Two proposals are made for power supply systems comprising at least one resonant inverter and one control unit. According to the first proposal the power supply system comprises two inverters and produces two output voltages, the control circuit processing as an actual value on the one hand the sum of and on the other hand the difference between the two output voltages. According to the second proposal a control circuit does not directly process the controlled variables for a power supply system comprising at least one inverter, but difference units for controlled variables determine the deviations from a preceding sampling instant and these difference values are processed. Also the correcting variable calculated in this way is a difference value which is converted into a correcting variable value by a correcting variable summing unit. The two proposals can be advantageously combined. As an important improvement is proposed the use of a limiting controller which generally becomes active in case of imminent transgression of a maximum value and which limits the actuation. The control circuit is preferably used as a digital control circuit for a state space control.
There is provided a high-efficiency DC-DC converter which comprises a voltage resonance circuit to which electric power from a low-voltage direct-current power supply, including a household fuel cell and a solar cell, is input and performs DC-AC conversion by zero-voltage switching, an insulating high-frequency transformer which transmits the converted power, a current resonance circuit which is provided on the secondary side of the transformer and performs zero-current switching, a rectifier circuit which rectifies the output from the current resonance circuit, and a smoothing circuit which rectifies the output from the rectifier circuit.
A technique is provided for direct digital phase control of resonant inverters based on sensing of one or more parameters of the resonant inverter. The resonant inverter control system includes a switching circuit for applying power signals to the resonant inverter and a sensor for sensing one or more parameters of the resonant inverter. The one or more parameters are representative of a phase angle. The resonant inverter control system also includes a comparator for comparing the one or more parameters to a reference value and a digital controller for determining timing of the one or more parameters and for regulating operation of the switching circuit based upon the timing of the one or more parameters.
A semiconductor switch 12 connected in series with a smoothing capacitor 12 is constituted by connecting in parallel a diode 13D which permits to flow current regenerated from energy of electric charges stored in a high voltage capacitor 17 to a primary side of a high voltage transformer 15 for the smoothing capacitor 12 and switching means 13S which interrupts an output from the smoothing capacitor 12, and after turning off the switching means 13S, through alternative on and off control of switching means 161S.about.164S the energy of electric charges stored in the high voltage capacitor 17 is regenerated to the smoothing capacitor 12 by making use of parasitic leakage inductance 15L. As a result, an X-ray high voltage device is provided which permits to drop a wave tail of a tube voltage in a high speed without complexing the structure of the high voltage part thereof.
