Interleaved Inverter

Abstract

A system and method for an interleaved inverter includes a group of module circuits and an inverter controller. The module circuits include a plurality of switches. The inverter controller is configured to assign a first phase shift value to each module circuit during a normal operating mode and assign a second phase shift value to at least one module circuit during a fault operating mode. The second phase shift value is greater than the first phase shift value.

Description

Technical Field

[0001] The present application relates to the field of power conversion circuits for transferring power from an input source to an output load. Background Art

[0002] Power converters can perform a variety of functions, including converting between different types of electrical power (e.g., direct current (DC), single-phase alternating current (1-phase AC), and three-phase alternating current (3-phase AC)) or different frequencies (e.g., 50 Hz, 60 Hz, or 400 Hz). Power converters can also adjust the level of one or more characteristics of the electrical power (e.g., voltage amplitude or equivalent amplitude, or current amplitude or equivalent amplitude).

[0003] Power converters can be divided into various categories, two of which are switching power supplies and linear power supplies. Switching power supplies can switch the current through various paths at different times throughout the duty cycle. The switching of current can cause ripples in the current. Switching power supplies can selectively apply voltage between two references. Selectively applying voltage between two references can cause ripples or fluctuations in the output voltage. Current ripple and voltage ripple are undesirable. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Exemplary embodiments are described herein with reference to the following drawings.

[0005] Figure 1 An exemplary module of an H-bridge circuit including an inductive element is shown.

[0006] Figure 2 An exemplary module of a bidirectional boost converter including an inductive element is shown.

[0007] Figure 3 An exemplary module of a combined H-bridge circuit and a bidirectional boost converter including an inductive element is shown.

[0008] Figure 4 An exemplary module of an H-bridge circuit including fuses is shown.

[0009] Figure 5 An exemplary module of a bidirectional boost converter including a fuse is shown.

[0010] Figure 6 An exemplary module of a combined H-bridge circuit and a bidirectional boost converter including a fuse is shown.

[0011] Figure 7 Shows that it contains multiple Figures 1 to 6 Circuitry of an exemplary system of modules of any example.

[0012] Figure 8 Shows that it contains multiple Figures 1 to 6 A circuit of a system of another example of a module of any example.

[0013] Fig. 9 Shown is a diagram containing Figure 7 An exemplary system of multiple modules and a central controller of a system.

[0014] Fig.10 Shown is a diagram containing Figure 7 An exemplary system of a driving circuit and a switch array of a system.

[0015] Fig.11 Shows the normal mode Figures 1 to 10 Example graph of ripples in any of the examples.

[0016] Fig.12 An example graph showing ripple in a fault mode.

[0017] Fig.13 Shows from Fig. 9 Example graph of ripple during failure mode recovery.

[0018] Fig.14 An example graph showing the efficiency of an inverter.

[0019] Fig.15 Another example graph showing the efficiency of an interleaved inverter.

[0020] Fig.16 An exemplary controller is shown.

[0021] Fig.17 Shows Fig.16 An exemplary flow chart of the operation of a controller. DETAILED DESCRIPTION

[0022] The following embodiments include bidirectional power converters for converting direct current (DC) to alternating current (AC), which are generally referred to as inverters hereinafter. Specifically, an interleaved inverter includes a switch module that operates in an interleaved manner to transfer power from an input source to an output load. The switch modules are connected in parallel to each other and to at least one common circuit element. Power transmission can be bidirectional. In some examples, the input source includes a direct current (DC) power supply, such as a battery, a solar array, a fuel cell, an AC-DC converter, or other power supplies. The input source can be charged, connected to, or otherwise connected to a utility or generator, such as a collection of engine-generators (generator sets), wind turbines, hydro turbines, or other devices that convert mechanical energy into electrical energy. The generator set may include an alternator connected to an engine, as described in more detail below. The output of the interleaved inverter may be an alternating current (AC) signal.

[0023] The output current of the switching modules varies with time and is added together by the parallel connection of the modules to produce the output signal. The switching modules can be operated at a lower frequency than the output, but still produce a high frequency at the output. The switching frequency can be less than the output frequency by a certain ratio, which is determined by the number of modules. Therefore, four modules can allow the switching frequency to be 1 / 4 of the output frequency. Any number of interleaved modules can be used. For example, 20 100kHz modules can provide an effective output frequency of 2MHz. Such a high frequency output may only require a small capacitor for the output filter, thereby simplifying the circuit (e.g., lower cost, fewer components).

[0024] As a possible result, the components of the switching module have a lower cost. Using lower frequency modules, the components of the switch can be lower rated and reduced in cost. In addition, the components can run at lower temperatures and require less ventilation or other cooling techniques when implemented. Having a lower switching frequency can also improve the efficiency of the power conversion.

[0025] As another possible result, when the same components are used, losses are reduced and the efficiency of the system is improved. That is, if the output power is maintained at the switching frequency, the efficiency is improved because the output is the combined output of each module, and each module switches at 1 / 4 of the usual frequency, reducing switching losses (usually directly related to the switching frequency).

[0026] Another benefit of interleaved inverters involves protection of the underlying circuitry. When the switches have a negative temperature coefficient, as is the case with some insulated gate bipolar transistors (IGBTs), the forward voltage decreases as temperature increases. These switches are thermally stable, and losses decrease as temperature increases. However, problems can arise when two of these types of switches are connected in parallel. One of the parallel switches that heats up has a lower voltage across it, and more current flows through that switch. The greater the current, the higher the temperature of the switch, and the cycle repeats. Eventually, that switch may overheat, while the paralleled switches will carry hardly any current. In an interleaved inverter topology, however, the outputs of the switches are effectively connected in parallel, but the inserted inductors between the modules reduce the effects of temperature changes on the current distribution between the switches.

[0027] As an example, two parallel switches in an H-bridge (400V DC bus) can have different switch temperatures, such that the first switch has a temperature that requires a 1.7V voltage drop to allow 20A to flow through it, while the second switch has a temperature that requires a 2.2V voltage drop to allow 20A to flow through it. If the two switches were directly connected in parallel, the currents through the switches could be: 35A through the first switch, causing a 2.0V voltage drop across the first switch, and 5A through the second switch, causing a 2V voltage drop across the second switch. With this current difference, the power dissipation in the first switch is 70W, and the power dissipation in the second switch is 10W, which causes the first switch to operate at a significantly higher temperature and maintain the current difference through the switches.

[0028] As opposed to an H-bridge with switches connected directly in parallel, an interleaved H-bridge can provide better temperature stability. Using the exemplary switches used above, a first H-bridge consisting of switches will provide 400–1.7V–1.7V=396.6V across the output inductor at the temperature of the first switch, while a second H-bridge with switches will provide 400–2.2V–2.2V=395.6V across the output inductor at the temperature of the second switch. Turning into an ohmic load, the two switches will have very similar currents because they have similar voltages (396.6–395.6=1V / 400V=0.25% difference). The switches in the first H-bridge dissipate 20A×1.7V=34W of power, while the switches in the second H-bridge dissipate 20A×2.2V=44W of power, so the temperatures of the switches will tend to equalize.

[0029] Each interleaved H-bridge can be driven with a matching signal, a phase shifted signal, a discontinuous signal, or another signal to operate the H-bridge. The H-bridge can be controlled by a controller that monitors the current output from the combined interleaved inverter. The H-bridges can be operated to independently control the current. The H-bridges can operate as a combined system to control the output voltage to a target. The H-bridges can be operated independently to control the output voltage to a target. A combination of these control strategies or other control strategies can balance the temperature of the switching elements or match the load between the elements of the interleaved inverter.

[0030] In addition to current sharing issues, interleaved switching may also help reduce switch temperature deviations due to inherent component characteristics and temperature-induced switching speed differences. Switching parallel devices may cause a single switch to turn on before the other switches, or turn off after the other switches, potentially causing device overload, but interleaved switching may not experience this undesirable situation because each switch has only the current available to a single switch due to the presence of the output inductor 103.

[0031] The switch modules can be centrally controlled so that a single device monitors all switch modules and / or provides control signals to the switch modules. When one of the switch modules fails or goes offline (e.g., disconnected from an output load or input source), the central control device can adjust control of the remaining switch modules. For example, the output current or power of other switch modules can be increased to account for the power loss of the disconnected switch module. Alternatively, one or more parameters can be adjusted in the switch modules to account for the transition to fewer switch modules. Thus, the central control device detects or causes the disconnection of one of the switch modules and controls at least one other switch module in response to the disconnection.

[0032] The fuse can be connected in series with one or more switch modules (e.g., circuit elements included in one or more switch modules) and electrically connected to a current source to protect the circuit elements from overcurrent or current exceeding a predetermined threshold, which may be provided by the current source and / or an external source. The fuse may include a conductor (e.g., a metal strip) configured to melt or otherwise physically deform to prevent overcurrent from flowing through the circuit element. When the fuse blows, an open circuit occurs between the circuit element and the current source. The fuse is an example of an electrical isolator or circuit disconnect device between a current source such as a DC bus and at least one switch module. Other examples of circuit disconnect devices include circuit breakers, vacuum fault circuit breakers, relays, semiconductor switches, manual contacts, withdrawable contact systems, connectors, and other disconnect devices.

[0033] In some embodiments, as an alternative to a blown fuse, certain fault conditions may involve a partially functional module. Rather than detecting whether a fuse is blown, a partially functional module may be identified by analyzing the output of the switch module (e.g., current trace). The control circuit may choose to disconnect the module, continue to operate the module in a limited capacity, or perform other backup operations related to the fault.

[0034] Figure 1 An exemplary module circuit 100 of an H-bridge is shown, which includes at least one fuse 101, at least one switch SW1, SW2, SW3, SW4 and at least one inductive element 103. The module circuit 100 can be an inverter that changes direct current (DC) into alternating current (AC). Various other circuit topologies can be used to perform this function. The H-bridge topology includes a predetermined number of switches arranged in an H shape. The switches of the inverter circuit are controlled to produce a specific output, which can be a periodic function of an AC signal with a predetermined frequency (e.g., a triangle wave, a square wave, a sine wave or its approximation). The inverter circuit can drive a load, including a load circuit. The module circuit 100 can be referred to as a modular inverter circuit or a modular H-bridge circuit.

[0035] Specifically, the module circuit 100 may include four switches SW1, SW2, SW3, and SW4 connected to a power rail 102 (DC link or DC bus) and an output (AC output). The voltage of the power rail 102 is connected to a power source (e.g., a source or voltage source). From the perspective of circuit topology, the switches are arranged on a first side (including SW1 and SW3) and a second side (including SW2 and SW4). An inductor 103a is connected between the first side switch pair SW1 and SW3, and an inductor 103b is connected between the second side switch pair SW2 and SW4. By alternating switching between the first side switch pair and the second side switch pair, the DC power supplied to the module circuit 100 is converted into an AC output. The output of the module circuit 100 provides an AC signal through an AC L line terminal and an AC N neutral terminal. Outside the module 100, the AC output may be connected to an output filter, which may include a capacitor 107 connected between the AC L line terminal and the AC N neutral terminal. As discussed in more detail herein, there may be multiple module circuits 100 connected in parallel and connected to the same output filter or capacitor 107. Additionally, more, different, or fewer components may be included.

[0036] Each switch may consist of a single device, such as a field effect transistor (FET) or an insulated gate bipolar transistor (IGBT), or may consist of multiple devices in the same package, such as a combination of a FET and a body diode or a combination of an IGBT and a body diode. A switch may consist of multiple devices connected in series, such as two FETs or two IGBTs. More than two devices may be connected in series, and the series connection may contain steering devices and energy storage or dissipation elements to equalize the voltage across the switch. A switch may consist of multiple devices connected in parallel similar to FETs connected in parallel and IGBTs connected in parallel. A switch may consist of a parallel combination of FETs and IGBTs or a combination of one or more IGBTs and one or more FETs connected in parallel. A switch may consist of a back-to-back combination of FETs or a back-to-back combination of IGBTs. A FET may be a simple FET or a FET combined with a body diode. An IGBT may be a simple IGBT or an IGBT combined with a body diode. Furthermore, the concept of a switch is to interrupt or significantly reduce the current flowing through a path and is not limited to the embodiments detailed herein.

[0037] Figure 2An exemplary module circuit 110 is shown, which includes a bidirectional boost converter, which includes at least one fuse 101, at least one switch SW5, SW6, and at least one inductor 103. The module circuit 110 can be a DC-DC converter that receives an input signal at a first voltage and converts it to an output signal at a second voltage (e.g., the second voltage is greater than the first voltage). In addition, the input signal can be reduced from a first current to a second current (e.g., the second current is less than the first current) at the output signal. The output signal can be connected to a DC link capacitor 109 (e.g., a filter capacitor or a storage capacitor) to limit fluctuations in the DC output of the bidirectional boost converter.

[0038] It may be desirable to reduce the ripple of the current flowing into the DC link capacitor 109 or to reduce the voltage ripple seen across the DC link capacitor 109. This reduction may be achieved by inserting multiple module circuits 110 from a single input source to a common DC link capacitor 109.

[0039] Figure 3 An exemplary module 120 is shown that includes a combined H-bridge circuit and a bidirectional boost converter comprising an inductive element 103. The output of the bidirectional boost converter provides a power rail 102 that is stabilized by a DC link capacitor 105 for the H-bridge circuit. Figure 3 In the combined H-bridge circuit and bidirectional boost converter, one or more fuses 101 are connected to the input of the bidirectional boost converter, and one or more fuses 101 are connected to the output of the H-bridge circuit.

[0040] Figure 3 The internal DC link capacitor 105 in the 1000A helps reduce ripple in the DC signal provided to the H-bridge circuit from the bidirectional boost converter, and can also provide energy storage to allow the H-bridge elements to provide or absorb reactive power. In the following embodiments, the capacitor 105 can be the element that experiences a fault, resulting in the removal or disconnection of the individual modules from the interleaved inverter. With this design, embodiments can be envisioned where the modules do not contain this DC link capacitor 105 or where the DC link capacitor 105 can be replaced independently.

[0041] Figures 4 to 6 Shows Figures 1 to 3 Another embodiment of the circuit, modified Figures 1 to 3 In the embodiment, the inductor 103 is outside the modular circuit. That is, Figures 4 to 6 The modular circuit can be moved independently of the inductor 103 . Figure 4 An exemplary block of an H-bridge circuit is shown. Figure 5 An exemplary module of a bidirectional boost converter is shown. Figure 6An exemplary module of a combined H-bridge circuit and bidirectional boost converter including an internal DC link capacitor 105 is shown.

[0042] Regardless of whether the inductor 103 is Figures 4 to 6 As shown in the external or Figures 1 to 3 Internally, an inductor for each module circuit is coupled to at least one terminal of a common filter element, as shown in Figure 7 as shown in .

[0043] Figure 7 An exemplary system is shown, which includes multiple Figures 1 to 6 The module of any example in the embodiment of the present invention comprises a common capacitor 107 or a common filter element. The common filter element is connected to each module circuit 200 and is configured to reduce the electric ripple output from the module circuit 200. The AC filter capacitor 108 is an example of a common filter element. Alternatively, the common filter element may be a DC link capacitor 109.

[0044] Figure 8 Shows that it contains multiple Figures 1 to 6 An exemplary system of a module of any example in Figure 4 and Figure 5 Modules 1 to 8 (representing Figure 5 The bidirectional boost converter modules 110 are interleaved, fed through inductor 103c, and fed to the DC link capacitor 109 as a common filter element. Figure 4 The combined DC bus input of the H-bridge module 100 is provided from a DC link capacitor 109 which is also connected to the combined output of the bidirectional boost converter 110. The outputs from the H-bridge module 100 are combined through inductors 103a and 103b in an AC output capacitor 108 which serves as a common filter element.

[0045] Fig. 9 An exemplary system including a plurality of modules 200A to 200G, collectively or individually referred to as modules 200, and a central controller 202 is shown. The controller may be a microprocessor, a microcontroller, an application specific integrated circuit. The modules may all be of the same type or of different types. The modules 200 may be, for example, Figure 1 and 4 The H-bridge module 100 shown in FIG. Figure 2 and 5 The boost converter module shown, and / or Figure 3 and 6The combined H-bridge circuit and bidirectional boost converter module 120 shown. The controller 202 is configured to select timing control for the switches of the module. The controller 202 can generate a pulse width modulated signal for the switch. The width of the pulse can correspond to the duty cycle of the switch. The controller 202 can selectively disable or remove the module 200 based on information from the sensor 201. More, different or fewer components may be included.

[0046] Fig.10 Another exemplary system including a drive circuit 310 and a switch array 301 is shown. Different types of switches can be used. All switches in the array 301 can be of the same type or of different types. Exemplary switches include: a mechanical switch 311a, which includes at least one throw for making an electrical connection between a module and an interleaved inverter, an electronic switch 311b, which makes or breaks an electrical connection on a printed circuit board or integrated circuit, or a magnetic switch 311c, which makes or breaks an electrical connection when a magnetic field is applied to the magnetic switch. The magnetic field can be controlled by the drive circuit 310 or the controller 202. In some examples, the switch and the sensor can be combined in a single device (e.g., a thermocouple 311d). The thermocouple 311d can be turned on in one temperature range and turned off in another temperature range, so that when the ambient temperature is within a specified range, the thermocouple only connects the associated module to the interleaved inverter. The thermocouple can be a thermal fuse.

[0047] exist Fig.10 In the example of , control of the switch array 301 is implemented by a drive circuit 310, which may include a sensor or other device for generating data and measuring characteristics (the switch control depends on these characteristics). Exemplary sub-circuits or sensor circuits may include a temperature sensor 302, an electrical sensor 303, a timer 304, and / or a user input 305. The temperature sensor 302 can monitor the environment of the module and provide an output signal indicating the ambient temperature. The electrical sensor 303 may include a circuit for detecting a voltage, a current, or another electrical characteristic of the output of the module 200. The timer 304 may set a predetermined time period or time window to measure using another sensing circuit. The timer 304 may set a time window for replacing the module 200. The user input 305 may include a circuit for receiving a user's input (e.g., a button press, a change of a toggle switch). Even without a controller, the drive circuit 310 provides an example of measuring performance and directly actuating the switch 311 in response to the measured data. The following examples discussed with respect to controller 202 may be implemented using drive circuit 310 and one or a combination of temperature sensor 302 , electrical sensor 303 , timer 304 , and / or user input 305 .

[0048] Generally, the nature of the connection structure of the modules 200A to 200G in combination with the fuse 101, or controller-based activation / deactivation, allows the interleaved inverter to isolate a given module from the DC and AC sides of the circuit to allow it to continue to operate even in the presence of a faulty module. Controller-based activation / deactivation means that the controller 202 can disconnect and / or reconnect individual modules 200 from the interleaved inverter in addition to or in lieu of the fuse 101. Efficiency and THD may change with the absence of a module.

[0049] The module command may instruct the module 200 to enable or disable one of a plurality of operating modes. Example modes of operation include a normal operating mode and a fault operating mode. The fault modes of operation may include a variety of remedial actions that may be performed together or selected from, and include a load shedding mode, a sacrifice operating mode, a peak efficiency operating mode, a module replacement mode, and other modes. In each example, the controller 202 may execute a phase shift sequence in response to the fault mode. These modes may be executed simultaneously. The controller 202 may select and implement a mode in response to user input or sensor data.

[0050] The modules 200, under the control of the controller 202, can generate AC output signals that are combined to form a system output. Since the outputs of the modules 200 are electrically connected in parallel, the individual outputs of the modules 200 can be added together to form a system output. As discussed in more detail herein, the outputs of the modules 200 can include substantially similar sinusoidal signals that are offset in time or exhibit ripple characteristics that are offset in time with substantially similar primary through currents. At any point in the system output of the interleaved inverter, the module outputs are combined at their respective phase shift positions. The controller 303 actively sets these phase shift positions to achieve the desired system output.

[0051] The system may include one or more sensors 201A to 201G, collectively or individually referred to as sensors 201, corresponding to respective ones of the modules 200A to 200G and electrically coupled to the controller 202. The sensors 201 may be various types of sensors that detect faults in the modules 200. The sensors 201 are configured to generate sensor data of electrical parameters of at least one of the modules 200. The controller 292 is configured to receive the sensor data and detect a fault or disconnection of at least one of the modules 200. The disconnection may be intentional (e.g., user initiated) or unintentional (e.g., component failure).

[0052] The fuse sensor can detect the operation of the fuse 101. The fuse sensor can detect whether the fuse 101 is conducting electricity, which indicates whether the fuse 101 is blown. The fuse sensor is a type of electrical sensor. Other types of electrical sensors may include voltage sensors, current sensors, or inductance sensors.

[0053] The sensor 201 may be embodied as a separate device connected to the module 200. Alternatively, the controller 202 may contain circuitry that detects the operation of the module 200 in lieu of the sensor 201. The sensor 201 generates sensor data indicative of the operation of the fuse 101 and / or the module 200. The sensor 201 may reside on the module 200 and communicate signals back to the controller 202 using some type of communication bus.

[0054] The controller 202 (inverter controller) may be configured to generate module commands and send the module commands to the modules 200. The module commands may be addressed to a specific module using a module address (e.g., a network address of a communication network between the controller 202 and the modules 200) or a module identifier in the module command. Alternatively, the module command may be a signal sent directly to the module 200 based on a predetermined communication path (e.g., the controller may have a separate output terminal or output pin or connection corresponding to each module 200).

[0055] The module command may include separate switch commands for the switches of module 200. The switch command may instruct a first pair of switches (SW1, SW4) to provide a positive voltage and current to the output, while another pair of switches (SW2, SW3) provides a negative voltage and current to the output. Pulse width modulation (PWM) may be used to control the circuit so that the module command sends a PWM signal to the switch. The pulse width of the PWM signal may be proportional to the output amplitude of the switch. That is, when the output filter smoothes the PWM signal into a sinusoidal output, the longer pulses of the PWM signal correspond to the larger amplitude of the sinusoidal output. The combined switch signal includes a first pulse width modulation signal for the first side switch pair and a second pulse width modulation signal for the second side switch pair. The module command may include a first pulse width modulation signal for a normal operating mode and a second pulse width modulation signal for a fault operating mode.

[0056] Fig.11 shows that during normal operation the Figures 1 to 10 4. An example graph of ripple current 401 fed into filter capacitor 109 in any example of FIG. In this example, the target output current is approximately 295A. As shown by ripple 400, the output fluctuates between 290A and 300A. Therefore, the ripple baseline in this example is 10A. The current ripple of 10A in this example results in a THD of approximately 0.8%.

[0057] In the normal operating mode, the module command instructs the module 200 to operate normally to produce a sinusoidal output signal. The module 200 may generate an output signal according to a target frequency and / or amplitude. The output signal may include a ripple having a minimum level and / or a maximum level for the normal operating mode. The ripple may be determined based on the number of modules 200 that cooperate to produce the output signal. The normal operating mode may not specify efficiency or total harmonic distortion (THD) limits, but may naturally include these characteristics.

[0058] The module command may instruct the module 200 to activate (on) or deactivate (off) based on the sensor data. For example, in a fault operation mode, the module command may disable the switch of the module or at least one of the pairs of switches in the module by disconnecting the switch in response to the fault as a remedial measure. In response to the detected fault, the controller 202 may disconnect at least one of the modules 200. Alternatively, the module 200 may be automatically disconnected. Thus, the fault mode involves disconnecting the module by user intervention, a circuit disconnecting device, or an instruction of the controller 202.

[0059] In response to the fault mode, the controller 202 executes a phase shift sequence. The controller 202 generates module commands to cause a change in the phase shift of the module 200 or the relative phase shift between modules. In normal mode, with n modules, the phase shift between modules 200 can be 360 / n. For example, Figure 7 and Figure 8 As shown, with 8 or more modules, the phase shift between consecutive modules can be 40°. The controller 202 can assign the phase shift to the modules 200 in the normal operation mode or be performed by the modules 200 in other ways. In one embodiment, the controller 202 sends a signal or message specifying the initial phase shift value to each module 200. When entering the fault operation mode, the controller 202 can determine a new phase shift value for one or more modules 200 after the controller 202 determines that a module should be deactivated or the corresponding fuse has blown. In response to or corresponding to the disconnected module, the second phase shift value is assigned to other modules 200 (e.g., except for the faulty module or the removed module).

[0060] The new phase shift value may be greater than the initial phase shift value. In this failure mode, there are now n-1 modules because one of the modules has been disabled or offline, and the phase shift between modules 200 may be 360 / (n-1). For example, with 7 modules remaining, the phase shift between successive modules may be 51.4°. Table 1 summarizes the failure mode with 8 modules. Figure 7 As more modules 200 fail or become disabled and no longer contribute to the output signal, the phase shift values ​​assigned to the remaining modules increase.

[0061] 8 modules 45° 7 modules 51.4° 6 modules 60° 5 modules 72° 4 modules 90° 3 modules 120° 2 modules 180°

[0062] Table 1

[0063] The general case of calculating the phase shift value is provided in equations 1 and 2. The phase shift value (PSV) can be calculated based on the number of remaining modules (ie, the number of initial modules (I) minus the number of failed modules (F)), using 360 as a reference.

[0064] PSV=360 / (IF) Formula 1

[0065] Formula 2 provides a calculation of a second phase shift value (SPSV) based on a first phase shift value (FPSV) according to a total number (Q) of the plurality of module circuits and a number (F) of failures of the plurality of module circuits:

[0066] SPSV=Q*FPSV / (Q–F) Formula 2

[0067] Fig.11 An example graph of interleaved inverter current output to filter capacitor 108 during module failure is shown. After a switch fails open or experiences other mechanical failures (e.g., loss of connection, disconnected circuit board) or loses connection to the other half of the switch, the failed pair of switches no longer operates for half a cycle, resulting in a continued drop in current at time t1 when switching the module would have increased current. Fig.11 In the example of , the switch has failed open inside the module, preventing that module from applying a positive voltage across the output inductor and increasing the output current of that module to offset the reduced current from the other modules.

[0068] At t2, the corresponding module is disconnected and the phase angle between the other modules is adjusted to account for the disconnected module. In this example, the interleaved inverter has been reduced from 8 to 7 modules, requiring the phase between the interleaving signals to change from 45° to 51.4°. At t3, the output returns to approximately the same average output current level, but with a slight increase in ripple.

[0069] Fig.13 Shown for Fig.11 and Fig.12 The phase between the switching signals has increased to 51.4° and only 7 modules are switching in a given period of time, instead of 100. Fig.11 The 8 modules shown are switched. The ripple observed in the event of a single module failure among the 8 modules increases to about 12A in this example, which will give a final interleaved inverter THD level of about 1%. In most cases, the increased current ripple and corresponding THD are acceptable, especially in fault conditions. If the situation is unacceptable, the interleaved inverter will have to be operated in a THD reduction mode.

[0070] In addition to changing the phase shift values ​​of the remaining modules, other characteristics of the remaining modules may also be changed. For example, the output amplitude of each module may be increased. The increase may be due to the loss of output from the disabled module. Assuming the modules are balanced (i.e., each module operates under the same parameters and outputs the same output), the percentage increase in module output is given by the ratio of the number of failed modules (F) to the number remaining (Q), as shown in Equation 3:

[0071] Δ=F / Q Formula 3

[0072] For example, in normal mode, if Fig. 9 If each of the eight modules in the interleaved inverter outputs 10 kW, then when one of the modules is disabled, leaving seven modules (e.g., in phase shift mode), each of the remaining modules is instructed to increase output by 1 / 7 or 14.3%. The controller 202 generates and sends one or more module commands to increase or provide an output of 11.43 kW. Thus, in normal mode, the modules of the interleaved inverter operate below the maximum load, so that full power can be maintained in the event of a module failure.

[0073] In some examples, the output rating of the module may be selected with the failure mode in mind. That is, in the failure mode, the module operates at a higher power than in the normal mode. Thus, the modules may be selected based on the potential failure mode power level. For example, for a 10kW operation, if two modules are disabled, the modules may be selected to operate at 13.3kW. The modules may be selected to operate in a failure mode with one failed module, in a failure mode with two failed modules, or in a failure mode with another number of failed modules.

[0074] In the module replacement mode, the controller 202 generates module commands to modify the operation of the modules so that one or more modules can be replaced by a user or service personnel. The modules to be replaced can be referred to as replaceable modules. After disconnecting the replaceable modules, the other modules continue to operate and provide output signals of the interleaved inverter.

[0075] The controller 202 can detect that the replaceable module should be removed. The controller 202 can detect a change in the operation of the replaceable module. The change in operation can be a fault or another fault described in other embodiments. The change in operation can be a partial fault. In one embodiment, one or more components can cause the output of the replaceable module to change. The controller 202 can detect a partial fault by analyzing the output of the module. For example, the controller 202 can identify one or more electrical characteristics in the output that indicate that the module should be replaced.

[0076] In another embodiment, for an H-bridge module, a component may fail so that the first pair of switches or the second pair of switches in the H-bridge module does not provide an output. Therefore, the replaceable module only generates the positive portion of the output waveform or the negative portion of the output waveform.

[0077] When operating in the module replacement mode, the controller 202 may disconnect the replaceable module, where applicable, and change the phase shift of other modules 200 (not the replaceable module) as described herein.

[0078] The controller 202 may also provide instructions to the user to remove the replaceable module. For example, when multiple module circuits other than the disconnected module circuit continue to operate, the controller 202 may generate a module circuit replacement message for the fault operation mode. The message may be provided to a display or sent to a computer or mobile device over a network. The module circuit replacement message may include an identifier of the module. The module circuit replacement message may include instructions on how to remove the module and / or install a new module. The module circuit replacement message may include specifications (e.g., electrical specifications) required to order or request a new module.

[0079] After the replaceable module is disconnected, the controller 202 performs a phase shift sequence and / or changes the output of the remaining modules so that the interleaved inverter can continue to operate and provide power to the load even when the replaceable module is inoperable (e.g., during replacement or waiting for a new module to be provided).

[0080] In one embodiment, the replaceable module is a module that requires maintenance. Maintenance examples include updating the firmware in the module, replacing the switching element, the lugs on the wire, thermal imaging or other maintenance measures or hardware changes. The controller 202 can maintain a maintenance schedule for the module 200 in a memory or database. For example, the module 200 can undergo scheduled maintenance at a time interval. The time interval can be a calendar interval (e.g., once a year) or based on operating hours (e.g., business hours). When the scheduled maintenance time for the replaceable module arrives, the controller 202 disconnects the module and performs a phase shift sequence and / or changes the output of the remaining modules, so that even if maintenance is performed, the interleaved inverter can continue to operate and supply power to the load. The schedule can also be set by the drive circuit 310 and the timer 304 and the interval is determined.

[0081] In the module sacrifice mode, the controller 202 generates module commands to modify the operation of the modules so that one or more modules can be sacrificed to protect other modules and keep the other modules operating to provide the output signal of the interleaved inverter. For example, the surge may come from an external event (such as lightning). If an unexpected surge occurs at the output (e.g., through the load), all modules 200 in parallel may be damaged. However, if one of the modules 200 designated as the sacrifice module is designated to receive a majority (e.g., a predetermined portion) of the surge, the fault can be limited to the sacrifice module.

[0082] Consider an example of an overload condition, such as a surge on a load for a short period of time. The surge may last less than one second (e.g., 50 milliseconds, 200 milliseconds, or another value between 10-900 milliseconds). The controller 202 may detect the overload condition by analyzing sensor data for the DC link voltage to detect a short circuit in one of the modules 200. Alternatively, the controller 202 may detect the overload condition from the current through one of the inductors 103 (e.g., an internal inductor or an external inductor). When the inductor current is zero or within a predetermined range of zero, the controller 202 determines that the overload condition is occurring. Additionally or alternatively, the controller 202 may analyze sensor data for the output of the inverter circuit. For example, the controller 202 calculates the amount of ripple in the output signal and monitors the output within a time window. The time window may be from a current time to a past time. When the ripple fluctuates by a predetermined amount or a predetermined percentage (e.g., 20%, 50%) over the time window, the controller 202 identifies that the overload condition is occurring.

[0083] The controller 202 may select a sacrificial module circuit in response to an external overload condition, and operate the sacrificial module circuit in response to the detected external overload condition to reduce the probability of failure in other module circuits except the sacrificial module circuit.

[0084] The controller 202 is configured to sacrifice one of the modules by sending one or more module commands, which instruct the sacrificial module to clamp the output voltage and / or perform a sacrificial setting on the switch element. In order to clamp the output voltage, the switch can be operated in the linear region by partially enabling the gate on the switch. Clamping can also be performed by making the switches follow the order of increasing the current flowing through the filter inductor 103 to prevent the output filter element from reaching an excessively high voltage state. For example: To prevent the DC bus from overvoltage, all switches in the module can be turned on, such as activating SW1, SW2, SW3, and SW4 of the H-bridge module 100. That is, the first pair of switches and the second pair of switches are both turned on at the same time. The short circuit through the sacrificial module is the lowest resistance path for the surge current, otherwise an overvoltage state will be generated on the DC link capacitor 109. As a result, the surge may damage the sacrificial module. However, all other modules receive much less surge current or even no current, thereby protecting the other modules. In the time it takes to burn out fuse 101 or otherwise damage components of the sacrificial module, the sacrificial module will draw enough current from the common capacitor 109 to reduce the voltage and protect the other modules.

[0085] The selection of the sacrificial module can be performed by a variety of techniques. The sacrificial module may be the oldest module. The controller 202 can record the installation date of the module in a database or memory. A clock in the controller 202 can generate a timestamp stored in response to the installation of each module 200. To select the sacrificial module, the controller 202 compares the timestamps and selects the module associated with the earliest timestamp. The selection of the sacrificial module based on time can be performed by the driver circuit 310 and the timer 304.

[0086] The controller 202 may designate a sacrificial module based on user input. For example, a dip switch may be set to designate a module as a sacrificial module. As another example, a user may select a sacrificial module using a user interface for the controller 202. The controller 202 may detect the presence of a setting and designate a module as a sacrificial module in response to detecting the setting. The user input may be received and interpreted by a subcircuit for a user input 305 circuit in the driver circuit 310.

[0087] The controller 202 may designate a sacrificial module based on the different hardware included in the sacrificial module. For example, the sacrificial module may include one or more protection elements (e.g., transient voltage suppressors). The controller may detect the presence of the protection element and designate the module as a sacrificial module in response to detecting the protection element.

[0088] Fig.14The efficiency curves for the exemplary module 200 are shown. The module efficiency at light loads is low because the switching losses within the module account for a large portion of the system power. The efficiency at high loads is lower because the conduction losses through the various components in the inverter increase non-linearly with increasing output current. The exemplary module 200 has a peak efficiency at 50% of rated load and has an efficiency of >98% for loads between 25% and 100% of rated capacity.

[0089] When the controller 202 operates in peak efficiency mode, the controller 202 generates module commands to modify the operation of the modules so that the optimal number of modules operate to maximize the efficiency of the interleaved inverter. In other words, under partial load conditions, the controller 202 can intentionally disable one or more modules to reduce the switching losses associated with those modules. The controller 202 can then adjust one or more other operating parameters in response to the change in the module to keep the interleaved inverter at or near peak efficiency in a manner that minimizes the impact on THD. For example, the controller 202 can adjust the phase between the drive signals for the interleaved modules as described in the previous embodiments. The controller 202 can be configured to calculate the efficiency for each combination of switching modules under a given load.

[0090] The switching modules in the interleaved inverter may have different size ratings or different loss characteristic curves. The controller 202 may select appropriate modules to minimize the losses and wear of each module under given load conditions. The controller 202 may operate different modules in turn to verify continued correct operation and balance wear between modules. After designating a single module as a sacrifice module, the controller 202 may intentionally maximize its operating time. The controller 202 may also have constraints on the minimum number of modules to operate for reasons such as redundancy (fault handling) and THD (due to increased ripple with fewer modules operating).

[0091] In an exemplary system with 8 interleaved inverters, each module may have peak efficiency at 50% of rated load. If the system is operating at 30% of the total rated load, the inverter efficiency will be less than optimal when all 8 modules are switching. Reducing the number of switching modules from 8 to 5 will increase the total load per module to 48%, which is very close to the peak efficiency operating point of the module. This change in the number of modules will reduce wear on some modules while reducing losses in the inverter, but may increase current ripple and / or THD on the inverter output.

[0092] Fig.15The overall efficiency curve of the interleaved inverter is shown, where the THD and current ripple produced by single module switching are acceptable. The efficiency curve illustrates the efficiency of the interleaved inverter by the optimal number of module switching at each load.

[0093] In another system embodiment, the controller 202 may have a minimum target efficiency that is determined by a user setting, a measured parameter (e.g., temperature), or a measured input with a predetermined behavior. In this case, the controller may selectively disable one or more modules by either disabling the control signal to them or disconnecting them using the associated switch 311. If the efficiency target is higher than the efficiency that can be achieved at full load, the controller 202 may reduce the output power by reducing the downstream load or by adjusting the output current target.

[0094] In yet another exemplary system, the system has 8 interleaved modules, each of which can operate at 33% overload, allowing up to 2 faulty modules when operating at full load. Due to the failure of one or more modules, the peak efficiency operating mode of the controller 202 may require the interleaved inverter output power to be reduced, even if the remaining modules can support the load when operating under overload conditions. The efficiency of the modules operating under overload conditions may be lower than the minimum efficiency, which may result in reduced output power after a module failure. Similar judgment criteria can also be used for THD or current ripple. In order to reduce the load, the controller 202 can send a load command to the load 300 based on the reduced total peak efficiency output to reduce the load. If connected to a large power grid (such as a utility), the controller can simply reduce the output power by reducing the current output target of the inverter.

[0095] In one embodiment, the load command is a load shedding command that removes a portion of the load to achieve a reduced output, either due to a module failure or due to a reduction in output rating caused by operating in a peak efficiency mode. This example can be considered a load shedding mode, where the controller 202 generates module commands to modify the operation of the modules so that one or more modules are disconnected, and generates load shedding instructions in response to the disconnected modules to reduce one or more load components connected to the interleaved inverter. A circuit breaker that receives a circuit breaker actuation command from the controller 202 or the drive circuit 310 can be used to remove or add load components of the load 300.

[0096] In addition, the controller 202 can disconnect and / or reconnect modules in response to the load 300. For example, the controller 202 can determine the power level of the load 300 and calculate the number of modules required to power the load 300. In one embodiment, the controller 202 can calculate the number of modules required to supply the load 300 at peak efficiency while operating at a peak efficiency output level. The controller 202 reduces switching losses by removing modules from operation under light load conditions and restoring them to operation under heavier load conditions. In another embodiment, the controller 202 can maintain the minimum number of modules required to power the load while disconnecting or disabling unnecessary modules to reduce wear on unnecessary modules.

[0097] In the THD reduction mode, the controller 202 generates module commands to modify the operation of the modules so that one or more modules can operate while generating minimal THD or current ripple. The controller 202 is configured to calculate a first estimated total harmonic distortion value in a normal operating mode and a second estimated total harmonic distortion value in a case where the number of modules is reduced due to module failure, maximum efficiency mode, user intervention, or other reasons.

[0098] The controller 202 may generate a module command to increase the switching frequency in order to reduce THD. The controller 202 may generate a load shedding command to add or remove a load in order to reduce THD. In addition, the controller 202 may generate a message to the user as a notification of the THD level. The message may prompt the user for authorization to continue operating at the increased THD level, otherwise, minimize THD until the user authorizes an increase in THD in the output.

[0099] The current ripple amplitude generally decreases as the number of connected modules increases and / or increases as the number of disconnected modules increases. In particular, for a module with a current ripple level (I module ), Equation 4 provides the relationship between the number of modules (n) and the total current ripple level (I ripple ). The THD generated by an interleaved inverter generally increases with increasing ripple and decreases with decreasing ripple.

[0100] i ripple =i module / n formula 4

[0101] In any of these examples, the controller 202 is configured to return the module 200 to normal operation. That is, once the module is replaced, as indicated by the sensor data, the data indicates that the module is replaced into the inverter circuit. The sensor data can be generated from a mechanical detector for physical hardware. The sensor data can be generated by any of the examples described herein. After returning to the normal operating mode, the controller 202 can adjust the module command to return to the original phase shift value, to adjust the switching frequency of at least one of the multiple switches, to adjust the load release command to connect or disconnect the load from the multiple modules, or to adjust the output level of at least one module. In one embodiment, any action taken by the controller 202 or the drive circuit 310 in response to entering the fault mode can be reversed when leaving the fault mode and returning to the normal mode.

[0102] The controller 202 can operate a control system for the inverter. The control system can run at a fixed frequency, or can run once per cycle of each switching module, or can run as each switching module runs (the frequency is the product of the base module frequency and the number of connected modules). The control system can also measure the current in each output inductor individually, thereby controlling each switching module to prevent damage to the module and balance the load between the switching modules. Alternatively, the control system can rely on the similarity between the switching elements in the interleaved inverter to control the total body current output by the interleaved modules without measuring the output of each module individually. This technique may be more ideal for components with positive temperature coefficients for losses (such as FETs), which naturally play a role in balancing the load between modules.

[0103] Fig.14 and Fig.15 The comparison of can illustrate the comparison of the baseline efficiency (e.g., the output power of the power conversion circuit (not the interleaved inverter)) and the efficiency of the interleaved inverter. Fig.14 In the example of , a fully effective level or maximum efficiency (e.g., 98% in this example) can be obtained over an output power range P1 that spans only a small output power range (e.g., 30% to 75% of the rated output). Fig.15 In the interleaved inverter, the fully efficient level or maximum efficiency can be obtained over a larger output power range P2 (eg, 5% to 95% of the rated output).

[0104] Fig.16 Shown for Figure 8 and Fig. 9The controller 202 of the system. The controller 202 may include a processor 210, a memory 211, an input device 204, and a communication interface 203. The communication interface 203 may communicate with one or more sensors (e.g., sensor 201) and one or more switches or modules 200. More, different, or fewer components may be included. Fig.17 Shows Fig.16 This is an exemplary flow chart of the operation of a controller of the invention. More, different, or fewer actions may be included.

[0105] In action S101, processor 210 accesses a first phase shift value for a normal operating mode from memory 211. Memory 211 may include a lookup table of different phase shift values ​​associated with different operating modes. Processor 210 may include a circuit, module, or dedicated controller as a means for accessing the first phase shift value for the normal operating mode from memory. Memory 211 is an exemplary means for storing phase shift values ​​associated with operating modes.

[0106] In action S103, the processor 210 generates a first switching command for each of the plurality of module circuits based on the first phase shift value. The switching command may include one or more pulse width modulation commands that use the first phase shift value to drive the operation of the switch in the inverter. The switching command may include an amplitude value for the output of the module. The switching command may include a frequency of the module output. The processor 210 may include a circuit, a module, or a dedicated controller as a means for generating a first switching command for each of the plurality of module circuits based on the first phase shift value.

[0107] In action S105, processor 210 receives sensor data indicating that one of the plurality of module circuits has failed. Processor 210 may include a circuit, module, or dedicated controller as a means for receiving sensor data indicating that one of the plurality of module circuits has failed. Sensor 201 is an exemplary means for detecting sensor data indicating a failure in the plurality of module circuits.

[0108] In action S107, in response to a fault in the fault operating mode, the processor 210 accesses a second phase shift value from the memory. The second phase shift value may be accessed from a lookup table in the memory 211 described in action S101. The processor 210 may include a circuit, a module, or a dedicated controller as a means for accessing the second phase shift value from the memory in response to a fault in the fault operating mode.

[0109] In action S109, processor 210 generates a second switching command for each of the plurality of module circuits based on the second phase shift value. The switching command may include a second phase shift value for a new phase difference between the modules. The switching command may include an amplitude value for the output of the module. The switching command may include a frequency of the module output.

[0110] The processor 210 may include a circuit, a module, or a dedicated controller as a means for generating a second switching command based on the second phase shift value of each of the plurality of module circuits.

[0111] The processor 210 may include a general purpose processor, a digital signal processor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), an analog circuit, a digital circuit, a combination thereof, or other processors now known or later developed that can process instructions, solve logic or calculate values. The processor 210 may be a single device or a combination of devices, such as associated with a network, distributed processing, or cloud computing.

[0112] The memory 211 may be a volatile memory or a non-volatile memory. The memory 211 may include one or more of a read-only memory (ROM), a random access memory (RAM), a flash memory, an electronically erasable program read-only memory (EEPROM), or other types of memory. The memory 211 may be removable from the network device, such as a secure digital (SD) memory card.

[0113] In addition to the inlet and outlet, the communication interface 203 may include any operable connection. An operable connection may be a connection in which signals, physical communications, and / or logical communications may be sent and / or received. An operable connection may include a physical interface, an electrical interface, and / or a data interface.

[0114] The communication interface 203 can be connected to a network. The network can include a wired network (e.g., Ethernet), a wireless network, or a combination thereof. The wireless network can be a cellular telephone network, an 802.11, 802.16, 802.20, or WiMax network. In addition, the network can be a public network (e.g., the Internet), a private network (e.g., an Intranet), or a combination thereof, and can utilize various network protocols that are currently available or developed later, including but not limited to network protocols based on TCP / IP.

[0115] The input device 204 may include buttons, switches, keyboards, touch screens, or other structures configured to allow a user to input data, such as the number of modules included in the interleaved inverter, the preferred output level of the modules (e.g., peak efficiency output level), the installation date of the modules, the model of the modules, the designation of sacrificial modules, the maintenance date or schedule of the modules, the THD threshold or another threshold module for identifying a fault. The input device 204 may receive data about when a fault mode is entered. The input device 204 may receive real-time instructions from the user in response to instructions entered at the input device 204 to enable or disable any specific instructions or to cause the controller 202 to enter a specific mode. The input device 204 may include a connection to a network, a smart phone, a tablet, a personal computer, configured to electronically send a trigger instruction to the control system. The communication may be wireless or wired (e.g., received by the communication interface 203).

[0116] The battery input source can also be charged by a bidirectional boost converter using power from a utility that is connected to the output of the interleaved inverter and is able to absorb or source power. The battery can be selectively charged or discharged based on the commands used. The battery charge rate can be adjusted throughout the 24-hour period to minimize charging costs by reducing the charging current when electricity costs are highest. The battery can also be charged by other input sources such as generator sets, fuel cells, or other input sources.

[0117] The fuel cell input source may be part of a larger fuel cell system that includes a fuel cell, an engine that burns the fuel cell exhaust, and an alternator driven by the engine. The combination of the engine and the alternator may be referred to as a genset. An interleaved inverter may receive power from multiple sources, such as both a fuel cell and a genset. The inverter may draw power from a utility source that is connected to the output to start the rotation of the genset using the alternator as a motor.

[0118] The generator set may include an alternator coupled to an engine. The controller 202 may be combined with a controller for the alternator or the engine. The controller 202 may be an engine control unit (ECU) 100a (or engine control module). The controller may be a generator controller. The controller may be an alternator controller. The controller 202 may be a remote controller. The remote controller may communicate with the generator set via a network.

[0119] The engine can be any type of engine in which the combustion of an oxidant (e.g., air) and fuel in a chamber applies a force to a drive component (e.g., a piston, turbine, or other component) of the engine. The drive component rotates or otherwise moves to perform work. The drive component can rotate a crankshaft. The fuel tank stores fuel, which can be provided to the engine from a fuel tank or a fuel line. In one embodiment, the fuel is delivered to a carburetor or mixer. The carburetor or mixer can provide fuel to the cylinders of the engine. In another embodiment, the fuel is delivered by a directional injection system or a fuel injection system.

[0120] The ECU is also configured to provide instructions for subsystems of the engine. The ECU receives data from various sensors and provides instructions to other components of the engine. For example, the ECU may receive sensor data from an oxygen sensor, an air-fuel ratio sensor, a throttle position sensor, and / or an air mass flow sensor. The ECU may calculate fuel injection commands sent to one or more fuel injectors in response to any aspect or combination of aspects of the sensor data. The ECU may receive sensor data from a crankshaft position sensor and calculate idle speed timing in response to the sensor data. The ECU may send instructions for engine timing to the injectors to control fuel injection, to generate sparks through spark plugs for combustion in the cylinders of the engine, or to the valves of the engine to control the start and end times of a combustion sub-cycle.

[0121] In addition to dynamically controlling the load, the generator controller can also generate instructions at the generator level. Generator level instructions can include messages exchanged with other generators. For example, a generator message can coordinate the order of closing the bus. The generator message can contain a command sent from the generator set 10 to another generator set. For example, the generator controller can perform a parallel function with one or more other generator sets. For example, when the load is above a threshold, the generator controller can generate a parallel signal to bring other generators online. The instruction can cause the generator set or another generator to close the bus or start operation. The parallel signal can contain time values ​​to synchronize multiple generators, including setting the order of closing the bus between parallel generators.

[0122] In power generation, synchronization is the process of matching the amplitude and frequency (in the case of a single-phase generator) or the amplitude, frequency and phase sequence (in the case of multiphase) of two or more generators that are connected in a network, such as to the grid of a vehicle, ship, building or utility. Unless the generators run at substantially the same output and at substantially the same speed, they cannot supply power to the grid. More specifically, the two or more generators have substantially the same line voltage, frequency, phase sequence and phase angle before they are connected.

[0123] In one embodiment, the interleaved inverter can be synchronized with the utility before connecting to the utility. In another embodiment, after the utility is connected to the output, the interleaved inverter can adjust the internal current and voltage targets to match the utility's targets and synchronize after shutdown instead of before shutdown.

[0124] By comparison, the following process can be used to connect two generators to the bus. First, the first generator is connected to the bus. Next, the other generator is accelerated. The speed can be the known synchronous speed of the first generator or based on measurements from the grid. After exciting the second generator, the output is tested. The output of the second generator is measured and the phase is adjusted to match the phase of the grid or the first generator. When the match is sufficient, the second generator is connected to the bus. Alternatively, to transfer output between generators, the generators can exchange messages containing zero crossing messages, synchronization messages, and shutdown timing messages. The messages can be relayed through a variety of technologies, including analog signals, digital signals, and data packets switched on the network or transmitted directly between the generators.

[0125] In addition to dynamically controlling the load, the alternator controller can also generate instructions internal to the alternator. For example, the alternator controller can control the electrical parameters of the output of the alternator. In one representation, the alternator includes a rotor and a stator. The rotor has an excitation winding, which can be a series-wound coil on a magnetically permeable core. The rotor can rotate freely around a concentric axis within the stator. The stator consists of armature windings; these are sinusoidally distributed coils placed inside a stack of annular laminations. The laminations contain slots for placing the armature windings. The gap between the freely rotating rotor and the stationary stator is represented as an air gap. The function of a synchronous alternator is to convert mechanical power from a drive mechanism into electrical energy. The drive mechanism is represented as a prime mover (e.g., an internal combustion engine) and provides torque to the rotor. Electrical energy is drawn from terminals crimped to the ends of the armature windings. In order to convert mechanical energy into electrical energy, there is a magnetic coupling between the rotor and the stator.

[0126] The alternator controller may receive sensor data from one or more sensors and, in response, generate one or more alternator commands. The sensor data may be a measurement of an electrical parameter of the field armature or field coil. The electrical parameter may include current, voltage, or resistance. The electrical parameter may be the flux induced on the field coil assembly by the current in the armature winding. In this way, the sensor data may indicate the output of the generator. In addition, since the load on the generator affects the current in the armature winding, the sensor data may indicate the load on the generator. The sensor data may be temperature data, which may indicate the resistance of the field coil or armature winding.

[0127] The alternator controller may analyze one or more components of the sensor data at the controller. For example, the alternator controller may compare a value in the sensor data to a threshold value. The alternator controller may classify, average, or filter the sensor data. The alternator controller may remove outliers from the sensor data. The alternator controller may calculate a moving average of the sensor data. The alternator controller may use the sensor data to query a lookup table. The alternator controller generates an alternator command at the alternator controller based on the sensor data. The generator command may be an adjustment to the current in the field winding of the rotor, which directly affects the output of the generator. For example, the alternator controller may compare an estimated output voltage or current of the generator to a threshold value. When the output drops below a low threshold value, the alternator controller will increase the current of the field winding. When the output exceeds a high threshold value, the alternator controller will reduce the current of the field winding. The alternator command may adjust the speed of an engine driving the rotor of the generator. For example, the alternator controller may compare an estimated output frequency of the generator to a threshold value. When the output frequency drops below a low threshold value, the alternator controller will increase the speed of the engine. When the output frequency exceeds a high threshold value, the alternator controller will reduce the speed of the engine. The alternator controller can also identify anomalies from the sensor data and generate commands to shut down the generator set or issue a warning to the user.

[0128] The communication may occur over a dedicated communication line extending between the generator controllers (e.g., a serial cable, a USB cable). The communication may occur over a wired computer network (e.g., Ethernet). The communication may be modulated for transmission over a bus. In this example, the generator set and the bus bypassing the circuit breaker may provide another communication path. The communication may occur wirelessly, such as a cellular network, a family of protocols known as Wi-Fi or IEEE 802.11, a family of protocols known as Bluetooth, or other protocols. Example wireless networks may include wireless mesh networks (e.g., a Bluetooth mesh network). The wireless mesh network may include many-to-many communications.

[0129] Although the computer-readable medium (e.g., memory 211) is shown as a single medium, the term "computer-readable medium" includes a single medium or multiple media (e.g., a centralized or distributed database) and / or associated caches and servers storing one or more sets of instructions. The term "computer-readable medium" should also include any medium that can store, encode, or carry a set of instructions for execution by a processor or cause a computer system to perform any one or more of the methods or operations disclosed herein.

[0130] In a specific non-limiting exemplary embodiment, the computer-readable medium may include a solid-state memory, such as a memory card or other package storing one or more non-volatile read-only memories. In addition, the computer-readable medium may be a random access memory or other volatile rewritable memory. In addition, the computer-readable medium may include magneto-optical or optical media or other storage devices such as disks or tapes to capture carrier signals such as signals transmitted through a transmission medium. A digital file attachment to an email or other independent information archive or archive set may be considered a tangible storage medium. Therefore, the present disclosure is considered to include any one or more of a computer-readable medium or distribution medium and other equivalents and successor media, in which data or instructions may be stored. The computer-readable medium may be non-temporary, which includes all tangible computer-readable media.

[0131] In alternative embodiments, dedicated hardware implementations, such as application specific integrated circuits, programmable logic arrays, and other hardware devices, may be constructed to implement one or more of the methods described herein. Applications that may include the devices and systems of various embodiments may broadly include various electronic and computer systems. One or more embodiments described herein may implement functionality using two or more specific interconnected hardware modules or devices with associated control and data signals that may communicate between and through the modules, or as part of an application specific integrated circuit. Thus, the present system includes software, firmware, and hardware implementations.

[0132] According to various embodiments of the present disclosure, the methods described herein may be implemented by a software program executable by a computer system. In addition, in an exemplary, non-limiting embodiment, the implementation may include distributed processing, component / object distributed processing, and parallel processing. Alternatively, a virtual computer system process may be constructed to implement one or more methods or functions described herein.

[0133] For example, processors suitable for executing computer programs include general-purpose microprocessors and special-purpose microprocessors, and any one or more processors in any kind of digital computer. In general, the processor can receive instructions and data from a read-only memory or a random access memory or both. The basic elements of a computer are a processor for executing instructions and one or more storage devices for storing instructions and data. In general, a computer may also include or be operatively coupled to receive data from or transfer data to or from one or more mass storage devices, such as magnetic disks or optical disks. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and storage devices, including, for example, semiconductor storage devices, such as EPROM, EEPROM and flash memory devices; magnetic disks, such as internal hard disks or removable disks; magnetic disks; and CD ROM and DVD-ROM disks. The processor and memory may be supplemented by or incorporated into special-purpose logic circuits.

[0134] The illustrations of the embodiments described herein are intended to provide a general understanding of the structures of the various embodiments. These descriptions are not intended to be used as a complete description of all elements and features of the devices and systems utilizing the structures or methods described herein. After reviewing the present disclosure, many other embodiments may be apparent to those skilled in the art. Other embodiments may be utilized and derived from the present disclosure, so that structural and logical replacements and changes may be made without departing from the scope of the present disclosure. In addition, these illustrations are representative only and may not be drawn to scale. Certain proportions in the accompanying drawings may be enlarged, while other proportions may be minimized. Therefore, the present disclosure and the accompanying drawings should be considered illustrative rather than restrictive.

[0135] Although this specification contains many details, these details should not be interpreted as limitations on the scope of the invention or the scope of what may be claimed, but rather should be understood as descriptions of features specific to particular embodiments of the invention. Certain features described in this specification in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. In addition, although features may be described above as functioning in certain combinations, or even initially stated as such, in some cases one or more features from a claimed combination may be cut out of the combination, and a claimed combination may be directed to a sub-combination or a variation of a sub-combination.

[0136] One or more embodiments disclosed herein may be referred to individually and / or as a whole by the term "invention", only for convenience, and without any intention to limit the scope of the present application to any particular invention or inventive concept. In addition, although specific embodiments have been illustrated and described herein, it should be understood that any subsequent arrangement designed to achieve the same or similar purpose may replace the specific embodiments shown. This disclosure is intended to cover any and all subsequent modifications or variations of the various embodiments. Combinations of the above embodiments and other embodiments not specifically described herein will be apparent to those skilled in the art by reading the specification.

[0137] It is intended that the foregoing detailed description be regarded as illustrative rather than restrictive, and it should be understood that the following claims, including all equivalents, are intended to define the scope of the invention. The claims should not be understood to be limited to the described order or elements unless otherwise stated. Therefore, all embodiments that fall within the scope and spirit of the appended claims and their equivalents are claimed to protect the present invention.

Claims

1. An interleaved inverter, comprising: A plurality of module circuits including a plurality of switches; as well as an inverter controller configured to assign a first phase shift value to each of the plurality of module circuits during a normal operating mode and to assign a second phase shift value to at least one of the plurality of module circuits during an alternate operating mode, wherein the second phase shift value is greater than the first phase shift value, The second phase shift value is calculated based on the first phase shift value, the total number of the plurality of module circuits and the number of failures of the plurality of module circuits. The inverter controller is configured to calculate a first peak efficiency power rating for the normal operating mode and a second peak efficiency power rating for the alternate operating mode.

2. The interleaved inverter according to claim 1, further comprising: An electrical isolator is coupled between a direct current (DC) bus and at least one module circuit among the plurality of module circuits, wherein the electrical isolator is configured to disconnect the at least one module circuit among the plurality of module circuits.

3. The interleaved inverter according to claim 1, further comprising: A common filter element is coupled to each of the plurality of module circuits and is configured to reduce an electrical ripple output from the module circuit.

4. The interleaved inverter according to claim 3, wherein: The common filter element includes a common capacitor electrically coupled to each module circuit of the plurality of module circuits.

5. The interleaved inverter according to claim 4, wherein: The common filter element is a DC link capacitor for a DC bus, or an alternating current (AC) output capacitor.

6. The interleaved inverter according to claim 3, further comprising: A modular filter element for each of the plurality of modular circuits, the modular filter element being coupled to a first terminal of the common filter element.

7. The interleaved inverter according to claim 1, wherein: The controller is configured to select a timing control for the plurality of switches in response to the first phase shift value.

8. The interleaved inverter according to claim 1, further comprising: A sensor is configured to generate sensor data for an electrical parameter of at least one module circuit among the plurality of module circuits, wherein the controller is configured to receive the sensor data and detect a fault or disconnection of at least one module circuit among the plurality of module circuits.

9. The interleaved inverter according to claim 8, wherein: The controller disconnects the at least one module circuit among the plurality of module circuits in response to the detected fault.

10. The interleaved inverter according to claim 8, wherein: The second phase shift value is allocated to other module circuits of the plurality of module circuits corresponding to the disconnected module circuit.

11. The interleaved inverter according to claim 1, wherein: The controller selects a sacrificial module circuit in response to an external overload condition, and operates the sacrificial module circuit in response to the detected external overload condition to reduce a probability of failure of module circuits other than the sacrificial module circuit among the plurality of module circuits.

12. The interleaved inverter according to claim 1, wherein: The controller provides a module circuit replacement message for the alternative operation mode when module circuits other than the disconnected module circuit among the plurality of module circuits continue to operate.

13. The interleaved inverter according to claim 1, wherein: The inverter controller is configured to detect a replacement module circuit and, in response to the detected replacement module circuit, redistribute the first phase shift value to a modified plurality of module circuits including the replacement module circuit according to the normal operating mode.

14. The interleaved inverter according to claim 1, wherein: The inverter controller is configured to calculate a first estimated total harmonic distortion value for the normal operating mode and a second estimated total harmonic distortion value for the alternate operating mode.

15. The interleaved inverter according to claim 1, wherein: The inverter controller is configured to generate a module command to adjust a switching frequency of at least one of the plurality of switches, generate a load release command to connect or disconnect a load connected to the plurality of module circuits, or generate an output level for at least one of the plurality of module circuits in response to the alternative operating mode.

16. The interleaved inverter according to claim 1, wherein: The inverter controller is configured to generate a first pulse width modulated signal for the normal operating mode and a second pulse width modulated signal for the alternate operating mode.

17. An interleaved inverter, comprising: A plurality of module circuits including a plurality of switches; as well as an inverter controller configured to assign a first phase shift value to each of the plurality of module circuits during a normal operating mode and to assign a second phase shift value to at least one of the plurality of module circuits during an alternate operating mode, wherein the second phase shift value is greater than the first phase shift value, The second phase shift value is calculated based on the first phase shift value, the total number of the plurality of module circuits and the number of failures of the plurality of module circuits. The inverter controller is configured to calculate a first estimated total harmonic distortion value for the normal operation mode and a second estimated total harmonic distortion value for the alternative operation mode.

18. An interleaved inverter, comprising: A plurality of module circuits including a plurality of switches; as well as an inverter controller configured to assign a first phase shift value to each of the plurality of module circuits during a normal operating mode and to assign a second phase shift value to at least one of the plurality of module circuits during an alternate operating mode, wherein the second phase shift value is greater than the first phase shift value, The second phase shift value is calculated based on the first phase shift value, the total number of the plurality of module circuits and the number of failures of the plurality of module circuits. The inverter controller is configured to generate a module command to adjust a switching frequency of at least one of the multiple switches, generate a load release command to connect or disconnect a load connected to the multiple module circuits, or generate an output level for at least one of the multiple module circuits in response to the alternative operating mode.

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