In-Vehicle Motor Control Device Rapid Capacitor Discharge
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Solution Overview
Problem
Conventional control systems for in-vehicle electric motors take a long time to discharge capacitors during abnormal vehicle conditions, such as collisions, due to inefficient torque generation and regenerative charging, leading to prolonged capacitor discharge times.
Innovation Solution
A control device with a relay switch between the DC power source and capacitor, which generates torque in the electric motor to quickly consume capacitor charge and interrupt continuity between the power source and capacitor, using specific switching patterns to expedite discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor is controlled to inhibit torque generation during capacitor discharge, then the control system prevents motor interference, but the capacitor discharge time is prolonged
Solution Approach 1:
Instead of inhibiting torque generation during capacitor discharge as in conventional systems, this patent inverts the approach by actively generating torque to drive the motor. This torque generation creates a load that accelerates capacitor discharge, reducing discharge time from several seconds to under 1 second while the relay maintains isolation from the DC power source
2Reliability
If the relay switch disconnects the DC power source from the capacitor, then the capacitor can discharge independently, but the discharge rate is insufficient without motor load
Solution Approach 1:
The motor acts as an intermediary load between the capacitor and the discharge process. By controlling the motor to generate torque, the system creates an effective load that accelerates energy consumption from the capacitor, transforming the discharge rate without requiring direct connection to the DC power source
3Loss of energy
If regenerative charging occurs during motor operation, then energy is recovered, but the capacitor discharge time is extended
Solution Approach 1:
The control system applies preliminary anti-action by detecting regenerative charging conditions and immediately adjusting motor control parameters to prevent excessive energy return to the capacitor. This includes limiting torque generation during phases when regenerative charging would occur, ensuring net energy removal from the capacitor
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
The control device enables rapid discharge of capacitors during abnormal conditions, ensuring the voltage drops below a safety threshold in a shorter time, enhancing safety and efficiency.
Implementation Method 1
a capacitor for stabilizing the output voltage output from the DC power source to the drive circuit
Implementation Method 2
the inverter circuit outputs an alternating current to an electric motor... the electric motor on the basis of an output voltage from a DC voltage source
Data Source
AI summary
In a control device controlling a drive circuit that drives an in-vehicle electric motor based on an output voltage of a DC power source, a capacitor for stabilizing the output voltage is disposed between the DC power source and the drive circuit, and a relay switch is disposed between the DC power source and the capacitor. The control device includes: an anomaly determining device that determines whether an anomaly occurs in a vehicle; and a discharge control device that controls the drive circuit to generate a torque at the electric motor based on an output voltage of the capacitor in a state where the relay switch disconnects between the DC power source and the capacitor when the anomaly determining device determines that the anomaly occurs in the vehicle.