High Voltage Generation Apparatus Power Factor Control
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Solution Overview
Problem
High voltage generation apparatuses for X-ray CT systems face challenges in maintaining a stable power factor and voltage during X-ray irradiation, leading to fluctuations in X-ray dose due to abrupt changes in load, which existing solutions like reactors and power factor improvement circuitry fail to adequately address without increasing size and weight.
Innovation Solution
Incorporating power factor improvement circuitry and gain adjustment circuitry to dynamically adjust the output voltage gain based on the start and end of X-ray irradiation periods, using feedback control to maintain a constant inverter input voltage and improve power factor without the need for reactors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power factor improvement circuitry is used to improve power factor to 0.95-0.99, then apparent power of AC power source is reduced and dimensions/weight are suppressed, but output voltage fluctuates when load abruptly changes during X-ray irradiation
Solution Approach 1:
The control circuit proactively detects transitions in X-ray irradiation state and preemptively adjusts the operating state of the power factor improvement circuitry before significant voltage fluctuations occur. This preliminary detection and response mechanism prevents voltage instability rather than reacting to it after the fact.
Solution Approach 2:
The control circuit continuously monitors the operational state of the power factor improvement circuitry and the load conditions, then dynamically adjusts control parameters based on this feedback. This closed-loop control ensures that voltage stability is maintained while preserving the high power factor improvement, adapting in real-time to load changes during X-ray irradiation.
2Loss of energy
If reactor is used to improve power factor to approximately 0.8, then power factor is improved, but dimensions and weight of apparatus are significantly increased
Solution Approach 1:
The invention replaces the mechanical/reactive approach of using physical reactors with an electronic control system. The power factor improvement circuitry uses active electronic components and control algorithms to achieve power factor correction, eliminating the need for bulky magnetic reactor components and their associated mechanical structures.
3Device complexity
If gain of power factor improvement circuitry is kept constant, then control is simple, but tube voltage fluctuates when load changes during X-ray irradiation
Solution Approach 1:
The invention transitions from a static, fixed-gain control system to a dynamic control system where the gain of the power factor improvement circuitry is continuously adjusted based on real-time detection of X-ray irradiation state and load conditions. This dynamic adaptation allows the system to maintain optimal performance across varying operational conditions without excessive 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 maintains a high power factor and stable X-ray dose by reducing the apparent power and size of the AC power source, suppressing fluctuations in voltage and dose, and avoiding the use of reactors, thus downsizing the apparatus while maintaining performance.
Implementation Method 1
power factor improvement circuitry improves a power factor of AC power
Implementation Method 2
feedback circuitry detects an inverter input voltage, and outputs a feedback signal based on the detected inverter input voltage
Implementation Method 3
gain adjustment circuitry adjusts a gain of an output voltage relative to a reference voltage so that the gain differs between a first period including a start of irradiation of X-rays
Data Source
AI summary
A high voltage generation apparatus according to an embodiment includes power factor improvement circuitry and gain adjustment circuitry. The power factor improvement circuitry improves a power factor of alternating current (AC) power output from an AC power source in order to supply an X-ray tube with power that is controlled based on a reference voltage. The gain adjustment circuitry is included in the power factor improvement circuitry, and adjusts a gain of an output voltage relative to the reference voltage so that the gain differs between a first period including a start of irradiation of X-rays by the X-ray tube or an end of irradiation of X-rays by the X-ray tube, and a second period different from the first period.