Motor Control Modulation Switching for Efficiency
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Solution Overview
Problem
Existing motor control systems face challenges in improving power efficiency without deteriorating starting characteristics and drive characteristics, particularly at low rotational speeds, where disturbances can lead to waveform disruptions and overvoltage issues.
Innovation Solution
A motor control method that dynamically switches between three-phase and two-phase modulation schemes based on rotational speed, using a microcontroller to determine when to perform current correction and switch between the two schemes, thereby optimizing power efficiency and maintaining drive characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If two-phase modulation scheme is used, then power efficiency is improved by reducing switchings, but starting characteristics and drive characteristics deteriorate at low rotational speeds due to waveform disturbances
Solution Approach 1:
The patent applies dynamics by dynamically switching between two-phase and three-phase modulation schemes based on the detected rotational speed. When rotational speed is below the reference speed, the system switches to three-phase modulation to ensure stable drive characteristics, and when above the reference speed, it uses two-phase modulation to reduce power losses from switchings.
2Temperature
If two-phase modulation scheme is used, then switching element temperature increase is reduced, but disturbance effects become significant causing overvoltage and harmonics at low currents
Solution Approach 1:
The system dynamically adjusts the modulation scheme based on operational conditions. By switching to three-phase modulation when rotational speed is low (where currents are smaller and disturbance effects are more significant), the system prevents overvoltage and harmonics while still allowing two-phase modulation at higher speeds to reduce temperature increases from frequent switchings.
3Reliability
If three-phase modulation scheme is used, then starting characteristics and drive characteristics are maintained, but power efficiency decreases due to increased switchings
Solution Approach 1:
The patent implements dynamic switching between modulation schemes based on rotational speed thresholds. Three-phase modulation is used only when rotational speed is below the reference speed to maintain starting characteristics, while two-phase modulation is used above the reference speed to reduce power losses, thus optimizing both reliability and energy efficiency across different operating conditions.
4Stability of the object's composition
If three-phase modulation scheme is used, then waveform stability is maintained at low speeds, but the number of switchings increases causing higher power loss
Solution Approach 1:
The system dynamically selects the modulation scheme based on rotational speed. By using three-phase modulation only when rotational speed is below the reference speed (where waveform stability is critical), and switching to two-phase modulation above the reference speed (where power loss reduction is more beneficial), the system achieves optimal balance between waveform stability and energy efficiency.
Data Source
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AI summary
A method of controlling a motor (9) includes the steps of a) acquiring a rotational speed parameter; b) selecting one of a three-phase modulation scheme and a two-phase modulation scheme as a switching signal generation system based on a result of comparing a rotational speed (S45) of the motor (9) with a predetermined reference speed; c) calculating phase voltage command values (S49) based on a target rotational speed (S40) and the rotational speed parameter; d) generating switching signals (S4) by employing the selected switching signal generation system based on the phase voltage command values (S49); and e) outputting the switching signals (S4) to an inverter (2). In step b), the two-phase modulation scheme is selected when the rotational speed (S45) of the motor (9) is higher than the reference speed. Thus, a switching loss can be reduced and power efficiency can be improved without deteriorating starting characteristics and motor drive characteristics when the rotational speed (S45) is low.