Electric Compressor Interlock Control for Rapid Residual Charge Discharge
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Solution Overview
Problem
Conventional methods for discharging residual charge in high-voltage apparatuses, such as electric compressors, face inefficiencies and safety risks due to reliance on passive resistor discharge methods and active voltage-based detection, which can lead to false detection and prolonged discharge times, increasing the risk of electric shock.
Innovation Solution
A control device with an interlock loop annexed to the connector that detects connection/disconnection and forcibly discharges residual charge through the motor windings or a discharge circuit, independent of operating conditions and disturbances, allowing for quick and reliable discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a passive discharge method using multiple discharge resistors is used to balance discharge time and self-heating, then discharge time is reduced, but discharge current always flows between power line and ground line leading to low efficiency and increased mounting space and cost
Solution Approach 1:
The patent transitions from a static passive discharge method to a dynamic active discharge method. The control device actively controls the discharge timing and current path based on real-time detection of connector connection status, enabling discharge only when necessary rather than continuous discharge, thus improving energy efficiency while maintaining fast discharge capability.
Solution Approach 2:
The patent extracts the discharge function from the continuous power path and creates a separate dedicated discharge circuit. This allows the discharge current to be directed through a specific path (through the connector to ground) rather than always flowing between power line and ground line, improving efficiency and reducing unnecessary energy loss.
2Speed
If the threshold value for voltage drop detection is set higher to shorten detection time, then detection speed is improved, but the risk of false detection increases due to fluctuations from inverter switching operations
Solution Approach 1:
The patent implements a feedback-based detection system that continuously monitors the voltage between power line and ground line and compares it against dynamically adjusted criteria. The control device uses the detected voltage information to determine connector status, and this feedback loop allows for reliable detection even with moderate threshold values by considering the temporal pattern and context of voltage changes rather than relying solely on absolute threshold values.
Solution Approach 2:
The patent performs preliminary detection of the voltage state before making a definitive judgment on connector disconnection. By monitoring voltage fluctuations and identifying patterns that precede actual disconnection events, the system can prepare for detection without requiring excessively high threshold values, thus maintaining both speed and reliability.
3Measurement precision
If a current sensor is provided to judge connector connection state based on current direction, then detection accuracy is improved, but the current through discharge resistor must be increased which conflicts with the goal of reducing discharge current
Solution Approach 1:
The patent replaces the mechanical/electrical current sensor detection method with a voltage-based detection method. Instead of measuring current direction through a sensor, the system detects connector connection status by monitoring voltage between power line and ground line. This substitution eliminates the need for additional sensors and allows discharge current to remain low while maintaining high detection accuracy.
Solution Approach 2:
The patent uses voltage as an intermediary parameter to infer connector connection status without directly measuring current. By detecting voltage changes that occur when the connector is disconnected, the system can accurately determine connection state without requiring current sensors or increasing discharge current, thus resolving the contradiction between detection accuracy and energy loss.
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 solution enables rapid and accurate detection of connector disconnection and efficient discharge of residual charge, enhancing safety by reducing the risk of electric shock and eliminating the need for multiple discharge resistors, thus improving efficiency and reducing installation space and cost.
Implementation Method 1
an interlock loop annexed to a connector for connecting a high-voltage apparatus to a high-voltage power supply, wherein connection/disconnection of the connector is detected on the basis of a state of the interlock loop
Implementation Method 2
the inverter output circuit is controlled so as to forcibly discharge, through a winding of the motor, the residual charge accumulated in the smoothing capacitor
Data Source
AI summary
To provide a high-voltage apparatus control device capable of judging the connection state of a connector and discharging residual charge in a short time. A control device 1 controls an electric compressor and is provided with an interlock loop 4 annexed to a connector 9 for connecting the electric compressor to an HV battery 17. The control device 1 detects connection/disconnection of the connector 9 on the basis of the state of the interlock loop 4 and forcibly discharges residual charge in an internal smoothing capacitor 14 when disconnection of the connector 9 is detected.