Single Shunt Motor Control via Software Current Determination
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Solution Overview
Problem
Conventional motor control systems for PMSM, BLDC, and induction motors require costly high-performance ADCs for accurate low-speed operations, leading to increased costs and potential noise introduction.
Innovation Solution
A method and apparatus utilizing a single shunt and software-based implementation to generate PWM signals, determining direct-axis and quadrature-axis currents without the need for high-performance ADCs, by integrating a voltage signal and commanded angle from a reference signal, and applying these signals to an inverter for motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-performance ADCs are used for accurate low-speed motor control, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces expensive high-performance ADCs with a single shunt and software-based current determination. The shunt provides basic current measurement capability, while the complex current component calculation is performed through software algorithms rather than requiring expensive hardware ADCs for each phase.
Solution Approach 2:
The patent substitutes hardware-based current measurement (multiple ADCs) with a software-based approach. The software determines the complex current components by processing the single shunt measurement along with PWM signal information and motor parameters, replacing the need for multiple high-performance ADC channels.
2Measurement precision
If multiple shunts are used for accurate current measurement, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the current measurement function into a single shunt located in the DC link. Instead of using separate shunts for each phase, the single shunt measurement is combined with PWM signal information and software calculations to determine all three phase currents, reducing hardware complexity while maintaining measurement accuracy.
Solution Approach 2:
The single shunt serves multiple functions: it provides the basis for determining all three phase currents, enables calculation of complex current components, and works in conjunction with the PWM controller to provide comprehensive motor control information, replacing what would traditionally require multiple dedicated measurement devices.
3Measurement precision
If high-performance ADCs are used, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent employs a single inexpensive shunt instead of multiple high-performance ADCs. The cost-saving approach uses basic analog-to-digital conversion combined with software processing to achieve the same measurement precision that would otherwise require expensive dedicated ADC hardware for each phase.
4Measurement precision
If conventional FOC control with multiple ADCs is used, then current measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent replaces the conventional hardware-based multi-ADC approach with a software-based current determination system. The software processes the single shunt measurement along with PWM signal data and motor parameters to calculate the complex current components, substituting hardware complexity with software intelligence.
Solution Approach 2:
The patent introduces software algorithms as an intermediary between the single shunt measurement and the required phase current information. This software mediator performs the complex calculations to derive all three phase currents from the single shunt measurement, eliminating the need for multiple ADCs while maintaining measurement accuracy.
Data Source
AI summary
A method for driving a motor is provided. Pulse width modulation (PWM) signals are generated from a voltage signal and a commanded angle signal, which drives a motor with multiple phases. A motor current from a motor is measured with a single shunt and converted into a digital signal. Based on the digital signal and the commanded angle signal, direct-axis and quadrant-axis currents for the motor can be determined, and the voltage signal and the commanded angle signal can be adjusted based at least in part on the direct-axis and quadrant-axis currents.