DC-DC boost converter for hysteresis control of flying vehicle
阅读说明：本技术 用于飞行载具的滞环控制的dc-dc升压转换器 (DC-DC boost converter for hysteresis control of flying vehicle ) 是由 J.W.特劳伯 于 2018-04-24 设计创作，主要内容包括：一种功率转换单元可包括用于向电气负载(诸如,飞行载具上的一个或多个推进马达)提供高电压直流功率的两个或更多个功率模块。所述功率模块中的每一个可通过滞环控制,并且可包括一对或多对晶体管,所述一对或多对晶体管由门驱动器基于在参考电流与穿过升压电感器的感测电流之间的差值进行切换。所述功率模块的数量、大小和形状可被选择以适应所述电气负载,并且可根据需要导通或关断。所述功率转换单元可具有比满足所有预期的电气负载所需的功率模块至少多一个的功率模块,从而确保即使在所述功率模块中的一个发生任何类型的故障的情况下,所述功率转换单元也可继续提供功率。(A power conversion unit may include two or more power modules for providing high voltage direct current power to electrical loads, such as one or more propulsion motors on a flight vehicle. Each of the power modules may be controlled by a hysteresis loop and may include one or more pairs of transistors that are switched by a gate driver based on a difference between a reference current and a sense current through a boost inductor. The number, size and shape of the power modules may be selected to accommodate the electrical load and may be switched on or off as desired. The power conversion unit may have at least one more power module than is required to meet all anticipated electrical loads, ensuring that the power conversion unit continues to provide power even in the event of any type of fault in one of the power modules.)
1. A flying vehicle, comprising:
a frame;
a DC battery mounted to the chassis;
a plurality of propulsion motors mounted to the frame, wherein each of the propulsion motors is configured to rotate a propeller about an axis defined by a shaft;
a power conversion unit configured to receive electrical power from the battery and provide electrical power to each of the propulsion motors, wherein the power conversion unit comprises:
a housing mounted to the chassis;
a plurality of power modules releasably mounted within the housing, wherein each of the power modules is configured to provide electrical power up to a predetermined voltage level and a predetermined current level, and wherein each of the power modules comprises:
a boost inductor;
a current sensor aligned to sense a current flowing through the boost inductor and generate a voltage signal corresponding to the current flowing through the boost inductor;
a pair of MOSFETs, wherein the pair of MOSFETs includes: a first MOSFET aligned in series between the boost inductor and at least one of the propulsion motors, and a second MOSFET aligned in series between the boost inductor and ground;
a gate driver, wherein the gate driver is configured to supply a gate voltage to turn on or off each of the pair of MOSFETs;
an output capacitor connected in parallel with at least one of the propulsion motors;
an error amplifier, wherein a first input of the error amplifier is a reference voltage and a second input of the error amplifier is a voltage across the output capacitor, and wherein an output of the error amplifier is a voltage signal corresponding to a reference current; and
a hysteretic controller for controlling operation of the gate driver, wherein a first input of the hysteretic controller is the voltage signal corresponding to the reference current and a second input of the hysteretic controller is the voltage signal corresponding to the current flowing through the boost inductor sensed by the current sensor, and wherein an output of the hysteretic controller is a voltage signal to the gate driver for turning on one of the pair of MOSFETs and for turning off one of the pair of MOSFETs; and
a supervisory controller within the enclosure, wherein the supervisory controller is in communication with each of the power modules, and wherein the supervisory controller is configured to determine a predetermined number of the power modules required to provide electrical power in response to demand.
2. The flying vehicle of claim 1, wherein each of the power modules further comprises: a first isolation switch upstream of the boost inductor and a second isolation switch downstream of the first MOSFET, and
wherein each of the first and second isolation switches is in communication with the supervisory controller.
3. A power conversion unit, comprising:
a housing;
a controller mounted within the housing;
a DC power supply;
a first power module releasably mounted within the housing, wherein the first power module comprises:
a first boost inductor;
a first current sensor configured to sense a current flowing through the first boost inductor;
a first pair of transistors;
a first gate driver configured to operate each of the first pair of transistors;
a first output capacitor;
a first error amplifier, wherein a first input to the first error amplifier is a first reference voltage associated with a first load on the first power module, wherein a second input to the first error amplifier is a first output voltage of the first power module, and wherein an output from the first error amplifier is a voltage signal representing a first reference current determined based at least in part on a difference between the first reference voltage and the first output voltage of the first power module;
a first hysteretic controller, wherein a first input to the first hysteretic controller is the voltage signal representative of the first reference current, wherein a second input to the first hysteretic controller is a voltage signal representative of the current through the first boost inductor, and wherein an output from the first hysteretic controller is a first control signal for operating the first gate driver based at least in part on a difference between the first reference current and the current through the first boost inductor,
wherein a first one of the first pair of transistors is aligned in series between the first boost inductor and the load on the first power module, and wherein a second one of the first pair of transistors is aligned in series between the first boost inductor and ground;
a second power module releasably mounted within the housing, wherein the second power module comprises:
a second boost inductor;
a second current sensor configured to sense a current flowing through the second boost inductor;
a second pair of transistors;
a second gate driver configured to operate each of the second pair of transistors;
a second output capacitor;
a second error amplifier, wherein a first input to the second error amplifier is a second reference voltage associated with a second load on the second power module, wherein a second input to the second error amplifier is a second output voltage of the second power module, and wherein an output from the second error amplifier is a second reference current determined based at least in part on a difference between the second reference voltage and the second output voltage of the second power module; and
a second hysteretic controller, wherein a first input to the second hysteretic controller is the voltage signal representing the second reference current, wherein a second input to the second hysteretic controller is a voltage signal representing the current through the second boost inductor, and wherein an output from the second hysteretic controller is a second control signal for operating the second gate driver based at least in part on a difference between the second reference current and the current through the second boost inductor;
wherein a first of the second pair of transistors is aligned in series between the second boost inductor and the load on the second power module, and wherein a second of the second pair of transistors is aligned in series between the second boost inductor and ground.
4. The power conversion unit of claim 3, wherein the first control signal is configured to: when the current flowing through the first boost inductor is equal to a zero voltage switching current, turning off the first one of the first pair of transistors and turning on the second one of the first pair of transistors, and
wherein the first control signal is configured to: turning on the first one of the first pair of transistors and turning off the second one of the first pair of transistors when the current flowing through the first boost inductor is equal to the first reference current.
5. The power conversion unit of claim 3 or 4, wherein the first hysteretic controller is configured to select a switching frequency of the first one of the first pair of transistors and the second one of the first pair of transistors based at least in part on the difference between the first reference current and the current flowing through the first boost inductor, and
wherein the first control signal is transmitted according to the switching frequency.
6. The power conversion unit of claim 3, 4 or 5, wherein the first hysteretic controller comprises:
a first comparator configured to receive the first input of the first hysteretic controller and the second input to the first hysteretic controller;
a second comparator configured to receive the second input of the first hysteretic controller and a voltage signal corresponding to a negative zero voltage switching current;
a third comparator configured to receive the first input of the first hysteretic controller and the second input to the first hysteretic controller;
a fourth comparator configured to receive the second input of the first hysteretic controller and a voltage signal corresponding to a positive zero voltage switching current; and
a latch configured to generate the first control signal based at least in part on at least one of an output of the first comparator, an output of the second comparator, an output of the third comparator, and an output of the fourth comparator,
wherein if the output of the first comparator indicates that the current through the first boost inductor is less than the first reference current, and if the output of the second comparator indicates that the current through the first boost inductor is less than the negative zero voltage switching current, the first control signal instructs the first gate driver to turn off the first one of the pair of transistors and turn on the second one of the pair of transistors, and
wherein if the output of the third comparator indicates that the current through the first boost inductor is greater than the reference current, and if the output of the fourth comparator indicates that the current through the first boost inductor is greater than the positive zero voltage switching current, the first control signal instructs the first gate driver to turn on the first one of the pair of transistors and turn off the second one of the pair of transistors.
7. The power conversion unit of claim 3, 4, 5 or 6, wherein the first power module comprises: a first isolation switch, a second isolation switch, and a first power stage connected in series between the first isolation switch and the second isolation switch,
wherein the first power stage comprises: the first boost inductor, the first current sensor, the first pair of transistors, the first gate driver, the first output capacitor, the first error amplifier, and the first hysteretic controller,
wherein the first isolation switch is a first high side switch in communication with the controller, and
wherein the second isolation switch is a second high side switch in communication with the controller.
8. The power conversion unit of claim 3, 4, 5, 6, or 7, wherein the first one of the first pair of transistors is a first MOSFET configured to be energized by a gate voltage from the first gate driver, and
wherein the second one of the first pair of transistors is a second MOSFET configured to be energized by the gate voltage from the first gate driver.
9. The power conversion unit of claim 3, 4, 5, 6, 7, or 8, wherein the power conversion unit is configured to generate up to a maximum output voltage based on a nominal voltage of the DC power supply,
wherein the nominal voltage of the DC power supply is in a range of about forty-eight volts to about sixty volts, and
wherein the maximum output voltage of the power conversion unit is approximately one hundred fifty volts.
10. The power-conversion unit of claim 3, 4, 5, 6, 7, 8, or 9, wherein the power-conversion unit is configured for installation within a flying vehicle having a plurality of propulsion motors.
11. A power conversion unit in accordance with claim 3, 4, 5, 6, 7, 8, 9, or 10, wherein said first power module has a first size of about two inches and a second size of about six inches.
12. The power conversion unit of claim 3, 4, 5, 6, 7, 8, 9, 10, or 11, wherein the power conversion unit includes a first predetermined number of power modules,
wherein the first predetermined number is at least four,
wherein the first predetermined number of power modules comprises: the first power module and the second power module,
wherein the power conversion unit is provided in association with at least one predetermined electrical load,
wherein the predetermined electrical load requires a second predetermined number of power modules to operate, and
wherein the first predetermined number is at least one more than the second predetermined number.
13. The power conversion unit of claim 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, wherein the first power module further comprises at least one of a first over-current comparator at the second input of the first hysteretic controller or a second over-current comparator at the second one of the pair of transistors, and
wherein the first gate driver is configured to turn off each of the first transistor and the second transistor in response to an over-current signal from one of the first over-current comparator or the second over-current comparator.
14. A power module, comprising:
a boost inductor;
a current sensor aligned to sense current flowing through the boost inductor;
a pair of MOSFETs, wherein the pair of MOSFETs includes: a first MOSFET aligned in series between the boost inductor and at least one load, and a second MOSFET aligned in series between the boost inductor and ground;
a gate driver, wherein the gate driver is configured to turn on or off each of the MOSFETs;
an output capacitor connected in parallel with the at least one load;
a first high-side switch upstream of the boost inductor;
a second high side switch between the output capacitor and the at least one load;
an error amplifier, wherein a first input of the error amplifier is a reference voltage and a second input of the error amplifier is a voltage across the output capacitor, and wherein an output of the error amplifier is a voltage signal corresponding to a reference current; and
a hysteretic controller for controlling operation of the gate driver, wherein a first input of the hysteretic controller is the voltage signal corresponding to the reference current of the output of the error amplifier and a second input of the hysteretic controller is the voltage signal corresponding to the current flowing through the boost inductor sensed by the current sensor, and wherein an output of the hysteretic controller is a control signal to the gate driver for turning off or on at least one of the pair of MOSFETs.
15. The power module of claim 14 wherein the power module is configured to perform a method comprising:
receiving electrical power from a direct current power source at the first high-side switch;
sensing, by the current sensor, a current flowing through the boost inductor;
comparing, by the error amplifier, the voltage level across the output capacitor to the reference voltage;
providing, by the error amplifier, the voltage signal corresponding to the reference current to the hysteretic controller, wherein the voltage signal is proportional to a difference between the voltage level across the output capacitor and the reference voltage;
determining, by the hysteretic controller, that the reference current exceeds the current flowing through the boost inductor;
providing a control signal to the gate driver through the hysteretic controller; and is
Switching the first MOSFET and the second MOSFET by the gate driver in response to the control signal.
Background
Unmanned aerial vehicles (or "UAVs") are used more and more frequently today in an increasing number of applications, including but not limited to surveillance, law enforcement, military, security, crop management, inspection, or delivery operations. Modern unmanned aerial vehicles are typically integrated systems that include numerous propellers, motors, communication equipment, imaging devices, power sources, and various other components or machines, and in some embodiments, may be configured to retrieve, transport, or store payloads of various sizes. Unmanned aerial vehicles are characterized by their relatively small size and high maneuverability compared to other powered vehicles (e.g., manned vehicles), which can typically perform tasks at lower cost and with a lower level of risk to humans.
Unmanned aerial vehicles include circuitry for powering various propulsion motors, control surfaces, control systems, payload engagement systems, and other electrical loads disposed thereon. Typically, unmanned aerial vehicles include a power source, such as a Direct Current (DC) battery, that provides power to an onboard electrical load through paired positive and negative leads. Such power sources are typically configured to provide power at or near a nominal voltage level, and may be recharged, for example, by removing the power source from the unmanned aerial vehicle and connecting the power source to a charging lead, or by recharging the power source in situ inside the unmanned aerial vehicle.
The output voltage of a battery is a function of its state of charge. As the battery discharges, the output voltage of the battery also decreases over time. In the case where a battery is provided as a power source for one or more propulsion motors of the unmanned aerial vehicle, a reduction in the output voltage of the battery necessarily reduces the amount of thrust that the unmanned aerial vehicle can generate. Furthermore, many electrical loads on unmanned aerial vehicles (such as propulsion motors) are subject to a surge in starting current or other factors, which may cause voltage levels on unmanned aerial vehicles to fluctuate to an undesirable degree.
Drawings
Fig. 1A and 1B are views of aspects of an aircraft having a power conversion unit, according to embodiments of the present disclosure.
Fig. 2 is a block diagram of a power conversion unit according to an embodiment of the present disclosure.
Fig. 3 is a schematic diagram of one power stage that may be disposed in a power conversion unit according to an embodiment of the present disclosure.
Fig. 4A and 4B are flow diagrams of one process for operating a power conversion unit according to an embodiment of the present disclosure.
Fig. 5 is a graph of current flowing through a power conversion unit according to an embodiment of the present disclosure.
Fig. 6A is a schematic diagram of a hysteretic controller that may be disposed in a power stage of a power conversion unit in accordance with embodiments of the present disclosure.
Fig. 6B and 6C are graphs of current flowing through the hysteretic controller of fig. 6A according to an embodiment of the present disclosure.
Fig. 7 is a diagram of aspects of a flight vehicle having a power conversion unit, according to an embodiment of the present disclosure.
Fig. 8 is a graph of transient output power according to one embodiment of the present disclosure.
Fig. 9 is a graph of efficiency versus power according to one embodiment of the present disclosure.
Fig. 10 is a graph of load transient response according to one embodiment of the present disclosure.
FIG. 11 is a graph of input voltage transient response according to one embodiment of the present disclosure.
Fig. 12 is a graph of output voltage during a module fault according to the present disclosure.
Fig. 13 is a block diagram of a system according to an embodiment of the present disclosure.
Detailed Description
As set forth in more detail below, the present disclosure relates to systems and methods for boosting a Direct Current (DC) voltage level. More particularly, the present disclosure relates to power conversion units configured to boost a Direct Current (DC) voltage level in response to changes in demand. In some embodiments, the power conversion unit may be releasably mounted within a flight vehicle or other system where an increased DC voltage level is desired. The power conversion unit may include any number of power modules of any shape or size that may be releasably mounted within a housing or other similar structure of the power conversion unit and may be activated or deactivated in response to changes in demand. Thus, the power conversion unit provides a lightweight fault tolerant system for providing power at desired voltage and current levels to power loads on unmanned aerial vehicles ("UAVs") or drones. In addition, the power modules may operate using analog components rather than digital or software driven components, thereby reducing the risk that such modules may be subject to one or more software related failures and/or hacking attacks. In some embodiments, the power module may be releasably mounted within the power conversion unit.
Referring to fig. 1A and 1B, views of aspects of a
In some embodiments, the
In some embodiments, the motors 120-1, 120-2, 120-3, 120-4 may be any type or form of motor or other prime mover for causing one or more propellers to rotate at a selected speed or angular velocity. For example, one or more of the motors 120-1, 120-2, 120-3, 120-4 may be a brushless DC motor, such as an external or internal rotor brushless motor. Alternatively, one or more of the motors 120-1, 120-2, 120-3, 120-4 may be shunt motors, separately excited motors, permanent magnet motors, reluctance motors, hysteresis motors, induction motors, or synchronous motors.
The
As shown in fig. 1B, the
As further shown in FIG. 1B, the power modules 135-1, 135-2, 135-3, 135-4 are releasably inserted within a housing or other structure of the
Each of the power modules 135-1, 135-2, 135-3, 135-4 includes: one or more components for receiving electrical power at one voltage level and/or current level and releasing electrical power at one or more other voltage levels and/or current levels; and one or more isolation switches (e.g., high-side switches) and/or voltage regulators. For example, each of power modules 135-1, 135-2, 135-3, 135-4 may include circuitry having one or more inductors, transistors, capacitors, amplifiers, gates, resistors, and/or other components that may be needed to provide power to motors 120-1, 120-2, 120-3, 120-4 and other electrical loads on
In some embodiments, operation of the respective power modules 135-1, 135-2, 135-3, 135-4 may be triggered by one or more computer processors operating in a supervisory role, and one or more of the respective power modules 135-1, 135-2, 135-3, 135-4 may be selected in response to a sensed or expected change in electrical load or demand. For example, such a processor may initiate operation of one or more of the modules simultaneously with or subsequent to operation of one or more of the motors 120-1, 120-2, 120-3, 120-4 (e.g., when an increase in current to such motors is sensed, or before one or more of the motors 120-1, 120-2, 120-3, 120-4 are expected to be started). Likewise, such a processor may stop operating one or more of the power modules 135-1, 135-2, 135-3, 135-4 when such power modules 135-1, 135-2, 135-3, 135-4 are not needed to meet existing electrical loads.
The
In some embodiments, one or more of the power modules 135-1, 135-2, 135-3, 135-4 may have a first dimension (e.g., width, depth, or diameter) of about two inches and a second dimension (e.g., height) of about six inches. Alternatively, the power conversion unit and/or the power module of the present disclosure may have any other shape and/or cross-section. The dimensions of the
In addition, although the
Thus, in accordance with the present disclosure, an unmanned aerial vehicle or other powered system may be equipped with a power conversion unit having two or more independently controlled and operated power modules for providing electrical power to a load (such as a propulsion motor) at desired voltage and current levels in response to demand. Furthermore, the power conversion unit of the present disclosure enables the power source (e.g., battery) and the electrical load (e.g., propulsion motor) to be decoupled from each other and optimized independently with respect to each other. Each of the power modules may operate independently within the circuit or be isolated from the circuit, for example by one or more isolation switches, which may be normally closed but may open in the event of a fault (e.g., overcurrent). Further, the power module may also include a power stage formed from hardware components, such as inductors, transistors (e.g., metal oxide semiconductor field effect transistors or MOSFETs), amplifiers (e.g., operational amplifiers), capacitors, and/or resistors, among other components, to reduce one or more risks of failure associated with the software components. For example, a single software failure may not simultaneously adversely affect each of the power modules, as the power modules are configured to operate individually without the use of software.
Each of the power modules may operate subject to hysteresis control. For example, the output voltage provided by one or more power modules to a propulsion motor or other electrical load may be boosted or boosted relative to their input voltage by alternately increasing and decreasing the current flowing through the boost inductor, which causes the magnetic field strength to increase and decrease. The increasing and decreasing current flowing through the boost inductor is controlled by the alternating operation of the switches downstream of the boost inductor. The switch may be a MOSFET or any other form of transistor or other switching equipment that is operable based on the gate voltage supplied by the hysteresis controlled gate driver. For example, the error amplifier may determine a difference between a reference voltage corresponding to a desired voltage to be generated by the power stage (e.g., based on a load required by the power stage) and an output voltage actually generated by the power stage. The error amplifier may then generate a voltage signal based on the difference corresponding to the reference current used to generate the desired voltage. The hysteretic controller may receive a voltage signal corresponding to a reference current and compare the voltage signal to a voltage signal proportional to the current flowing through the boost inductor. If the current flowing through the boost inductor is less than the reference current, the hysteretic controller will cause the gate driver to operate the switch less frequently, increasing the current flowing through the boost inductor, thus causing the generation of a magnetic field of increased strength until the output voltage generated by the power stage is equal to the reference voltage. If the current flowing through the boost inductor is greater than the reference current, the hysteretic controller will cause the gate driver to operate the switch more frequently, thereby reducing the current flowing through the boost inductor and reducing the generated magnetic field strength until the output voltage generated by the power stage is equal to the reference voltage. The hysteretic controller may take the form of one or more amplifiers, comparators, or any other components configured to determine the difference between the reference current and the current flowing through the boost inductor, thus controlling the operation of the switch at the selected frequency based on such difference.
The power module may be configured for zero voltage switching, or "ZVS". For example, the power module may be configured to operate the switch when the current flowing through the boost inductor reaches a desired current level (e.g., defined by a reference current provided to the hysteretic controller by the error amplifier), and to operate the switch again when the current flowing through the boost inductor reaches a negative value (e.g., the amount of current flowing through the boost inductor in the reverse direction), i.e., zero voltage switching current. The magnitude of the zero voltage switching current may be adjusted to create resonance between a boost inductor and one or more capacitors in the circuit such that the voltage across the switch when the switch is on is zero, thereby eliminating most of the power loss due to switching and improving the efficiency of the power module.
The power module may be further configured for bi-directional operation. For example, in some implementations, power provided at a first voltage level at an output connection of a power module may be stepped down to a second voltage level, and power provided at an input connection of the power module by the same components that may step up an input voltage to an output voltage, as described in connection with one or more embodiments disclosed herein. In some embodiments, the hysteretic controller may include one or more components (e.g., a comparator, amplifier, or other) for comparing the current flowing through the boost inductor to different values of the reference current, such as a positive value of the reference current and a negative value of the reference current, in order to support this bidirectional operation.
In addition, in some embodiments, the hysteretic controller of the power stage may include one or more components for comparing the value of the current flowing through the boost inductor to both a reference current corresponding to a desired voltage to be generated by the power stage and a zero-voltage switching current level, thereby ensuring that the current through the boost inductor is always sufficient to operate the switch under zero-voltage switching conditions.
The power module may also be configured to stop operation in the event of an overcurrent condition or any other adverse event, for example, by stopping the switching of one or more pairs of transistors and/or opening one or more of the isolation switches, as desired.
Referring to fig. 2, a block diagram of one
As shown in fig. 2, the
The
Where the
The
The power stages 240A, 240B, 240C, 240D may include any components (e.g., inductors, transistors, capacitors, amplifiers, gates, resistors, and/or other components) for receiving electrical power at a predetermined voltage level and providing electrical power at another voltage level (e.g., a higher voltage level) to one or more electrical loads. For example, the power stages 240A, 240B, 240C, 240D may include: one or more inductors and capacitors, and one or more pairs of transistors for controlling the flow of current to one or more electrical loads.
In some embodiments, the power stages 240A, 240B, 240C, 240D may include only analog components. In some other embodiments, the power stages 240A, 240B, 240C, 240D may include both analog and digital components, or only digital components.
The isolation switches 242A, 242B, 242C, 242D may be configured to provide power to one or more loads when the isolation switches 242A, 242B, 242C, 242D are closed, or to manually or automatically isolate the
As discussed above, the power module of the present disclosure may have a power stage configured to automatically raise a voltage level and/or a current level in order to provide electrical power in response to a demand. Referring to fig. 3, a schematic diagram of one
The
As shown in fig. 3, the
With
The switching of the
Therefore, when the output voltage is less than the reference voltageV REFTime, reference currentI REFWill be less than the current through boost inductor 350I L. Based on reference currentI REFWith the current through boost inductor 350I LThe difference between, the
When the output voltage is greater than the reference voltageV REFTime, reference currentI REFWill be greater than the current through boost inductor 350I L. Based on reference currentI REFWith the current through boost inductor 350I LThe difference between, the
As shown in fig. 3,
Referring to fig. 4A and 4B, a
At
At
At
At
After determining that none of the operating power modules are malfunctioning at
If no change in the high voltage power demand from the power converter is identified, the process returns to block 435 where the power modules continue to self-regulate their respective voltage levels through their respective gate drivers with hysteresis control while experiencing the load applied at
If a change in demand for high voltage power from the power control unit is identified at
If the number of power modules being operated is sufficient to meet the existing demand for high voltage power, the process proceeds to block 470 where a determination is made as to whether it is still desirable to provide high voltage power from the power conversion unit. If high voltage power is still desired from the power conversion unit, the process returns to block 435 where the power modules continue to self-regulate their respective voltage levels through their respective gate drivers with hysteresis control while experiencing the load applied at
Referring to fig. 5, a graph of current flowing through one power conversion unit of the present disclosure is shown. FIG. 5 is a graph illustrating current through a boost inductor (e.g.,
Since the boost inductor is energized by the power source, e.g. at timet 0At least one of the transistors in the pair of transistors is connected to a boost inductor, and a current flowing across the boost inductor and through one of the pair of transistors to one or more loads is increased until at least one of the pair of transistors is connected to the boost inductort 1At a current equal to the reference currentI REFUntil now. At the sensingCurrent flowing through boost inductorI LEqual to the reference currentI REFWhen the hysteretic controller (such as
When the current is at both ends of the boost inductorI LWhen dropping, power is provided to the load through a downstream capacitor (such as
When in timet 5When the electrical load is observed to increase, the error amplifier causes the reference current to increaseI REFIncreasing based on an increase in load. Thus, the current across the boost inductorI LIs allowed to increase until the current is at timet 6To reach a new reference currentI REFBy this time, the hysteretic controller will cause the transistor to switch again, resulting in a current across the boost inductorI LAnd then again descends. At the time oft 7When boosting the current across the inductorI LHas reached zero voltage switching currentI ZVSThe transistor will switch again and allow the current across the boost inductorI LAnd again increased.
Nominal peak pulse current before load increaseI PP-NOMIs defined as being at a reference currentI REFWith zero voltage switching currentI ZVSThe difference between them. Therefore, for the timet 5Reference current previously flowing at the level shown in fig. 5I REFTime of peakt 1Andt 3difference between, or at minimum current timet 2Andt 4the difference between them is defined as the switching frequency of the gate driver with respect to the load levelF NOMOr 1-F NOM. After the load increases, the transistor is at a lower frequencyF MINSwitching so as to be at a minimum current timet 7Andt 4the difference between them is greater than the minimum current timet 2Andt 4the difference between them. Since the losses on the boost inductor are proportional to the change in direction of the current (i.e., the switching frequency), the reduced switching frequency results in a more efficient delivery of electrical power. The increase in load also results in a maximum peak pulse currentI PP-MAXSaidI PP-MAXIs defined as being at the new reference currentI REFWith zero voltage switching currentI ZVSThe difference between them.
Although the graph of current of fig. 5 illustrates the effect of an increase in electrical load on the power module of the present disclosure, one of ordinary skill in the relevant art will recognize that an effect of a decrease in electrical load on the power module will result in a current that is relative to a lower reference currentI REFSimilar graph of (a).
Although the
As shown in fig. 6A, the
Referring to fig. 6B and 6C, graphs of current flowing through the hysteretic controller of fig. 6A are shown, according to an embodiment of the present disclosure. As shown in FIG. 6B, a graph of current flowing through the boost inductor is shown when the power stage is configured for reference current, e.g., at greater than zeroI REFTo boost the voltage. The hysteresis controller can be in timet 0Operating transistors of a power stage to cause current flowI LFlows through the boost inductor, forming a magnetic field in which energy is stored. Electric currentI LSwitching current from negative zero voltage-I ZVSIncrease until in timet 1To reach the reference currentI REFTo a value of (c), the skew loop controller operates the transistor to cause current flowing through the boost inductorI LAnd is reduced, thereby releasing energy from the magnetic field. Electric currentI LEventually dropping below zero, i.e. reverse polarity, until the current flowI LAt the time oft 2Switching current at the negative zero voltageI ZVSUntil now. The hysteretic controller then operates the transistor to cause current to flow through the boost inductorI LIncrease to regenerate the magnetic field in which energy is stored until current flowI LAt the time oft 3To reach the reference currentI REFTo (3) is added. The hysteretic controller then operates the transistor again to cause current flowI LDecrease until current flowI LAt the time oft 4Switching current at the negative zero voltageI ZVSUntil now, and the hysteretic controller again operates the transistor to cause current flowI LBegins to increase.
As shown in FIG. 6C, a graph of the current flowing through the boost inductor is shown, when the power stage is configured for reference current less than zero, for exampleI REFTo reduce the voltage. The hysteresis controller can be in timet 0Operating transistors of a power stage to cause current flowI LFlows through the boost inductor, forming a magnetic field in which energy is stored. Electric currentI LFrom a reference currentI REFIncrease until in timet 1The voltage reaches zero and the current is switchedI ZVSTo a value of (c), the skew loop controller operates the transistor to cause current flowing through the boost inductorI LAnd is reduced, thereby releasing energy from the magnetic field. Electric currentI LFinally drops below zero again, i.e. reverse polarity, until the current flowsI LAt the time oft 2To reach the reference currentI REFUntil now. The hysteretic controller then operates the transistor to cause current to flow through the boost inductorI LIncrease to regenerate the magnetic field in which energy is stored until current flowI LAt the time oft 3The voltage reaches zero and the current is switchedI ZVSTo (3) is added. The hysteretic controller then operates the transistor again to cause current flowI LDecrease until current flowI LAt the time oft 4To reach the reference currentI REFUntil now, and the hysteretic controller again operates the transistor to cause current flowI LBegins to increase.
As described in fig. 6A-6C, the hysteretic controller of the present disclosure may maintain zero voltage switching regardless of the direction of the desired current therethrough, i.e., by causing the transistor to switch based on a reference current selected according to the intended mode of operation. In addition, since the hysteretic controller acts on the sensed current information, zero voltage switching can be maintained regardless of input voltage, output voltage, or circuit parameters (such as inductance and capacitance). This capability is different from typical zero voltage switching controllers that maintain ZVS only within a relatively limited operating range. Further, the hysteretic controller of the present disclosure may have any configuration and is not limited to the configuration shown in fig. 3 or 6A.
The power conversion unit of the present disclosure may also be configured to charge a power source (e.g., a battery), such as when the propulsion motor is powered off and slowed down from operating speed. For example, in a similar manner to regenerative braking, the rotating propeller of the propulsion motor may be used as a generator to convert rotational energy into electrical energy and thereby charge the battery. Alternatively, the resistance provided by such a unit may thereby accelerate the deceleration of the propulsion motor and propeller when the power conversion unit is not operating under power.
Referring to fig. 7, a diagram illustrating aspects of a
As shown in fig. 7, the flying
Some requirements of DC-DC boost converters are high power density, fault tolerance and seamless bi-directional power flow. These requirements may be taken into account when selecting a topology for the DC-DC boost converter.
High power density
By combining small magnetic elements with high efficiency, high power densities can be achieved. Magnetic elements are by far the most important components in power converters, as they consist of a metal core material and copper windings. In addition, compressing a large amount of power into a small space means that the converter must have high efficiency-otherwise the heat generated will overwhelm the heat blocking capability. This is particularly true for air-cooled power converters, which require large, heavy heat sinks to reject heat. A block diagram of one method of achieving high power density is shown in fig. 13.
Reducing the size of magnetic components
The magnetic element can be made smaller in three ways. First, the number of magnetic components in the topology. Second, a topology may be selected that handles less power through the magnetic components. Third, the energy stored in the magnetic component can be reduced by reducing the inductance.
The number of magnetic components. Some power converter topologies have more magnetic components than other topologies. For example, single-ended primary inductor converters (or SEPICs) and Ć uk converters have two inductors, while buck-boost converters have only one inductor. Some topologies require a transformer as well as an inductor. Generally, the number of magnetic components in the topology can be reduced by coupling inductors or by using the leakage inductance or magnetizing inductance of a transformer as an energy storage element.
Less power is handled by the magnetic component. To determine what power is being handled by the magnetic component, the following questions are answered: from the front to the backWhether or not all electrons flowing out of the output of the converter have at a certain point passed one or more of the magnetic components of the converter
The energy stored in the magnetic component is reduced by reducing the inductance. The size of the magnetic components determines how much energy can be stored in them. If less energy can be stored, the magnetic component can be smaller for processing the same power.
Increase efficiency
Efficiency is improved by reducing converter losses. Most of the power in the converter is lost in the transistors and magnetic elements.
In a transistor, the sources of loss are switching loss and conduction loss. Conduction losses can be reduced by using MOSFETs with low on-resistance or IGBTs with low forward voltage drop. Switching losses can be reduced by lowering the switching frequency, reducing junction capacitance, or using soft switching techniques. Unfortunately, none of these strategies are free-to-charge-they all trade off converter complexity, magnetic element size, and/or device cost.
In magnetic elements, the sources of loss are core loss and copper loss. Core losses are caused by magnetization and demagnetization of the magnetic core and are exacerbated by high switching frequencies and high magnetic flux ripples in the core. Core losses can be reduced by using low loss core materials or by reducing flux ripple by reducing current ripple or by eliminating the flux in the legs (in the case of coupled inductors). Copper losses can be divided into DC losses and AC losses. The DC loss, which is a function of the DC resistance of the winding, can only be reduced by adding additional copper (and thus weight). AC losses are a function of switching frequency and conductor size, and in some embodiments AC losses can be reduced by using Litz (Litz) wires, which is expensive but effective.
Fault tolerant
Preferably, the DC-DC boost converter will be single fault tolerant, such that failure of any one component will not destroy the entire vehicle propulsion system. Fault tolerance can be achieved by full redundancy, although this may result in carrying a large extra weight that is almost never used. One strategy may be a fault that allows for a reduction in the peak power output of the converter while maintaining sufficient power output to safely transition, hover, and land.
The DC-DC boost converter may require any amount or proportion of the available peak power in order to safely transition, hover, and/or land. In some embodiments, a DC-DC boost converter may be sufficient with half the peak power output. For example, if the peak output of the DC-DC boost converter is twelve kilowatts (12 kW), the power output at single fault operation would be six kilowatts (6 kW). Preferably, the output voltage of the converter will remain the same, meaning that the output current of a single fault will be half the peak current.
There are at least two ways to achieve half the peak current operation. For example, a converter may be constructed from two modules arranged in parallel, allowing one module to fail. Additionally or alternatively, the converter may be constructed by using naturally redundant topologies (such as full-bridge operable as half-bridge) such as Levy Costa, Giampaolo butichi and Marco Liserre in: a factory-Tolerant Series-resistant DC-DC Converter, IEEEtransactions on Power Electronics, Vol.32, No. 2 (2 months 2017), the entire contents of which are incorporated herein by reference.
The two module approach is simpler and allows any component in one module to fail without affecting the other module. However, in some implementations, there may be a loss in power density because no components are shared between modules. One trade-off may be to share the most reliable components between modules, e.g. passive components such as inductors and capacitors (especially if one module fails such components are still operable), and to separate the most vulnerable components (i.e. transistors) between modules.
Seamless bidirectional power flow
To support regenerative braking, bi-directional power flow is critical. The term "seamless" bi-directional power flow means that there is no separate control mode for reverse power flow. In contrast, reverse power flow is only a continuous extension of nominal converter operation. For example, a duty cycle of greater than fifty percent (>50%) may result in forward power flow, while a duty cycle of less than fifty percent (<50%) may result in reverse power flow. Alternatively, a positive phase shift may result in a forward power flow, while a negative phase shift may result in a reverse power flow. Typically, bidirectional converters do not have diodes, but rely on synchronous rectification that can be switched on (e.g., using metal oxide semiconductor field effect transistors or MOSFETs instead of diodes) to reduce conduction losses, but also allow reverse power flow. Most converter topologies can be converted to a bi-directional topology by replacing the diodes with synchronous rectifiers, and possibly with minor modifications to the control scheme.
Summary of the invention
Based on the above discussion, a preferred converter topology may utilize one or more of the following strategies: soft-switching and/or high bandgap transistors; a coupled magnetic element; a low core loss magnetic material; the use of low AC current ripple or litz or similar lines of magnetic elements; modular design with shared passive components; or for synchronous rectification of bi-directional power flow.
Selecting a topology
Some topologies of converters may include the following. First, a voltage-fed dual active bridge is used for high boost and galvanic isolated transformer turns-ratio and zero voltage switching (or ZVS) at full load. This topology can reduce the switching frequency at high loads, allowing a slight change in output voltage at low loads, and also have a burst mode at low loads. Second, a current-fed dual active bridge with a transformer and a boost inductor to boost in two ways. This topology may have different modulation schemes and sub-options. Third, cascaded synchronous boosting can have fewer switches, with natural zero voltage switching (or ZVS) and operate in an efficient mode and in a bi-directional manner, and natural redundancy if the phases are staggered. Inductors may be coupled to increase power density. In addition, at light loads, the switching frequency may increase and some modules may stop running.
Cascaded synchronous boost with coupled inductors
One topology of a DC-DC boost converter is cascaded synchronous boost with coupled inductors, as shown below. One proposed converter with this topology comprises four modules, for example, two low voltage modules and two high voltage modules. The low voltage modules are placed in series with the high voltage modules so that each group of modules only needs to boost the voltage by half of the total amount. For example, the low voltage module may be boosted from the battery voltage to 100V, while the high voltage module may be boosted from 100V to 200V. By keeping the duty cycle close to fifty percent (50%), this cascading strategy is expected to improve the efficiency of each group of modules, which will help keep the converter in a zero voltage switching state and allow each group of modules to tune to its own voltage range (e.g., low voltage modules may use 200V MOSFETs at higher currents, while high voltage modules may use 400V MOSFETs at lower currents).
In some implementations, a boost inductor for a low voltage module may be coupled between the two modules, which may reduce the size and loss of the inductor. A similar strategy may be employed by the high voltage module. The inductors may be designed such that they can operate in a coupled state and an uncoupled state. In some embodiments, the coupled state will be used during nominal operation, while the uncoupled state will be used when one of the low or high voltage modules fails. In addition, in some embodiments, fuses may be used to ensure that a failure of any one module causes the inductor winding of that module to open and not affect the operation of any other module. In some implementations, transient performance of the inductor during a fault may be modeled to ensure that the output voltage remains compliant with specifications during the fault.
The converter may operate under Quasi-square wave (QSW) resonance transitions, as described by v. vorerion in Quasi-square-wave converters, topologies and analysis,
In some implementations, with two low voltage modules and two high voltage modules placed in parallel, current sensing can be utilized to ensure that the modules share power equally. The converter can be designed to maximize the benefits of current sensing. For example, the converter may also be used to limit the maximum current flowing through the MOSFET, or to sense when a module failure occurs.
Various digital control strategies may also be added to improve converter efficiency. For example, in some embodiments, at light loads, increasing the switching frequency may reduce current ripple through the boost inductor, thereby improving light load efficiency. At high loads, the switching frequency may be reduced to ensure that zero voltage switching (or ZVS) is maintained.
Specification of
The following are some specifications of one embodiment of a DC-DC boost converter super-derivative according to the present disclosure.
Electrical specification
Thermal specification
Parameter(s)
Value of
Tolerance of
Note
Cooling down
Forced ventilation or natural convection
Range of ambient temperature
-20 to 50C
Mechanical specification
Parameter(s)
Value of
Tolerance of
Note
Weight (D)
<= 1 kg
Maximum value
Length of
<= 7.5”
Target, may have exceptions
Width of
<= 3.5”
Target, may have exceptions
Depth of field
<= 2.5”
Target, may have exceptions
Communication specification
Other specifications
In some embodiments, the translator may have one or more Controller Area Network (CAN) buses, e.g., Atmel SAM C21 having two CAN buses, for implementing CAN communications and providing a software interface, such as to interact with software to obtain measurements associated with one or more specifications. In some implementations, the CAN bus CAN have at least thirty-two kilobytes (32 kB) of flash memory and at least eight kilobytes (8 kB) of random access memory (or RAM).
In some embodiments, the converter may have one or more over-temperature power limits, and an output current limit having a programmable value. In some implementations, the converter may have an output current limit of programmable value between ten and sixty amps (10A to 60A). In some implementations, the converter may have output short circuit detection and disabling features.
In some embodiments, the converter may meet one or more noise criteria or power criteria. In some embodiments, the converter may satisfy MIL-STD-461F CE 102.
In some embodiments, the transducer may be configured to withstand up to or at least ten Grm vibrations.
In some embodiments, the converter may be configured with two or more separate CAN transceivers (e.g., for redundancy), and such transceivers may interface with a common processor. In some embodiments, the converter may be designed to have an operating life in excess of ten thousand hours. In some embodiments, the converter may be constructed of a modular design and be able to withstand failure of any one module. In some embodiments, when one module fails, the peak power output may be reduced, but the converter itself may still provide the rated output power. At nominal output power, the output voltage produced after failure of any one module should not fall outside the specification shown in fig. 12. In addition to this, the converter can identify when a module fails and can report the failure through software.
The DC-DC boost converter may include two low voltage modules and two high voltage modules. The low voltage modules may be placed in series with the high voltage modules such that each of the modules need only boost the voltage by half the total amount. The boost inductor may be coupled between pairs of modules, such as between two low voltage modules and between two high voltage modules, thereby reducing inductor size and losses. The boost inductor is operable in a coupled state and an uncoupled state. The converter may operate at quasi-square wave (QSW) resonant transitions. The boost inductance and the switch node capacitance may be selected to ensure that the resonant transition is maintained over the entire operating range.
Implementations disclosed herein may include a bidirectional DC-DC converter comprising: a first low voltage module; a second low voltage module; a boost inductor disposed between the first low voltage module and the second low voltage module, wherein the boost inductor is configurable to operate in a coupled state and in a non-coupled state, and wherein the boost inductor is coupleable between the first low voltage module and the second low voltage module in the coupled state; a first high voltage module; a second high voltage module; and a boost inductor disposed between the first high voltage module and the second high voltage module, wherein the boost inductor is configurable to operate in a coupled state and a non-coupled state, and wherein the boost inductor is coupleable between the first high voltage module and the second high voltage module in the coupled state, wherein the first low voltage module is arrangeable in series with the first high voltage module, wherein the second low voltage module is arrangeable in series with the second high voltage module, wherein the first low voltage module is arrangeable in parallel with the second low voltage module, and wherein the first low voltage module is arrangeable in parallel with the second low voltage module.
Implementations disclosed herein may include a flight vehicle comprising: a frame; a DC battery mounted to the chassis; a plurality of propulsion motors mounted to the frame, wherein each of the propulsion motors is configured to rotate a propeller about an axis defined by a shaft; a power conversion unit configured to receive electrical power from the battery and provide electrical power to each of the propulsion motors, wherein the power conversion unit comprises: a housing mounted to the chassis; a plurality of power modules releasably mounted within the housing, wherein each of the power modules is configured to provide electrical power up to a predetermined voltage level and a predetermined current level, and wherein each of the power modules comprises: a boost inductor; a current sensor aligned to sense a current flowing through the boost inductor and to generate a voltage signal corresponding to the current flowing through the boost inductor; a pair of MOSFETs, wherein the pair of MOSFETs includes: a first MOSFET aligned in series between the boost inductor and at least one of the propulsion motors, and a second MOSFET aligned in series between the boost inductor and ground; a gate driver, wherein the gate driver is configured to supply a gate voltage to turn on or off each of the pair of MOSFETs; an output capacitor connected in parallel with at least one of the propulsion motors; an error amplifier, wherein a first input of the error amplifier is a reference voltage and a second input of the error amplifier is a voltage across the output capacitor, and wherein an output of the error amplifier is a voltage signal corresponding to a reference current; and a hysteretic controller for controlling operation of the gate driver, wherein a first input of the hysteretic controller is the voltage signal corresponding to the reference current and a second input of the hysteretic controller is the voltage signal corresponding to the current flowing through the boost inductor sensed by the current sensor, and wherein an output of the hysteretic controller is a voltage signal to the gate driver for turning on one of the pair of MOSFETs and for turning off one of the pair of MOSFETs; and a supervisory controller within the enclosure, wherein the supervisory controller is in communication with each of the power modules, and wherein the supervisory controller is configured to determine a predetermined number of the power modules required to provide electrical power in response to demand.
Optionally, operating each of the propulsion motors may require electrical power from a first predetermined number of the power modules, wherein the flight vehicle includes a second predetermined number of the power modules, and wherein the second predetermined number is at least one more than the first predetermined number.
Optionally, each of the power modules further comprises a first isolation switch upstream of the boost inductor and a second isolation switch downstream of the first MOSFET, and each of the first and second isolation switches is in communication with the supervisory controller.
Implementations disclosed herein may include a power conversion unit comprising: a housing; a controller mounted within the housing; a DC power supply; a first power module releasably mounted within the housing, wherein the first power module may include: a first boost inductor; a first current sensor configured to sense a current flowing through the first boost inductor; a first pair of transistors; a first gate driver configured to operate each of the first pair of transistors; a first output capacitor; a first error amplifier, wherein a first input to the first error amplifier may be a first reference voltage associated with a first load on the first power module, wherein a second input to the first error amplifier may be a first output voltage of the first power module, and wherein an output from the first error amplifier may be a voltage signal representing a first reference current determined based at least in part on a difference between the first reference voltage and the first output voltage of the first power module; a first hysteretic controller, wherein a first input to the first hysteretic controller may be the voltage signal representing the first reference current, wherein a second input to the first hysteretic controller may be a voltage signal representative of the current through the first boost inductor, and wherein the output from the first hysteretic controller may be a first control signal for operating the first gate driver based at least in part on a difference between the first reference current and the current through the first boost inductor, wherein a first one of the first pair of transistors may be aligned in series between the first boost inductor and the load on the first power module, and wherein a second one of the first pair of transistors may be aligned in series between the first boost inductor and ground; a second power module releasably mounted within the housing, wherein the second power module may include: a second boost inductor; a second current sensor configured to sense a current flowing through the second boost inductor; a second pair of transistors; a second gate driver configured to operate each of the second pair of transistors; a second output capacitor; a second error amplifier, wherein a first input to the second error amplifier may be a second reference voltage associated with a second load on the second power module, wherein a second input to the second error amplifier may be a second output voltage of the second power module, and wherein an output from the second error amplifier may be a second reference current determined based at least in part on a difference between the second reference voltage and the second output voltage of the second power module; and a second hysteretic controller, wherein a first input to said second hysteretic controller may be said voltage signal representative of said second reference current, wherein a second input to the second hysteretic controller may be a voltage signal representative of the current through the second boost inductor, and wherein the output from the second hysteretic controller may be a second control signal for operating the second gate driver based at least in part on a difference between the second reference current and the current through the second boost inductor, wherein a first one of the second pair of transistors may be aligned in series between the second boost inductor and the load on the second power module, and wherein a second one of the second pair of transistors may be aligned in series between the second boost inductor and ground.
Optionally, the first control signal may be configured to: when the current flowing through the first boost inductor is equal to a zero voltage switching current, the first one of the first pair of transistors is turned off and the second one of the first pair of transistors is turned on, and the first control signal may be configured to: turning on the first one of the first pair of transistors and turning off the second one of the first pair of transistors when the current flowing through the first boost inductor is equal to the first reference current.
Optionally, the first hysteretic controller may be configured to select a switching frequency of the first one of the first pair of transistors and the second one of the first pair of transistors based at least in part on the difference between the first reference current and the current flowing through the first boost inductor, and the first control signal may be transmitted according to the switching frequency.
Optionally, the first hysteretic controller may comprise: a first comparator configured to receive the first input of the first hysteretic controller and the second input to the first hysteretic controller; a second comparator configured to receive the second input of the first hysteretic controller and a voltage signal corresponding to a negative zero voltage switching current; a third comparator configured to receive the first input of the first hysteretic controller and the second input to the first hysteretic controller; a fourth comparator configured to receive the second input of the first hysteretic controller and a voltage signal corresponding to a positive zero voltage switching current; and a latch configured to generate the first control signal based at least in part on at least one of an output of the first comparator, an output of the second comparator, an output of the third comparator, and an output of the fourth comparator, wherein if the output of the first comparator indicates that the current through the first boost inductor may be less than the first reference current, and if the output of the second comparator indicates that the current through the first boost inductor may be less than the negative zero voltage switching current, the first control signal instructs the first gate driver to turn off the first one of the pair of transistors and turn on the second one of the pair of transistors, and wherein if the output of the third comparator indicates that the current through the first boost inductor may be greater than the reference current, and if the output of the fourth comparator indicates that the current through the first boost inductor may be greater than the positive zero voltage switching current, the first control signal instructs the first gate driver to turn on the first one of the pair of transistors and turn off the second one of the pair of transistors.
Optionally, the first power module may include: a first isolation switch, a second isolation switch, and a first power stage connected in series between the first isolation switch and the second isolation switch, and the first power stage may include: the first boost inductor, the first current sensor, the first pair of transistors, the first gate driver, the first output capacitor, the first error amplifier, and the first hysteretic controller.
Optionally, the first isolation switch may be a first high side switch in communication with the controller and the second isolation switch may be a second high side switch in communication with the controller.
Alternatively, the first one of the first pair of transistors may be a first MOSFET configured to be energized by a gate voltage from the first gate driver, and the second one of the first pair of transistors may be a second MOSFET configured to be energized by the gate voltage from the first gate driver.
Optionally, the power conversion unit may be configured to generate the maximum output voltage based on a nominal voltage of the direct current power supply source. Alternatively, the nominal voltage of the direct current power supply may be in a range of about forty-eight volts to about sixty volts, and the maximum output voltage of the power conversion unit may be about one hundred fifty volts.
Optionally, the power conversion unit may be configured for installation within a flying vehicle having a plurality of propulsion motors. Alternatively, the first power module may have a first size of about two inches and a second size of about six inches.
Alternatively, the power conversion unit may include a first predetermined number of power modules, the first predetermined number may be at least four, and the first predetermined number of power modules may include the first power module and the second power module. Alternatively, the power conversion unit may be provided in association with at least one predetermined electrical load, the predetermined electrical load may require a second predetermined number of power modules to operate, and the first predetermined number may be at least one more than the second predetermined number.
Optionally, the first power module may further comprise a first over-current comparator at the second input to the first hysteretic controller or a second over-current comparator at the second one of the pair of transistors, and the first gate driver may be configured to turn off each of the first and second transistors in response to an over-current signal from one of the first or second over-current comparators.
Implementations disclosed herein may include a power module comprising: a boost inductor; a current sensor aligned to sense current flowing through the boost inductor; a pair of MOSFETs, wherein the pair of MOSFETs includes: a first MOSFET aligned in series between the boost inductor and at least one load, and a second MOSFET aligned in series between the boost inductor and ground; a gate driver, wherein the gate driver is configured to turn on or off each of the MOSFETs; an output capacitor connected in parallel with the at least one load; an error amplifier, wherein a first input of the error amplifier is a reference voltage and a second input of the error amplifier is a voltage across the output capacitor, and wherein an output of the error amplifier is a voltage signal corresponding to a reference current; and a hysteretic controller for controlling operation of the gate driver, wherein a first input of the hysteretic controller is the voltage signal corresponding to the reference current of the output of the error amplifier and a second input of the hysteretic controller is the voltage signal corresponding to the current flowing through the boost inductor sensed by the current sensor, and wherein an output of the hysteretic controller is a control signal to the gate driver for turning off or on at least one of the pair of MOSFETs.
Optionally, the power module may include a first high-side switch upstream of the boost inductor and a second high-side switch between the output capacitor and the at least one load.
Optionally, the power module may be configured to perform a method comprising: receiving electrical power from a direct current power source at the first high-side switch; sensing, by the current sensor, a current flowing through the boost inductor; comparing, by the error amplifier, a voltage level across the output capacitor to the reference voltage; providing, by the error amplifier, the voltage signal corresponding to the reference current to the hysteretic controller, wherein the voltage signal is proportional to a difference between the voltage level across the output capacitor and the reference voltage; determining, by the hysteretic controller, that the reference current exceeds the current flowing through the boost inductor; providing a control signal to the gate driver through the hysteretic controller; and switching the first MOSFET and the second MOSFET by the gate driver in response to the control signal.
Although the present disclosure has been described herein using exemplary techniques, components, and/or processes for implementing the systems and methods of the present disclosure, it will be appreciated by those of ordinary skill in the art that other techniques, components, and/or processes, or other combinations and sequences of techniques, components, and/or processes described herein, that perform one or more of the same functions and/or one or more results described herein, and are included within the scope of the present disclosure, may be used or performed.
For example, although some of the embodiments disclosed herein refer to circuits and components arranged in a discrete configuration, the systems and methods of the present disclosure are not limited to any particular circuit, component, or configuration disclosed herein. Additionally, although some of the embodiments disclosed herein refer to a power conversion unit having four power modules, each power module having one power stage, the power conversion unit disclosed herein is not limited to any number of power modules, and each power module may have one or more power stages. In some embodiments, the power conversion unit and/or the power module may include any number of other components in addition to those discussed herein, including one or more additional sensors, monitors, or other components for determining voltage levels and/or current levels of various aspects of the various systems or methods. In addition, although some of the embodiments disclosed herein refer to the use of power conversion units and/or power modules on unmanned aerial vehicles, the systems and methods of the present disclosure are not so limited and may be used during operation of any type or form of vehicle, including: manned vehicles, unmanned vehicles, or any other type or form of vehicle, as well as in any system where it is desirable to obtain electrical power at one or more predetermined voltage levels.
It should be understood that any of the features, characteristics, alternatives, or modifications described with respect to a particular embodiment herein may also be applied, used, or incorporated with any other embodiment described herein, unless expressly or implicitly indicated herein, and it should be understood that the drawings and the detailed description of the present disclosure are intended to cover all modifications, equivalents, and alternatives to the various embodiments defined by the appended claims. Further, with respect to one or more methods or processes of the present disclosure described herein (including, but not limited to, the flowchart shown in fig. 4), the order in which such methods or processes are presented is not intended to be construed as any limitation on the claimed invention, and any number of the method or process steps or blocks described herein can be combined in any order and/or in parallel to implement the method or process described herein.
In addition, it will be appreciated that the embodiments are set forth with reference to the accompanying drawings, which are not to scale. The use of the same or similar reference numbers in different drawings indicates the same or similar items or features. Unless otherwise indicated, one or more left-most digits of a reference number identify the reference number first appearing in one or more figures, while the two right-most digits of the reference number in a figure indicate components or features that are similar to components or features in other figures having the same two right-most digit reference number.
Conditional language (such as "may", "might", or "may" and other conditional language) is generally intended to convey in a permissive manner that certain embodiments may, or may not, include, but do not mandate or require certain features, elements, and/or steps, unless specifically stated otherwise or otherwise understood within the context of use. In a similar manner, terms such as "including", "including" and "including" are generally intended to mean "including, but not limited to". Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for determining, with or without user input or prompting, that such features, elements, and/or steps are included or are to be performed in any particular embodiment.
Unless specifically stated otherwise, a turning language such as the phrase "X, Y or at least one of Z" or "X, Y and at least one of Z" is additionally understood, in general, in the context of the usage scenario, to suggest that an item, term, etc. may be either X, Y or Z, or any combination thereof (X, Y and/or Z). Thus, such inflected language is generally not intended to, and should not, imply that at least one X, at least one Y, or at least one Z are each present.
Articles such as "a" or "an" should generally be construed to include one or more of the described items unless specifically stated otherwise. Thus, phrases such as "a device configured to" are intended to include one or more of the recited devices. Such one or more recited means may also be collectively configured to perform the recited recitations.
The terms of degree (such as "about," "generally," "nearly" or "substantially," as used herein) refer to a value, amount or characteristic that is close to the recited value, amount or characteristic, yet performs the desired function or achieves the desired result. For example, the terms "about," "generally," "nearly," or "substantially" may refer to an amount within less than 10%, within less than 5%, within less than 1%, within less than 0.1%, and within less than 0.01% of the stated amount.
While the invention has been described and illustrated with respect to illustrative embodiments thereof, the foregoing and various other additions and omissions may be made therein and thereto without departing from the spirit and scope of the present disclosure.
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