Rotating Transformer Power Transmission with DC/DC Control
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Solution Overview
Problem
Existing contactless inductive rotary joints for power transmission between rotating and stationary parts, such as in computer tomographs, face challenges with variable coupling factors leading to significant voltage changes, require complex resonance circuits that are difficult to control, and lack efficient feedback mechanisms for maintaining constant output parameters, resulting in increased power losses and control complexities.
Innovation Solution
A rotating power transmission device with a transformer-like design featuring a primary winding coupled via a series capacitor to an AC voltage supply, forming a resonance circuit with an additional inductor to adjust resonance frequency, and an AC voltage supply that includes a DC power stage and an inverter circuit for controlled output voltage and frequency, along with a measuring circuit to maintain constant load parameters, minimizing switching losses and optimizing dynamic behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inductive rotary joints are used for contactless power transmission, then torque, wear, and maintenance are minimized, but significant voltage changes occur due to variable coupling factors and stray inductance
Solution Approach 1:
The patent applies parameter changes by using a DC/DC converter to dynamically adjust the output voltage parameters. The converter monitors the actual output voltage and adjusts its output parameters in real-time to compensate for voltage fluctuations caused by variable coupling factors, thereby maintaining stable output voltage while preserving the contactless transmission benefits
Solution Approach 2:
The patent implements feedback control through a voltage sensor that continuously monitors the output voltage and feeds this information back to the DC/DC converter. This closed-loop feedback mechanism enables the converter to detect voltage deviations and automatically adjust its output to maintain constant voltage, resolving the stability issue without compromising the contactless transmission advantage
2Power
If resonance circuits are used to transmit higher power via the rotary joint, then power transmission capability is improved, but control becomes very difficult and energy stored in resonance elements must be discharged before changing output parameters
Solution Approach 1:
The patent replaces the mechanical resonance circuit approach with an electronic DC/DC converter system. Instead of relying on resonant LC circuits that store energy and are difficult to control, the invention uses a modern power electronic converter that can rapidly adjust output parameters without energy storage constraints, thereby maintaining high power transmission capability while dramatically improving ease of control
Solution Approach 2:
The patent applies dynamics by using a DC/DC converter that can dynamically and rapidly adjust its output voltage and current in real-time. Unlike static resonance circuits that require energy discharge before parameter changes, the dynamic converter can instantly modify its output characteristics to match load requirements, enabling flexible control while transmitting high power
3Stability of the object's composition
If sensors and control amplifiers are added to maintain constant electrical parameters at the output side, then output parameter stability is improved, but device complexity increases and additional rotary joints are required for feedback
Solution Approach 1:
The patent merges the power conversion and control functions into a single integrated DC/DC converter unit. Instead of adding separate sensors, control amplifiers, and feedback rotary joints to an existing system, the invention incorporates voltage monitoring and regulation directly within the converter itself, maintaining output parameter stability while minimizing additional system complexity
Solution Approach 2:
The patent applies self-service by designing the DC/DC converter to autonomously monitor and regulate its own output voltage. The converter includes built-in voltage sensing and control circuitry that automatically adjusts its operation to maintain constant output parameters without requiring external sensors or complex feedback mechanisms, thereby reducing overall system complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables constant output voltage or current without the need for feedback sensors, reduces switching losses, and provides enhanced control over output power, ensuring efficient and stable power transmission across varying load conditions.
Implementation Method 1
The series capacitor (28) forms together with the inductance of the rotating transformer a resonance circuit having a preferred resonance frequency
Implementation Method 2
a primary winding (27) and a secondary winding (11)... for transmission of electrical power between a first part (20; 10) and a second part (10; 20), of which one of the parts is a rotating part and the other part is a stationary part
Implementation Method 3
an inverter circuit (23) for converting a DC voltage into an AC voltage at a controlled frequency and amplitude
Implementation Method 4
furthermore magnetic cores comprising iron or ferrite materials are provided to control the magnetic field between primary and secondary winding
Data Source
Figure 1~2
Figure 3
AI summary
An inductive coupled power transmission circuit has a rotating transformer, comprising an AC voltage supply for feeding an AC voltage via a series capacitor into the primary winding of said rotating transformer and a load being coupled to the secondary winding of said rotating transformer. The AC voltage supply comprises a line rectifier for receiving AC voltage from a power line and generating a DC voltage. This is fed into a DC/DC converter for converting the DC voltage from the line rectifier into a controlled intermediate DC voltage. An AC generator generates an AC voltage from the intermediate DC voltage and feeds this via a matching transformer into the primary winding of the rotating transformer. A measuring circuit measures voltages and/or currents within the AC voltage supply and a function generator estimates voltage and/or current values at the load based on the measured values and controls the DC/DC converter and/or the AC generator based on the estimated values.