Inductive rotary joint with multimode inverter
First Claim
1. An inductive power transfer circuit comprisingan inductive rotating coupler having a primary side rotatably arranged against a secondary side, the primary side comprising at least a primary winding the secondary side comprising at least a secondary winding that is connected to a rectifier configured to deliver a DC output, the inductive rotating coupler further having a stray inductance;
- a resonance capacitor coupled in series with at least one of the primary winding and secondary winding the resonance capacitor forming a series resonance circuit together with the stray inductance defining at least one series resonance frequency,an inverter configured to convert a DC input voltage from a DC voltage source into an AC voltage, the inverter including at least four semiconductor switches that forma first branch of a first switch and a second switch anda second branch of a third switch and a fourth switch in a full bridge circuit, anda control circuit configured to generate control signals to control the at least four semiconductor switches, the control circuit being configured to generate control signals for a full bridge mode operation wherein alternatingly are closed the first switch together with the fourth switch, and the second switch together with the third switch,wherein the control circuit is further adapted to generate control signals for a half bridge mode operation, in which one switch of one of the first and second branches is closed to connect an inverter output to either a positive output of the DC voltage source or a negative output of the DC voltage source, and switches of the other of the first and second branches are closed alternatingly, andwherein the half bridge mode operation is initiated by independent and asynchronous depowering of one of drivers of one half bridge by a circuit that is independent from a bridge control circuit,wherein the control circuit is adapted to generate control signals for the half bridge mode operation for a given time and to switch later to a full bridge mode operation, wherein the control signals start with a low-duty cycle, which is increased with time.
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Accused Products
Abstract
An inductive power transfer circuit or inductive rotary joint has an inductive rotating coupler with a primary side and a primary winding rotatably arranged against a secondary side and a secondary winding. The secondary side is connected via a rectifier to a load. The stray inductance of the coupler together with a resonance capacitor a series resonance circuit having a series resonance frequency. An inverter in a full bridge circuit is provided for converting a DC input voltage into an AC voltage. The inverter is operable in a full bridge mode to deliver a high power level and in a half bridge mode to deliver a low power level. This results in a broad dynamic range, soft power on and improved safety, as switching between the modes may be controlled by a simple hardware.
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Citations
10 Claims
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1. An inductive power transfer circuit comprising
an inductive rotating coupler having a primary side rotatably arranged against a secondary side, the primary side comprising at least a primary winding the secondary side comprising at least a secondary winding that is connected to a rectifier configured to deliver a DC output, the inductive rotating coupler further having a stray inductance; -
a resonance capacitor coupled in series with at least one of the primary winding and secondary winding the resonance capacitor forming a series resonance circuit together with the stray inductance defining at least one series resonance frequency, an inverter configured to convert a DC input voltage from a DC voltage source into an AC voltage, the inverter including at least four semiconductor switches that form a first branch of a first switch and a second switch and a second branch of a third switch and a fourth switch in a full bridge circuit, and a control circuit configured to generate control signals to control the at least four semiconductor switches, the control circuit being configured to generate control signals for a full bridge mode operation wherein alternatingly are closed the first switch together with the fourth switch, and the second switch together with the third switch, wherein the control circuit is further adapted to generate control signals for a half bridge mode operation, in which one switch of one of the first and second branches is closed to connect an inverter output to either a positive output of the DC voltage source or a negative output of the DC voltage source, and switches of the other of the first and second branches are closed alternatingly, and wherein the half bridge mode operation is initiated by independent and asynchronous depowering of one of drivers of one half bridge by a circuit that is independent from a bridge control circuit, wherein the control circuit is adapted to generate control signals for the half bridge mode operation for a given time and to switch later to a full bridge mode operation, wherein the control signals start with a low-duty cycle, which is increased with time. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for operating an inductive power transfer circuit that comprises
an inductive rotating coupler having a primary side rotatably arranged against a secondary side, the primary side comprising at least a primary winding, the secondary side comprising at least a secondary winding connected to a rectifier configured to deliver a DC output, the inductive rotating coupler further having a stray inductance, a resonance capacitor coupled in series with at least one of the primary winding and the secondary winding, the resonance capacitor forming a series resonance circuit together with the stray inductance defining at least one series resonance frequency, an inverter configured to convert a DC input voltage from a DC voltage source into an AC voltage, the inverter comprising at least four semiconductor switches forming a first branch of a first switch and a second switch and a second branch of a third switch and a fourth switch in a full bridge circuit, the method comprising: -
in a full bridge mode, alternatingly switching the first switch together with the fourth switch and the second switch together with the third switch, and in a half bridge mode, switching one switch of one of the first and second branches to a closed state to connect an inverter output to either a positive output of the DC voltage source or a negative output of the DC voltage source, and alternatingly switching switches of another of the first and second branches to closed states, wherein the control circuit is adapted to generate control signals in the half bridge mode in a start sequence and to switch later to the full bridge mode, wherein the control signals start with a low duty cycle, which is increased with time. - View Dependent Claims (9, 10)
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Specification