PWM Current Compensation in Rotating Machine Control
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Solution Overview
Problem
Existing rotating machine control devices face challenges in reducing switching events to minimize voltage and current harmonics while preventing peak electric-currents from exceeding safe limits, which can lead to demagnetization or device breakdown.
Innovation Solution
A rotating machine control device with an instruction voltage compensator that adjusts switching instructions based on detected electric current values to ensure they do not exceed a threshold, using a hysteresis comparator to invert PWM pulses when necessary, thereby controlling peak electric-currents and reducing switching events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the number of switching events is decreased to minimize losses and harmonics, then switching losses are reduced, but peak electric-current increases causing demagnetization or device breakdown
Solution Approach 1:
The control device predicts future peak electric-current values before they actually occur by analyzing the instruction voltage waveform and motor characteristics in advance. This allows the system to prepare compensation measures beforehand, preventing peak current from exceeding safe thresholds while maintaining reduced switching events.
Solution Approach 2:
The system continuously monitors actual electric-current values and compares them with predicted values. Based on this feedback, the control device dynamically adjusts the PWM instruction voltage to compensate for predicted peak currents, ensuring reliable current control while maintaining low switching losses.
2Loss of energy
If the number of switching events is decreased, then switching losses are reduced, but voltage harmonics increase
Solution Approach 1:
The control device changes the timing parameters of PWM switching events based on predicted peak current positions. By strategically adjusting when switching occurs rather than simply increasing the number of switches, the system minimizes both switching losses and voltage harmonics simultaneously.
3Loss of energy
If PWM pulses are not instantaneously manipulated, then switching losses are reduced, but peak electric-current cannot be controlled when it instantaneously increases
Solution Approach 1:
The system performs preliminary prediction of peak current events before they occur, allowing the control device to prepare and execute compensation actions proactively. This eliminates the need for instantaneous reactive manipulation while maintaining both low switching losses and effective peak current control.
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
Effectively curbs peak electric-currents and protects the rotating machine and electric power converter by ensuring they do not exceed safe limits, while minimizing switching events and harmonics, thus maintaining device stability and efficiency.
Implementation Method 1
A rotating machine control device with an instruction voltage compensator that adjusts switching instructions based on detected electric current values to ensure they do not exceed a threshold, using a hysteresis comparator to invert PWM pulses when necessary
Data Source
AI summary
A rotating machine control device comprises a switching instruction generation unit for exchanging a DC voltage for AC voltages by means of an electric power converter to apply them to a rotating machine, and also for instructing the switching operations of PWM pulses in the electric power converter. The switching instruction generation unit comprises an instruction voltage generator for producing an instruction voltage, and an instruction voltage compensator for compensating the aforementioned instruction voltage by means of the instruction voltage generator; and the instruction voltage compensator compensates the aforementioned instruction voltage on the basis of electric current related information of the rotating machine so that the electric current related information does not exceed a threshold value being set in advance.