Rotary Electric Machine Control Device Modulation
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Solution Overview
Problem
Existing rotary electric machine control devices face challenges in achieving flexible and high positional accuracy, particularly in low-speed rotation regions, due to limitations in interpolation methods and device configurations.
Innovation Solution
A control device and method that utilize a combination of rotation angle sensors, an interpolation angle calculating unit, a modulation amount determining unit, and a driving waveform generating unit to supply specific driving waveforms to an inverter circuit, allowing for finely tuned rotation control by determining modulation amounts based on interpolation angles and rotational speeds, without the need for high-resolution position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a plurality of Hall sensors are used for position detection, then the device cost is reduced, but the positional accuracy deteriorates due to discrete angular levels
Solution Approach 1:
An interpolation calculation unit is introduced as an intermediary component that processes the discrete signals from Hall sensors and generates high-resolution position information. This mediator translates low-resolution sensor data into high-resolution position angles through interpolation calculations, resolving the contradiction between using simple sensors and achieving high positional accuracy.
Solution Approach 2:
The patent replaces the need for high-resolution mechanical position sensors with a combination of low-resolution Hall sensors and computational interpolation. Instead of using expensive high-resolution sensors, the system substitutes mechanical sensing with electronic signal processing and mathematical interpolation to achieve high positional accuracy.
2Ease of operation
If fixed interpolation methods are selected based on rotational speed regions, then control simplicity is maintained, but control flexibility deteriorates
Solution Approach 1:
The patent implements dynamic switching between different interpolation methods based on rotational speed. The control system automatically selects appropriate interpolation strategies (such as changing interpolation orders or methods) according to the current operational region, providing both simplicity through automation and flexibility through adaptability to different speed conditions.
Solution Approach 2:
The system changes interpolation parameters dynamically based on rotational speed regions. By adjusting interpolation orders, calculation methods, or other parameters according to the operating conditions, the system maintains simple control logic while achieving flexible adaptation to different speed ranges and accuracy requirements.
3Measurement precision
If high-resolution position sensors are used, then positional accuracy is improved, but device complexity and cost increase
Solution Approach 1:
An interpolation calculation unit serves as a mediator that bridges the gap between low-resolution Hall sensors and high-resolution position requirements. This computational intermediary processes simple sensor inputs and generates high-resolution position information without requiring complex or expensive high-resolution sensors.
Solution Approach 2:
The system creates a high-resolution position information copy through interpolation calculations based on low-resolution Hall sensor data. Instead of directly measuring high-resolution position, the system generates a computational copy of high-resolution position information from simpler sensor inputs, achieving the same effect with lower hardware complexity.
Data Source
AI summary
A motor control device performs rotation control of a motor by supplying a first driving waveform and a second driving waveform respectively to a pair of switching elements which make up part of upper and lower arms in an inverter circuit. The motor control device determines the amount of modulation of the second driving waveform from a combination of the calculated interpolation angle and the rotational speed of the motor. The motor control device generates the first driving waveform having a rectangular shape, and further generates the second driving waveform by performing pulse modulation by the determined amount of modulation.