Leakage Detection Circuit With Pre-Charging for Variable Capacitance
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Solution Overview
Problem
Existing electrical leakage determination devices struggle to accurately detect leakage between a power supply circuit and ground due to changes in common capacitance caused by factors like temperature changes and variations in electric devices connected to the battery, leading to reduced detection accuracy.
Innovation Solution
An electrical leakage determination device that applies a low amplitude voltage and a high amplitude voltage to a detection resistor, with the high amplitude voltage being applied before the low amplitude voltage to ensure complete charging of common capacitance, and adjusts the pulse widths of these voltages based on detected voltage changes to maintain accurate peak value detection, thereby adapting to changes in common capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only low amplitude voltage is applied to the detection resistor, then the detection circuit operates normally, but the common capacitance is not completely charged leading to inaccurate leakage detection
Solution Approach 1:
The patent applies high amplitude voltage before the low amplitude voltage to pre-charge the common capacitance. This preliminary action ensures that when the low amplitude voltage is applied for normal detection, the capacitance is already charged, enabling accurate leakage detection without requiring excessively long detection time.
Solution Approach 2:
The patent uses periodic voltage application with alternating high and low amplitude phases. The high amplitude voltage is applied in pulses during each driving cycle to charge the capacitance, followed by low amplitude voltage for detection. This periodic pattern maintains accurate detection while managing the time required for capacitance charging.
2Measurement precision
If high amplitude voltage is applied to charge common capacitance, then detection accuracy improves, but the circuit may be damaged or excessive current may flow
Solution Approach 1:
The high amplitude voltage is applied as a preliminary charging step before the actual detection phase. By separating the charging function (high amplitude) from the detection function (low amplitude), the system achieves complete capacitance charging without maintaining high voltage during detection, thus avoiding continuous excessive current and potential damage.
Solution Approach 2:
The high amplitude voltage is applied periodically in controlled pulses rather than continuously. This periodic application limits the total energy delivered to the capacitance while ensuring it is sufficiently charged for detection, reducing the risk of overheating or damage from sustained high voltage.
3Measurement precision
If the detection time is extended to charge common capacitance, then accurate leakage detection is achieved, but the response time and productivity decrease
Solution Approach 1:
The common capacitance is charged in advance using high amplitude voltage during the preliminary phase of each driving cycle. This eliminates the need for extended detection time, as the capacitance is already charged when detection begins, thus maintaining both accuracy and fast response.
Solution Approach 2:
The system uses periodic high amplitude voltage pulses to rapidly charge the capacitance at the start of each driving cycle, followed by immediate low amplitude detection. This periodic structure enables repeated accurate detections without requiring long charging periods, thereby maintaining high productivity.
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
This configuration ensures accurate determination of electrical leakage between the power supply circuit and ground, even with fluctuations in common capacitance, by optimizing the charge amount and discharge of common capacitance, thus enhancing the robustness of the detection process.
Implementation Method 1
a capacitor whose first end is connected to a positive electrode or a negative electrode of the battery
Implementation Method 2
a detection resistor connected to a second end of the capacitor
Data Source
AI summary
An electrical leakage determination device includes: a capacitor connected to a battery; a detection resistor connected to the capacitor; a detection unit detecting a voltage value at a connection point between the detection resistor and the capacitor; a low amplitude voltage application unit applying a low amplitude voltage to the detection resistor every driving cycle; a high amplitude voltage application unit applying, before the application of the low amplitude voltage to the detection resistor, a high amplitude voltage to the detection resistor. The device determines whether there is electrical leakage between the power supply circuit and the ground based on a peak value of the voltage value detected when the low amplitude voltage is being applied, and changes a time integral value of the high amplitude voltage applied to the detection resistor based on a change in the voltage value detected when the low amplitude voltage is being applied.