A power converter circuit to convert multiple direct current (dc) inputs to one or more dc outputs. This dc-dc power converter allows its load to be powered by multiple,...
A power converter circuit to convert multiple direct current (dc) inputs to one or more dc outputs. This dc-dc power converter allows its load to be powered by multiple, different sources of various voltage and current levels (such as solar panels, batteries, fuel cells, etc.). This converter has both buck and boost capability.
This circuit can simultaneously draw power from several dc electrical energy sources of different kinds (such as solar panels, batteries, fuel cells, etc.). The circuit topology is capable of an arbitrary number of input sources of different voltage/current/power levels. There is a single output voltage that can directly supply a load, or can supply another power converter. The default circuit uses an inductor, but it may be substituted with a transformer to provide electrical isolation or multiple output as well. The power flow from each source can be controlled separately in order to optimize the power flow characteristics for cost, environmental protection, or any other performance objective. Low power applications regulate source switching with a control circuit. High power applications regulate and optimize flow characteristics with a digital signal processor (DSP). This circuit contains a minimum number of components which reduce overall complexity and cost when compared to other implementations. In addition, due to efficiency in design, this circuit can be scaled to work across a multitude of power ranges.
Applications:
This technology can be used in any application which uses multiple dc energy sources and in situations where backup or simultaneous alternative energy sources are used. Such sources include solar cells, fuel cells, batteries, and thermoelectric sources.
Benefits:
Simple: Designed with minimal parts, allowing for reduced complexity in design and higher reliability.
Low Cost: Requires fewer inductors and transistors when compared to equivalent dc-dc converters, therefore manufacturing costs are reduced.
Efficient: Less loss and higher conversion efficiency due to the minimal design parts.
Adaptable: Easily integrated into existing systems and combined with other converters (i.e. ac-dc).
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A method for generating pulse width modulated control signal has the steps of providing a base carrier waveform, segmenting the base carrier waveform into a plurality of...
A method for generating pulse width modulated control signal has the steps of providing a base carrier waveform, segmenting the base carrier waveform into a plurality of carrier waveforms, and providing at least one modulating signal. The first and second waveforms are compared to the at least one modulating signal to produce first and second comparator outputs, which are then mathematically combined to produce a pulse width modulated control signal.
The technology is a process that can be applied to dc-ac power converters (i.e., inverters) that use pulse width modulation (PWM), to provide two features:
It allows inverters to use a high-frequency ac link bus instead of the conventional dc; and,
It allows multiple signals to be put onto the same PWM carrier or data stream for delivery to multiple switches.
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The combination of a unique series-input parallel-output (SIPO) circuit configuration and a sensorless current mode (SCM) technique ensures automatic and nearly perfect...
The combination of a unique series-input parallel-output (SIPO) circuit configuration and a sensorless current mode (SCM) technique ensures automatic and nearly perfect load sharing of multiple dc:dc converters even during fast dynamic changes.
A power supply in an embodiment of the invention includes a plurality of dc--dc switching power converters, each of which has its input isolated from its output. The power converters are arranged with their respective inputs being series connected and their respective outputs being parallel connected in an embodiment of the invention. In another embodiment of the inputs are parallel connected and the outputs series connected. Each power converter includes an input filter in each of said dc--dc switching power converters and an output filter. Each power converter includes a sensorless current mode control circuit controlling its switching duty ratio.
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This invention is a technique that resolves current commutation challenges in various types of ac-ac switching power converters. It also applies to inverters and...
This invention is a technique that resolves current commutation challenges in various types of ac-ac switching power converters. It also applies to inverters and rectifiers with high-frequency links. Direct ac-ac converters such as matrix converters and cycloconverters benefit from the approach. This technology commutates load current without inserting dead-time into the switching sequence or using large inductors to limit shoot-through current. Both of these prior techniques intrinsically compromise a converter's performance and efficiency.
The new technology provides a continuous path for load current and control of ac-ac converter switching so voltage sources do not short-circuit during commutation. If input voltage sources short-circuit they result in dangerously high shoot-through currents, while a disruption in the load current results in dangerously high voltages.Either scenario can damage or destroy equipment. In the past, additional components or timing constraints have been required to address current commutation. This new technology prevents both shoot-through and load current disruption, and allows load-current zero-crossings to occur naturally without the distortion associated with prior techniques. The preferred embodiment of the new invention is a state-machine-based controller that tracks the switch sequencing needed to avoid trouble.
Applications
Link inverters - The high-frequency link pulse width modulation (HF PWM) topology is a reduced-cost solution ideal for producing ac voltage from alternative energy sources such as solar panels and fuel cells. Other applications include uninterruptible power supplies (UPS), portable generators, and inverters for automobiles.
Matrix converters - ac-ac converters based on direct switch matrix circuits are difficult to implement with conventional commutation methods. The invention facilitates the design and operation of matrix converters.
Cycloconverters - Applications for cycloconverter-type ac-ac converters have traditionally been limited to relatively low frequencies, in part because of complicated current management. Effective commutation has been a significant barrier to wider application of these circuits. This invention resolves the commutation challenge and greatly expands the application range of cycloconverters.
Benefits
Smooth half-cycle transitions - Proper selection of switch sequencing allows a load current to transition smoothly from one half-cycle to the next without disruptions.
Reduced distortion and EMI - Smooth current zero-cross transitions eliminate distortion inherent with dead-time techniques. Natural current commutation provides superior EMI performance compared with forced current commutation.
Increased conversion and cost efficiency - The new technology facilitates increased power conversion efficiency while supporting miniaturization. It reduces cost by reducing the need for commutation chokes or large snubbers.
Protects equipment - This technology prevents current shoot-through and load current disruptions that damage equipment.
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The invention recognizes that filter size can be reduced substantially as power factor is permitted to deviate below unity in systematic ways. Preferred methods of the...
The invention recognizes that filter size can be reduced substantially as power factor is permitted to deviate below unity in systematic ways. Preferred methods of the invention provide specific, computable waveforms that permit use of a minimum filter size given a desired target power factor.
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Hot-spotting is a common problem in solar panel configurations that can potentially damage photovoltaic cells by forcing the conduction of reverse current in shaded or...
Hot-spotting is a common problem in solar panel configurations that can potentially damage photovoltaic cells by forcing the conduction of reverse current in shaded or dysfunctional cells. The proposed invention offers a solution at the modular level by incorporating the photovoltaic panel into an open circuit to prevent hot-spotting. As a result, other panels in the photovoltaic string will remain functional under all adverse conditions.
Researchers from the University of Illinois have developed a method and apparatus to protect solar cells from hot spotting and damage resulting from arc faults. This device would also provide a way to shut off the solar array remotely. By preventing the damage caused by hot spotting and arc faults this device increases the longevity of solar arrays. It also reduces the risk of fire and provides a remote way to cut the power in cases of emergency.
