| 摘要 |
In order to improve the efficiency of an X-ray generator, to decrease the number of maintenance men required for an X-ray CT apparatus mounting the X-ray generator, to improve the reliability and to decrease the installation space, the X-ray generator comprises power transfer means for receiving electric power from an AC power source and for transferring it, a converter for converting an AC voltage transferred from the power transfer means into a DC voltage, an inverter for converting the DC voltage of the converter into an alternating current, a high-voltage transformer for boosting the AC voltage converted by the inverter, rectifier means for rectifying the output voltage of the high-voltage transformer into a direct current, and an X-ray tube connected to the rectifier means. The X-ray generator is mounted on a scanner rotating unit of the X-ray CT apparatus. The converter comprises a full-wave rectifier circuit constituted by self-extinguishing switches, inductors connected to the phases at the AC input terminals of the full-wave rectifier circuit, and a converter controller which so controls the self-extinguishing switches that the phase is brought into agreement between the phase current and the phase voltage of the AC power source and that the output voltage of the full-wave rectifier circuit is brought into agreement with a target voltage. The inverter comprises zero-voltage switching means for turning the switching element on and off by setting the voltage of the switching element to be nearly zero at the time when the semiconductor switching element constituting the inverter is turned on and off, current free-wheeling means for free-wheeling the current flowing into the zero-voltage switching means when the zero-voltage switching means is shut off, and control means for controlling the timing for turning the switching element of the inverter on and off in response to signals for setting the voltage to be applied to the X-ray tube and for setting the current to be fed to the X-ray tube. <IMAGE> |
