System and method for modulation index control of a DC-AC inverter

Abstract

A technique for recursively determining the modulation index for controlling a DC-AC inverter is disclosed. The modulation index can first be selected. The input voltage to the power inverter can be measured. Based on the input voltage and the selected modulation index, the output voltage of the power inverter may be estimated. The output current of the power inverter can be measured. Using the estimated output voltage and the measured output current, the active power and reactive power can be determined. Using the active power and reactive power, the updated modulation index can be determined. The updated modulation index coefficient can be used to generate a pulse-width modulated signal used to control the power inverter.

Description

[Technical Field]

[0001]

[0001] Cross-reference of related applications This application claims priority to U.S. Provisional Patent Application No. 63 / 507,604, filed June 12, 2023, entitled "SYSTEMS AND METHODS FOR MODULATION INDEX CONTROL OF A DC-TO-AC INVERTER," all of which are incorporated herein by reference in their entirety for all purposes. [Background technology]

[0002]

[0002] Vehicle power systems can be used to supply both DC and AC power to various loads. Equipment used for power generation and power line regulation can occupy limited space within the vehicle. Furthermore, the characteristics of various loads, which can be important for the operation of the vehicle power system, can vary considerably, thus complicating the design and implementation of the power system.

[0003]

[0003] Therefore, improved methods and systems related to power generation systems are needed in the art. [Overview of the project]

[0004]

[0004] Embodiments of the present invention relate to power generation systems. More specifically, embodiments of the present invention provide methods and systems for controlling the output of a power inverter via modulation index control. As merely an example, embodiments of the present invention are applied to machine controllers, but the present invention has broader applicability in power systems.

[0005]

[0005] An overview of various embodiments of the present invention is provided below as a list of examples. Any reference to a set of examples, as used below, should be understood disjunctively as a reference to each of those examples (for example, “Examples 1-4” should be understood as “Examples 1, 2, 3, or 4”).

[0006]

[0006] Example 1 is a method for controlling a power inverter. This method may be performed, for example, by a control component of the power inverter or by a control system connected to the power inverter. This method includes selecting a modulation index, measuring the input voltage to the power inverter, and estimating the output voltage of the power inverter based on the input voltage and the modulation index. This method also includes measuring the output current of the power inverter. This method can be used to determine the active power and reactive power using the output current and output voltage. This method also includes determining an updated modulation index using the active power and reactive power, generating a pulse-width modulated signal using the updated modulation index, and controlling the power inverter using the pulse-width modulated signal.

[0007]

[0007] Example 2 is the same method as Example 1, and updating the modulation index further includes calculating the estimated output voltage of the power inverter using the modulation index and the measured input voltage.

[0008]

[0008] Example 3 is the method of Example 2, and determining the active power and reactive power involves applying a dq0 transformation to the output current to generate the linear current component and the orthogonal current component, and using the linear current component, the orthogonal current component and the estimated output voltage to calculate the active power and reactive power.

[0009]

[0009] Example 4 is the method of Examples 1 to 3, further comprising generating an updated pulse-width modulated signal using the updated modulation index, the updated pulse-width modulated signal causing the power inverter to generate an updated output current.

[0010]

[0010] Example 5 is the method of Examples 1 to 4, in which the modulation index is updated iteratively at a predetermined rate.

[0011]

[0011] Example 6 is the method of Example 5, wherein measuring the input voltage includes measuring the input voltage at a predetermined rate, and measuring the output current includes measuring the output current at a predetermined rate.

[0012]

[0012] Example 7 is the method of Example 5, and the predetermined rate is approximately 19.2 kHz.

[0013]

[0013] Example 8 is the method of Examples 1 to 7, and determining the updated modulation index further includes applying a gain coefficient to the selected modulation index, the determined active power, and the determined reactive power.

[0014]

[0014] Example 9 is the method of Examples 1 to 8, and controlling the power inverter includes using a pulse width modulated signal to control the switching elements of the power inverter and generating an output current from the power inverter.

[0015]

[0015] Example 10 is a method for controlling a power inverter. This method may be performed, for example, by a control component of the power inverter or by a control system connected to the power inverter. This method includes the steps of (a) measuring the input voltage to the power inverter and (b) calculating the nominal output voltage based on the modulation index. This method also includes the steps of (c) measuring the output current of the power inverter, (d) determining the active power and reactive power using the nominal output voltage and output current, and (e) determining the updated modulation index using the active power and reactive power. This method also includes the step of iteratively performing steps (a) to (e).

[0016]

[0016] Example 11 is the method of Example 10, in which determining the active power and reactive power involves applying a dq0 transformation to the output current to generate the linear current component and the orthogonal current component,

number

number

[0017]

[0017] Example 12 is the method of Example 11, and the linear voltage component V D = 0, orthogonal axis voltage component

number

[0018]

[0018] Example 13 is the method of Examples 10 to 12, further comprising measuring the load voltage at a load electrically connected to a power inverter.

[0019]

[0019] Example 14 is the method of Example 13, and determining the updated modulation index includes: applying integral correction to the load voltage using a proportional-integral controller to generate a corrected load voltage; calculating a first exponential coefficient using active and reactive power; calculating a second exponential coefficient using the corrected load voltage; and calculating a weighted sum of the first and second exponential coefficients to generate the updated modulation index.

[0020]

[0020] Example 15 is the same method as in Examples 10 to 14, and generating an output current involves generating a pulse-width modulated signal using an updated modulation index, the pulse-width modulated signal can be used to control the switching elements of the power inverter to generate an output current from the power inverter.

[0021]

[0021] Example 16 is the method of Examples 10 to 15, and steps (a) to (e) are performed iteratively at a predetermined rate.

[0022]

[0022] Example 17 is a power inverter system. The power inverter system includes a line interface filter and a generator controller bus regulator electrically connected to the line interface filter. The line interface filter may include filter components having predetermined component values. The generator controller bus regulator can be configured to receive DC power and generate AC power by iteratively updating the modulation index. The modulation index may be characterized by predetermined component values.

[0023]

[0023] Example 18 is a power inverter system of Example 17, in which the generator controller bus regulator is configured to measure the input voltage of DC power, measure the output current from the generator controller bus regulator to the line interface filter, determine the active power and reactive power using the input voltage and output current, and iteratively update the modulation index by determining the modulation index using the determined active power, determined reactive power and load-independent modulation index.

[0024]

[0024] Example 19 is a power inverter system of Examples 17-18, further comprising an isolation transformer electrically connected to a line interface filter.

[0025]

[0025] Example 20 is a power inverter system of Example 19, in which the isolation transformer is characterized by its turns ratio and number of turns, and the line interface filter and isolation transformer are configured to receive AC power generated by the generator controller bus regulator and transmit the corresponding AC output to a load connected to the isolation transformer.

[0026]

[0026] Example 21 is a system including a vehicle engine, a generator connected to the vehicle engine, a generator controller bus regulator electrically connected to the generator, and a power inverter electrically connected to the generator controller bus regulator. The generator may be operable to generate current. The power inverter may be operable to rectify the current to generate DC input power. The power inverter may be operable to receive DC input power and generate output AC power by iteratively updating the modulation index.

[0027]

[0027] Example 22 is the system of Example 21, where the generator controller bus regulator is a first generator controller bus regulator, and the power inverter comprises a second generator controller bus regulator and a line interface filter, the second generator controller bus regulator is configured to measure the input voltage of the DC input power to the second generator controller bus regulator, measure the output current from the second generator controller bus regulator, determine the active power and reactive power using the input voltage and output current, and iteratively update the modulation index using the determined active power and determined reactive power.

[0028]

[0028] Example 23 is the system of Example 22, in which the line interface filter includes filter components having predetermined component values, and determining the active power and reactive power includes calculating the active power and reactive power using the input voltage, output current, and predetermined component values.

[0029]

[0029] Example 24 is a system of Examples 21 to 23, further comprising a sensor electrically connected to the output of a power inverter and configured to measure the output voltage from the power inverter to a load electrically connected to the power inverter.

[0030]

[0030] Example 25 is the system of Example 24, wherein the output voltage is three-phase, and the sensor is configured to measure the voltage of each phase of the output voltage.

[0031]

[0031] The present invention achieves many advantages over the prior art. For example, embodiments of the present invention provide a method and system for controlling the modulation index of a power inverter to approximate the output current / voltage using measured input current / voltage values ​​and to achieve a substantially constant output voltage regardless of load changes. These and other embodiments of the present invention, along with many of their advantages and features, will be described in more detail below in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0032] [Figure 1] This is a block diagram of an exemplary method for recursively updating the modulation index for use in generating output AC power, according to one embodiment. [Figure 2] This is a block diagram of a power inverter configured to recursively update the modulation index, according to several embodiments. [Figure 3] This is a block diagram of another exemplary method for updating the modulation index according to one embodiment. [Figure 4] This is a block diagram of exemplary steps for determining the active and reactive power output from a power inverter, according to several embodiments. [Figure 5] This is a block diagram of a system for generating AC power from rectified DC power using recursive modulation index control, according to several embodiments. [Figure 6] This plot shows the linearity of modulation index values ​​versus apparent power for various power factors of the load, according to several embodiments. [Figure 7] This is a schematic diagram of an exemplary line interface filter for a power inverter, according to several embodiments. [Figure 8] This is a block diagram of a control circuit for calculating the modulation index using measured output current and measured load voltage, according to several embodiments. [Figure 9]This is a block diagram of a circuit for generating a pulse-width modulated signal to control the switching elements of a power inverter, according to several embodiments. [Figure 10] This is a block diagram of a proportional-integral (PI) controller for determining the average modulation index according to one embodiment. Figures 11A to 11C are plots showing the response of exemplary power inverters when an inductive load is connected, according to several embodiments. [Figure 11A] This shows the AC output voltage from the power inverter when an inductive load is connected and then disconnected. [Figure 11B] This shows the power factor, modulation index, and phase angle sine of the power inverter when an inductive load is connected and then disconnected. [Figure 11C] Figures 12A–12C show the apparent power, active power, and reactive power from the power inverter when an inductive load is connected and then disconnected. Figures 12A–12C are plots showing the exemplary power inverter response when a capacitive load is connected, according to several embodiments. [Figure 12A] This shows the AC output voltage from the power inverter when a capacitive load is connected and then disconnected. [Figure 12B] This shows the power factor, modulation index, and phase angle sine of the power inverter when a capacitive load is connected and then disconnected. [Figure 12C] This shows the apparent power, active power, and reactive power from the power inverter when a capacitive load is connected and then disconnected. [Modes for carrying out the invention]

[0033]

[0050] According to certain exemplary embodiments, similar reference numerals in various drawings indicate similar elements. Furthermore, multiple instances of an element may be indicated by a letter or hyphen followed by a second number after the first number of that element.

[0034]

[0051] This disclosure relates to a method and system for providing DC-AC power inversion using a machine controller by recursively updating the modulation index used to control the machine controller. In particular, a vehicle power generation system may include a first machine controller that provides rectification and regulation of AC power generated by a motor or generator. The machine controller may include an active three-phase bridge, a DC link capacitor, sensors for input and output current and voltage, and control electronics. The output of the first machine controller may be a DC voltage output on a DC voltage bus that can supply power to various loads, such as batteries, electronic equipment, etc. To supply power to other loads that use an AC input, such as a motor, the DC voltage from the first machine controller can be inverted using a second machine controller to produce an AC output.

[0035]

[0052] The use of a second machine controller enables a simplified and economical system design using a dual machine controller that provides both AC-DC and DC-AC stages without a dedicated AC-DC inverter. However, the second machine controller does not need to have a mechanism for sensing voltage and current at the load, which limits its ability to control the generated AC output waveform when the load characteristics change. A typical DC-AC inverter includes control electronics for generating the switching waveform, an active bridge, a low-pass filter for suppressing switching artifacts on the output, and sensing elements for its input to and output to the load. In contrast, the load driven by the machine controller (e.g., a motor or generator) contains inductance that inherently provides filtering of high-frequency artifacts, so the machine controller does not include a filter at its output. A line filter can then be included in the vehicle power system at the output of the second machine controller. The second machine controller can sense its output current and voltage supplied to the line filter, but does not need to have the ability to sense voltage and current at the load.

[0036]

[0053] To compensate for the inability to sense voltage and current at the load, a second machine controller may be configured to adjust the output current at the load using a local measurement of the current output from the second machine controller. More specifically, the second machine controller may be configured to iteratively adjust the modulation index based on the apparent power supplied by the second machine controller. The modulation index is a dimensionless parameter that modulates the amplitude of a sinusoidal input signal used to generate a pulse-width modulated control signal within the machine controller. Aspects of this disclosure reveal that the modulation index changes substantially linearly with respect to the apparent power generated by the machine controller acting as a DC-AC inverter. This linearity allows for a stable, recursive definition of the modulation index independent of load characteristics (e.g., load impedance), thereby enabling the machine controller to be configured to rapidly adjust the AC output in response to changing load conditions without directly sensing the voltage and current supplied to the load.

[0037]

[0054] Figure 1 is a block diagram of an exemplary method 100 for recursively updating the modulation index for use in generating output AC power, according to one embodiment. In some examples, one or more of the operations described for method 100 may be performed by a generator controller bus regulator (GCBR), which is an example of a machine controller briefly described above and described in detail below with respect to Figures 2 and 5. Additionally or alternatively, one or more of the operations of method 100 may be performed by one or more components of a power inverter system 500, described below with respect to Figure 5.

[0038]

[0055] This method may include selecting a modulation index (110). The selected modulation index value can be used as the initial value of the modulation index for the recursive calculation of the updated modulation index. In the case of a three-phase voltage source DC-AC inverter, the modulation index m is Vpk = mV DC determines the amplitude of the output voltage waveform, where V DC is the DC voltage at the input of the inverter (e.g., the DC bus voltage at the input of the second machine controller). In the case of a single phase, the voltage amplitude is [Number] decreases only by the coefficient of, and the relationship between the modulation index, the desired output voltage V AC , and the input DC voltage is [Number] is given as. Since the characteristics of the load may change the value of the current supplied to the load, it may be necessary to update the modulation index to maintain a fixed value of V AC . As will be described later with respect to FIG. 6, the value of the modulation index required to maintain a constant V AC is linearly related to the apparent power entering the load. The apparent power entering the load depends on the output voltage V AC and the output current from the GCBR. The linear relationship between the modulation index and the apparent power in the load indicates the value of the load-independent modulation index, which is the value of the modulation index when the load is not connected (the intercept of the linear relationship). The load-independent modulation index m0 (i.e., the no-load modulation index) may depend on the characteristics of the filter components (e.g., the impedance values of inductive, capacitive, and resistive elements). In some embodiments, selecting the modulation index in operation (110) can include selecting the value of the load-independent modulation index m0.

[0039]

[0056] Referring to Figure 2, the power inverter 200 can be configured to recursively update the modulation index according to method 100. The power inverter may include a GCBR 202. The output 207 of the power inverter 200 may be connected to a line interface 204. The line interface 204 may be a low-pass filter for the AC output of the GCBR 202 to suppress high-frequency switching artifacts from the GCBR 202. The line interface 204 may include inductive elements such as line reactors, common-mode chokes, and isolation transformers, as well as an RC filter network, to provide appropriate filtering characteristics for the output voltage and current signals. In some examples, the input to the power inverter 200 may be a DC input 206 provided by a first machine controller that provides AC-DC power conversion from a motor or generator driven by the vehicle's engine. In a specific example of a vehicle power system, the DC input 206 may be 600V DC It may have a nominal value.

[0040]

[0057] The AC output 208 from the line interface 204 can be a three-phase voltage / current. The AC output 208 can supply power to a load 210. The load 210 may be various systems that rely on AC power, including motors, high-power electronic equipment, etc. As a specific example of a vehicle power system, the AC output 208 is Y-connected (120V AC 208V (Line vs. Neutral) AC It may have a nominal value for (line to line). In some examples, the AC output 208 from the line interface 204 may also be determined by the turns ratio and winding configuration of the isolation transformer.

[0041]

[0058] The GCBR202 may include sensing elements for measuring voltage and current at both its input (e.g., DC input 206) and its output (e.g., output 207). As briefly described above, the output voltage of the GCBR202 may include high-frequency switching artifacts that can cause the measured output voltage to differ substantially from the nominal voltage value of the expected AC waveform.

[0042]

[0059] Returning to Figure 1, Method 100 may also include generating a pulse-width modulated signal using a modulation index to generate an output current. The PWM signal may be used to control switching elements within a GCBR. For example, the PWM signal may be used to control insulated-gate bipolar transistors (IGBTs) used to provide the output AC waveform. The PWM signal may be generated, for example, by spatial vector modulation using a three-phase sinusoidal input signal. Each of the sinusoidal input signals may be multiplied by a modulation index and used to generate the output PWM signal.

[0043]

[0060] Method 100 may also include measuring the input voltage (114). The input voltage may be the input voltage to the power inverter (e.g., DC input 206 to power inverter 200). The output current from the power inverter may also be measured (116). Referring to Figure 2, GCBR202 can measure its input voltage (DC input 206) and its output current (output 207).

[0044]

[0061] The measured input voltage and output current can be used to determine the active power and reactive power (118). Active power and reactive power are components of the apparent power supplied by the inverter. Apparent power may depend on the output current and output voltage from the power inverter. The output voltage may contain artifacts that make any measured value unsuitable for calculation, therefore the measured input voltage V DC The above relationship

number

[0045]

[0062] Next, the updated modulation index can be determined using the active and reactive power values ​​determined in (118) (120). The linear relationship between the modulation index and apparent power is given by m = γ[m0 + μ p P avg +μ q Q avg ] can be expressed as, in the formula, P avg Q is active power. avg ∫ reactive power, m0, μ p , and μ q m0 and μ are coefficients that depend on the characteristics of the load and filter, and γ is the gain coefficient. p , and μ q The gain coefficient γ is determined empirically for a given configuration of the filter components. The gain coefficient γ is the measured input voltage (V DC ) and the nominal DC voltage (V) input to the power inverter nom This can be used as a correction for any deviation between )

number

[0046]

[0063] After determining the updated modulation index, the previous operation can be iteratively repeated using the updated modulation index (122). Using the updated modulation index, the PWM signal used to generate the output current can be modified to generate a new output current. The new output current can result in a change corresponding to the apparent power supplied to the load. The input voltage and output current can be measured again and used to update the modulation index again. The iterative process can be carried out at a predetermined rate. For example, a GCBR can be configured to measure its input and output signals at 19.2 kHz to update the modulation index.

[0047]

[0064] Figure 1 shows exemplary blocks of Method 100, but in some embodiments, Method 100 may include additional blocks, fewer blocks, different blocks, or blocks in different arrangements than those shown in Figure 1. Additionally or alternatively, two or more blocks of Method 100 may be performed in parallel. According to alternative embodiments, other sets of steps may also be performed. For example, alternative embodiments of the present disclosure may perform the steps outlined above in a different order. Furthermore, the individual steps shown in Figure 1 may include multiple substeps that can be performed in various orders as appropriate for the individual steps. Furthermore, additional steps may be added or removed depending on the particular application. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0048]

[0065] Figure 3 is a block diagram of another exemplary method 300 for updating the modulation index according to one embodiment. One or more of the operations of method 300 may be performed by a power inverter including GCBR202 in Figure 2. Method 300 may include the step (310) of measuring the input voltage to the power inverter. The input voltage to the power inverter may be a DC voltage. Using the measured input voltage, the nominal output voltage of the power inverter can be calculated (312). Calculating the nominal output voltage may include multiplying the measured input voltage by the modulation index. The nominal output voltage may be the amplitude of the AC output voltage waveform. For example, the measured input voltage V DC And for a modulation index m, the nominal output voltage is V AC =mV DC It is possible. The AC output from the power inverter may be a three-phase output, thereby reducing the nominal output voltage V AC This can be the line voltage, and the corresponding phase voltage is V AC of

number

[0049]

[0066] Method 300 may also include the step (314) of measuring the output current of a power inverter. The output current may be a three-phase AC output. Measuring the output current may include measuring the instantaneous currents of all three phases of the AC output. For example, the output current may be I as the magnitude of the three-phase currents. a , I b , and I c It can include, thereby measuring the output current, a , I b , and I c This may include measuring each of them.

[0050]

[0067] The active power and reactive power output from the power inverter can be determined from the measured output current and the calculated output voltage (316). Active power and reactive power are calculated from the measured output current component I a , I b and I c This can be determined using the dq0 transformation. Further details regarding the application of the dq0 transformation are provided below with respect to Figure 4.

[0051]

[0068] Method 300 may also include the step (318) of determining the updated modulation index using active and reactive power. The updated modulation index is given by m = γ[m0 + μ p P avg +μ q Q avg It may also be given as ], in the formula, P avg Q is the active power. avg μ is reactive power, p and μ q γ is a coefficient that depends on the characteristics of the load and filter, and γ is the gain coefficient. The updated modulation index can be used by the power inverter to generate output current from the power inverter (320). As described above with respect to Figure 1, the power inverter can use the modulation index as a multiplier to scale the control waveform of the pulse-width modulated signal used to generate the output current.

[0052]

[0069] The updated modulation index may cause the output current to change. Method 300 allows for iterative updating of the modulation index by again measuring the input voltage and output current and determining further updates to the modulation index (322). The iterative process can be carried out at a predetermined rate. Furthermore, if the characteristics of the load receiving power from the power inverter change, iterative updating of the modulation index can enable the power inverter to respond quickly to the changes in order to maintain the nominal output current value.

[0053]

[0070] Method 300 may include additional embodiments, such as any single embodiment or any combination of embodiments relating to one or more other processes described below and / or elsewhere in this specification.

[0054]

[0071] In one embodiment, the power inverter may be configured to acquire a measurement of the load voltage. Method 300 then may include measuring the load voltage at a load electrically connected to the power inverter. Determining the updated modulation index may then include applying an integral correction to the load voltage to generate a corrected load voltage, calculating a first exponential coefficient using the active and reactive powers, calculating a second exponential coefficient using the corrected load voltage, and calculating a weighted sum of the first and second exponential coefficients to generate the updated modulation index. Further details of this hybrid calculation are discussed below with respect to Figure 10.

[0055]

[0072] Figure 3 shows exemplary blocks of Method 300, but in some embodiments, Method 300 may include additional blocks, fewer blocks, different blocks, or blocks in different arrangements than those shown in Figure 3. Additionally or alternatively, two or more blocks of Method 300 may be performed in parallel. According to alternative embodiments, other sets of steps may also be performed. For example, alternative embodiments of the present disclosure may perform the steps outlined above in a different order. Furthermore, the individual steps shown in Figure 3 may include multiple substeps that can be performed in various orders as appropriate for the individual steps. Furthermore, additional steps may be added or removed depending on the particular application. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0056]

[0073] Figure 4 is a block diagram of an exemplary step 400 for determining the active and reactive power output from a power inverter, according to several embodiments. The exemplary step 400 may be an example of operation 316 of method 300 described above with respect to Figure 3, and may be performed by any of the power inverters described herein, including the power inverter 200 of Figure 2.

[0057]

[0074] Step 400 may include step (410) of applying a dq0 conversion to the (measured) output current from the power inverter. In the case of a three-phase output current from a power inverter, the output current has components for each phase. The measured output current is I a , I b , and I c The instantaneous amplitude of each component, expressed as , can be included. The measured output current can also include the measured or assumed phase angle between each component. For example, a typical three-phase current signal has a phase angle of 120° between each component. The dq0 transform can convert the components of a three-phase waveform into a rotational basis where the transformed components are DC signals, thereby simplifying the analysis. The dq0 transform produces three corresponding signal components: a linear "D", a quadrature "Q", and a zero "0" component.

[0058]

[0075] The dq0 conversion is,

number

number

[0059]

[0076] Active power is,

number

number

[0060]

[0077] Reactive power is

number

number

[0061]

[0078] Figure 5 is a block diagram of a system 500 for generating AC power from rectified DC power using recursive modulation index control, according to several embodiments. The system 500 may also be a vehicle power system that uses an engine 502 (e.g., a vehicle engine) to drive a generator 504 and generate input power for AC-DC and DC-AC power conversion stages. Exemplary vehicles that can implement the power inverter technology described herein may include variations of medium tactical vehicles (MTVs), light MTVs (LMTVs), mine-resistant ambush defense (MRAP) all-terrain vehicles (M-ATVs) and other MRAP vehicle variations, Humvees, Stryker variations, and the like. The generator 504 may be a generator connected to the engine 502, for example, integrated into the vehicle's transmission. The generator 504 may include a magnetic rotor that is rotated in a stator winding by the vehicle transmission to generate three-phase AC power 520. The three-phase AC power can be of variable voltage and variable frequency (VVVF) according to the speed of the engine / transmission driving the rotor of the generator 504.

[0062]

[0079] Three-phase AC power 520 can be supplied to a first generator controller bus regulator (GCBR) 506. The first GCBR 506 can convert the AC input power to DC output power. The first GCBR 506 may include an active three-phase bridge, a DC link capacitor, sensors for input and output current and voltage, and control electronics for controlling the switching elements of the active bridge (when the active bridge is acting as a rectifier). The output from the first GCBR 506 can be a DC voltage. The first GCBR 506 can be configured to provide a range of DC voltages at its output. As a specific example, the DC voltage present on the DC voltage bus of the first GCBR 506 can be 600V. A pre-charge network 508 having contactors and resistors can be used to limit the inrush current on the DC voltage bus when the DC voltage 522 is applied to the second GCBR 512.

[0063]

[0080] The second GCBR512 can be configured to invert an input DC voltage 522 to a three-phase AC electrical output 524. In some embodiments, the second GCBR512 can be the same machine controller as the first GCBR506, having similar components including an active three-phase bridge, a DC link capacitor, sensors for measuring the input DC voltage 522 and the three-phase AC electrical output 524, and control electronics for controlling the switching elements of the active bridge. The three-phase AC electrical output 524 can include three components for each phase of voltage and current. In some embodiments, the three-phase AC electrical output is provided in a delta configuration. As a particular example, for a 600V DC input, the second GCBR512 can be configured to produce a 360V AC output. In most cases, the three-phase AC electrical output 524 can include high-frequency voltage artifacts generated by the switching elements of the second GCBR512. The second GCBR512 can measure the voltage of the DC voltage 522 instead of the voltage of the three-phase AC electrical output 524, and the measured input voltage can be used as a substitute for the output voltage.

[0064]

[0081] System 500 may also include a line interface 514. The line interface 514 may be a low-pass filter used to adjust the three-phase AC electrical output 524 and attenuate the high-frequency components of the three-phase AC electrical output 524. In some examples, the line interface 514 may include one or more inductive three-phase reactors, one or more inductive three-phase common-mode chokes, a passive RC network filter, and the like. The values ​​of the components of the line interface 514 (e.g., inductance, capacitance, resistance) are given by coefficients m0, μ, etc., which are described in more detail herein. p , and μ q This can be used to determine the following. The line interface 514 may produce a filtered AC output 526. Further details of an exemplary line interface are provided below with respect to Figure 7.

[0065]

[0082] System 500 may also include an isolation transformer 516 between the line interface 514 and the load 518. The isolation transformer 516 may be a transformer that provides electrical isolation between the line interface 514 and the load 518. The isolation transformer 516 may have an inductance that provides additional filtering of the filtered AC output 526. The output from the isolation transformer 516 may be an AC load input 528. The isolation transformer 516 may also provide a boost or buck voltage for the filtered AC output 526 according to the design parameters of System 500 and the power requirements of the load 518 (e.g., the design of the vehicle power system, the input voltage requirements of the load equipment, etc.). As a specific example, for a filtered AC output 526 in a 360V delta configuration, the AC load input 528 may be a three-phase Y-connection configuration of 208V (line-to-line) and 120V (neutral-to-neutral) after bucking from the isolation transformer 516.

[0066]

[0083] The load 518 may be various devices that utilize AC power. In some examples, the load 518 may be a motor, radar transmitter, and other field equipment connected to a vehicle power system such as system 500, which may have high power demands during operation. The characteristics of the load 518 (e.g., impedance) may also change during operation, for example, due to switching components on and / or off, or because the load 518 draws some power. The modulation index control technique described herein can maintain the voltage of the AC load input 528 at a substantially constant voltage even if the characteristics of the load 518 change. System 500 may be configured to provide a stable AC load input 528 for a range of apparent power supplied to the load 518. For example, the range of apparent power supplied to the load 518 may vary from 0 kVA to 150 kVA.

[0067]

[0084] Therefore, the system 500 shown in Figure 5 receives power from the generator 504, generates a DC voltage (e.g., 600V DC) shown as DC voltage 522 on the DC voltage bus, and inverts the DC voltage to generate a three-phase AC voltage (e.g., a 208V AC three-phase voltage) shown as AC load input 528 that can be supplied to the load 518.

[0068]

[0085] Figure 6 is a plot 600 showing the linearity of the modulation index versus apparent power values ​​for various power factors of the load, according to several embodiments. Plot 600 was generated by an electrical circuit simulation of components of an exemplary vehicle power system (e.g., system 500 in Figure 5), including a line interface filter (e.g., line interface 514 in Figure 5) with an inductance value of 150 μH and RC filter network values ​​of 0.167 Ω and 150 μF. The simulation also included parasitic resistance and capacitance to better approximate the actual filter components.

[0069]

[0086] Each line in plot 600 represents the value of the modulation index required to maintain a 208V input to a load for a specific value of the load connected to the power inverter (e.g., load 518 in Figure 5). Each load is represented by the phase angle φ of the load current, characterized by its impedance. For example, line 604 corresponds to a lagging phase angle φ = 36.87°, representing a load with inductive reactance, and line 606 corresponds to a leading phase angle φ = -36.87°, representing a load with capacitive reactance. Line 608 corresponds to a load phase angle φ = 0, representing a purely resistive load.

[0070]

[0087] As shown by plot 600, each of the lines for the various types of loads is substantially linear over a wide range of apparent power supplied to the load. Due to linearity, the formula for the modulation index m is in the form of m = γ[m0 + μ p P avg +μ q Q avgIt can be given as ]. Intercept 602 corresponds to the load-independent modulation index m0, which is the modulation index when apparent power is not supplied to the load (e.g., when no load is connected). The load-independent modulation index m0 can also be called the no-load modulation index.

[0071]

[0088] By performing a curve fitting operation, such as least squares regression, on the data generated for plot 600, m0, μ p , and μ q The value of can be determined. For the example filter component values ​​listed above, these values ​​are m0 = 0.8464430, μ p = 1.268 × 10 -4 , and μ q = 7.288 × 10 -4 Similar calculations can be performed for different filter component values ​​corresponding to components of different embodiments of vehicle power systems and power inverters implementing the modulation index control technique described herein. Furthermore, the value of m0 may be analytically determined based on a circuit analysis of the filter network used in conjunction with the power inverter, as described below. The calculated modulation index m can then be used to control the output of the inverter (e.g., GCBR#2 512 as illustrated in Figure 5).

[0072]

[0089] Figure 7 is a schematic diagram of an exemplary line interface filter 700 of a power inverter according to several embodiments. The line interface filter 700 may be an example of the line interface 514 described with respect to Figure 5. The line interface filter 700 may be connected to an AC power supply 706 and a load 704. The AC power supply 706 may be an example of a three-phase AC electrical output 524 from a GCBR. The voltage of the AC power supply 706 is V AC It may also be represented as follows. Load 704 may be an example of load 518 in Figure 5. For simplicity, the circuit diagram shown in Figure 7 represents a single phase of a three-phase system, with the other phases connected to similar filter components.

[0073]

[0090] The line interface filter 700 may include reactors 708 and 710, each being a single phase of a three-phase reactor. As described above, in a particular example, the inductance values ​​L1 and L2 of reactors 708 and 710 may be 150 μH. The line interface filter 700 may also include an RC network 702. The RC network 702 may include resistive and capacitive elements. In the particular example described above, the RC network 702 may have R1 and C1 values ​​of 0.167 Ω and 150 μF, respectively. Those skilled in the art will recognize many variations in predetermined component values ​​in order to provide appropriate low-pass filtering to the AC power supply 706 containing high-frequency switching artifacts. The filter output 712 receives a voltage signal V applied to the load 704. out This is also possible. The impedance of the load 704 may be an unknown value Z.

[0074]

[0091] The circuit analysis of the line interface filter 700 circuit involves V with respect to the impedance Z and component values ​​of the load 704. out This yields the following equation.

number

number

number

number

number

[0075]

[0092] FIG. 8 is a block diagram of a control circuit 800 for calculating a modulation index using measured output current and measured input voltage according to some embodiments. The blocks of the control circuit 800 represent logic elements for performing calculations, signal processing, and / or logical operations using signals measured in a system implementing recursive modulation index control of an AC output from a power inverter. The measured signal (e.g., the output current 806 at the output of the GCBR) may be sampled at a predetermined sampling rate (e.g., 19.2 kHz).

[0076]

[0093] The output current 806 can be measured at the output of the GCBR acting as a power inverter. The output current 806 can be a three-phase current having a, b, and c components (e.g., I a , I b , and I c ). Each current component of the measured output current 806 can be input to a dq0 conversion block 802. The dq0 conversion block 802 (e.g., a Clarke-Park converter) performs an operation to convert the a, b, c components into D, Q, and zero components. The output of the dq0 conversion block 802 can include a direct-axis current component 810 and a quadrature-axis current component 812. The zero current component signal should have a value of zero, and in some embodiments, the output from the dq0 conversion block 802 for the zero current component can be used as an error detection signal.

[0077]

[0094] The input voltage 808 can be measured at the input of the GCBR acting as a power inverter. The input voltage 808 can be a DC signal (e.g., V DC ). The input voltage 808 can be input to a conversion block 804. The conversion block 804 generates a quadrature-axis voltage component 816

Number

[0078]

[0095] The linear current component 810 and the orthogonal current component 812 can be input to a finite impulse response (FIR) filter 818. The FIR filter 818 can be configured to determine a weighted sum of a finite number of samples of the linear current component 810 and the orthogonal current component 812 input to the FIR filter 818. For example, the FIR filter 818 may calculate a weighted sum of N samples, and as each new sample is acquired, the oldest sample used by the FIR filter 818 can be discarded to update the filtered output from the FIR filter 818. In some embodiments, although this is not required by the present invention, the weights used in the weighted sum can be set to give more weight to the newest sample in the weighted sum. In other embodiments, the weights are identical and are set to effectively 1 / N, where N is chosen so that one complete cycle of the ripple frequency can be represented in the FIR window.

[0079]

[0096] The direct-axis voltage component 814 and the quadrature-axis voltage component 816 can similarly be input to the FIR filter 820. The FIR filter 820 is configured similarly to the FIR filter 818 and can determine the weighted sum of a finite number of samples of the direct-axis voltage component 814 and the quadrature-axis voltage component.

[0080]

[0097] The filtered outputs from the FIR filter 818 and the FIR filter 820 can be input to the power calculation block 822. The power calculation block 822 can be configured to calculate the active power 824 and the reactive power 826. As described above with respect to FIG. 4, the active power 824 can be determined using

Number

Number

[0081]

[0098] The active power 824 and the reactive power 826 can be input to the modulation index calculation block 828. The modulation index calculation block 828 can be configured to determine an updated value of the modulation index 834 using m = γ[m0 + μ p P avg + μ q Q avg . The coefficients μ p and μ qThis can be calculated as described above with respect to Figure 6 using regression analysis on the simulation results of the power inverter and line filter circuit components in the vehicle power system. The control circuit 800 may also be configured to select a load-independent modulation index m0830, which may depend on the component values ​​of the line filter used to adjust the output current 806 in the vehicle power system. The modulation index calculation block 828 may also be configured to determine the gain coefficient 832. The gain coefficient 832 is,

number

[0082]

[0099] Figure 9 is a block diagram of a circuit 900 for generating a pulse-width modulated signal to control the switching element 912 of a power inverter, according to several embodiments. The power inverter can be a GCBR (e.g., a second GCBR 512) as described with respect to Figure 5. The circuit 900 may include a space vector PWM 902 that receives three sinusoidal signals 906, each separated by a 120° phase.

[0083]

[0100] Each amplitude of the sinusoidal signal 906 is multiplied by a modulation index 904 in a multiplier 908. The modulation index 904 may be a modulation index 834 calculated by the control circuit 800 in Figure 8. The scaled sinusoidal signal is input to a space vector PWM 902. The space vector PWM 902 is configured to generate a pulse width modulated signal by comparing the scaled sinusoidal signal to a reference sawtooth signal 910 and controlling the input to a switching element 912 of a power inverter. The switching element 912 may be an IGBT used as part of an active bridge. Those skilled in the art will recognize many variations in the implementation of the space vector PWM 902 for driving the switching element 912.

[0084]

[0101] Figure 10 shows the weighted average modulation index m according to one embodiment. avg This is a block diagram of a control circuit 1000 including a proportional-integral (PI) controller 1002 for determining 1014. If the output voltage 1004 is sensed by a load connected to a power inverter and supplied to the control circuit of the power inverter, further improvements to the control of the output voltage 1004 can be made in conjunction with the iterative modulation index technique described herein.

[0085]

[0102] The PI controller 1002 can be configured to determine an error signal as the difference between the measured output voltage 1004 and the nominal voltage 1006. The nominal voltage 1006 may be the voltage value at the load that the power inverter's machine controller attempts to maintain by iteratively updating the modulation index. The PI controller 1002 can be configured to use the error signal to determine integral correction, as well as to use the error signal to determine proportional correction. By combining proportional and integral corrections, the estimated modulation index m est 1008 can be determined. The control circuit 1000 determines the estimated modulation index m est The weighted average m of 1008 and the modulation index 1012 determined using the measured output current of the power inverter as described above with respect to Figures 3, 4, and 8. avg It can include a weighted average block 1010 which can be configured to calculate 1014. Then, the weighted average m avg 1014 can be input to a control circuit to iteratively update the modulation index (e.g., control circuit 800 in Figure 8). By using calculations of both the updated modulation index, the control circuit for the power inverter can take advantage of both the fast response of the iterative update method and the accuracy of direct measurement of the output voltage at the load (if such measurement is available).

[0086]

[0103] Figures 11A–11C are plots showing the response of exemplary power inverters when an inductive load is connected, according to several embodiments. The exemplary power inverter can be configured to output a 360V AC voltage, which can then be filtered and stepped down to a 208V three-phase input voltage at the load. The load impedance includes a purely resistive component using 120kW of power and an inductive component using 90kVAR of power, which is connected in 0.5 seconds and then disconnected in 1.5 seconds.

[0087]

[0104] Figure 11A is a plot of the AC output voltage from the power inverter. When the inductive component of the load is added for 0.5 seconds, the amplitude of the AC output voltage decreases for a short time, as expected for an inductive load on an AC power supply. When the inductive component of the load is removed for 1.5 seconds, a similar short-term increase in the amplitude of the power supply voltage is observed. As shown in plot 1100, the AC output voltage stabilizes within several hundred milliseconds of the change in load characteristics.

[0088]

[0105] Figure 11B is a plot 1110 showing the power factor cosφ, modulation index m, and phase angle sine of the power inverter when the inductive component of the load is connected and then disconnected. Since the load is purely resistive 0.5 seconds earlier, the power factor is 1 as expected, but the modulation index 1112 is approximately 0.85, corresponding to the value of m shown in the plot of line 608 in Figure 6 at 120 kVA. When the inductive component of the load is added in 0.5 seconds, the control circuit of the power inverter rapidly updates the modulation index. The updated modulation index 1114 reaches a stable value of approximately 0.915 within approximately 15 ms. The addition of the 90 kVA inductive component results in an apparent power of 150 kVA and a phase angle of 36.87°, which corresponds to line 604 in Figure 6 at 150 kVA. When the inductive component of the load is removed, a similarly fast response is observed in 1.5 seconds.

[0089]

[0106] Figure 11C is a plot 1120 showing the apparent power S, active power P, and reactive power Q from the power inverter when an inductive load is connected and then disconnected. As expected, the addition of the inductive component to the load results in an increase in apparent power 1122, which stabilizes relatively quickly. Some fluctuation in active power 1124 can be seen over approximately 30 ms. After the inductive component of the load is removed in 1.5 seconds, the apparent power 1126 supplied by the power inverter stabilizes to its original value within approximately 15 ms.

[0090]

[0107] The rapid stabilization of the AC output voltage, apparent power 1122, and active power 1124, as well as the change in the modulation index 1112, may be due to the fast response of the recursive calculation of the modulation index, which is updated in real time. At the sample rate used by the power inverter to measure the output apparent power, each continuous value of the modulation index can be given as follows: m n =γ n-1 [m0+μ p P avg、n-1 +μ q Q avg、n-1 (5) In other words, the modulation index is initially set to the no-load value m0 by the power inverter controller. The measurement of the filter input current (to approximate the load current) and the estimate of the drive voltage (to approximate the load voltage) are used to determine the active power P avg and reactive power Q avg It is used to calculate the number of active and reactive powers, and then the number of active and reactive powers is weighted by μ. p and μ qThe updated modulation index is calculated using the same method, which may be further adjusted in response to changes in the DC bus voltage due to the feedforward gain γ. This updated modulation index is then used to adjust the PWM signal driving the switching elements, which then drives the filter and load, resulting in changes in the load current. This process is then repeated indefinitely, and the modulation index fluctuates in response to changes in the DC bus and load. A similar response and rapid updating of the modulation index using recursive calculation is seen with respect to the addition and removal of capacitive loads, as described below with respect to Figures 12A-12C.

[0091]

[0108] Figures 12A–12C are plots showing the response of exemplary power inverters when a capacitive load is connected, according to several embodiments. The exemplary power inverter can be configured to output a 360V AC voltage, which can then be filtered and stepped down to a 208V three-phase input voltage at the load. The load impedance includes a purely resistive component using 120kW of power and a capacitive component using 90kVAR of power, which is connected in 0.5 seconds and then disconnected in 1.5 seconds. This configuration is similar to the configurations in Figures 11A–11C, but shows the response to the addition of capacitive impedance at the load.

[0092]

[0109] Figure 12A is plot 1200 showing the AC output voltage from the power inverter when the capacitive component of the load is connected for 0.5 seconds and then disconnected for 1.5 seconds. When the capacitive component of the load is connected for 0.5 seconds, a short-lived increase 1202 in the AC output voltage is observed, as expected for a capacitive load, followed by a corresponding decrease 1204 in the AC output. Similar to plot 1100 in Figure 11, the AC output voltage stabilizes within several hundred milliseconds of the change in load characteristics.

[0093]

[0110] Figure 12B is a plot 1210 showing the power factor cosφ, modulation index m, and phase angle sine of the power inverter when a capacitive load is connected and then disconnected. Since the load is purely resistive 0.5 seconds earlier, the power factor is 1 as expected, but the modulation index 1212 is approximately 0.85, corresponding to the value of m shown in the plot of line 608 in Figure 6 at 120 kVA. When the capacitive component of the load is added in 0.5 seconds, the control circuit of the power inverter rapidly updates the modulation index. The updated modulation index 1214 reaches a stable value of approximately 0.785 within approximately 15 ms. The addition of a 90 kVAR capacitive component results in an apparent power of 150 kVA and a phase angle of -36.87°, which corresponds to line 606 in Figure 6 at 150 kVA. When the capacitive component of the load is removed, a similarly fast response is seen in 1.5 seconds. The modulation index 1216 returns to a value of approximately 0.85 within approximately 15 ms.

[0094]

[0111] Figure 12C is a plot 1220 showing apparent power S, active power P, and reactive power Q from the power inverter when the capacitive component of the load is connected and then disconnected. As expected, the addition of the capacitive component to the load increases the apparent power 1222, which stabilizes relatively quickly. After the capacitive component of the load is removed in 1.5 seconds, the apparent power 1224 supplied by the power inverter stabilizes to its original value within approximately 15 ms.

[0095]

[0112] The methods, systems, and devices described above are examples. Various configurations may omit, substitute, or add various steps or components as needed. For example, in alternative configurations, the method may be performed in a different order than described, and / or various steps may be added, omitted, and / or combined. Also, features described for a particular configuration may be combined in various other configurations. Different aspects and elements of a configuration may be combined in similar ways. Furthermore, technology is evolving, and therefore many of the elements are examples and do not limit the scope of this disclosure or the claims.

[0096]

[0113] Specific details are provided in the description to provide a complete understanding of the exemplary configuration (including embodiments). However, the configuration may be implemented without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques are shown without unnecessary details to avoid obscuring the configuration. This description provides only exemplary configurations and does not limit the claims, applicability, or configuration. Rather, the foregoing description of the configuration provides a possible description for implementing the described techniques to those skilled in the art. Various modifications may be made to the function and arrangement of the elements without departing from the spirit or scope of this disclosure.

[0097]

[0114] The configuration may also be described as a process shown as a flow chart or block diagram. Each operation may be described as a sequential process, and many of the operations may be performed in parallel or simultaneously. The order of operations may also be changed. The process may have additional steps not included in the diagram. Furthermore, examples of methods may be implemented by hardware, software, firmware, middleware, microcode, hardware description language, or any combination thereof. If implemented in software, firmware, middleware, or microcode, the program code or code segments for performing the required tasks may be stored in a non-temporary computer-readable medium such as a storage medium. A processor can perform the described tasks. For example, the processor may reside inside a GCBR or machine controller. The processor may control the switching of the TIG winding configuration between import / export and power generation.

[0098]

[0115] While several exemplary configurations have been described, various modifications, alternative configurations, and equivalents can be used without departing from the spirit of this disclosure. For example, the elements described above may be components of a larger system, and other rules may take precedence over the application of this disclosure, or otherwise modify the application of this disclosure. Also, several steps may be taken before, during, or after considering the elements described above.

Claims

1. A method for controlling a power inverter, Selecting a modulation index, To measure the input voltage to the power inverter, Estimating the output voltage of the power inverter based on the input voltage and the modulation index, To measure the output current of the aforementioned power inverter, Using the output voltage and output current, the active power and reactive power are determined, Determining the updated modulation index using the active power and the reactive power, The process involves generating a pulse-width modulated signal using the updated modulation index, A method comprising controlling the power inverter using the pulse width modulated signal.

2. The method according to claim 1, further comprising updating the modulation index by calculating an estimated output voltage of the power inverter using the modulation index and the measured input voltage.

3. Determining the active power and the reactive power is Applying a dq0 conversion to the output current in order to generate a linear axis current component and a quadrature axis current component, The method according to claim 2, comprising calculating the active power and the reactive power using the linear current component, the orthogonal current component and the estimated output voltage.

4. The method according to claim 1, further comprising generating an updated pulse-width modulated signal using the updated modulation index, wherein the updated pulse-width modulated signal causes the power inverter to generate an updated output current.

5. The method according to claim 1, wherein updating the modulation index is performed iteratively at a predetermined rate.

6. The method according to claim 5, wherein measuring the input voltage includes measuring the input voltage at a predetermined rate, and measuring the output current includes measuring the output current at a predetermined rate.

7. The method according to claim 5, wherein the predetermined rate is approximately 19.2 kHz.

8. The method according to claim 1, further comprising determining the updated modulation index by applying a gain coefficient to the selected modulation index, the determined active power, and the determined reactive power.

9. The method according to claim 1, wherein controlling the power inverter includes controlling the switching elements of the power inverter using the pulse width modulated signal to generate an output current from the power inverter.

10. A method for controlling a power inverter, (a) a step of measuring the input voltage to the power inverter, Step (b) calculates the nominal output voltage based on the modulation index, The steps include (c) measuring the output current of the power inverter, (d) A step of determining the active power and reactive power using the nominal output voltage and the output current, The step (e) determines an updated modulation index using the active power and the reactive power, Repeat steps (a) through (e). method.

11. Determining the active power and the reactive power is Applying a dq0 conversion to the output current in order to generate a linear axis current component and a quadrature axis current component, [Math 1] Accordingly, the active power is calculated, P ａｖｇ V is the active power, Ｄ This is the linear voltage component, V Ｑ This is the orthogonal axis voltage component, and I Ｄ This is the linear current component, and I Ｑ This involves calculating the active power, which is the orthogonal axis current component, [Math 2] Accordingly, the reactive power is calculated, Q ａｖｇ The method according to claim 10, comprising: calculating the reactive power, which is the reactive power.

12. The aforementioned linear voltage component V Ｄ = 0, the orthogonal axis voltage component [Math 3] and V ＡＣ The method according to claim 11, wherein is the nominal output voltage.

13. The method according to claim 10, further comprising measuring the load voltage at a load electrically connected to the power inverter.

14. Determining the updated modulation index is A proportional-integral controller is used to apply integral correction to the load voltage to generate a corrected load voltage, The first exponential coefficient is calculated using the active power and the reactive power, The second exponential coefficient is calculated using the corrected load voltage, The method according to claim 13, comprising calculating a weighted sum of a first exponential coefficient and a second exponential coefficient in order to generate the updated modulation index.

15. The method according to claim 10, wherein generating the output current includes generating a pulse-width modulated signal using the updated modulation index, the pulse-width modulated signal being usable to control the switching elements of the power inverter to generate the output current from the power inverter.

16. The method according to claim 10, wherein steps (a) to (e) are performed iteratively at a predetermined rate.

17. A line interface filter comprising filter components having predetermined component values, A power inverter system comprising: a generator controller bus regulator electrically connected to the line interface filter and configured to receive DC power and generate AC power by iteratively updating the modulation index, wherein the modulation index is characterized by the predetermined component values.

18. The aforementioned generator controller bus regulator The input voltage of the DC power is measured, The output current from the generator controller bus regulator to the line interface filter is measured, The active power and reactive power are determined using the input voltage and output current, The power inverter system according to claim 17, configured to iteratively update the modulation index by determining the modulation index using the determined active power, the determined reactive power, and the load-independent modulation index.

19. The power inverter system according to claim 17, further comprising an isolation transformer electrically connected to the line interface filter.

20. The power inverter system according to claim 19, wherein the isolation transformer is characterized by a turns ratio and number of turns, and the line interface filter and the isolation transformer are configured to receive the AC power generated by the generator controller bus regulator and transmit the corresponding AC output to a load connected to the isolation transformer.

21. It is a system, Vehicle engine and A generator connected to the vehicle engine and capable of operating to generate electric current, A generator controller bus regulator, electrically connected to the generator and capable of operating to rectify current and generate DC input power, A system comprising: a power inverter electrically connected to the generator controller bus regulator, the power inverter capable of receiving the DC input power and generating output AC power by iteratively updating the modulation index.

22. The generator controller bus regulator is a first generator controller bus regulator, and the power inverter comprises a second generator controller bus regulator and a line interface filter, and the second generator controller bus regulator is The input voltage of the DC input power to the second generator controller bus regulator is measured. The output current from the second generator controller bus regulator is measured, Using the input voltage and output current, the active power and reactive power are determined. The system according to claim 21, configured to iteratively update the modulation index using the determined active power and the determined reactive power.

23. The system according to claim 22, wherein the line interface filter includes a filter component having predetermined component values, and determining the active power and the reactive power includes calculating the active power and the reactive power using the input voltage, the output current, and the predetermined component values.

24. The system according to claim 21, further comprising a sensor electrically connected to the output of the power inverter and configured to measure the output voltage from the power inverter to a load electrically connected to the power inverter.

25. The system according to claim 24, wherein the output voltage is three-phase, and the sensor is configured to measure the voltage of each phase of the output voltage.

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