ROTARY TRANSFORMER WITH SYNCHRONIZED OPERATION
First Claim
1. A rotary transformer, comprising:
- a primary coil;
a secondary coil;
a resonant circuit coupled to the primary coil;
a coil drive circuit coupled to the primary coil; and
a microprocessor connected to the primary coil for detecting a voltage across the primary coil, wherein a control voltage is input to the coil drive circuit when the microprocessor detects a transition of the voltage across the primary coil from a positive voltage to a negative voltage.
1 Assignment
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Accused Products
Abstract
A rotary transformer includes a resonant circuit and a coil drive circuit. The resonant circuit includes a resonating capacitor connected to a power MOS transistor, coupled across the primary coil of the transformer. The coil drive circuit includes a diode connected to a power MOS transistor coupled across the primary coil of the transformer. A microprocessor detects changes in the voltage across the primary coil. The resonant circuit is connected and disconnected from the transformer during a power transfer mode and a data transfer mode, respectively. During the power transfer mode, stored energy in the leakage inductance of the primary coil is used for power coupling, via the resonant circuit, instead of being dissipated as heat. The resonant circuit is disconnected from the rotary transformer during the data transfer mode to maximize bandwidth for two-way data transfer between the primary and secondary sides of the transformer. The transformer uses a synchronous mode of operation in which the power MOS transistor of the coil drive circuit is turned on when the voltage across the primary coil changes from a positive to a negative value during the power transfer mode. The synchronous mode of operation virtually eliminates a current spike through the diode of the coil drive circuit and provides the microprocessor an appropriate amount of time to recognize the voltage changes across the primary coil.
6 Citations
18 Claims
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1. A rotary transformer, comprising:
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a primary coil;
a secondary coil;
a resonant circuit coupled to the primary coil;
a coil drive circuit coupled to the primary coil; and
a microprocessor connected to the primary coil for detecting a voltage across the primary coil, wherein a control voltage is input to the coil drive circuit when the microprocessor detects a transition of the voltage across the primary coil from a positive voltage to a negative voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A rotary transformer, comprising:
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a primary coil;
a secondary coil;
a resonant circuit coupled to the primary coil, the resonant circuit including a capacitor connected to the primary coil and a first drive transistor connected to the capacitor; and
a coil drive circuit coupled to the primary coil, the coil drive circuit including a diode connected to the primary coil and a second drive transistor connected to the diode, wherein a control voltage input to the second drive transistor turns the second drive transistor on when a voltage across the primary coil transitions from a positive voltage to a negative voltage. - View Dependent Claims (10, 11, 12, 13, 14, 16, 17, 18)
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15. A method of operating a rotary transformer having a primary coil, a second coil, a resonant circuit coupled to the primary coil, a coil drive circuit coupled to the primary coil, the method comprising the steps of:
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supplying a control voltage to the resonant circuit;
detecting a transition of a voltage across the primary coil when the control voltage is supplied to the resonant circuit; and
supplying a control voltage to the coil drive circuit when the transition of the voltage across the primary coil is detected in the detecting step.
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Specification