Plywheel-powered mobile X-ray apparatus

A power supply for providing pulsed power to X-ray generating equipment comprising:

• (a) a flywheel mounted for rotation;
• (b) an electrical rotating machine having a rotor coupled by a shaft to the flywheel, a stator power winding, a rotor control winding, power terminals electrically coupled to the power winding and control terminals electrically coupled to the control winding;
• and
• (c) control power means, responsive to a signal from the operator requesting an exposure, for providing a control current through the control winding of the electrical machine such that the output voltage at the power terminals of the machine reaches a desired output level after a characteristic rise time, and for applying an increase in current through the control winding a selected period of time before the X-ray load is connected to the power terminals to provide a rise in output voltage at the power terminals that will substantially compensate for the sag in output voltage occuring upon connection of the X-ray load.

Mobile X-ray generating apparatus comprising:

• (a) a flywheel mounted for rotation;
• (b) an electrical rotating machine having a rotor coupled by a shaft to the flywheel, a stator power winding, a rotor control winding, power terminals electrically coupled to the power winding and control terminals electrically coupled to the control winding;
• (c) an X-ray tube having an anode and a cathode;
• (d) a transformer having a primary selectively receiving power from the power terminals of the electrical machine and increasing the voltage of the power received to a high voltage level at the secondary thereof;
• (e) rectifier means for rectifying the AC voltage from the secondary of the transformer to a direct voltage, and connected to provide the rectified high voltage across the anode and cathode of the X-ray tube;
• (f) control power means connected to the control terminals of the electrical machine for supplying a selected control current to the control winding during operation of the electrical machine as a motor and for supplying another selected control current to the control winding when the machine is operated as a generator;
• (g) motor drive means selectively connectable to the power terminals of the electrical machine for providing a varying electrical voltage to the power terminals at a frequency and phase selected to drive the rotor of the machine and the flywheel connected therewith;
• and
• (h) motor-generator mode select switch means, connected to the power terminals of the electrical machine and to the output power of the motor drive means and having output lines connected to the primary of the transformer, for responding to control signals to selectively connect the power terminals of the electrical machine to the motor drive means and for responding to a control signal to selectively disconnect the power terminals of the electrical machine from the motor drive means and to connect the power terminals to the output lines to apply power to the transformer.

Mobile X-ray generating apparatus comprising:

• (a) a flywheel mounted for rotation;
• (b) an electrical rotating machine having a rotor coupled by a shaft to the flywheel, a stator power winding, a rotor control winding, power terminals electrically coupled to the power winding and control terminals electrically coupled to the control winding;
• (c) an X-ray tube having an anode and a cathode;
• (d) a transformer having a primary selectively receiving power from the power terminals of the electrical machine and increasing the voltage of the power received to a high voltage level at the secondary thereof;
• (e) rectifier means for rectifying the AC voltage from the secondary of the transformer to a direct voltage, and connected to provide the rectified high voltage across the anode and cathode of the X-ray tube;
• and
• (f) control power means, responsive to a signal from the operator requesting an exposure, for providing a control current through the control winding of the electrical machine such that the output voltage at the power terminals of the machine reaches a desired output level after a characteristic rise time, and for applying an increase in current through the control winding a selected period of time before the primary of the transformer is connected to the power terminals to provide a voltage across the X-ray tube to tend to increase the output voltage at the power terminals to substantially compensate for the sag in output voltage occurring upon connection of the transformer to the power terminals.

A method of controlling the voltage supplied by a flywheel driven generator, having stator power windings and a rotor control winding, through a transformer and rectifier to an X-ray tube, comprising the steps of:

• (a) providing a current through the control winding sufficient to produce a desired open circuit output voltage from the stator windings;
• (b) connecting the primary of the transformer to the terminals of the stator power windings to supply power from the generator to the X-ray tube;
• and
• (c) a selected period of time before connecting the transformer to the stator power windings, increasing the current in the control winding to a level selected to cause the potential increase in output voltage dur to the increased current to substantially cancel the potential decrease in output voltage occurring as the stator power windings of the generator are loaded so that the output voltage remains substantially constant during an X-ray exposure.

A power supply for providing pulsed power to X-ray generating equipment comprising:

• (a) a flywheel mounted for rotation;
• (b) an electrical rotating machine having a rotor coupled by a shaft to the flywheel, a stator power winding, a rotor control winding, power terminals electrically coupled to the power winding and control terminals electrically coupled to the control winding;
• (c) control power means connected to the control terminals of the electrical machine for supplying a selected control current to the control winding during operation of the electrical machine as a motor and for supplying a selected control current to the control winding when the machine is operated as a generator, wherein the control power means is responsive to a signal provided by an operator to increase the current in the control winding to a level selected to provide a desired open circuit output voltage on the power terminals of the electrical machine after a characteristic rise time, whereafter the power terminals of the machine may be connected to a load, and wherein the control power means provides a step increase in current through the control winding a selected period of time before a load is connected to the power terminals to provide a compensatory increase in output voltage to substantially cancel the effect of the sag in output voltage at the power terminals upon connection of the load;
• and
• (d) motor drive means selectively connectable to the power terminals of the electrical machine for providing a varying electrical voltage to the power terminals at a frequency and phase selected to drive the rotor of the machine and the flywheel connected therewith.

Mobile X-ray generating apparatus comprising:

• (a) a flywheel mounted for rotation;
• (b) an electrical rotating machine having a rotor coupled by a shaft to the flywheel, polyphase stator power windings, a rotor control winding, power terminals electrically coupled to the power windings and control terminals electrically coupled to the control winding;
• (c) an X-ray tube having an anode and a cathode;
• (d) a transformer having a primary selectively receiving power from the power terminals of the electrical machine and increasing the voltage of the power received to a high voltage level at the secondary thereof;
• (e) rectifier means for rectifying the AC voltage from the secondary of the transformer to a direct voltage, and connected to provide the rectified high voltage across the anode and cathode of the X-ray tube;
• (f) control power means connected to the control terminals of the electrical machine for supplying a selected control current to the control winding during operation of the electrical machine as a motor and for supplying another selected control current to the control winding when the machine is operated as a generator;
• and
• (g) motor drive means selectively connectable to the power terminals of the electrical machine for providing a varying electrical voltage to the power terminals at a frequency and phase selected to drive the rotor of the machine and the flywheel connected therewith, the motor drive means including:
• (1) means for sensing the position of the rotor shaft and providing a signal indicative thereof;
• and
• (2) means for receiving the signal indicative of rotor shaft position and providing output signals equal in number to the number of stator phase windings, each of the output signals being in the form of pulses of voltage extending over a selected portion of the revolution of the rotor, the output signal pulses for each of the phase windings being spaced in phase at regular intervals to cover the entire revolution of the rotor and supplied to the stator phase windings such that the voltages across the phase windings combine to provide a magnetic field from the stator rotating in synchrony with the rotor.

Mobile X-ray generating apparatus comprising:

• (a) a flywheel mounted for rotation;
• (b) an electrical rotating machine having a rotor coupled by a shaft to the flywheel, a stator power winding, a rotor control winding, power terminals electrically coupled to the power winding and control terminals electrically coupled to the control winding;
• (c) an X-ray tube having an anode and a cathode;
• (d) a transformer having a primary selectively receiving power from the power terminals of the electrical machine and increasing the voltage of the power received to a high voltage level at the secondary thereof;
• (e) rectifier means for rectifying the AC voltage from the secondary of the transformer to a direct voltage, and connected to provide the rectified high voltage across the anode and cathode of the X-ray tube;
• (f) control power means connected to the control terminals of the electrical machine for supplying a selected control current to the control winding during operation of the electrical machine as a motor and for supplying another selected control current to the control winding when the machine is operated as a generator, wherein the control power means is responsive to a signal provided by an operator to increase the current in the control winding to a level selected to provide a desired open circuit output voltage on the power terminals of the electrical machine after a characteristic rise time, whereafter the power terminals of the machine may be connected to a transformer, and wherein the control power means provides a step increase in current through the control winding a selected period of time before the transformer is connected to the power terminals to provide a compensatory increase in output voltage to substantially cancel the effect of the sag in output voltage at the power terminals upon connection of the transformer;
• and
• (g) motor drive means selectively connectable to the power terminals of the electrical machine for providing a varying electrical voltage to the power terminals at a frequency and phase selected to drive the rotor of the machine and the flywheel connected therewith.

Mobile X-ray generating apparatus comprising:

• (a) a flywheel mounted for rotation;
• (b) an electrical rotating machine having a rotor coupled by a shaft to the flywheel, three phase stator power windings producing a three phase output, a rotor control winding, three phase power terminals electrically coupled to the power windings and control terminals electrically coupled to the control winding;
• (c) an X-ray tube having an anode and a cathode;
• (d) a transformer having a three phase primary winding selectively receiving power from the power terminals of the electrical machine and increasing the voltage of the power received to a high voltage level at the secondary thereof, the secondary having two sets of three phase windings;
• (e) rectifier means for rectifying the AC voltage from the secondary of the transformer to a direct voltage, and connected to provide the rectified high voltage across the anode and cathode of the X-ray tube, the rectifier means having diodes connected such that the output of one set of transformer secondary windings is rectified to produce a positive rectified voltage which is applied to the X-ray tube anode and such that the output of the other set of transformer secondary windings is rectified to produce a negative rectified voltage which is applied to the X-ray tube cathode;
• (f) control power means connected to the control terminals of the electrical machine for supplying a selected control current to the control winding during operation of the electrical machine as a motor and for supplying another selected control current to the control winding when the machine is operated as a generator;
• and
• (g) motor drive means selectively connectable to the power termains of the electrical machine for providing a varying electrical voltage to the power terminals at a frequency and phase selected to drive the rotor of the machine and the flywheel connected therewith.