Variable Resistor Inverter Surge Suppression
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Solution Overview
Problem
In power steering systems, when an inverter fails, the generation of surge voltage can lead to insulation breakdown or damage to motor windings and switches, making it difficult for a driver to control a large vehicle without assistance.
Innovation Solution
A drive control device with variable resistive elements connected between motors and inverters, which are controlled by a controller to gradually increase resistance when a fault is detected, suppressing surge voltage and allowing normal inverters to continue motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switch is provided between a faulty inverter and a motor to enable continuous operation by other inverters, then the motor can continue operating with one inverter, but a large surge voltage is generated when the circuit changes from short-circuit state to open state, causing insulation breakdown or switch damage
Solution Approach 1:
A variable resistive element is introduced as an intermediary component between the faulty inverter and the motor. This element gradually increases its resistance value to disconnect the faulty inverter, preventing direct switching that causes surge voltage. The variable resistive element acts as a buffer that mediates the energy release from the motor's inductance, avoiding insulation breakdown and component damage while enabling continuous operation by other inverters.
Solution Approach 2:
The resistance value of the variable resistive element is dynamically changed from a low initial value to a high final value during the disconnection process. This parameter change allows the circuit to transition smoothly from a conductive state to a disconnected state, controlling the rate of current change and thereby limiting surge voltage generation. The gradual parameter change resolves the contradiction between enabling continuous operation and preventing harmful surge voltage.
2Reliability
If an inverter fails in a power steering system, then the steering assistance is lost requiring large driver force, but the system can continue operating with remaining inverters if properly controlled
Solution Approach 1:
The power steering system is segmented into multiple independent inverter units, each capable of driving the motor separately. When one inverter fails, the system automatically isolates the faulty segment using the variable resistive element and continues operation with the remaining functional segments. This segmentation provides redundancy, ensuring steering assistance remains available and reducing the burden on the driver by maintaining electric power support.
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 solution effectively suppresses surge voltage, preventing damage to the motor and variable resistive elements, enabling continuous operation of the motor by other inverters and reducing the burden on the driver.
Implementation Method 1
a variable resistive element that is connected between the motor and each of the inverters, and has its resistance value capable of being externally and variably controlled
Implementation Method 2
a surge voltage is generated by an inductance component in the circuit
Data Source
AI summary
The invention provides a drive control device that comprises: inverters that are connected to a motor; a variable resistive element that is connected between the motor and each of the inverters; a current/voltage detection device connected between the motor and each of the inverters; and a controller that, when detecting a fault of an inverter that drives the motor based on a detection signal from the current/voltage detection device, gradually increases a resistance value of a variable resistive element provided between the faulty inverter and the motor at a velocity of a resistance variation such that a surge voltage has a voltage value for which the variable resistive element and the motor are not damaged, and executes drive control of the motor by a normal inverter other than the faulty inverter.