A self-excited power conversion circuit for secondary side control output power includes a comparator unit and a transistor installed directly in a secondary side output module, and the comparator unit is electrically coupled to at least one load, and the transistor is electrically coupled between to a conversion module of the circuit and the load. The comparator unit is provided for adjusting the duty cycle of the transistor after detecting the amount of energy outputted from the conversion module to the load from, so as to adjust the amount of energy actually received by the load to achieve a constant power effect.

A DC/DC conversion apparatus includes a DC voltage source that outputs a DC power supply voltage, an oscillation circuit electrically connected to the DC voltage source, switch elements, a switch controller that connects or disconnects electrical connection between the DC voltage source and the oscillation circuit by switching turn-on and turn-off of the switch elements, and switches a direction of a voltage applied to the oscillation circuit between a first direction and a second direction, and a transformation circuit that outputs a current generated in the oscillation circuit and converts the current into a DC current. The switch controller disconnects the electrical connection between the oscillation circuit and the DC voltage source before the direction of the voltage applied to the oscillation circuit is switched from the first direction to the second direction, and connects the electrical connection between the oscillation circuit and the DC voltage source and switches the direction of the voltage applied to the oscillation circuit to the second direction after a current flowing through the oscillation circuit has been outputted to the transformation circuit.

A DC/DC conversion apparatus includes a DC voltage source that outputs a DC power supply voltage, an oscillation circuit electrically connected to the DC voltage source, switch elements, a switch controller that connects or disconnects electrical connection between the DC voltage source and the oscillation circuit by switching turn-on and turn-off of the switch elements, and switches a direction of a voltage applied to the oscillation circuit between a first direction and a second direction, and a transformation circuit that outputs a current generated in the oscillation circuit and converts the current into a DC current. The switch controller disconnects the electrical connection between the oscillation circuit and the DC voltage source before the direction of the voltage applied to the oscillation circuit is switched from the first direction to the second direction, and connects the electrical connection between the oscillation circuit and the DC voltage source and switches the direction of the voltage applied to the oscillation circuit to the second direction after a current flowing through the oscillation circuit has been outputted to the transformation circuit.

A DC/DC conversion apparatus includes a DC voltage source, an oscillation circuit, switch elements, a switch controller, and a transformation circuit. An inductor is provided in the oscillation circuit, a transformer is provided in the transformation circuit and a primary side of the transformer is connected in series with the oscillation circuit. Before a direction of a voltage applied to the oscillation circuit is switched from a first direction to a second direction, the switch controller disconnects electrical connection between the oscillation circuit and the DC voltage source and a first resonance loop is defined by a portion of the plurality of switch elements and the oscillation circuit. When a current flowing through the inductor is equal or substantially equal to an excitation current on the primary side of the transformer in the first resonance loop, at least one switch element in the first resonance loop is turned off to define a second resonance loop. After a current in the second resonance loop oscillates for a first period, the electrical connection between the oscillation circuit and the DC voltage source is connected and the direction of the voltage applied to the oscillation circuit is switched to the second direction.

A DC/DC conversion apparatus includes a DC voltage source, an oscillation circuit, switch elements, a switch controller, and a transformation circuit. An inductor is provided in the oscillation circuit, a transformer is provided in the transformation circuit and a primary side of the transformer is connected in series with the oscillation circuit. Before a direction of a voltage applied to the oscillation circuit is switched from a first direction to a second direction, the switch controller disconnects electrical connection between the oscillation circuit and the DC voltage source and a first resonance loop is defined by a portion of the plurality of switch elements and the oscillation circuit. When a current flowing through the inductor is equal or substantially equal to an excitation current on the primary side of the transformer in the first resonance loop, at least one switch element in the first resonance loop is turned off to define a second resonance loop. After a current in the second resonance loop oscillates for a first period, the electrical connection between the oscillation circuit and the DC voltage source is connected and the direction of the voltage applied to the oscillation circuit is switched to the second direction.

The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor of the second resonant DC-DC power converter are configured for magnetically coupling the first and second resonant DC-DC power converters to each other to forcing substantially 180 degrees phase shift, or forcing substantially 0 degree phase shift, between corresponding resonant voltage waveforms of the first and second resonant DC-DC power converters. The first and second inductors are corresponding components of the first and second resonant DC-DC power converters.

An example apparatus may include a power supply circuit comprising a first stage, the first stage comprising a current-fed topology and a transformer for isolating a primary side of the first stage from a secondary side of the first stage; a control module configured to provide control signals to one or more switches of the power supply circuit and to perform startup operations comprising: determining a peak line voltage value of an AC input voltage to the power supply circuit; initiating, when the power supply circuit is started, a hard-switching method; determining a center tap voltage of the transformer; stopping the hard-switching method, when the center tap voltage crosses a fraction of the peak line voltage value; and initiating, when the hard-switching method stops, a zero-voltage switching method with peak current mode control.

A method and apparatus is disclosed herein for harvesting ambient energy. In one embodiment, an energy harvester comprises: a first RF rectifier to output a first voltage determined by rectified RF energy in response to received RF energy; a first energy reservoir coupled to the first RF rectifier to store energy at the first voltage; a DC/DC converter coupled to the first energy reservoir to convert the first voltage to a second voltage; a second reservoir coupled to the DC/DC converter to store energy at the second voltage, the second voltage being greater than the first voltage; and a third reservoir coupled to the second reservoir to receive energy transferred from the second reservoir periodically.

A method and apparatus is disclosed herein for harvesting ambient energy. In one embodiment, an energy harvester comprises: a first RF rectifier to output a first voltage determined by rectified RF energy in response to received RF energy; a first energy reservoir coupled to the first RF rectifier to store energy at the first voltage; a DC/DC converter coupled to the first energy reservoir to convert the first voltage to a second voltage; a second reservoir coupled to the DC/DC converter to store energy at the second voltage, the second voltage being greater than the first voltage; and a third reservoir coupled to the second reservoir to receive energy transferred from the second reservoir periodically.

In described examples, a converter circuit includes a primary-side ground, a current sensor, a control signal generator, first and second control switches, and a transformer with a center-tapped primary-side coil. A first terminal of the first control switch is coupled to a first terminal of the coil and a first input of the current sensor. A first terminal of the second control switch is coupled to a second terminal of the coil and a second input of the current sensor. Second terminals of the first and second control switches are coupled to ground. The control signal generator closes the first control switch and opens the second control switch in a first phase; opens the first control switch and closes the second control switch in a second phase that alternates with the first phase; and adjusts first phase duration in response to current sensor output, without changing converter period duration.