Motor Controller Current Decay for EV Charging NVH Control
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Solution Overview
Problem
The rapid reduction of current in the motor winding when the charging pile stops supplying power leads to rapid torque release, causing mechanical structures in electric vehicles to slip and rebound, resulting in poor noise, vibration, and harshness (NVH) performance.
Innovation Solution
A powertrain system with a motor controller that includes three bridge arms connected in parallel, allowing the motor controller to gradually decrease the motor current when the direct current power supply stops, thereby controlling the torque release and reducing mechanical slipping sounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging pile actively stops supplying power, then the charging process can be ended, but the motor current rapidly reduces causing torque release and mechanical structure slipping resulting in poor NVH performance
Solution Approach 1:
The control method applies preliminary anti-action by detecting when the charging pile stops supplying power and immediately implementing a current decay control strategy. The motor controller switches from constant current charging to a mode where the current gradually decays to zero, preventing the rapid torque release that would otherwise cause mechanical structure slipping and poor NVH performance.
Solution Approach 2:
The system dynamically adjusts the motor current based on the charging pile's power supply state. When the charging pile stops supplying power, the controller transitions from a static constant current mode to a dynamic current decay mode, where the current gradually reduces to zero. This dynamic adjustment ensures smooth torque release and prevents mechanical vibrations and noises.
2Loss of time
If the motor winding current is rapidly reduced when power supply stops, then the charging process ends quickly, but torque release causes mechanical structures to slip and rebound creating noise and vibration
Solution Approach 1:
The control method implements periodic action by using pulse-width modulation (PWM) to control the motor current decay. The controller periodically switches the bridge arm transistors to regulate the current flow, creating a controlled decay pattern that gradually reduces torque while preventing sudden mechanical releases that would generate noise and vibration.
Solution Approach 2:
The system uses feedback control to monitor the motor current and adjust the bridge arm transistor switching accordingly. When the charging pile stops supplying power, the controller continuously monitors the current decay process and adjusts the PWM duty cycle to ensure the current reduces at an optimal rate, preventing excessive torque release and mechanical structure slipping that would cause NVH issues.
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 improves the NVH performance of electric vehicles by gradually reducing motor torque and minimizing mechanical slipping sounds when the charging pile stops supplying power.
Implementation Method 1
a motor controller and a drive motor, the motor controller includes three bridge arms connected in parallel... bridge arm midpoints of the three bridge arms are configured to connect to three phase windings of the drive motor
Data Source
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AI summary
This application provides a powertrain, a control method for a motor controller, and an electric vehicle. The powertrain includes a motor controller and a drive motor, the motor controller includes three bridge arms connected in parallel, each bridge arm includes an upper bridge arm switching transistor and a lower bridge arm switching transistor, one end of each bridge arm is configured to connect one end of a direct current power supply and one end of a power battery, the other end is configured to connect to the other end of the power battery, bridge arm midpoints of the three bridge arms are configured to connect to three phase windings of the drive motor, and a bridge arm midpoint of one of the three bridge arms is configured to connect to the other end of the direct current power supply. In response to that the direct current power supply switches from outputting a direct current to stopping outputting the direct current, an upper bridge arm switching transistor of one bridge arm of the other two bridge arms of the three bridge arms is turned on and a lower bridge arm switching transistor of the other bridge arm of the other two bridge arms is turned on. The power battery is configured to supply power to one phase winding and another phase winding, to reduce slipping sound and improve an NVH feature of the electric vehicle.