Three-Level Motor Inverter Control for Midpoint Voltage Stability
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Solution Overview
Problem
Three-phase full-bridge inverters suffer from high harmonic content in output voltage and current, leading to increased motor loss and noise, particularly in small torque areas, and three-level inverters face midpoint voltage fluctuations that can damage switches and reduce efficiency.
Innovation Solution
A motor driving apparatus with a three-level inverter and a control circuit that adjusts working modes based on motor conditions, stabilizing midpoint voltage by switching between two-level and three-level modes to maintain efficiency and prevent switch damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling apparatus is integrated into the motor housing to cool the motor, then the motor temperature is reduced, but the overall device size increases
Solution Approach 1:
The cooling apparatus is integrated into the motor housing structure, merging the cooling function with the structural housing. The housing serves dual purposes: providing mechanical protection and acting as a thermal management system through embedded cooling channels that circulate coolant to remove heat from the motor.
Solution Approach 2:
The motor housing is designed to perform multiple functions simultaneously: structural support, protection of internal components, and active cooling. The housing incorporates cooling channels and fluid communication paths, allowing it to serve as both a mechanical enclosure and a thermal management system, eliminating the need for separate cooling components.
2Quantity of substance
If the battery is disposed of after reaching end-of-life, then resource availability is maintained, but resource waste occurs
Solution Approach 1:
Instead of discarding end-of-life batteries, the system recovers and reuses them through a battery swapping mechanism. When a battery reaches its discharge limit, it is automatically replaced with a charged battery from the second battery group, and the depleted battery is recharged during vehicle idle time, thereby recovering its utility and preventing resource waste.
Solution Approach 2:
The system provides self-service battery management by automatically managing battery swapping and recharging operations. The vehicle can recharge depleted batteries during idle periods without requiring external intervention, maintaining continuous operation and maximizing resource utilization of the battery fleet.
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
Stabilizes midpoint voltage, reduces harmonic distortion, and enhances motor efficiency by dynamically adapting the inverter's operating mode to match torque conditions, thereby improving overall system performance.
Implementation Method 1
a cooling apparatus integrated into the motor housing to cool the motor
Data Source
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AI summary
This application provides a motor driving apparatus, a motor system, and an electric vehicle, to improve running efficiency of a motor and avoid damaging an inverter. The motor driving apparatus includes a three-level inverter, a motor parameter obtaining circuit, and a control circuit. The three-level inverter is configured to be separately connected to a first power supply and a motor, to invert a direct current provided by the first power supply into an alternating current, and provide the alternating current for the motor; the motor parameter obtaining circuit is configured to be separately coupled to the motor and the control circuit, and is configured to: obtain a motor working condition signal of the motor, and provide the motor working condition signal for the control circuit; and the control circuit is configured to: select a target working mode from a plurality of working modes based on the motor working condition signal, and control the three-level inverter in the target working mode, so that a midpoint voltage of the three-level inverter is less than a first voltage threshold.