Feedback Pulse Edge Control for EMI-Limited Motor Drives
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Solution Overview
Problem
Modern electric powertrains with high slew rate voltage pulses generate harmful electromagnetic interference and can damage motor coils, necessitating effective control of pulse rise and fall times to mitigate these issues.
Innovation Solution
A voltage pulse generator (VPG) with a controller and negative feedback circuit dynamically controls the rise and fall times of voltage pulses by comparing output voltage to a time-dependent reference voltage, using a hysteretic comparator to adjust the switching of semiconductor switches, thereby regulating the average slew rate of pulse edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high slew rate voltage pulses are used in voltage source inverters, then power delivery efficiency to motor coils is improved, but electromagnetic interference and coil damage increase
Solution Approach 1:
The patent implements dynamic slew rate control by continuously adjusting the rise and fall times of voltage pulses based on real-time operating conditions. The controller modifies pulse characteristics dynamically rather than using fixed parameters, allowing optimization of power delivery while preventing EMI generation under varying load and frequency conditions
Solution Approach 2:
The invention changes the temporal parameters of voltage pulses (rise time and fall time) to control slew rate. By adjusting these time parameters, the system maintains effective power transfer while limiting the rate of voltage change that causes electromagnetic interference and coil stress
2Power
If high slew rate voltage pulses are used, then power delivery efficiency is improved, but coil damage risk increases
Solution Approach 1:
The system dynamically adapts pulse characteristics to protect coils from damage while maintaining power delivery efficiency. The controller monitors operating conditions and adjusts slew rate in real-time to prevent excessive voltage changes that would stress coil windings and insulation
Solution Approach 2:
The patent employs feedback control mechanisms that monitor voltage and current conditions to regulate slew rate. This feedback ensures that voltage pulses remain within safe limits for coil durability while maintaining sufficient power delivery, preventing cumulative damage from excessive slew rates
3Object-affected harmful factors
If slew rate is limited to reduce EMI, then electromagnetic interference decreases, but power delivery efficiency deteriorates
Solution Approach 1:
The system dynamically adjusts slew rate limits based on operating conditions such as load demand, frequency, and temperature. During high power demand periods, the controller allows higher slew rates to maintain efficiency, while reducing slew rates during steady-state operation to minimize EMI, optimizing both objectives simultaneously
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 VPG effectively limits the slew rate of voltage pulses, reducing electromagnetic interference and protecting motor coils, while maintaining desired pulse characteristics for efficient power delivery to electric motors.
Implementation Method 1
A voltage pulse generator (VPG) with a controller and negative feedback circuit dynamically controls the rise and fall times of voltage pulses by comparing output voltage to a time-dependent reference voltage
Data Source
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Figure 2B
AI summary
A voltage pulse generator comprising: circuitry controllable to generate a voltage pulse at an output of the circuitry; and an interruptor that monitors voltage at the output during a transition edge of the voltage pulse and interrupts a voltage change associated with the transition edge if the monitored voltage differs from a predetermined reference voltage by a predetermined amount.