A self-excited push-pull converter, where between the bases of the push-pull converter's transistors (TR1, TR2) and the effective power suppler there is provided a constant current source (II), which provides a constant current to the bases of the transistors. With the working voltage increases, the circuit enters into an operating mode not based on the core-saturation working mode, because the transistors' base current is limited by the constant current source and consequently the transistors' collector current cannot increase.

A self-oscillating electronic LC resonant inverter for use in fixed-frequency power converters, providing zero-current and zero-voltage soft switching. The inverter incorporates an active fixed-frequency series resonant current pump capable of pumping the tank circuit current up as well as down. The magnitude of the resonant current is controlled at the resonant frequency of the LC tank circuit.

In a switching power supply device with reduced size and increased power conversion efficiency, a secondary-side rectifier circuit includes an adder-rectifier circuit that stores a voltage generated in a secondary winding in a capacitor as electrostatic energy in an on period of one of a high-side and low-side switching circuits or, and adds the voltage in the capacitor and the voltage generated in the secondary winding and outputs the sum as a direct-current voltage during in an on period of the other of the high-side and low-side switching circuits. A switching control circuit adjusts an output power to be output from the secondary-side rectifier circuit, by using on-period ratio controller that controls a proportion of periods during which the respective high-side side and low-side switching elements are brought into a conductive state.

In a switching power supply device with reduced size and increased power conversion efficiency, a secondary-side rectifier circuit includes an adder-rectifier circuit that stores a voltage generated in a secondary winding in a capacitor as electrostatic energy in an on period of one of a high-side and low-side switching circuits or, and adds the voltage in the capacitor and the voltage generated in the secondary winding and outputs the sum as a direct-current voltage during in an on period of the other of the high-side and low-side switching circuits. A switching control circuit adjusts an output power to be output from the secondary-side rectifier circuit, by using on-period ratio controller that controls a proportion of periods during which the respective high-side side and low-side switching elements are brought into a conductive state.

The present invention provides, in at least one embodiment, a micro-energy harvester with an integrated power manager that provides a complete solution for transforming and storing electrical energy from micro-energy power sources to efficiently power applications that do not require continuous power.

A power converter controller and methods for its operation are provided that can control a self-oscillating power converter that uses a Bipolar Junction Transistor (BJT) as a switch by manipulating the current flowing in a control winding. The controller is able to determine the optimum time to remove a short circuit applied to the control winding, as well as being able to determine the optimum time to pass current through the control winding. The controller can further draw power from the power converter using the control winding. The controller is capable of maintaining the midpoint voltage of the power converter in the case that the converter has more than one switch. The controller estimates the output power of the converter without requiring a connection to the secondary side of the converter transformer. The controller further controls entry and exit into a low-power mode in which converter oscillations are suppressed.

A power converter controller and methods for its operation are provided that can control a self-oscillating power converter that uses a Bipolar Junction Transistor (BJT) as a switch by manipulating the current flowing in a control winding. The controller is able to determine the optimum time to remove a short circuit applied to the control winding, as well as being able to determine the optimum time to pass current through the control winding. The controller can further draw power from the power converter using the control winding. The controller is capable of maintaining the midpoint voltage of the power converter in the case that the converter has more than one switch. The controller estimates the output power of the converter without requiring a connection to the secondary side of the converter transformer. The controller further controls entry and exit into a low-power mode in which converter oscillations are suppressed.

A power supply device including: a transformer generating, from an input voltage, low output voltage and high output voltage; an upper limiter circuit receiving the high output voltage and controlling the high output voltage not to exceed a maximum; a power controller performing feedback control on the input voltage so that the low output voltage matches a target voltage; an operation mode acquirer configured to acquire an operation mode of an image forming device; and a target value controller configured to change the target voltage depending upon the acquired operation mode. The target voltage when consumption amount of current with the high output voltage is relatively great ensures that the high output voltage does not fall below a minimum of a rated voltage range of the high output voltage, and is higher than the target voltage when consumption amount of current with the high output voltage is relatively small.

The power supply apparatus for obtaining a direct current from an alternating voltage source includes a first DC/DC converter for outputting a first direct current and a second DC/DC converter for a second direct current lower than the first direct current from the first DC/DC converter, and the output voltage of the first DC/DC converter is changed to a lower direct current and the second DC/DC converter is driven in a continuously-conducting state.

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.