a multi-phase electric motor or a multi-phase electric generator, or a multi-phase electric machine that operates as both an electric motor and an electric generator. In some embodiments, the torque controller 120 can be implemented as a different device, such as a high bandwidth current controller or a flux controller.

[0060] While the disclosure has been described in terms of several preferred embodiments, it is to be appreciated that alterations, modifications, arrangements, and various alternatives, etc., will become apparent to others skilled in the art upon reading the foregoing description. It is intended that the following claims be interpreted as including all such alterations, modifications, arrangements, and various alternatives, etc. As used herein, the phrase "A, B, or C" should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean exclusively one of A or B or C. Each step in a process can be an optional step and is not required. Different embodiments can remove one or more steps or can provide steps in a different order. Additionally, various embodiments can provide different steps simultaneously rather than sequentially. Further, elements shown and described separately can also be combined into a single device or a single step. For example, steps described sequentially can be simultaneous. Further, steps described sequentially in one order can be performed in another order.

Claims

1. An electric machine comprising: a multi-phase electric machine; a power inverter electrically connected to the multi-phase electric machine; and an inverter controller electrically connected to the power inverter, wherein the inverter controller receives a user torque command request to transition the multi-phase electric machine from a first torque to a second torque, wherein the inverter controller provides switching signals to the power inverter, wherein the inverter controller includes a trajectory calculator that provides an optimized trajectory for transitioning the multi-phase electric machine from the first torque to the second torque based on at least one of maximum torque per amp (MTPA), maximum torque per loss (MTPL), maximum torque per flux (MTPF), and maximum torque per volt (MTPV). The trajectory calculator provides the optimized trajectory, and any other computer generated optimal trajectory, using at least one of: optimal torque rate limits for maximum bus voltage utilization, optimal Id / Iq rate limits / voltage angles for maximum bus voltage utilization, open loop Iq control with Iq feedback as Id reference.

2. The electric machine of claim 1, wherein, The trajectory calculator uses a look-up table.

3. The electric machine of claim 2, wherein, The trajectory calculator provides an optimized trajectory that minimizes losses, and wherein the electric machine follows the optimized trajectory.

4. The electric machine of claim 1, wherein, The trajectory calculator provides at least one voltage magnitude and at least one voltage vector angle.

5. The electric machine of claim 1, wherein, 6. An electric machine comprising: a multi-phase electric machine; a power inverter electrically connected to the multi-phase electric machine; an inverter controller electrically connected to the power inverter, wherein the inverter controller provides switching signals to the power inverter, wherein the inverter controller includes a trajectory calculator that provides an optimized trajectory for transitioning the multi-phase electric machine from a first torque to a second torque based on at least one of maximum torque per amp (MTPA), maximum torque per loss (MTPL), maximum torque per flux (MTPF), and maximum torque per volt (MTPV); and a pulse torque controller connected to the inverter controller, the pulse torque controller providing a pulse periodic torque operation to the inverter controller. The pulse periodic torque operation provides an overall average system output that has a higher energy conversion efficiency during the pulse periodic torque operation of the electric machine than the electric machine running at a third torque to provide the same average output in a continuous manner driving the electric machine.

7. The electric machine of claim 6, wherein, The period is a period that provides reduced noise, vibration, and harshness.

8. The electric machine of claim 7, wherein, 10. A method for transitioning a multi-phase electric machine from a first torque level to a second torque level, wherein the multi-phase electric machine is controlled by an inverter controller, comprising:

9. The electric machine of claim 8, wherein, receiving a user torque command request to transition the multi-phase electric machine from a first torque to a second torque; and ​ ​ providing an optimized trajectory from the inverter controller to the multiphase electric machine based on at least one of maximum torque per amp (MTPA), maximum torque per loss (MTPL), maximum torque per flux (MTPF), and maximum torque per volt (MTPV), wherein the optimized trajectory provides an optimized trajectory for transitioning the multiphase electric machine from the first torque level to the second torque level.

11. The method of claim 10, wherein, the inverter controller providing a series of voltages to the multiphase electric machine to provide the optimized trajectory.

12. The method of claim 10, wherein, the optimized trajectory is provided using at least one of: optimal torque rate limits for maximum bus voltage utilization, optimal Id / Iq rate limits / voltage angles for maximum bus voltage utilization, open loop Iq control with Iq feedback as Id reference, and any other computer generated optimal trajectory.

13. The method of claim 12, wherein, the optimized trajectory reduces noise, vibration, and harshness.

14. The method of claim 10, wherein, the optimized trajectory minimizes losses, and wherein the multiphase electric machine follows the optimized trajectory.

15. A method for transitioning a multiphase electric machine from a first torque level to a second torque level, wherein the multiphase electric machine is controlled by an inverter controller, comprising: providing an optimized trajectory from the inverter controller to the multiphase electric machine based on at least one of maximum torque per amp (MTPA), maximum torque per loss (MTPL), maximum torque per flux (MTPF), and maximum torque per volt (MTPV), wherein the optimized trajectory provides an optimized trajectory for transitioning the multiphase electric machine from the first torque level to the second torque level, wherein the inverter controller provides a series of voltages to the multiphase electric machine to provide the optimized trajectory, wherein the inverter controller further provides a vector angle of the voltages.

16. A method for transitioning a multiphase electric machine from a first torque level to a second torque level, wherein the multiphase electric machine is controlled by an inverter controller, comprising: providing an optimized trajectory from the inverter controller to the multiphase electric machine based on at least one of maximum torque per amp (MTPA), maximum torque per loss (MTPL), maximum torque per flux (MTPF), and maximum torque per volt (MTPV), wherein the optimized trajectory provides an optimized trajectory for transitioning the multiphase electric machine from the first torque level to the second torque level; and providing a pulsed torque signal to provide a pulsed periodic torque operation between the first torque level and the second torque level, wherein a period of the pulsed periodic torque operation is less than one second.

17. The method of claim 16, wherein, the first and second torque levels and period provide an overall average system output having a higher energy conversion efficiency during the pulsed periodic torque operation of the multiphase electric machine than if the multiphase electric machine were operated in a continuous manner driving the multiphase electric machine at a third torque level to provide the same average output.

18. The method of claim 17, wherein, the period is a period that provides reduced noise, vibration, and harshness.

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