Rotating electric machines

Abstract

An exemplary system includes a rotating electric machine. The rotating electric machine includes a rotor that is cylindrical and configured to rotate, and a stator disposed relative to the rotor. The stator has a stepped configuration that defines a stator first diameter and a stator second diameter. The first diameter is greater than the second diameter. A zone of the stator at the first diameter carries direct axis (D-axis) windings, and a zone of the stator at the second diameter carries quadrature axis (Q-axis) windings. An air gap between the rotor and the Q-axis windings is greater than an air gap between the rotor and the D-axis windings.

Description

[Technical Field]

[0001] This specification describes examples and applications of rotating electrical machines having a non-uniform air gap between the stator bore and rotor bore. [Background technology]

[0002] High-density rotating electric machines, such as induction motors, use primary or stator members with a uniform air gap between the stator bore and the outer diameter of the associated rotor. Therefore, in this case, the basic reluctance of the direct and quad axes of the machine can be identical. In such machines, differences in output reactance can be obtained by varying direct and quad winding parameters such as number of turns, coding, or distribution ratio. Summary of the Invention

[0003] An exemplary system includes a rotating electric machine. The rotating electric machine includes a rotor that is cylindrical and configured to rotate, and a stator disposed relative to the rotor. The stator has a stepped configuration that defines a first stator diameter and a second stator diameter. The first diameter is larger than the second diameter. A zone of the stator at the first diameter carries direct-axis (D-axis) windings, and a zone of the stator at the second diameter carries quadrature-axis (Q-axis) windings. An air gap between the rotor and the Q-axis windings is larger than the air gap between the rotor and the D-axis windings. The exemplary system can include one or more of the following features, alone or in combination:

[0004] The stator may include a neutralization winding between the sets of D-axis and Q-axis windings. The neutralization winding may be configured to vary the air-gap radial flux between adjacent D-axis and Q-axis windings. The system may include an inertial energy storage device that provides power to the D-axis windings to enable rotation when the rotor is disconnected from an external power source.

[0005] The Q-axis winding may be configured to output energy to a load. The rotating electric machine may be configured to supply power to the D-axis winding through an external power source until the rotor reaches a predetermined speed, after which the D-axis winding may be powered by an inertial energy storage device. While the D-axis winding is powered by the inertial energy storage device, the rotating electric machine is configured to output energy from the D-axis winding to boost the energy output by the Q-axis winding. The energy from the D-axis winding may be superimposed on the energy output by the Q-axis winding. Boosting the energy output by the Q-axis winding may include at least one of adding a current or a voltage to the current or voltage output by the D-axis winding. The electrical reactance of the Q-axis winding may be lower than the electrical reactance of the D-axis winding based on a difference in radial air gaps associated with the Q-axis winding and the D-axis winding. The combined energy from the Q-axis winding and the D-axis winding may be pulsed or continuous. The combined energy from the Q-axis winding and the D-axis winding may be at the end of a rise in power output from the Q-axis winding.

[0006] The rotating electric machine may be configured to output energy from the D-axis winding that boosts energy output from the Q-axis winding to the load. The system may include a transformer between the rotating electric machine and the load. The transformer may be configured to receive current from the D-axis winding and the Q-axis winding and to generate boosted energy output to the load based on the current from the D-axis winding and the Q-axis winding.

[0007] As described above, the rotating electric machine can be configured to output energy from the D-axis winding to boost the energy output from the Q-axis winding to the load. The rotating electric machine can include a switch controllable to interrupt a circuit between the rotating electric machine and the load. The interruption of the circuit can occur simultaneously with the injection of energy from the D-axis winding. The interruption of the circuit can generate transient voltages and currents that boost the energy output from the Q-axis winding. The transient voltages and currents can increase the rate of rise of the energy output from the Q-axis winding. The transient voltages and currents can increase the total energy output to the load. The transient voltages and currents can generate pulsed energy output to the load. The Q-axis winding, the switch, and the D-axis winding can form a current loop that is interrupted by controlled opening of the switch. The output current from the D-axis winding can circulate in a closed loop until the current reaches a target value, at which point the switch can be controlled to interrupt the circuit between the rotating electric machine and the load.

[0008] The system may further include circuitry to change the D-axis winding from a polyphase input to a single-phase alternating current (AC) excitation, thereby causing a spatial peripheral shift of the air gap magnetic flux of the D-axis winding and, as a result, boosting the energy output by the Q-axis winding.

[0009] As described above, the rotating electric machine is configured to output energy from the D-axis winding to boost the energy output from the Q-axis winding to the load. The system may include a rectifier for rectifying a current component of the energy from AC (alternating current) to DC (direct current). The system may also include an inductive storage device for receiving current from the rectifier and boosting the output energy from the Q-axis winding. The load may include a pulse-forming network (PFN) with inductive and capacitive components. The PFN may generate shaped pulses. The system may include a subharmonic filter for extracting subharmonics from the rectifier according to the output of the Q-axis winding, and a thyristor modulator for supplying the subharmonics to the D-axis winding when the induction machine is disconnected from external power. The subharmonics may include reactive power.

[0010] As described above, the rotating electric machine can be configured to output current from the D-axis winding that boosts energy output from the Q-axis winding to the load. The system can include a harmonic filter that forms a resonant circuit with the D-axis winding, the harmonic filter connected to an output current port from the D-axis winding, a boost transformer in series with the harmonic filter that receives and boosts the current from the harmonic filter, and a multi-phase rectifier that receives the boosted current and provides a rectified output based on the boosted current to boost the energy output to the load.

[0011] As described above, the rotating electric machine can be configured to output current from the D-axis winding to boost energy output from the Q-axis winding to a load. The system can include a boost transformer for receiving current from the D-axis winding according to the output of the D-axis winding, a rectifier for rectifying the output of the boost transformer, a pulse-forming network having a storage element that charges based on the rectified output from the pulse-forming network, and a switch triggerable to output energy from the pulse-forming network and combine it with the energy output from the Q-axis winding. The switch can include a spark gap switch, and the system can include a capacitive storage device that stores energy output from the Q-axis winding and an inertial storage device that transfers energy using the capacitive storage and the pulse-forming network during operation of the induction machine.

[0012] The D-axis winding can be configured to receive a multi-phase input. When the multi-phase input is interrupted, a negative-sequence primary current can be generated in the D-axis winding. The system can include a neutralization winding switchable in a closed short-circuit loop to induce a transient voltage in the D-axis winding or the Q-axis winding. The negative-sequence primary current can generate a transient voltage that boosts the output voltage to the load from the Q-axis winding.

[0013] The induction machine may include a multi-phase wound rotor induction machine configured to receive a multi-phase input. A change in magnitude or phase shift of the multi-phase input may generate an out-of-phase primary current in the D-axis winding. The system may include a neutralization winding switchable in a closed short-circuit loop to induce a transient voltage in the D-axis winding and the Q-axis winding. The transient voltage initiated by the rotor induction machine may boost the output voltage to the load from the Q-axis winding.

[0014] The system may include a polyphase power supply that provides excitation to the D-axis winding. The polyphase power supply may be controllable to provide pulsed single-phase excitation to the D-axis winding. When the excitation to the D-axis winding changes from polyphase to single-phase, a reverse-phase current may be generated through the D-axis winding, resulting in a flux compression effect in the magnetic field of the air gap between the rotor and the Q-axis winding and the air gap between the rotor and the D-axis winding. The flux compression may affect a change in the effective impedance associated with the D-axis winding and the Q-axis winding.

[0015] The Q-axis winding can be configured to output energy to a load, which can include a pulse-forming network or a radar system.

[0016] As previously described, the rotating electric machine can be configured to output current from the D-axis winding that boosts the energy output from the Q-axis winding to the load. The system can include a thyristor modulator that controls active and reactive components of power to affect the power applied to the load, and an inductive storage that receives current from the thyristor modulator to boost the output energy from the Q-axis winding.

[0017] Any two or more of the features described herein, including in this summary section, may be combined to form an implementation not specifically described herein.

[0018] The devices, systems, and / or components thereof described herein may be configured through, for example, designing, building, configuring, arranging, programming, operating, activating, deactivating, and / or controlling.

[0019] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view of an exemplary induction machine. [Figure 2] FIG. 1 is a cross-sectional view of an exemplary induction machine having a non-uniform air gap between a stator assembly and a rotor bore. [Figure 3A] 10 is a graph illustrating an exemplary voltage boost output by an induction machine occurring prior to a Q-axis winding current peak. [Figure 3B] 10 is a graph illustrating an exemplary voltage boost output by an induction machine occurring after a Q-axis winding current peak. [Figure 3C] 4 is a graph illustrating an exemplary voltage boost output by an induction machine at the end of an entire pulse. [Figure 4] FIG. 1 is a circuit diagram of an exemplary system including an induction machine for boosting the voltage output to a load. [Figure 5] FIG. 1 is a block diagram of another example system including an induction machine for boosting a voltage output to a load. [Figure 6] FIG. 1 is a block diagram of another example system including an induction machine for boosting a voltage output to a load. [Figure 7] FIG. 1 is a circuit diagram of an example series injection transformer, filter, and thyristor modulator that may be used in one or more of the systems described herein. [Figure 8] FIG. 1 is a block diagram of another example system including an induction machine for boosting a voltage output to a load. [Figure 9] FIG. 1 is an example circuit diagram of a thyristor modulator that may be used in one or more of the systems described herein. [Figure 10] FIG. 1 is an example circuit diagram of a subharmonic pass filter that may be used in one or more of the systems described herein. [Figure 11] FIG. 2 is a circuit diagram of another example system including an induction machine for boosting the voltage output to a load. [Figure 12] FIG. 1 is a circuit diagram of an example bidirectional VVVF rectifier inverter that may be used in one or more of the systems described herein. [Figure 13] FIG. 2 is a circuit diagram of another example system including an induction machine for boosting the voltage output to a load. [Figure 14] FIG. 1 is a block diagram of another example system including an induction machine for boosting a voltage output to a load. [Figure 15] FIG. 2 is a circuit diagram of another example system including an induction machine for boosting the voltage output to a load. [Figure 16] FIG. 2 is a circuit diagram of another example system including an induction machine for boosting the voltage output to a load. [Figure 17A] FIG. 1 is a winding layout circuit diagram of an exemplary four-pole induction machine. [Figure 17B] FIG. 1 is a winding layout circuit diagram of an exemplary four-pole induction machine. [Figure 17C] FIG. 1 is a winding layout circuit diagram of an exemplary four-pole induction machine. [Figure 18] FIG. 2 is a cross-sectional view of another example induction machine having a non-uniform air gap between the stator and rotor bore. [Figure 19] FIG. 1 is a winding diagram of an exemplary eight-pole induction machine having three sets of polyphase stator windings. [Figure 20] FIG. 1 is a diagram of an exemplary stator design layout for an induction machine having a non-uniform air gap between the stator bore and rotor bore. DETAILED DESCRIPTION OF THE INVENTION

[0021] Like reference numbers in different figures indicate like elements.

[0022] Exemplary rotating electrical machines include induction machines, such as induction motors, and field-wound synchronous machines. While the examples provided below focus on induction machines, the structures and systems described herein can be used with any suitable type of rotating electrical machine.

[0023] Exemplary induction machines include electric motors in which current in a rotor, which generates motor torque, is generated by electromagnetic induction from magnetic fields generated by stator windings. Induction machines can also be used to provide pulsed power to loads using stator assemblies with multiple independent windings. The induction machine 10 of FIG. 1 has a stator assembly including a cylindrical structure with a uniform bore diameter. Multiple stator slots are arranged around this uniform bore diameter and carry either input or output windings. In stator assemblies such as that of FIG. 1, the magnetic air-gap reluctance between the cylindrical rotor laminations and the stator bore is substantially uniform around the stator bore, except for small perturbations. Electromagnetic principles, such as flux compression in the range of 0.5 Tesla (T) to 2.0 T, can be applied to the stator assembly to provide pulsed power to loads, including, but not limited to, radar systems.

[0024] FIG. 2 is a cross-sectional view of an exemplary induction machine 12 including a stator assembly 13 and a cylindrical rotor 14. The induction machine 12 may be an induction motor with generator functionality as described herein. In contrast to the stator assembly of FIG. 1, the stator assembly 12 includes stepped, periodic variations in the stator or primary bore diameter to create zones and windings with high and low magnetic air-gap resistances. The magnetic energy stored in these stator air gaps varies with changes in the radial air-gap dimensions, with larger air-gap zones storing, for example, four to five times more energy than smaller air-gap zones. In this context, "high" and "low" magnetic air-gap resistances have no specific numerical meaning but are rather used to indicate relative levels of magnetic air-gap reluctance.

[0025] The exemplary stator assembly 13 is a four-pole structure that includes at least two different sets of electrically isolated stator windings 16, 17. Both types of windings are repeated around the entire circumference of the stator assembly 13, although the relative perimeter allocation to windings 16 and 17 is a design variable. In this example, each winding phase of electrical angle 30 occupies a mechanical angle 15, e.g., 19, 20, etc. Aside from the usual slot openings, the stator assembly 13 includes two different bore diameters. Primary bore diameter D s1 21 is the primary bore diameter D s1 As a result of this, the power input windings have a radial air gap g122. These windings are surrounded by magnetic slots established by, for example, magnetic laminated steel. The secondary bore diameter D s2 25 is the primary bore diameter D s2 As a result, for the output or power output winding having a radial air gap g226. As described herein, power is input to the input winding and output from both the input and output windings.

[0026] The input winding includes a direct (D)-axis winding 17 and has the smaller of two radial air gaps. This configuration produces a high reluctance, a high leakage inductance (Xl), and a high magnetizing reactance (Xm) relative to the output winding, as described below. The relative values of these parameters can be advantageous for operating the D-axis winding from a power source such as a prime mover or AC mains transmission line. The output winding is a quadrature (Q)-axis winding 16 and has the larger of two radial air gaps. This configuration produces a higher reluctance and a lower leakage reactance than the input winding. The relatively low leakage reactance can produce a high current output for the Q-axis winding with a smaller time constant than the D-axis winding. The Q-axis winding can include an air-gap winding that includes a conductor mechanically held by a non-magnetic structure. As a result, the effective radial air gap can be larger at g2' 27, which can be advantageous for the pulsed power output loads described herein. The individual windings can be either concentric coil windings, double layer lap windings, or a combination thereof.

[0027] The cylindrical rotor 14 may have a uniform outer diameter 30 and rotor conductors 31 regularly spaced around the rotor 14. The rotor 14 may be or include a squirrel-cage rotor. The rotor 14 may be or include a multi-phase wound AC rotor or a DC (direct current) wound rotor, each of which may receive external excitation. In an exemplary implementation, the rotor 14 has a wound rotor configuration that allows for external excitation of the rotor, thereby controlling the rotor slip frequency ω σ for any shaft speed of interest. The combination of slip frequency and rotor current amplitude ultimately controls the output power of the induction machine. For example, if the induction machine of Figure 2 is controlled to operate as an inertial storage device or pulse generator (discussed below), the rotor excitation controller will adjust the excitation application frequency ω as the shaft speed decreases following the pulse discharge. r continuously boosted to provide a nearly constant stator output frequency for the duration of the discharge pulse.

[0028] The induction machine 12 configuration therefore provides a spatial variation in reluctance between the stator and rotor structures, resulting in a lower quadrature-axis output reactance. The exemplary induction machine 12 also includes neutralizing stator winding insertions ("neutralizing windings") every 30 or 60 electrical degrees, which can aid in flux compression and magnetically isolate the D-axis winding from the Q-axis winding. The neutralizing windings are fully galvanically isolated from the D-axis and Q-axis windings and include separate controllers. An implementation including a D-axis neutralizing stator winding is shown in FIG. 18.

[0029] This galvanic isolation allows induction machine 12 to include input (D-axis) and output (Q-axis) windings within a single machine with a common magnetic core and common structure. Furthermore, because stator assembly 13 varies the primary reluctance of the input and output windings as a function of their bore diameter, the inherent leakage reactance and magnetizing reactance of the stator windings can have two or more values within stator assembly 13. This creates a flux compression effect, allowing the radial magnetic flux in the air gap to be continuously shifted. In the example described herein, the zone producing pulsed power can have four times the inherent stored energy in the air gap of the zone used for motoring functions.

[0030] In this regard, the output windings of the induction machine 12 and its variations described herein can be used to generate pulsed or continuous power, including polyphase or single-phase power, which can be used to power various loads, including, but not limited to, radar systems. For example, the output windings can be used to power a time-varying load power or a pulsed load having a power factor that varies as a function of time. The input windings of the induction machine 12 and its variations described herein can be used to generate pulsed or continuous power, either polyphase or single-phase, which can be used to power motoring functions, including rotor torque generation. Additionally, the input windings of the induction machine 12 and its variations described herein can be used to generate pulsed or continuous power, either polyphase or single-phase, which can be used to boost (i.e., increase or augment) the power provided by the output windings. The power generated by the output windings generally has a lower reactance than the power generated by the input windings. A lower output reactance of the output windings can improve energy and power delivery.

[0031] In addition to the relatively low output reactance in the output windings, the exemplary induction machine 12 and its variations described herein can be configured to generate a repeatable stream of time-varying voltage pulses with relatively high voltages and relatively fast rise times. In its motoring mode, the D-axis winding of the stator assembly 12 supplies input energy to an inertial energy storage device to bring the rotor 14 up to base speed or maintain that speed for a moderate or extended period of time prior to a discharge cycle. After the D-axis winding has served this purpose, the same D-axis winding can be configured and controlled to generate high-voltage pulses. In an exemplary implementation, the D-axis winding output (voltage pulses) can be superimposed on the Q-axis winding output (current pulses) to provide both high-current pulses to a load as described herein and high-voltage pulses to the same load. The superimposed pulses need not occur at exactly the same time. For example, there may be operational advantages to first peaking the Q-axis winding, generating a current pulse, followed by a controlled D-axis voltage pulse peak. The overlapping pulses boost the amount of energy to the load. The boosted energy may include boosted current, boosted voltage, and / or boosted power.

[0032] In this regard, some types of pulsed power loads may require voltage-current characteristics such as those shown in FIGS. 3A, 3B, or 3C. FIG. 3A illustrates an example in which the Q-axis winding provides a main output current pulse 28 at a time period “ta” prior to the interruption of the current pulse. The D-axis winding output is superimposed on the Q-axis voltage 29 to generate a boosted output voltage 30. This type of boosted output voltage may be required for certain types of pulsed power loads. FIG. 3B illustrates an example in which the Q-axis winding provides an output voltage 32 at a time period “tx” delayed from the peak after the current interruption. The D-axis winding output is superimposed on the Q-axis voltage 34 to generate a boosted output voltage 35. This type of boosted output voltage may be required for certain types of pulsed power loads. FIG. 3C illustrates a boosted voltage 36 that may be generated by superimposing the outputs from the Q-axis and D-axis windings as described herein. The boost output voltage is steep and appears at the end of the entire pulse 38, beginning at time t1, with energy E2 from the D-axis winding producing a faster rise time than the rise time from the initial energy E1 from the Q-axis winding. At time t2, the pulse decays to zero output, and the repeating pattern begins again at time t3. The initial energy E1 is typically greater than energy E2, but in some cases, energy E2 may be greater than energy E1. It is clear that the rate or slope of energy rise for E1 and E2 can be significantly different. The example output currents and voltages in Figures 3A, 3B, and 3C are AC quantities. The techniques described herein can also be used when the mechanical outputs from the Q-axis and D-axis windings are rectified to produce DC outputs.

[0033] FIG. 4 is a diagram of an exemplary system 40 that uses an induction machine 12, which may be of the type shown in FIG. 2, to provide pulsed power to a load 41. In starting mode, the D-axis winding brings the machine's rotor up to operating speed, so a certain amount of stored or inertial energy exists in the machine set's rotor. In the example of FIG. 4, the induction machine includes a dual D-axis winding to provide boost power used for series injection into the main Q-axis winding output. In this example, two sets of stator assembly windings (the aforementioned D-axis winding and Q-axis winding) are controlled by an electromechanical switchgear or electronic switching network to generate the output shown in FIG. 3C. In system 40, the load 41 includes a multi-stage pulse-forming network (PFN) that has its own energy storage capacity and also serves to sharpen the pulsed output. The PFN includes load switches VB3-VB7 46, which may include electronic switches such as IGBTs (insulated gate bipolar transistors) or thyristors. If electromechanical devices are used, the switching devices may include air-blast circuit breakers due to the large DC currents involved. The load may include additional circuitry 47 and may include one or more of the following, for example, an RL (resistive-inductive) circuit, an RC (resistive-capacitive) circuit, an LC (inductive-capacitive) circuit, a non-linear inductive load, or an LC tank circuit.

[0034] In the exemplary system 40, the Q-axis winding output 42 is routed through switch VB2 43, which may be implemented using a vacuum breaker or a solid-state multi-phase switch such as a thyristor or IGBT. In the example of FIG. 4, the D-axis winding output 44 is routed through switch VB1 49, which may be implemented using a vacuum breaker or a solid-state multi-phase switch such as a thyristor or IGBT. A series injection transformer 50 isolates the induction machine 12 from a multi-phase rectifier 51, a transmission line 52, and a load 41. The transformer 50 is configured to receive currents from the D-axis winding and the Q-axis winding on its windings and to generate a boosted power output to the load based on the current from the D-axis winding superimposed on the current from the Q-axis winding.

[0035] The AC power source 54 may include a polyphase power supply that supplies power to a variable voltage variable frequency (VVVF) drive 55. The VVVF drive is configured to convert the received power to a higher frequency f1, which is routed to the machine's D-axis winding 44 via a selector switch 57 in position 1. The inertial storage unit 59 is configured to maintain the energy input to the induction machine unless there is direct power input from the AC power source. The energy capacity of the inertial storage unit 59 is several times the output energy of each pulse, thereby providing a continuous stream of output pulses for an extended period of time. For example, the inertial storage unit 59 may be configured to maintain the energy / power input to the induction machine even as the rotor speed decreases as the stored energy is depleted after the direct power input from the AC power source is disconnected. Direct power can be disconnected after the rotor reaches a predefined or target upper speed limit. Once the target lower speed is reached during discharge mode, direct power input can be reapplied. Inertial storage unit 59 is also configured to maintain energy / power input to the induction machine when the induction machine is within target upper and lower speed limits while the D-axis winding provides boost power as described herein. Switches VB1 49 and VB2 43 are controlled, for example, by an external controller (not shown), to output the above-mentioned current and voltage pulses from the D-axis and Q-axis windings, respectively. Multi-phase rectifier 51 rectifies the superimposed current and voltage from AC to DC and supplies the resulting rectified output to load 41 via transmission line 52.

[0036] FIG. 5 illustrates an exemplary system having components in common with system 40. Elements with the same reference numbers in the drawings may have at least some or all of the same structure and function. In the example of FIG. 5, an air blast breaker 60 is used to control the voltage and current output from the D-axis winding and the superimposed voltage (Vz) and current output from the Q-axis winding. The current from the D-axis winding passes through a boost transformer (Xformer) 61, an AC / DC rectifier 62, and an intermediate inductive storage 63. The voltage from the Q-axis winding passes through a full-wave bridge (FWB) rectifier 64 and is stored in an intermediate capacitive storage 65. The air blast breaker 60 is controllable by an external controller 66, which combines the voltage output Vz across the inductive storage 63 with the voltage of the capacitive storage 65 to generate the superimposed boost output to the load described above. The voltage Vz is a transient voltage, preferably with a steep rise time, and is only triggered by the air blast breaker 60 opening. Exciter drive 59 provides variable voltage variable frequency power to drive the operation of the rotor of induction machine 12 .

[0037] FIG. 6 shows an example system with components in common with the system of FIG. 5. In the system of FIG. 6, a thyristor modulator 70 is connected to the D-axis winding output 42 along with an intermediate inductive storage 63. FIG. 7 shows details of an example six-device thyristor modulator 70, intermediate inductive storage 63, and combined LC filter circuit 74 that may be used according to the output of the D-axis winding. In this example, the output of the D-axis winding is output through switch 57 in position 2 and then to the thyristor modulator 70 with thyristor switches T1-T6, the intermediate inductive storage 63, a vacuum breaker (VB) 75, and a high-impedance winding of a series injection transformer 77, shown in FIG. 7 as a delta-to-wye combination. The intermediate inductive storage 63 also functions as a series LC tank filter that can be tuned to harmonics, such as 180 Hz, increasing the impedance at this frequency. Machine inductance and transformer inductance may also enter the resonant frequency of this LC tank filter.

[0038] In the system of Figure 6, if the post-transformation voltage of the low-impedance transformer winding is sufficiently high, the machine's D-axis winding can supply both real and reactive power to the input of the multi-phase rectifier 79. The phase delay angle "alpha" of the thyristor modulator 70 partially controls the split ratio of real and reactive power. In the circuit of Figure 7, one machine winding (the Q-axis winding) provides the majority of the output real power using a flywheel energy storage source that generates a continuous DC output. The second "motor" winding (the D-axis winding) functions as a modulation winding with the ability to provide programmed boost pulses to modify the tail or mid-shape of the final output current or to provide additional reactive power. In some implementations, the thyristor modulator 70 can include high-speed, high-voltage solid-state switches, thus allowing superimposed waves to be implemented on the output pulses with a response time of 10 to 100 microseconds (μs). 6 also includes a passively tuned harmonic filter 80 between the multi-phase rectifier 79 and the transmission line 52 for providing dual-mode superimposed pulses to the transmission line 52. In this implementation, the radar DC input 81 receives power from the transmission line for output to the load 41. The thyristor modulator 70 can be controlled based on the radar DC input to vary the boost power provided by the system, as described below.

[0039] Systems that superimpose two or more power outputs onto a common load may require an isolation system for the current supplies that can withstand high voltage potentials and transients caused by high voltage power sources. In the example induction machine described herein, the machine's windings are electrically isolated by design, and have relatively good voltage blocking capabilities due to strong isolation between adjacent winding groups. In some implementations, induction machine 12 is a doubly-fed machine with large variations in terminal impedance from D-axis to Q-axis parameters (e.g., greater than 10:1) and a rapid rise in D-axis winding voltage due to spatial shifts in magnetic flux.

[0040] FIG. 8 shows a variation of the system of FIG. 6 in which sub-frequency or ripple sub-harmonics, primarily reactive power, are extracted from the main DC multi-phase rectifier output 84. In this example, the low-frequency or ripple sub-harmonics are extracted by three current transformers in series, which may be included in the multi-phase rectifier 77, fed to two independent sets of sub-harmonic pass filters 85, and routed to the D-axis winding of the motor by the multi-phase thyristor modulator 70a via selector switch 57 in position 2. The multi-phase thyristor modulator 70a is dual-mode and configured to select one of two or more harmonic power filters and return certain harmonic energy to the induction machine's D-axis winding when the induction machine is disconnected from the utility grid input. In this example, when switch 57 is in position 2, the D-axis winding is supplied with sub-harmonic currents resulting primarily from low-frequency pulsations in the load current, in the range of 7 to 35 Hz for a 60 Hz system. Figure 9 shows an exemplary multi-phase 12-element thyristor modulator 70a that controls an LCL (inductive-capacitive-inductive) element including a filter 85 and also functions as a bidirectional phase angle controller to limit current. There can be more than two independent filter stages, but the two frequencies selected can handle the typical upper and lower limits of expected load pulses. The output to the load is fed through a passive tuned harmonic filter 88, Figure 8, to provide a DC output.

[0041] FIG. 10 illustrates an exemplary circuit implementation of FIG. 8 at connection point 84. FIG. 10 shows secondary winding 89 designed as a current transformer routed through either 1 / 6 of a fundamental frequency-tuned LCL filter or 1 / 2 of a fundamental frequency-tuned LCL filter. For example, if the base is 60 Hz, the first filter is a 10 Hz notch filter, and the second filter is a 30 Hz notch filter. If the circuit is used in a radar system, the filters can be used in sequence depending on what pulses the final load generates. For a radar system, referring to FIG. 9, thyristors T1 through T12 in thyristor modulator 70a receive feedback signals from radar input stage 81 (FIG. 8) that instruct them to gate on three pairs of thyristors. For example, if the radar is pulsing at a rate of 7 to 20 Hz, thyristors T1, T4, T5, T8, T9, and T12 are active, gating pairs spaced 120 degrees apart. When the radar is pulsing at a rate between 21 and 35 Hz, thyristors T2, T3, T6, T7, T10, and T11 are active, gating pairs spaced 120 degrees apart. Following the current transformer input to the reactive power modulation circuit in Figure 8, if the machine output is three-phase, the DC output includes a fifth-harmonic filter consisting of an LCL filter on each side of the output DC bus with two sets of inductors. These two sets of inductors can be wound as "Brooks coil" coupled inductors to increase the inductance and allow for an air-core filter. This creates a relatively high impedance for the fifth harmonic, which can be a dominant harmonic in radar applications. If the machine output is six-phase, the filter can be an 11th-harmonic filter with dual Brooks coil inductors in the same arrangement.

[0042] Figure 11 shows an example system with components common to the systems of Figures 4 and 5. In Figure 11, two sets of stator windings are controlled by electromechanical switchgear or an electronic switching network. Power is supplied by a polyphase AC power source 54 to a VVVF drive 90, which then converts it to a higher frequency, f1, and routes it to the machine's D-axis winding via a selector switch 57 in position 1. This D-axis winding drives the motor flywheel speed from zero to full speed in a typical constant torque or constant V / Hz mode. Simultaneously, the induction machine rotor is excited at a variable frequency, f2, from a similar power source via a VVVF drive 92, which is linked to the shaft speed in the control architecture. When the machine reaches full or near-full shaft speed and the full energy level of the flywheel energy storage reaches level E1, vacuum breaker VB2 43 and vacuum breaker AB3 94 are sequentially closed. These closures connect the Q-axis winding output 44, current i3 at frequency f3, to the main rectifier 95, and thus to the transmission line 92 and to the load 41, which in this example is an intermediate load. When capacitors C1-C5 of the load (in this example, the PFN) charge to their maximum DC voltage values, the main thyristor switch T1 97 closes, discharging the PFN to the final electrical load (not shown). The multi-stage PFN can be configured to generate a nearly square wave output current, which may be desirable for many pulsed power applications. When the PFN is fired through T1, it generates output pulses that are substantially square waves of voltage with a steep rise time, which may be desirable for some loads. The system is set up for continuous firing, or a continuous stream of output pulses, by repeatedly operating breakers VB2 and VB3.

[0043] To enhance output characteristics, vacuum breaker VB3 94 may be opened while switch 57 is in position 2 when the PFN is in the final charging process. Vacuum breaker VB1 49 is closed and is in series with the D-axis winding, multi-phase resonant capacitor C6 99, and multi-phase resonant inductor 100. This configuration generates a current i2 flowing through boost transformer 100 to boost rectifier bridge 101, thus generating a DC transient current Iz and a transient voltage Vz across the open contacts of AB3. The output diode of main rectifier 95 prevents Vz from adversely affecting the Q-axis winding. Voltage Vz then appears between transmission line 52 and the input to load 41, providing a boost or step voltage to the PFN input in the final charging mode. Capacitor C6 99 forms a resonant circuit with the leakage inductance of the D-axis winding, which is typically nonlinear, and the inductance from inductor 100, which is typically linear. The leakage and magnetizing inductance of the boost transformer causes the current through capacitor 99 to be higher than it would be without the resonant circuit.

[0044] The circuit in Figure 11 includes a combination of two machine output ports (one for the D-axis winding and one for the Q-axis winding). Each port has a different time constant and transient power capability. In the current and voltage curves in Figures 3A through 3C, the Q-axis winding provides a relatively slow, high-current ramp to the load, followed by a stepped boost pulse from the D-axis winding during the final time segment of current charging the load. The boost transformer 102 in Figure 11 can include a multi-phase unit and can be either a step-up or step-down transformer, which can be constructed using air-core windings to support fast discharge times. In one example, the output (secondary) voltage of the boost transformer is higher than the AC output level of the Q-axis winding. Therefore, this circuit uses two stator windings with different reactances and located on different spatial axes to superimpose the source voltage on the source current.

[0045] The circuit in Figure 11 operates as follows: At time T1, the AC power source 54 supplies input energy to both VVVF drives 90, 92. The VVVF drive 92 is energized, increasing the rotor excitation current to the wound rotor machine. The switch 57 is initially in Position 1. At time T2, the VVVF drive 90 operates to provide acceleration energy to the inertial energy storage unit and remains on until the inertial energy storage reaches its rated energy level E1. At time T3, the VVVF drive 90 is off, initiating a "coast" period during which the inertial energy storage unit maintains speed / energy without direct power input from the AC power source 54. At time T4, the vacuum breaker VB2 43 on the output of the Q-axis winding is closed, and the air breaker AB3 94 on the output of the main rectifier 95 is closed in turn, and the switch 57 is repositioned to Position 2. The transmission line and load are then charged by the DC voltage and current Idc. The output thyristor switch T1 97 opens. At the next time, T5, the load terminal voltage, with its time-dependent charge, is sensed. When it reaches an intermediate threshold, such as 90% of the desired voltage, the boost circuit is initiated. At the next time, T6, the vacuum breaker VB1 49 closes, starting the D-axis current i2 circulating in a closed "short-circuit" loop that includes the D-axis neutralization winding, the FWB rectifier 105, and the Q-axis winding. At the next time, T7, when i2 reaches the threshold, the breaker AB3 opens. This generates a transient voltage Vz that is applied directly across the breaker AB3 contacts and then injected as a series auxiliary voltage into the Q-axis DC output from the main rectifier 95. This action superimposes two sources of voltage, high current i3 and high voltage Vz. At the next time, T8, a resulting total voltage appears across both the transmission line and the PFN input—a combination of the slowly rising voltage and the step or peak voltage at the end of the charge cycle. This sum voltage charges the shunt-connected series PFN capacitors C1-C5 and series inductors L1-L4. At the end of time T8, VVVF 92 turns off. At the next time T9, breaker VB2 43 is opened first, followed by breaker VB1 49, removing all load charging power.At the next time T10, the load 41 is discharged to the final electrical load by firing the thyristor or similar high current switch T1 97. At the next time T11, the discharge of the single load or multiple loads in series is completed. After a rest period, the next cycle is ready. At the next time T12, the repeat cycle can be initiated again by first changing the selector switch 57 to position 1 and applying power to the VVVF drive 92.

[0046] FIG. 12 shows an exemplary bidirectional VVVF rectifier inverter 112 drive that can be used with the circuits described herein. This VVVF type drive powers both main D-axis windings and also powers a doubly-fed induction machine rotor polyphase AC excitation circuit (such as excitation drive 59 in FIG. 5) in a separate, compact rectifier-inverter unit. The upper voltage level of the output can be set by the rectifier, and the frequency and final voltage can be established by the inverter stage. Component 114 represents either the primary / stator rotor winding or the induction machine.

[0047] The rectifier 115 may include a six-thyristor full-wave bridge (FWB)-controlled rectifier for an "active" front end, including three saturable input inductors (Lxa, Lxb, Lxc) 116 for all input phases. The inverter circuit 118 includes an auto-sequential bridge inverter with six thyristors, six diodes, six commutation capacitors, and six saturation-limited reactors. DC bus filtering is performed by two balancing reactors 119 and 120, allowing DC power flow in both directions. The circuit of FIG. 12 can be implemented using alternating switching devices such as IGBTs, IGCTs, or MOSFETs. During operation, the circuit of FIG. 12 allows active power from the D-axis winding to be fed back to the AC input line of the induction machine, as needed.

[0048] FIG. 13 illustrates a variation of the system of FIG. 11. In FIG. 13, the circuit of block 120 is identical to the corresponding circuit of FIG. 11. In the circuit of FIG. 13, a flux-shifting mechanism is used to power two different types of output loads and improve output pulse generation when two different types of PFNs 121, 122 (which may be part of the output loads) use a common transmission line. An exemplary first load 121 includes a PFN with a quasi-square output, and an exemplary second load 122 includes a PFN with a triangular or sawtooth wave output. Source power is supplied to the VVVF drive by a polyphase power supply, converted to a higher frequency f1, and routed to the D-axis winding through a switch in position 1. With the switch in position 1 and input power applied, the D-axis winding increases the machine flywheel speed from zero to full speed or service speed (energy level E1) in a typical constant torque or constant V / Hz mode. When the machine reaches the specified speed and the flywheel energy storage reaches level E1, vacuum breaker VB2 closes, connecting the Q-axis winding output at frequency f3 to the main rectifier and filter capacitor Cx, and therefore to loads 121 and 122. In this example, the intermediate loads include main air blast circuit breaker AB3, transmission lines (Lx, Rx), and two multi-stage PFNs 121 and 122. When the switch moves to position 2, the system uses a resonant LC circuit connected to the D-axis winding through breaker VB1. The D-axis winding is no longer connected to the external power source or the power grid. The output of the D-axis winding is now rectified by a boost rectifier, whose output is connected through inductor L5 to form a DC current Iz, which is a high-current or short-circuit level current. When breaker AB3 is opened, a high boost voltage is generated across the AB3 contacts (or anode-cathode if a solid-state switch is used). This serves as the fundamental output of the main rectifier voltage across the capacitor Cx, which is then transferred to the system output, increasing the magnitude of the current Idc.

[0049] When current Idc flows, capacitors C1-C6 of PFN 121 charge to a maximum DC voltage value, closing the main thyristor load switch T1, discharging PFN 121 to the final electrical load (not shown). Using appropriate circuit parameters for C1-C5 and L1-L4, the output of PFN 121 becomes a quasi-square wave, which may be desirable for some pulsed power applications. The multi-stage LC circuit of PFN 121 generates a pulse stream that is repeatedly charged by induction machine 12 for a repetitive pulse stream after each discharge cycle. This system can be configured for continuous firing or a continuous stream of output pulses by operating breaker AB3, which can be programmed to repeatedly open and close. In second load circuit 122, which may be different from first load circuit 121, capacitors C7-C12 and inductors L7-L12 of PFN 122 charge to a maximum DC current value, closing the final output thyristor switch T2, discharging PFN 122 to the final electrical load (not shown). Using appropriate circuit parameters for C7-C12 and L7-L12, the output of PFN 122 can be a sawtooth or triangular waveform, which may be desirable for some pulsed power applications.

[0050] 13, by appropriate application of isolation diodes D1 124 and D2 125, the PFNs 121, 122 can share a common transmission line and a common machine output circuit 120. In an exemplary mode of operation, T1 is energized followed by T2, such that the conduction of the two output thyristors alternates.

[0051] FIG. 14 shows an exemplary system that shares components with the system of FIG. 5. The system of FIG. 14 includes an energy storage element on the D-axis circuit output, including a 15-stage PFN and boost transformer, and one capacitive storage element on the Q-axis circuit output. Superimposing the outputs of both the D-axis and Q-axis circuits results in DC rectification. In the system of FIG. 14, the precise timing of injecting D-axis energy into Q-axis energy is achieved by the combination of a Trigatron switch 129, which injects energy into the Q-axis circuit when the air blast breaker 60 opens. This creates a maximum transient or boost pulse on the transmission line 52 and the load 41. To this end, the system of FIG. 14 includes a multi-phase boost transformer 61, a full-wave bridge rectifier 62, a high-stage (e.g., 15-stage) PFN 128, and a Trigatron (trigger spark gap) switch 129 (which includes a high-voltage boost circuit but not a resonant circuit in this example). The Trigatron switch 129 may be a spark gap switch with a precision optical or laser trigger to activate the discharge of the high-voltage charge stored in the 15-stage PFN's capacitor bank. The trigger of the Trigatron switch can be timed to coincide with the opening of the air blast breaker 60, thereby optimally positioning the boost pulse from the D-axis output on the Q-axis DC output from the intermediate capacitive storage 65. In this regard, the system of FIG. 14 includes three energy sources: the PFN 128, the capacitive storage 65, and the flywheel energy storage device 67, which is an inertial energy storage device that provides energy input to the induction machine. During system operation, kinetic energy is transferred from the flywheel 67 to the PFN 128 and the capacitive storage 65 in a repetitive manner.

[0052] The circuit in Figure 15 shows an alternative system that shares components with the system in Figure 4 but is specific to wound-rotor induction machines. The system in Figure 15 is configured to use magnetic induction to repeatedly generate fast transients superimposed on the machine output winding to aid in generating output pulses. The circuit is configured to generate a negative-phase primary current in the D-axis winding output. The control system is configured to sequentially perform three of the following actions when the induction machine 12 reaches the target speed and / or inertial energy level: The D-axis excitation frequency, controlled by a VVVF drive, is periodically modulated above and below the half-synchronous speed point. This is because the maximum D-axis transient high voltage occurs at plus or minus a few percent of the half-speed point. The induction machine rotor circuit is intentionally forced to undergo wide current excursions by shorting breaker B1 across the external rotor reactor / inductor bank. Alternatively, the induction machine rotor circuit is shorted if it is a wound-rotor machine. A transient voltage is generated in a controlled and periodic manner in the Q-axis output winding 42, which is then rectified and sent to the load.

[0053] In an exemplary implementation, when the machine 12 is at half speed, the D-axis winding input 44 is charged by an electromechanical switch 138, a thyristor, or an IGBT switching system from a polyphase power input / source, but is limited to single-phase AC excitation (i.e., the polyphase input is periodically shut off). This causes a spatial circumferential shift of the D-axis winding's air-gap flux, high negative-sequence current, and asymmetric core flux. The net result is a reduction in the D-axis winding's input magnetizing reactance. This electromagnetic effect reduces the radial air-gap flux on the D-axis stator slots and also causes a flux shift, increasing the radial air-gap flux on the Q-axis slots and windings of each pole, thereby boosting the power output from the Q-axis winding. In some examples, the rotor winding may be partially shorted, provided that one phase is shorted through a low-reactance / low-resistance circuit and the other two phases remain open-circuited or have high-impedance loads but are not short-circuited. This also creates a counter-rotating magnetic field, which may be desirable for generating output pulses requiring high bursts of mechanical energy.

[0054] Figure 16 shows an example system having components in common with the system of Figure 15, with four independent loads, each controlled by a separate electronic switch represented as thyristors T1-T4 132. Also in this implementation, the induction machine rotor circuit is controlled by a multiphase resistor bank 134. This bank is periodically shorted by a circuit breaker or electronic switch, creating a large negative-sequence current, and an external controller is used to regulate the large transient rotor current and the resulting boosted output repetitive pulse stream in the Q-axis winding.

[0055] Figures 17a and 17b show exemplary winding layout diagrams for an exemplary four-pole machine, such as induction machine 12. This example includes 48 stator coils on the D-axis, 36 stator coils on the Q-axis, and 12 coils in the neutralization winding, for a total of 96 stator coils in Figure 17a. There may be 72 rotor coils in the exemplary four-pole induction machine of Figure 17b, and 24 rotor coils in the example four-pole synchronous machine of Figure 17c.

[0056] In this regard, a set of neutralization winding coils may be present within the stator or primary frame, which may serve several electromagnetic purposes. In one example, two or more sets of winding coils are interposed between each D-axis winding and the subsequent Q-axis winding (per pole) and are isolated from the diametrically opposite stator location. These isolated windings are configured to reduce or nullify the air-gap radial magnetic flux between these two sections. The current through these windings can be fully controlled by a system of multiple bidirectional thyristor switches under the control of an external control system. The current through each set of series-connected twin coils may be large. Furthermore, the ampere-turn magnitude of these coils may approach that of the D-axis winding. The example of FIG. 17A has a total of six sets of neutralization coil pairs. An exemplary schematic layout of the exemplary neutralization coils 135 is shown in FIG. 18.

[0057] In this regard, the induction machine 137 of Figure 18 shows features of induction machine 12 along with neutralizing coil 135. The induction machine 137 may be used in any suitable application, including the examples described herein.

[0058] The neutralizing coil may only be activated for intermittent use, and in some instances, the neutralizing coil is only used when transitioning from motoring mode to generating mode, or when the D-axis winding is being used as a boost winding to assist the Q-axis winding for pulse generation. These electromagnetic interactions, when spaced around the stator and within all phases, effectively isolate the D-axis winding from the Q-axis winding, even when these two main windings are wound on a common primary core (stator).

[0059] The neutralizing coils are also configured to shift the phase angle of the air-gap flux at the boundary between the D-axis and Q-axis zones. In this regard, in some implementations, when an induction machine transitions from motoring mode to generating mode and relies on the Q-axis winding to generate an output pulse, the air-gap flux at the boundary condition entering each pole's Q-axis zone must be in phase with the intrinsic air-gap flux generated by the rotor to generate maximum voltage output. The neutralizing coils enable this air-gap flux to be aligned in phase.

[0060] In this regard, when the machine is drawing power from an AC source, the multi-phase input to the D-axis winding may be interrupted in one phase, as in the implementations of Figures 15 and 16. This generates a large, negative-sequence primary current in the D-axis winding. At the same time, the neutralization winding may switch into a closed short-circuit loop. The closed short-circuit loop induces a transient voltage in either the Q-axis winding or the D-axis winding. This transient component can be used to increase the output pulse energy in the Q-axis winding or the rate of rise of the voltage delivered to the load. Additionally, the multi-phase input to the D-axis winding may be connected as a single-phase input to a boost transformer. This connection generates a large, negative-sequence primary current. At the same time, one set of neutralization windings may switch into a closed short-circuit loop, which induces a transient voltage in both the Q-axis winding and the D-axis winding. This transient component can be used to increase the output pulse energy in the second Q-axis winding or the rate of rise of the voltage delivered to the load.

[0061] In a wound rotor slip-ring induction machine, the rotor's external power circuit, which may be a resistive or inductive multiphase circuit, can be repeatedly shorted, generating transient components in the rotor current. These transient components are reflected in the Q-axis winding as recurring useful voltage and current transients. These transients can repeatedly or continuously enhance (i.e., boost) the output energy delivered to the load by the Q-axis winding.

[0062] In the exemplary configuration of a 4-pole machine shown in FIG. 17A, bidirectional thyristor T1 controls series closed-loop connected coils 4X and 25X, bidirectional thyristor T2 controls series closed-loop connected coils 11X and 32X, bidirectional thyristor T3 controls series closed-loop connected coils 18X and 39X, bidirectional thyristor T4 controls series closed-loop connected coils 7X and 28X, bidirectional thyristor T5 controls series closed-loop connected coils 14X and 35X, and bidirectional thyristor T6 controls series closed-loop connected coils 21X and 42X.

[0063] Figure 19 shows the coil configuration of an exemplary 8-pole stator winding layout that can be used with the induction machines described herein. The layout includes three sets of multi-phase stator windings, with the D-axis and Q-axis windings being equal in terms of the number of coils (24) and the circumferential arc along the air gap. The tertiary winding also includes a set of six coils, which can be shorted via a set of thyristors 140, as in the neutralization winding, Figure 17A, or can be excited individually by a multi-phase source to assist in the overall excitation of the machine. This type of winding is applicable to both wound rotor machines and squirrel-cage rotor induction machines.

[0064] Table 1 provides design parameters for an exemplary induction machine, e.g., an induction motor / generator of the type described herein. In this example, the radial air gap size for the D-axis (driving function) sector is 0.025 inches, and the radial air gap size for the Q-axis (motoring function) is 0.100 inches. This means there is a 4:1 difference in the air gaps. This change in spatial dimension results in a clear difference in reactance between the D-axis and Q-axis of at least 4:1. The machine has 96 slots and 4 poles, showing 4 slots / pole / phase for the D-axis winding (48 coils total) and 3 slots / pole / phase for the Q-axis winding (36 coils total). The 96 slots contain a neutral winding of 12 coils arranged as 6 pairs of coils. Each pole has separate D-axis and Q-axis winding areas, so each pole group is divided into two segments. Both winding sets are short-coded and span 12 stator slots, resulting in a 50% coding. The output reactance of the Q-axis winding is calculated to be 5.267 ohms, and the input reactance of the D-axis is 31.6 ohms, indicating a reactance ratio of 6.00 due to the design of the machine's magnetic circuit. This machine has essentially a 4:1 difference in energy stored in the air gap magnetic field based on the air gap selected. [Table 1]

[0065] An exemplary implementation of machine 12 constructed according to the specifications in Table 1 includes a cylindrical bore induction machine with a periodic, alternating step change in the stator bore, which defines a spatially variable air gap and, consequently, a variable magnetizing reactance, Xm, as a function of circumferential angle. In this example, the air gap step change is at least 4:1, which causes the magnetizing reactance to vary by at least a factor of 4:1, resulting in a larger value of Xmd for the D-axis winding and a smaller value of Xmq for the Q-axis winding. The same physical layout of slots and air gaps also results in a higher D-axis stator leakage reactance, X1d, than the Q-axis slot leakage reactance, X1q. In essence, Xmd > Xmq, and at the same time, X1d > X1q.

[0066] In this example, the Q-axis winding is configured for use as an output winding, and its low reactance is a design parameter that results in high output short-circuit current or high pulse output current. In this example, both the Q-axis winding and the D-axis winding share a common rotor or secondary electrical member. This is either a squirrel-cage rotor with a symmetrical slot layout and a uniform rotor diameter or a wound rotor. The rotor can be directly coupled to a flywheel or similar inertial energy storage rotating device, or coupled through a variable-speed gearbox.

[0067] The equivalent circuit parameters of the rotor leakage reactances X2d and X2q are also affected by the overall air gap step change geometry such that X2d > X2q, which may be desirable for producing high output current in the Q-axis winding.

[0068] In some implementations, in addition to increasing the magnitude of the discharge mode output current, the new slot and air gap arrangement also results in the Q-axis circuit having a lower L / R time constant than the D-axis circuit, which is advantageous for generating fast output pulses in a train of power pulses.

[0069] FIG. 20 shows an example stator or main design layout. In some implementations, the Q-axis winding is constructed using non-magnetic teeth 142 on the peripheral zone of the Q-axis winding, which do not provide a low-reluctance path on either side of the stator coil. Conversely, the D-axis winding is held in place by ferromagnetic teeth 141 using slot wedges. In some implementations, the Q-axis winding is held in place relative to the magnetic core by non-magnetic structural teeth 142, such as a fiberglass epoxy material. This design feature can further reduce the stator slot's leakage reactance, X1q, and improve high-current output performance. The neutralization winding can be configured as a single (multi-turn or single-turn) wound coil that surrounds the back of the machine's magnetic core. This winding layout technique is known as Gram-ring winding. Each neutralization coil can be connected in series with a similar coil spaced diametrically apart and controlled by an electronic switch to store current and MMF (magnetomotive force) when commanded to shift the air-gap flux in the direction of rotor rotation.

[0070] In this regard, and with reference also to FIG. 2, FIG. 20 illustrates an example of a first phase of the D-axis winding 17, an example of a first phase of the Q-axis winding 18, and an example of a second phase of the D-axis winding 17, as well as a neutralization winding 136.

[0071] The excitation ampere-turns (AT) or MMF current for either the D-axis or Q-axis winding can be calculated from standard textbook formulas as follows: AT=0.313*Bg*G*k s (ampere-turns / pole), where Bg is the radial magnetic flux density in the air gap, G is the radial air gap dimension, and k s is the air gap coefficient which takes into account the slot opening or magnetic fringe effect on both sides of the air gap. The magnetizing current Im, which is inversely proportional to the magnetizing reactance, can be calculated as follows: Im = 2.22*P*AT / (m s *N*f w *f c ) Ampere where P is the number of primary poles, m s is the number of phases, N is the total number of series conductors in series per phase, fw is the winding distribution ratio, and fc is the coding ratio. If the parameters Bg, ks, P, ms, N, fw, and fc are the same for the D-axis and Q-axis windings, increasing G by 4:1 will produce a magnetizing current in the Q-axis winding that is four times the excitation current of the D-axis winding. In an exemplary implementation, the Q-axis winding has a total of N series conductors per phase designed to be lower than the D-axis, e.g., N(Q) equals 0.25N(Q). Then, with changes in the air gap and number of turns combination, the Q-axis excitation current and excitation reactance become, respectively, as follows: Im(Q) = 16 times Im(D), therefore Xm(Q)=1 / 16 of Xm(D).

[0072] Any "electrical connection" as used herein may include a direct physical connection, or a wired or wireless connection that may or may not involve intervening components, but that nevertheless allows electrical signals to flow between the connected components. A "connection" that involves electrical circuitry that allows signals to flow is an electrical connection, unless otherwise specified, and not necessarily a direct physical connection, regardless of whether the word "electrical" is used to modify the "connection."

[0073] Elements of different described implementations may be combined to form other implementations not specifically described above. Elements may be removed from the described systems without adversely affecting their operation or the operation of the overall system. Additionally, various separate elements may be combined into one or more individual elements to perform the functions described herein.

[0074] Other implementations not specifically described herein are within the scope of the following claims.

Claims

1. A system including a rotating electric machine, the rotating electric machine comprising: a rotor that is cylindrical and configured to rotate; a stator disposed relative to the rotor, the stator having a stepped configuration defining a first stator bore diameter and a second stator bore diameter, the first bore diameter being smaller than the second bore diameter; and Including, a zone of the stator at the first bore diameter carrying direct-axis (D-axis) windings and a zone of the stator at the second bore diameter carrying quadrature-axis (Q-axis) windings; an air gap between the rotor and the Q-axis winding is larger than an air gap between the rotor and the D-axis winding; the stator includes a neutralization winding between the D-axis winding and the Q-axis winding set, the neutralization winding being configured to change an air gap radial magnetic flux between adjacent D-axis windings and Q-axis windings. system.

2. 10. The system of claim 1, further comprising an inertial energy storage device that provides power to the D-axis winding to enable rotation when the rotor is disconnected from an external power source.

3. the Q-axis winding is configured to output energy to a load, the rotating electric machine is configured to supply power to the D-axis winding through an external power supply until the rotor reaches a predetermined speed, and thereafter the D-axis winding is supplied with power by the inertial energy storage device; The D-axis winding is powered by the inertial energy storage device, and the rotating electric machine is configured to output energy from the D-axis winding that boosts the energy output by the Q-axis winding. The system of claim 2 .

4. The system of claim 3 , wherein the energy from the D-axis winding is superimposed on the energy output by the Q-axis winding.

5. 4. The system of claim 3, wherein boosting the energy output by the Q-axis winding includes at least one of adding a current or a voltage to a current or a voltage output by the D-axis winding.

6. 4. The system of claim 3, wherein the Q-axis winding has a lower electrical reactance than the D-axis winding based on a difference in radial air gaps associated with the Q-axis winding and the D-axis winding.

7. The system of claim 3 , wherein the combined energy from the Q-axis winding and the D-axis winding is pulsed.

8. The system of claim 3 , wherein the combined energy from the Q-axis winding and the D-axis winding is continuous.

9. 4. The system of claim 3, wherein the combined energy from the Q-axis winding and the D-axis winding is the combined energy at an end of a rise in power output of the Q-axis winding.

10. the rotating electric machine is configured to output energy from the D-axis winding that boosts energy output from the Q-axis winding to a load, The system includes a transformer between the rotating electric machine and the load, the transformer being configured to receive currents from the D-axis winding and the Q-axis winding, and to generate boosted energy that is output to the load based on the currents from the D-axis winding and the Q-axis winding. The system of claim 1 .

11. the rotating electric machine is configured to output energy from the D-axis winding that boosts energy output from the Q-axis winding to a load, The rotating electric machine includes: a switch that is controllable to interrupt a circuit between the rotating electric machine and the load, the interruption of the circuit occurring simultaneously with the injection of the energy from the D-axis winding, the interruption generating a transient voltage and a transient current that boost the energy output from the Q-axis winding; Including, The system of claim 1 .

12. The system of claim 11 , wherein the transient voltage and the transient current increase the rate of rise of the energy output from the Q-axis winding.

13. The system of claim 11 , wherein the voltage transients and the current transients increase the total energy delivered to the load.

14. The system of claim 11 , wherein the transient voltage and the transient current create pulsed energy that is output to the load.

15. The system of claim 11 , wherein the Q-axis winding, the switch, and the D-axis winding create a current loop that is interrupted by controlled opening of the switch.

16. 12. The system of claim 11, wherein the output current from the D-axis winding circulates in a closed loop until the output current reaches a target value, at which point the switch is controllable to interrupt the circuit.

17. further comprising a circuit for converting the D-axis winding from a polyphase input to a single-phase alternating current (AC) excitation; 2. The system of claim 1, wherein the system causes a spatial peripheral shift of the air gap flux of the D-axis winding, thereby boosting the energy output by the Q-axis winding.

18. the rotating electric machine is configured to output energy from the D-axis winding that boosts energy output from the Q-axis winding to a load, The system comprises: a rectifier for rectifying the current component of the energy from AC (alternating current) to DC (direct current); an inductive storage for receiving the DC from the rectifier and boosting the energy output from the Q-axis winding; Including, The system of claim 1 .

19. the rotating electric machine is configured to output energy from the D-axis winding that boosts energy output from the Q-axis winding to a load, the load comprising a pulse-forming network (PFN) including inductive and capacitive components for generating a shaped pulse; The system of claim 1 .

20. the rotating electric machine is configured to output a current from the D-axis winding that boosts energy output from the Q-axis winding to a load, The system comprises: a subharmonic filter that extracts subharmonics from a rectifier according to the output of the Q-axis winding; a thyristor modulator that supplies the subharmonic including reactive power to the D-axis winding when the rotating electric machine is disconnected from external power; Including, The system of claim 1 .

21. the rotating electric machine is configured to output a current from the D-axis winding that boosts energy output from the Q-axis winding to a load, The system comprises: a harmonic filter that forms a resonant circuit together with the D-axis winding and is connected to an output current port from the D-axis winding; a boost transformer in series with the harmonic filter that receives the current from the harmonic filter and boosts the current; a multi-phase rectifier that receives the boosted current and provides a rectified output based on the boosted current to boost the energy output to the load; Including, The system of claim 1 .

22. the rotating electric machine is configured to output a current from the D-axis winding that boosts energy output from the Q-axis winding to a load, The system comprises: a boost transformer according to the output of the D-axis winding for receiving the current from the D-axis winding; a rectifier for rectifying the output of the boost transformer; a pulse-forming network including a storage element that charges based on the rectified output from the rectifier; a switch triggerable to output energy from the pulse forming network to combine with the energy output from the Q-axis winding; Including, The system of claim 1 .

23. the switch comprises a spark gap switch; The system comprises: a capacitive storage that stores the energy output from the Q-axis winding; an inertial energy storage device that transfers energy using the capacitive storage and the pulse-forming network during operation of the rotating electric machine; Including, 23. The system of claim 22.

24. the D-axis winding is configured to receive a polyphase input; When the multi-phase input is interrupted, a negative-phase primary current is generated in the D-axis winding; the neutralization winding is switchable to a closed short-circuit loop that induces a transient voltage in the D-axis winding or the Q-axis winding, and the negative-phase primary current generates the transient voltage that boosts the output voltage from the Q-axis winding to a load. The system of claim 1 .

25. the rotating electrical machine including a multi-phase wound rotor configured to receive a multi-phase input; generating a negative-phase primary current in the D-axis winding when the magnitude or phase displacement of the multi-phase input changes; the neutralization winding is switchable into a closed short-circuit loop that induces a transient voltage in the D-axis winding and the Q-axis winding, and the transient voltage initiated by the rotating electric machine boosts an output voltage from the Q-axis winding to a load. The system of claim 1 .

26. a multi-phase power supply that provides excitation to the D-axis winding, the multi-phase power supply being controllable to provide pulsed single-phase excitation to the D-axis winding; When the excitation to the D-axis winding changes from polyphase to single phase, a reverse-phase current flows through the D-axis winding, causing a flux compression effect in the air gap between the rotor and the Q-axis winding and in the magnetic field of the air gap between the rotor and the D-axis winding, and the flux compression effect changes the effective impedance associated with the D-axis winding and the Q-axis winding. The system of claim 1 .

27. 10. The system of claim 1, wherein the Q-axis winding is configured to output energy to a load comprising a pulse-forming network and a radar system.

28. the rotating electric machine is configured to output a current from the D-axis winding that boosts energy output from the Q-axis winding to a load, The system comprises: a thyristor modulator for controlling the active and reactive components of power to affect the power applied to the load; an inductive storage that receives current from the thyristor modulator to boost the energy output from the Q-axis winding; Including, The system of claim 1 .

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