High-Voltage Precharge Monitoring Circuit for Fault Detection
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Solution Overview
Problem
High voltage circuit precharging can result in damaging current spikes, and existing precharge circuits may fail to monitor and control the precharging process effectively, leading to potential component damage or incomplete energization.
Innovation Solution
A precharge monitoring circuit that compares a scaled and offset version of the high voltage circuit voltage to a reference voltage, discontinuing precharging if the voltage does not increase as predicted, and activating a fault signal if precharging is not successful, using a switch control signal to enable or disable the precharge current based on this comparison.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a precharge circuit is used to slowly ramp up the supply voltage, then component damage is prevented, but the precharging process takes longer and may not reliably detect precharge failures
Solution Approach 1:
The patent implements a monitoring circuit that continuously compares the actual precharge voltage against an expected reference voltage curve. When the actual voltage deviates from the expected trajectory (indicating a precharge failure), the system immediately discontinues precharging and activates a fault signal. This feedback mechanism enables real-time detection of precharge failures without requiring extended precharge timing, thus maintaining reliability while reducing time loss.
2Measurement precision
If software is used to compare sensed voltage at discrete time intervals, then precharge monitoring is implemented, but the monitoring precision is insufficient to detect rapid voltage deviations
Solution Approach 1:
The patent introduces a reference voltage circuit that generates an expected voltage curve during precharging. The monitoring circuit compares the actual precharge voltage against this reference curve using a dedicated comparator. This intermediary reference voltage serves as a benchmark, enabling continuous and precise detection of voltage deviations without requiring complex software algorithms or high-speed sampling, thus achieving high measurement precision with moderate circuit complexity.
3Measurement precision
If the reference circuit time constant matches the high voltage circuit time constant, then monitoring accuracy is improved, but noise may cause false precharge discontinuation
Solution Approach 1:
The patent applies an offset voltage to the reference voltage curve to create a hysteresis buffer zone. This offset acts as a cushion that prevents the comparator from triggering on minor voltage fluctuations or noise during precharging. By designing the reference circuit with this built-in tolerance, the system maintains high detection accuracy for genuine precharge failures while filtering out spurious signals, thus reducing false discontinuations.
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
Effectively monitors and controls the precharging process to prevent component damage by ensuring the voltage increases as predicted, discontinuing precharging if deviations occur, and notifying controls of potential failures, thus ensuring reliable energization of high voltage circuits.
Implementation Method 1
A reference circuit generates a reference voltage curve having a predetermined time constant (e.g., R×C).
Data Source
AI summary
Methods and apparatus to monitor the precharging of high voltage circuits are disclosed. In one embodiment, an apparatus includes a switch that selectively enables or disables precharge current to a high voltage circuit based on a switch control signal. The apparatus also includes a comparison circuit that compares a scaled version of a circuit voltage to a reference voltage to generate the switch control signal. In one embodiment, the switch control signal is generated to enable the precharge current when the scaled version of the circuit voltage is greater than the reference voltage.