Electric Compressor Power Path Switching for Capacitor Charge Control
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Solution Overview
Problem
In electric compressors powered by external batteries, the buildup of electric charge in capacitors can damage devices or reduce their lifetimes when the vehicular system stops and the voltage from the high-voltage battery becomes lower than the low-voltage power supply.
Innovation Solution
An electric compressor configuration that includes a switch and a control circuit to connect or disconnect a power supply path from the power supply circuit to the drive circuit based on voltage differences between the capacitor and the inverter circuit, preventing electric charge buildup in capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inverter circuit converts DC power to AC power using a capacitor for filtering, then the power conversion function is improved, but electric charge buildup in the capacitor may damage devices or reduce their lifetimes
Solution Approach 1:
The control circuit monitors voltage levels and proactively opens the switch before dangerous charge buildup can occur in the capacitor. This preliminary action prevents the harmful effect while maintaining the beneficial power conversion function during normal operation.
Solution Approach 2:
The switch acts as an intermediary element between the power supply circuit and the inverter circuit. By controlling the connection state of this intermediary component, the system can isolate the capacitor from excessive voltage while maintaining normal power flow during safe conditions.
2Object-affected harmful factors
If a switch is added to control the power supply path, then electric charge buildup is prevented, but the device complexity increases
Solution Approach 1:
The control circuit automatically monitors voltage levels and controls the switch operation without external intervention. This self-service approach manages the additional complexity internally while providing a simple solution to the charge buildup problem.
Solution Approach 2:
The control circuit monitors voltage parameters and changes the switch state based on voltage threshold conditions. This parameter-based control strategy manages the complexity through automated decision-making rather than complex circuit design.
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
Prevents power for controlling the electric compressor from damaging devices or reducing their lifetimes by managing the electric charge in capacitors, ensuring safe operation and extended device lifespan.
Implementation Method 1
The filter circuit reduces noise in power supplied from the battery through the filter circuit. The capacitor constitutes a filter circuit.
Implementation Method 2
The inverter circuit receives power supplied from the battery through the filter circuit, converts the received power from DC power to AC power, and supplies the AC power to the electric motor.
Data Source
AI summary
An electric compressor includes an electric motor, a filter circuit, a capacitor, an inverter circuit, a drive circuit, a power supply circuit, a switch that connects or disconnects a power supply path that passes power from the power supply circuit to the drive circuit, and a control circuit that controls an operation of the switch. The control circuit connects the power supply path in response to the voltage between the capacitor and the inverter circuit being higher than that between the power supply circuit and the drive circuit, and the control circuit disconnects the power supply path in response to the voltage between the capacitor and the inverter circuit being lower than the voltage between the power supply circuit and the drive circuit.