Piezoelectric Sensor Ground Fault Compensation Circuit
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Solution Overview
Problem
Piezoelectric sensors in electrically perturbed environments, such as diesel engine glow plugs, face issues with high-intensity currents causing leakage currents and electrostatic discharges, leading to complex and expensive integrated circuit manufacturing.
Innovation Solution
A sensor design with a capacitive feedback loop and voltage adder circuit that compensates for potential differences between mechanical and electronic grounds, reducing leakage currents and parasitic effects, allowing for standard and cost-effective integrated circuit manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage regulator is electrically coupled to the mechanical ground to provide regulated voltage, then the sensor can operate in electrically perturbed environments, but potential differences between mechanical and electronic grounds increase leakage currents
Solution Approach 1:
A voltage adder circuit is introduced as an intermediary between the mechanical ground and the capacitive feedback loop. This circuit measures the potential difference between mechanical and electronic grounds and injects a compensating voltage that varies as a function of this potential difference, thereby eliminating leakage currents while maintaining reliable operation in electrically perturbed environments
2Ease of manufacture
If most components are connected to the mechanical ground in the integrated circuit, then the circuit can be produced as an integrated circuit, but this leads to risks of electrostatic discharges and parasitic electrical effects
Solution Approach 1:
The voltage adder circuit actively maintains equipotential conditions between the mechanical ground reference and the capacitive feedback loop by injecting a compensating voltage that counteracts potential differences. This prevents electrostatic discharges and parasitic effects while allowing standard integrated circuit manufacturing processes to be used
3Object-generated harmful factors
If a voltage adder circuit is used to compensate for potential differences, then leakage currents are reduced, but the device complexity increases
Solution Approach 1:
The voltage adder circuit is integrated within the existing capacitive feedback loop structure of the charge amplifier. The compensation function is combined with the signal processing function, adding minimal complexity while effectively reducing leakage currents. The circuit uses standard operational amplifiers and capacitors that can be manufactured using conventional integrated circuit processes
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 solution automatically compensates for potential differences across the entire passband of the detector, preventing electrostatic discharges and parasitic effects, ensuring reliable and inexpensive manufacturing while maintaining signal integrity.
Implementation Method 1
a piezoelectric detector mounted in a support
Implementation Method 2
a capacitive feedback loop between the output and the input of the processing amplifier receiving the signal delivered by the piezoelectric detector, said capacitive feedback loop comprising a capacitor
Data Source
AI summary
A sensor includes a piezoelectric detector (10) mounted in a support having electrically conductive walls forming a mechanical ground (MM), and an amplifier for processing the signal delivered by the piezoelectric detector, defining an electronic ground (ME) and at least a capacitive feedback loop (16). A voltage adder circuit (61) is inserted into the capacitive feedback loop in order to add an electrical voltage which varies as a function of the potential difference between the mechanical ground (MM) and the electronic ground (ME), so that the variations of this potential difference are continuously compensated for at the input (13) of the processing amplifier (12) receiving the signal delivered by the piezoelectric detector (10).