Pulsed Power Supply Charge Integration for Excess Energy Protection
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Solution Overview
Problem
PEF generators used in medical applications pose a risk of delivering excessive energy due to potential switch network failures, which can cause thermal damage to patients, necessitating a safety mechanism to limit energy output.
Innovation Solution
An over-energy protection (OEP) circuit that senses the output current, integrates it to determine charge delivery, and disables the power supply if the charge exceeds a threshold, ensuring safe energy levels are not exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the power supply uses high internal energy storage capacitor bank to produce well shaped square wave output voltages, then the output voltage quality is improved, but the risk of delivering excessive energy to the patient increases
Solution Approach 1:
The patent implements preliminary action by integrating an over-energy protection (OEP) circuit that continuously monitors and integrates the output current to track cumulative energy delivery before harmful effects occur. The circuit proactively disables the power supply when the integrated charge reaches a predetermined threshold, preventing excessive energy delivery before it can cause thermal damage to patient tissue.
Solution Approach 2:
The patent applies feedback by using an integrator circuit that continuously accumulates the output current signal and feeds back a representative voltage signal to the control system. This feedback mechanism allows real-time monitoring of total energy delivered, enabling the system to self-regulate and automatically shut down when energy thresholds are approached, thus maintaining safety while allowing high energy storage operation.
2Power
If the power supply is rated for extremely high peak power levels, then the therapeutic effectiveness is improved, but the potential harm from switch network failures increases
Solution Approach 1:
The patent implements beforehand cushioning by incorporating an OEP circuit that acts as a safety buffer against high power failures. The circuit integrates output current and compares the accumulated charge against a predetermined threshold, creating a protective barrier that limits maximum energy delivery even when the power supply is capable of much higher peak power levels. This cushioning effect prevents thermal damage while preserving therapeutic effectiveness.
3Power
If the switch network is used to deliver high energy from capacitor bank, then the power delivery capability is improved, but the reliability of safe operation decreases
Solution Approach 1:
The patent introduces an intermediary protective layer by placing the OEP circuit between the high-power switch network and the patient load. The integrator circuit serves as a mediator that continuously monitors the energy flow through the switch network, accumulating charge information and translating it into a safety-determining voltage signal. This intermediary mechanism adds reliability to safe operation without interfering with the power delivery capability of the switch network.
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
The OEP circuit effectively prevents excessive energy delivery, enhancing patient safety by immediately disabling the power supply when unsafe energy levels are detected, thereby preventing thermal damage.
Implementation Method 1
the current sensor comprises a shunt resistor and a rectifier, the shunt resistor being configured to produce a voltage drop proportional to the output current
Implementation Method 2
an integrator configured to integrate the sensed current signal to generate the charge-delivered signal that is representative of the total charge delivered by the power supply over a time interval
Implementation Method 3
a comparator configured to compare the charge delivered with the threshold, and to generate the fault signal to disable the power supply if the charge-delivered signal exceeds the reference voltage
Implementation Method 4
an integrating capacitor and a reset resistor coupled in parallel between the output of the operational amplifier and the inverting terminal of the operational amplifier, the reset resistor providing a path for the integrating capacitor to discharge after the time interval
Data Source
AI summary
An energy delivery system comprises a power supply configured to generate a pulsed output voltage and a pulsed output current, and an over-energy protection (OEP) circuit coupled to the power supply. The OEP circuit senses the output current of the power supply and generates a sensed current signal, generates a charge-delivered signal from the sensed current signal that is representative of the charge delivered by the power supply over a time interval, and generates a fault signal that disables the power supply if the charge-delivered signal exceeds a threshold.