Rotary Electrical Machine Modulation Transition Control
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Solution Overview
Problem
During the transition from full-wave to pulse-width modulation in rotating electrical machines, there are uncontrolled current variations that lead to voltage peaks exceeding the limits authorized by the vehicle's energy storage device control electronics, causing potential harm to the on-board energy system.
Innovation Solution
A control method that manages the transition by applying a pre-defluxing current setpoint equal to the direct axis current measurement, with a convergence time optimized to be within or greater than half the current setpoint refresh period, typically between 100 microseconds and 5 milliseconds, to maintain voltage limits and minimize torque variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the modulation type changes from full-wave to PWM during speed control, then precise control of the electrical machine is achieved, but uncontrolled current variations occur causing voltage peaks that exceed authorized limits
Solution Approach 1:
The control method applies a pre-defluxing current setpoint equal to the direct axis current measurement before the modulation change is completed. This preliminary action prepares the current in advance to match the required setpoint, preventing uncontrolled current variations and voltage peaks when transitioning from full-wave to PWM modulation mode.
Solution Approach 2:
The method optimizes the convergence time parameter to be within or greater than half the current setpoint refresh period (typically 100 microseconds to 5 milliseconds). By carefully controlling this time parameter, the current convergence is synchronized with the control system's refresh cycle, ensuring smooth transition without exceeding voltage limits while maintaining precise control.
2Reliability
If the convergence time is extended to allow current to converge properly, then voltage limits are maintained, but the transition duration increases affecting system responsiveness
Solution Approach 1:
The convergence time is optimized to a specific range (100 microseconds to 5 milliseconds, preferably within or greater than half the current setpoint refresh period). This parameter optimization ensures that the current has sufficient time to converge to the pre-defluxing setpoint while maintaining system responsiveness and not unnecessarily extending the transition duration.
Data Source
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Figure 5~6a
AI summary
The invention relates mainly to a method of controlling a rotating electrical machine (7) cooperating with a gearbox (1) of a motor vehicle, characterized in that, during a synchronization phase between two speed ratios (R1-Rn) during which the rotating electrical machine (7) is driven in speed and changes the type of modulation to go from full-wave modulation (PM) to pulse-width modulation (PWM), said method includes a control step aimed at limiting the variations of an output current of an inverter during the phase of changing the type of modulation without compensation for variations in torque.