Capacitor Discharge Control Without Current Sensors
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Solution Overview
Problem
Conventional electric discharge controllers rely on electric current sensors to detect phase currents, making it impossible to reliably discharge the capacitor when an abnormality occurs in the sensor, leading to potential durability issues in drive motor controllers.
Innovation Solution
An electric discharge controller that generates a voltage command value for electric discharge based on the difference between a target direct current voltage and the detected voltage, allowing for the generation of a driving signal to be supplied to the inverter without using an electric current sensor, enabling reliable discharge of the capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electric current sensors are used to detect phase currents for capacitor discharge control, then the discharge control can be implemented, but the system reliability deteriorates when sensor abnormalities occur
Solution Approach 1:
The patent extracts and eliminates the electric current sensor from the discharge control system. Instead of using sensor-based current detection, the invention uses voltage detection combined with discharge current command values to control the inverter switching, thereby removing the single point of failure associated with current sensors and improving system reliability
Solution Approach 2:
The patent introduces voltage detection as an intermediary mechanism. Rather than directly measuring current (which requires sensors), the system measures voltage and uses it as a mediator to control the discharge process through the inverter, indirectly achieving current control without physical current sensors
2Device complexity
If voltage command value for electric discharge is generated based on voltage difference, then electric current sensor is eliminated, but measurement precision requirements increase
Solution Approach 1:
The patent changes the measurement parameter from current to voltage. By measuring voltage (which can be done with high precision and without additional sensors) and using it to derive discharge control commands, the system achieves the same control objective with different measurement characteristics that are more favorable for reliability
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 allows for the reliable consumption of electric charge in the capacitor without relying on electric current sensors, thereby improving the durability of the drive motor controller and ensuring no drive motor torque is generated during discharge.
Implementation Method 1
an inverter for receiving a direct electric current supplied from a direct electric current source and generating an alternating electric current and supplying the alternating electric current to the electrically operated machine
Implementation Method 2
an electric charge corresponding to electrostatic capacity is accumulated in a capacitor arranged between the battery and the inverter
Implementation Method 3
The electric currents of the respective phases are supplied to the drive motor, and the drive motor is driven
Implementation Method 4
the drive motor receives torque by inertia of the electric automobile, and generates the direct electric current and supplies this electric current to the battery
Data Source
AI summary
The electric charge of a capacitor can be reliably discharged. Therefore, an electric discharge controller has an electrically operated machine, an inverter, a capacitor, a voltage command value generating processor for generating a voltage command value for driving, an electric discharge control processor for generating a voltage command value for electric discharge, and a driving signal generating processor. When an electric current is supplied from a direct electric current source to the inverter, the driving signal generating processor generates a driving signal on the basis of the voltage command value for driving. When the supply of the electric current from the direct electric current source to the inverter is interrupted, the driving signal generating processor generates the driving signal on the basis of the voltage command value for electric discharge, and supplies the driving signal to the inverter. The electric discharge control processor generates the voltage command value for electric discharge on the basis of the difference between a target direct current voltage and the direct current voltage. When the supply of the electric current from the direct electric current source to the inverter is interrupted, the driving signal is generated on the basis of the voltage command value for electric discharge and is supplied to the inverter.