Optical Voltage Probe Bias Compensation for Thermal Drift
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Solution Overview
Problem
Conventional high attenuation probes suffer from limited common mode signal rejection and are sensitive to temperature changes, requiring frequent and time-consuming calibrations to maintain measurement accuracy.
Innovation Solution
A probe device with an optical cable, sensor head, and probe interface that includes temperature sensors and bias voltage sources to automatically compensate for thermal drift by adjusting bias voltages within predefined temperature ranges, and triggers recalibration when temperatures exceed these ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional high attenuation probes are used to measure high voltages, then voltage measurement capability is achieved, but common mode signal rejection is limited
Solution Approach 1:
The patent introduces an optical intermediary (light) between the high voltage signal and the measurement instrument. The probe converts electrical signals to optical signals via a photodetector, transmits them through optical fiber, and converts back to electrical signals at the oscilloscope. This optical intermediary provides galvanic isolation, achieving high common mode rejection while maintaining measurement reliability.
2Reliability
If optical sources and photoreceivers are used to isolate the test instrument, then common mode signal rejection is improved, but sensitivity to temperature changes increases
Solution Approach 1:
The patent implements temperature sensing feedback to monitor the temperature of the optical source and photoreceiver. The system uses this temperature information to dynamically adjust bias voltages applied to these components, compensating for thermal drift and maintaining measurement accuracy despite temperature variations.
Solution Approach 2:
The patent changes the electrical parameters (bias voltages) of the optical source and photoreceiver based on temperature conditions. By adjusting these parameters in response to temperature changes, the system compensates for thermal effects on the optical components' performance.
3Measurement precision
If manual calibration is performed frequently to maintain accuracy, then measurement precision is maintained, but time consumption increases
Solution Approach 1:
The patent implements an automatic calibration system that performs self-calibration of the probe without requiring manual intervention. The system uses internal reference signals and processing to automatically adjust and maintain calibration, eliminating the need for frequent manual calibration operations.
Solution Approach 2:
The system uses feedback mechanisms to continuously monitor performance and automatically adjust calibration parameters. This closed-loop approach maintains measurement precision over time without requiring periodic manual calibration interruptions.
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 probe device achieves high common mode rejection and reliable high voltage measurements over a wider distance, providing increased safety and reducing the need for manual recalibration due to temperature fluctuations.
Implementation Method 1
a laser source configured to receive output electrical signals from the DUT, the output electrical signals driving the laser source to provide optical signals corresponding to the output electrical signals from the DUT
Implementation Method 2
a photoreceiver configured to receive the optical signals over the optical cable, to convert the optical signals to electrical test signals and to input the electrical test signals to the test instrument
Implementation Method 3
a first temperature sensor configured to monitor a first temperature of the laser source; a second temperature sensor configured to monitor a second temperature of the photoreceiver
Data Source
AI summary
A system and method for compensating for thermal drift of a probe device includes monitoring a first temperature of a laser source in a sensor head that receives output electrical signals from a DUT and outputs corresponding optical signals; monitoring a second temperature of a photoreceiver in a probe interface that converts the optical signals to electrical test signals to input to the test instrument; calculating a first value of a first bias voltage; applying the first value of the first bias voltage to the laser source to compensate for thermal drift when the first temperature is within a first predefined temperature range; calculating a second value of a second bias voltage for the photoreceiver; and applying the second value of the second bias voltage to the photoreceiver to compensate for thermal drift when the second temperature is within a second predefined temperature range.