Inverter AC Current Generation for Zero-Torque Battery Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle systems cannot efficiently heat batteries using DC voltage buses while controlling machine torque near zero, as conventional three-phase balanced currents generate DC current in the inverter bus, which is not suitable for rapid battery heating.
Innovation Solution
A system that generates three alternating current (AC) phases with specific amplitudes and phases, ensuring they sum to zero, allowing for AC current generation in the inverter DC bus, which heats the battery without producing torque in the electric motor, using a three-phase inverter and control module that adjusts currents based on rotor position and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional three-phase balanced currents are used in the inverter bus, then the electric motor operates normally, but DC current is generated in the inverter bus which prevents rapid battery heating
Solution Approach 1:
The patent applies asymmetry by using unbalanced three-phase currents instead of conventional balanced currents. The first AC phase has a different amplitude relationship (substantially equal to the sum of the second and third amplitudes) and phase relationship (second and third phases substantially equal to 180 degrees out of phase with the first phase) that creates AC current in the DC bus while maintaining motor operation. This asymmetric current distribution enables the DC bus to carry AC current that heats the battery rapidly without preventing the motor from functioning.
2Productivity
If AC current is generated in the inverter DC bus to heat the battery, then rapid battery heating is achieved, but torque may be generated in the electric motor
Solution Approach 1:
The patent applies parameter changes by carefully controlling the amplitude and phase parameters of the three AC phases. The specific parameter relationships (first amplitude substantially equal to the sum of the second and third amplitudes; second and third phases substantially equal to 180 degrees out of phase with the first phase) are designed to create AC current in the DC bus while generating substantially zero torque in the motor. This precise parameter control allows the system to achieve rapid battery heating without unwanted motor torque.
3Temperature
If external heaters are used to heat the battery, then battery heating is achieved, but additional components and system complexity are required
Solution Approach 1:
The patent applies universality by making the inverter DC bus serve multiple functions: it continues to operate as the power distribution bus for the electric motor while simultaneously functioning as a heating element for the battery. By controlling the inverter switches to generate AC current in the DC bus, the system uses existing components for dual purposes, eliminating the need for separate external heaters and reducing overall system complexity.
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 enables rapid battery heating without external convective heating, eliminating the need for external heaters and maintaining zero torque in the electric motor, effectively utilizing AC current in the inverter DC bus for thermal management.
Implementation Method 1
the AC generating module creates a heating alternating current in the DC battery
Data Source
AI summary
An apparatus for heating a DC battery in a vehicle including an electric motor. The apparatus comprises an AC generating module coupled to the battery and the electric motor that generates three AC phases. The first, second, and third AC phases are applied to first, second, and third windings of the electric motor, respectively. The first, second, and third AC phases create zero torque in the electric motor because the first AC phase amplitude is equal to the sum of the second and third AC phase amplitudes and the second and third AC phases are 180 degrees out of phase with the first AC phase. The AC generating module creates a heating alternating current in the DC battery.