Anti-Backflow Detection Circuit Using Current-Based Fault Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing anti-backflow circuits in electric vehicle charging systems suffer from low accuracy in failure detection, which can lead to safety hazards due to backflow of electric energy from high-voltage battery packs to charging piles, and current detection methods are unreliable and dependent on voltage precision.
Innovation Solution
A detection circuit that generates a first level signal based on detection current to determine the failure of the anti-backflow circuit, independent of input and output voltages, and includes a digital unit to output signals indicating circuit failure or non-failure, with additional components like a breaking circuit, detection diode, and resistor to protect the circuit and prevent backflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage-based detection methods are used to detect anti-backflow circuit failures, then the detection can be performed during charging operation, but the detection accuracy is low and depends on voltage precision
Solution Approach 1:
The patent introduces a detection diode as an intermediary component that converts the anti-backflow circuit's operational state into a detectable current signal. The detection diode is connected in reverse parallel with the anti-backflow circuit, and when the anti-backflow circuit fails (becomes conductive in reverse direction), current flows through the detection diode, generating a detectable signal that indicates failure without requiring precise voltage measurements
Solution Approach 2:
The patent replaces the conventional voltage-based detection method with a current-based detection method. Instead of measuring voltage levels to infer circuit state, the system uses a detection circuit that generates a current signal when failure occurs, which is then processed by a digital unit. This substitution improves detection accuracy by relying on current presence/absence rather than voltage precision
2Reliability
If the detection circuit operates continuously during charging, then real-time failure detection is possible, but the detection circuit may be damaged by backflow current
Solution Approach 1:
The detection diode serves as a protective intermediary that allows the detection circuit to monitor the anti-backflow circuit without being directly exposed to harmful backflow currents. The diode's directional conductivity enables it to conduct detection current in normal operation while blocking potentially damaging reverse currents from the anti-backflow circuit
Solution Approach 2:
The detection circuit uses the anti-backflow circuit's own failure state to generate the detection signal. When the anti-backflow circuit fails and becomes conductive in the reverse direction, this failure condition itself creates the current path that triggers the detection signal, eliminating the need for external test signals that could interfere with normal operation or damage the detection circuit
3Loss of time
If voltage-based detection is used, then the detection system can operate during charging, but it cannot detect failures before connection to power battery
Solution Approach 1:
The detection circuit is designed to perform failure detection before the charging connection is established. The detection diode and detection power supply are configured to activate the detection function in advance, allowing the system to verify anti-backflow circuit integrity before connecting to the high-voltage battery pack, thus preventing potential damage from undetected failures
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
Improves the accuracy of failure detection and prevents backflow before connecting to the power battery, prolonging the detection circuit's lifespan and enhancing safety by reducing reliance on voltage precision and enabling pre-connection detection.
Implementation Method 1
A detection power supply and a digital unit are disposed in the detection circuit, and the detection power supply and the digital unit are connected in series between the first end and the second end of the detection circuit
Implementation Method 2
The detection circuit includes a detection diode, and the detection diode is connected in series to both the detection power supply and the digital unit
Data Source
Figure 1~2
Figure 3~4
Figure 5~6a
AI summary
This application discloses a detection circuit, an anti-backflow system, and a charging pile. The detection circuit mainly includes a detection power supply and a digital unit that are connected in series. A first end and a second end of the detection circuit are respectively connected to an input end and an output end of an anti-backflow circuit. The detection power supply may make an electric potential at the second end of the detection circuit higher than that at the first end of the detection circuit. When transmitting a detection current, the digital unit may output a first level signal indicating that the anti-backflow circuit fails. The detection current is a current transmitted when a loop is formed between the first end and the second end of the detection circuit. In this application, a detection result of the detection circuit does not depend on detection precision of a voltage value. This helps improve accuracy of failure detection of the anti-backflow circuit. In addition, the detection circuit may perform failure detection before a charging pile is connected to a power battery. This further helps protect safety of an electric vehicle.