Waveform Shaping Circuit Fault Detection in Tissue Signal Generators
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Solution Overview
Problem
Signal generators used in pulsed electric field therapy face reliability issues due to the failure of solid state switches under high voltage and current conditions, particularly when operating under low impedance conditions.
Innovation Solution
A signal generator design incorporating capacitors, waveform shaping circuits, and a controller that performs fault tests on switches to ensure reliable operation by checking voltage and current thresholds, including a fault detection mechanism to identify stuck switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If solid state switches are used to generate pulsed electric field signals, then the signal generator can produce high voltage and high current pulses, but the switches may fail under low impedance conditions, reducing reliability
Solution Approach 1:
The system performs preliminary fault detection tests by attempting to turn on switches and measuring resulting current to identify stuck switches before actual treatment delivery, preventing failures during critical operations
Solution Approach 2:
The system continuously monitors switch status through current sensing circuits that provide feedback to the controller, enabling real-time detection of switch failures and adaptive control to maintain reliable operation
2Reliability
If fault detection tests are performed on switches, then switch failures can be identified and reliability improved, but the system complexity and test time increase
Solution Approach 1:
The system performs self-diagnosis by using its own switching network and power supply to conduct fault detection tests, eliminating the need for external testing equipment and reducing overall system complexity
Solution Approach 2:
The fault detection functionality is merged with the existing switching network and control circuitry, combining diagnostic capabilities with treatment delivery components to minimize additional 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
Enhances the reliability of signal generators by detecting and preventing switch failures, ensuring consistent and safe delivery of treatment signals.
Implementation Method 1
one or more capacitors coupled between a high voltage rail and a low voltage rail and configured to store energy that can be used to selectively generate a treatment signal
Implementation Method 2
each of the switches configured to allow current to pass through the switch when the switch is turned ON and to prevent current from passing through the switch when the switch is turned OFF
Implementation Method 3
The voltage sense circuit is configured to sense a voltage stored on the one or more capacitors
Implementation Method 4
The current sense circuit is configured to sense current having a magnitude that is indicative of a magnitude of current flowing through a pair of the switches that are turned ON by the controller
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Embodiments described herein relate to signal generators, systems including signal generators, and related methods. A signal generator includes capacitor(s) to store energy used to generate a treatment signal. The signal generator also includes a waveform shaping circuit, a controller, a voltage sense circuit, and a current sense circuit. The waveform shaping circuit is coupled to the capacitor(s) and includes first, second, third, and fourth switches, each of which is configured to be selectively turned ON and OFF, to allow current to pass through the switch when turned ON, and to prevent current from passing through the switch when turned OFF. The controller selectively controls the switches in order to generate the treatment signal. The controller also selectively controls the switches in order to perform certain fault tests, which rely on voltages sensed by the voltage sense circuit and currents sensed by the current sense circuit.