Pulsed Electric Machine Control Using Lookup Tables
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Solution Overview
Problem
Electric machines, such as motors and generators, often operate at suboptimal efficiency levels due to varying torque and speed requirements, leading to reduced energy conversion efficiency, particularly in applications like electric vehicles where they frequently transition between high and low efficiency operating regions.
Innovation Solution
Implementing pulse control methods that determine whether the electric machine should operate in continuous or pulsed mode, with tables indexing vehicle speed and torque requests to define pulsing frequency and duty cycle, optimizing energy conversion efficiency while minimizing Noise, Vibration, and Harshness (NVH).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the electric machine operates continuously at optimal efficiency points, then energy conversion efficiency is maximized, but the machine cannot adapt to varying torque and speed requirements
Solution Approach 1:
The patent applies periodic pulsed action to the electric machine, switching between on and off states in a controlled manner. This allows the machine to operate at optimal efficiency points during pulsed operation while still meeting varying torque and speed requirements through appropriate pulse timing and duty cycle control, thereby resolving the contradiction between energy efficiency and adaptability.
2Loss of energy
If the electric machine operates in pulsed mode to improve efficiency, then energy conversion efficiency increases, but Noise, Vibration and Harshness (NVH) levels may increase
Solution Approach 1:
The patent dynamically adjusts pulsed operation parameters including frequency, duty cycle, and pulse width based on real-time operating conditions. This dynamic control allows the system to optimize energy efficiency while minimizing NVH by adapting pulse characteristics to match vehicle speed, torque requirements, and noise sensitivity thresholds.
Solution Approach 2:
The patent changes multiple operating parameters simultaneously including pulse frequency, duty cycle, and pulse width ratio. By coordinating these parameter changes, the system achieves improved energy efficiency while maintaining acceptable NVH levels through optimized pulse train characteristics that avoid resonant frequencies and excessive vibration.
3Adaptability or versatility
If the electric machine operates outside optimal efficiency regions to meet varying drive cycle requirements, then adaptability to driving conditions improves, but energy conversion efficiency decreases
Solution Approach 1:
The patent uses periodic pulsed operation to allow the electric machine to operate at or near optimal efficiency points even when vehicle torque and speed requirements vary. By controlling the pulse timing and duration, the machine can meet varying drive cycle requirements while spending more time in high-efficiency operating regions, thus improving overall energy conversion efficiency across different driving conditions.
Data Source
AI summary
A variety of methods, controllers and electric machine systems are described for pulse control of electric machines (e.g., electric motors and generators). To improve the energy conversion efficiency of the machine, pulse control involves determining if the machine should operate in a continuous mode or pulse mode, and if the latter, defining a magnitude, duty cycle, and frequency for the pulses. One or more tables, indexing by a wide range of speeds and torque requests, is/are used to define the pulsing frequency or a pulsing frequency pattern.