Patent Application
20180234024
This application claims priority to India Patent Application No. 201711005087, filed Feb. 13, 2017, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in its entirety are herein incorporated by reference.
Exemplary embodiments pertain to the art of solid state power distribution systems, and more particularly to a variable resonant power converter with a tunable inductor.
Power supplies can experience heat energy loss generated by frequency switching and magnetics in the switch mode converters. In AC power systems, the switching frequency is different from the resonant frequency. Each change of switching frequency can change the power characteristics of the circuit. If the resonant frequency of the switch becomes more and more different from the resonant frequency the source frequency, the disparate resonance creates inefficiency due to heat loss. If output load or input voltages change, the efficiency of the power supply can be affected due to heat loss from each frequency change.
Disclosed is an electronic power converter configured to receive power from a power source. The power operates at a switching frequency. The electronic power converter further includes a resonant tank circuit operatively connected to the power converter. The resonant tank circuit operates at a tank resonant frequency. The electronic power converter includes a controller operatively connected to the resonant tank circuit. The electronic power converter further includes a variable inductor operatively connected to the resonant tank circuit. The variable inductor is configured to modify the tank resonant frequency to match the switching frequency within a predetermined margin.
Also disclosed is a method for converting electronic power. The method includes receiving power from a power source operating at a switching frequency. The method further includes transmitting the power to a variable inductor operatively connected to a resonant tank circuit. The resonant tank circuit operates at a tank resonant frequency. The method further includes modifying, via a controller operatively connected to the resonant tank circuit, the tank resonant frequency to match the switching frequency within a predetermined margin.
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
In general, inefficiencies are expressed with heat generation by the system. Efficiencies for power converters are generally higher as they become closer to the resonant frequencies experienced at each adjacent step of the switching apparatus. Some systems may include varying the DC voltage at output 110 and the load changes. Other systems may control switching frequency using a voltage control loop and a current control loop, but may not target high efficiency by coordinating the tank circuit to match switching frequency. Further approaches have included adding or subtracting flux in an inductor coil to change inductance of a tank circuit. But some applications with weight and space constraints (e.g., aeronautical applications) may not allow addition of additional inductor coils to modify inductance. Moreover, some systems may not provide for infinitely variable inductance adjustments based on voltage and load changes.
For high power applications used in aircraft, power efficiency increase as the AC system resonant frequency approach the switching frequencies. It is advantageous, then, to keep the resonant frequencies within a predetermined margin of difference without increasing physical space and weight needed to accommodate additional coils for inductors. For example, if an AC system resonates at 100 kHz, the switching frequency is controlled to be between 100 kHz to 105 kHz. In some aspects, a fully optimized switching frequency may be within 7% of the AC system. Maintaining this relatively narrow margin of switching frequency disparity between the AC system and the switch may be difficult due to changing loads and voltages. An infinitely tunable inductance provides fine adjustment in real time to compensate for dynamic system changes.
In some aspects, controller 208 may be a microcontroller or a field-programmable gate array (FPGA). Controller 208 may be configured to control the resonant frequency of system 200 to be within a predetermined threshold of difference from the AC source resonant frequency by varying the tunable inductor. For example, a predetermined threshold may be 1% difference between the resonant frequencies, 2% difference, etc. Converter 204 provides feedback to controller 208 that includes a tank current feedback 212 and a voltage control feedback 214. Controller 208 may dynamically control the tank resonant frequency of the tank circuit based on voltage control feedback 214 and tank current feedback 212, and the resonant frequencies of the AC source and the tank circuit.
Power source 202 can be a high voltage DC source in an aircraft such as, for example, a 240 V rectifier. Power source 202 operates at its own predetermined frequency, which may be static or may change dynamically based on operational factors of the vehicle in which it operates. As one exemplary application, system 200 reduces the 240 V input to a 28 V output. In other aspects, controller 208 may vary the resonant frequency based on tank current feedback 212 and tank voltage feedback 214 to change the resonant network characteristics for fixed value of C. By altering the inductance L in the resonant tank circuit 206, controller 208 may alter the tank frequency of the resonant tank circuit 206 to be closer to the circuit switching frequency, thereby keeping the behavior of system 200 constant under varying load conditions at DC output 210.
According to some embodiments, controller 208 can change the inductance by modifying the turns in an inductance coil operating as part of resonant tank circuit 206.
According to one embodiment, variable inductor 300 may further include one or more coil switches 306 configured to connect a predetermined number of loops of inductor coil loops 302 to short a number of loops. By shorting the current path, coil switch 306 may vary the flux density created by variable inductor 300 as current passes through inductor coil loops 302.
According to another embodiment, variable inductor 300 may further include an actuator 308 configured to slide laterally along a centerline of a cavity within inductor core 304. For example, inductor core 304 may be a tube of inductor core material configured to receive actuator 308 in infinitely variable amounts of engagement from no engagement to full engagement that inserts the entire length of actuator 308 into inductor core 304. As actuator 308 increasingly engages inductor core 304, inductance is varied according to a position of engagement.
Accordingly, in some aspects, controller 208 may receive tank current feedback 212 and tank voltage feedback 214, determine a difference between an AC resonant frequency and the switch resonant frequency, and modify an inductance of variable inductor 300 until a margin between the AC resonant frequency and the switch resonant frequency is within a predetermined threshold.
According to other embodiments, controller 208 may actuate one or more coil switches 306 to modify the inductance of variable inductor 300.
According to another embodiment, controller 208 may modify a position of an actuator bar to modify the inductance of variable inductor 300.
In another embodiment, controller may modify a position of an actuator bar and actuate one or more coil switches 306.
Accordingly, aspects of variable inductor 300 may alter the inductance of resonant tank circuit 206 to move the resonant frequency closer to the switching frequency, thereby keeping the behavior of the circuit constant under varying load conditions. Controller 208 may modify inductance by adding or subtracting operable turns in the coil via the one or more coil switches 306, or varying the flux density in the core by moving the actuator core out of magnetic circuit, or by using both of the one or more coils switches 306 and the movable bar of actuator 308.
Embodiments of the present disclosure include controller logic that varies the inductance present in tank circuit of any resonant power supply via a variable inductor. A precise movement of a controllable moving element of the variable inductor can be driven by closed-loop control logic implemented with the controller to tune the tank circuit. In some aspects, precise and infinitely variable control of the inductance results in precision control of the resonance frequency at each power conversion stage to achieve targeted efficiency.
Aspects of the present invention may increase power conversion efficiency. For example, some embodiments can allow tuning of the LC tank frequency to a target threshold based on the load and input line change, and deliver power to the load with a very high efficiency ranging from 98 to 99%.
The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.
While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201711005087 | Feb 2017 | IN | national |
