Efficiently control line and isolated power coupling using science of switching power
Our patented architecture works with the physics of switching power systems to feedback on superimposed duty cycle and phase signals (d+φ), allowing for stable simultaneous control of low frequency (line connected) current and linearized harmonic coupling between two isolated power bridges. An elegant synchronous average harmonic compensator superimposes feedback in a non-modulated and modulated reference frame to efficiently control multiple aspects of the same hardware using a synchronous modulation process.
Linearized power relationships, established for our architecture with beautiful frequency domain mathematics, result in simplified interfaces of the illustrated single stage power converter. The illustrated converter has a current controlled bridge which tracks commanded line current, and a voltage controlled bridge which tracks commanded voltage, with respective DC busses coupled with a commanded harmonic buck-boost (attenuation-gain) relationship.
The illustrated power converter is shown with multiple regulated interfaces which may be further simplified depending on application specific requirements for AC and DC connectivity. The flexible bidirectional multi-port power transfer of the patented power system is illustrated in the following figure as a versatile test apparatus in multiple configurations.
The figure illustrates the same single stage power converter architecture configured as: a solid state transformer which supports a power factor corrected line connection and an isolated DC energy storage element and an AC voltage connection, a single stage isolated AC/DC power converter, and a DC/DC power converter.
Our patented power control methods result in state of the art DC/DC power conversion which supports widely varying loads and operating points allowing for superimposed AC line connectivity. The following figure illustrates a brief comparison of several common DC/DC power converter architectures, given by (a) through (c), and our novel power architecture configured for DC/DC power conversion, (d). Interestingly, resonant variable frequency power converters (a) are quite common due to their efficiency, but may have significant control complexity due to their load (and duty cycle) dependent voltage versus frequency regulation relationship. Inductive phase shift (b), or dual active bridge, power converters have a simple current versus phase regulation relationship at fixed operating points, but can be more difficult to design for efficient switching and may be difficult to size for variable operating points (due to inductive filter tradeoffs between maximum transferred current and ripple current). The classic synchronous buck-boost power converter has an approximately ideal voltage regulation relationship dependent on buck and boost duty cycle degrees of freedom, but has additional switches relative to the other illustrated architectures and may require additional snubbing components to address switching behavior. Our synchronous average harmonic power converter is regulated using effective harmonic duty cycles, and combines positive aspects of the other architectures such as design for efficient magnetic and power switch integration, bidirectional power transfer, and simple voltage regulation.
Our technical library presents schematics and design relationships to assist in making specific developments and comparisons to prior art which depend on application requirements.