Electric Motor Controller Symmetric Wiring for Current Balance
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Solution Overview
Problem
In electric driving apparatuses for vehicles, the imbalance in driving current supplied by dual inverter circuits can lead to poor rotational balance of electric motors, affecting driver feedback during steering operations.
Innovation Solution
A controller design featuring two current-supply circuits, a control board, an integrated circuit, and a micro-computer, where the micro-computer outputs operation signals symmetrically to pre-driver circuits, ensuring equivalent impedance and balanced driving currents through symmetric wiring patterns, thereby improving rotational balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two systems of inverter circuits are provided for driving the electric motor, then the reliability is improved (continuous operation possible even when one breaks down), but the manufacturing precision deteriorates (rotational balance becomes worse due to current differences)
Solution Approach 1:
The patent applies asymmetry in reverse (achieving symmetry) by positioning the micro-computer on the center line of the control board and arranging output terminals and wiring patterns symmetrically with respect to this center line. This symmetrical arrangement ensures that the impedance from the micro-computer to both inverter circuits is substantially equal, thereby balancing the driving currents and improving rotational balance while maintaining the dual-system reliability
2Ease of manufacture
If the micro-computer is positioned off-center to simplify wiring, then the ease of manufacture is improved, but the manufacturing precision deteriorates (rotational balance worsens due to unequal impedance)
Solution Approach 1:
The patent creates electrical equipotentiality by positioning the micro-computer on the center line and arranging symmetric wiring patterns, ensuring that the impedance from the micro-computer to both inverter circuits is substantially equal. This equipotential arrangement balances the driving currents supplied to both inverter circuits, thereby improving rotational balance while maintaining manufacturing feasibility
Data Source
AI summary
Each of a first and a second inverter circuit supplies a driving current to an electric motor in a different power supply line. A custom IC has a first pre-driver circuit for outputting control signals to the first inverter circuit and a second pre-driver circuit for outputting control signals to the second inverter circuit. A micro-computer for outputting operation signals to the first and second pre-driver circuits is mounted to a control board on a center line. A distance between the center line and the first inverter circuit and a distance between the center line and the second inverter circuit is equal to each other. First and second output terminals of the micro-computer as well as first and second input and output terminals of the custom IC are symmetric with respect to the center line.