Onboard Electric System Discharge Switcher Reliability
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Solution Overview
Problem
In onboard electric systems, when an abnormal state occurs and the low voltage power supply fails to output voltage, the electronic control apparatus cannot generate a discharge control signal, preventing the smoothing capacitor from discharging its electric charge through the inverter circuit and stator coil.
Innovation Solution
An onboard electric system with a drive circuit, a smoothing capacitor, a discharge resistor, a normally-ON type discharge switcher, and an off-signal generator, where the discharge switcher automatically connects the capacitor's electrodes through the resistor when an abnormal state occurs, allowing for automatic discharge of electric charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a normally-OFF discharge switcher is used to discharge the smoothing capacitor, then the discharge function can be controlled during normal operation, but the discharge function fails when the control signal is not provided during abnormal states
Solution Approach 1:
The patent inverts the default state of the discharge switcher from normally-OFF to normally-ON. This means the discharge path is automatically activated during abnormal states when control signals are unavailable, while during normal operation the switcher is controlled to close (disconnecting the discharge path) through conventional control signals. This inversion ensures the discharge function remains reliable even when control signals are not provided.
2Reliability
If the discharge switcher remains connected during normal operation, then automatic discharge occurs during abnormal states, but energy is continuously dissipated during normal operation
Solution Approach 1:
The patent makes the discharge switcher dynamic by enabling it to change its state based on operational conditions. During normal operation, the switcher is controlled to close, connecting the discharge path and allowing energy dissipation through the discharge resistor. During abnormal states, the switcher automatically opens, disconnecting the discharge path and preventing continuous energy loss. This dynamic behavior balances reliability and energy efficiency.
3Ease of operation
If the discharge switcher is controlled by electronic control apparatus, then discharge timing can be precisely managed, but the system fails when the low voltage power supply fails
Solution Approach 1:
The patent introduces an intermediary mechanism in the form of a discharge switcher that responds to the absence of control signals. Instead of relying solely on the electronic control apparatus to manage discharge timing, the switcher is designed to automatically activate when control signals are not provided, serving as a backup mechanism that ensures discharge function availability even when the low voltage power supply fails.
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
Enables the discharge of electric charge from the smoothing capacitor even during abnormal states when the off signal is not provided, ensuring continued operation and stability of the electric motor.
Implementation Method 1
a first discharge resistor that is connected between a positive electrode and a negative electrode of the first smoothing capacitor; a first discharge switcher that is connected in series to the first discharge resistor between the positive electrode and the negative electrode of the first smoothing capacitor
Data Source
AI summary
An onboard electric system includes a drive circuit that drives an electric motor based on an output voltage of a direct current power supply; a first smoothing capacitor; a drive signal generator; a first discharge resistor that is connected between a positive electrode and a negative electrode of the first smoothing capacitor; a first discharge switcher that is connected in series to the first discharge resistor between the positive electrode and the negative electrode, and releases or makes a connection between the positive electrode and the negative electrode; and an off-signal generator that outputs an off signal to the first discharge switcher. The first discharge switcher is provided by a switcher of a normally-ON type that makes the connection between the positive electrode and the negative electrode through the first discharge resistor in a period other than a period while the off-signal generator provides the off signal.