Traction Inverter PWM Mode Selection for NVH and Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional control methods for traction power inverter modules in electric vehicles are less than optimal under varying vehicle operating conditions and loads, leading to inefficiencies and suboptimal performance.
Innovation Solution
A method is introduced where a controller automatically selects between continuous pulse width modulation (CPWM) and discontinuous pulse width modulation (DPWM) signals based on the commanded output torque of the traction motor, with CPWM chosen for high torque and DPWM for low torque, using a calibrated threshold and hysteresis band to optimize power conversion and reduce noise, vibration, and harshness (NVH).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional control methods are used for TPIM, then the system is simple to implement, but system efficiency and performance are suboptimal under varying operating conditions
Solution Approach 1:
The patent implements dynamic PWM mode selection that automatically transitions between CPWM and DPWM based on real-time operating conditions (torque, speed, temperature). This dynamic adaptation optimizes system efficiency across varying loads while maintaining manageable control complexity through automated decision-making algorithms.
Solution Approach 2:
The control system changes the PWM modulation parameter (switching between continuous and discontinuous modes) based on operating conditions. This parameter change enables the system to achieve optimal efficiency at different torque and speed points without requiring complete redesign of the control architecture.
2Measurement precision
If CPWM is used continuously, then torque control precision is maintained, but NVH performance deteriorates at light-to-medium loads
Solution Approach 1:
The patent applies different PWM control qualities to different operating conditions: DPWM is used for light-to-medium torque conditions where NVH reduction is prioritized, while CPWM is used for high torque conditions where precise torque control is critical. This local quality differentiation resolves the contradiction by matching control characteristics to operational requirements.
Solution Approach 2:
The system dynamically switches between CPWM and DPWM modes based on real-time torque and speed conditions. This dynamic adaptation allows the system to minimize NVH during light-to-medium loading while maintaining precise torque control during high-demand operations, eliminating the need for continuous use of a single PWM mode.
3Object-affected harmful factors
If DPWM is used continuously, then NVH is reduced at light loads, but torque control precision and system reliability deteriorate at high torque conditions
Solution Approach 1:
The patent implements local quality control by applying DPWM specifically to light-to-medium torque conditions where NVH is the primary concern, while reserving CPWM for high torque conditions where reliability and control precision are paramount. This targeted application resolves the contradiction by ensuring each PWM mode is used where it provides the greatest benefit.
Solution Approach 2:
The system dynamically transitions between DPWM and CPWM modes based on torque and speed thresholds. This dynamic switching ensures that DPWM's NVH reduction benefits are realized during appropriate operating conditions while CPWM maintains system reliability during high-torque operations, preventing continuous use of DPWM from compromising overall system performance.
4Device complexity
If single PWM mode is used, then control simplicity is maintained, but overall drive cycle efficiency deteriorates
Solution Approach 1:
The patent implements a dynamic dual-mode PWM control system that automatically selects between CPWM and DPWM based on real-time operating conditions. This dynamic approach optimizes drive cycle efficiency across varying loads and speeds while maintaining control simplicity through automated mode selection algorithms that eliminate the need for manual intervention.
Solution Approach 2:
The system changes the PWM operational parameter (switching between continuous and discontinuous modes) based on torque and speed conditions. This parameter change enables the system to achieve superior overall drive cycle efficiency compared to single-mode operation, while the automated decision-making process maintains control simplicity by eliminating complex manual tuning requirements.
Data Source
AI summary
A method for controlling a traction power inverter module (TPIM) in a vehicle includes determining a commanded output torque of the motor using a controller. The method further includes controlling the TPIM and motor using a discontinuous pulse width modulated (DPWM) signal when the commanded output torque is less than a calibrated torque threshold. A continuous pulse width modulated (CPWM) signal is used when the commanded output torque is greater than the threshold. The method may include determining a direction of a change in the commanded output torque, and controlling the TPIM, via the controller, using the DPWM signal only when the commanded output torque drops below a predetermined hysteresis level. A vehicle includes a traction motor producing a motor torque for propelling the vehicle, an ESS, a TPIM, and a controller configured as noted above.