Motor Current Sensor Temperature Compensation via Estimation
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Solution Overview
Problem
Control systems for three-phase electric rotating machines face challenges in accurately detecting phase currents due to temperature errors in current detection sections, especially when temperature detecting functions are lacking for some current detection sections, affecting controllability and accuracy.
Innovation Solution
A control apparatus that estimates temperature increases in current detection sections based on current flow, calculates reference temperatures, and compensates current detection values using temperature estimation and compensation sections to enhance accuracy, regardless of the presence of temperature detecting functions for all sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature detection sections are provided for all current detection sections, then current detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a virtual copy of the temperature detection function by estimating temperatures for current detection sections without physical temperature sensors. The estimation section generates temperature data based on measurements from sections with sensors, allowing the system to behave as if all sections had temperature detection capability without actually installing sensors everywhere.
Solution Approach 2:
The patent introduces an estimation section as an intermediary between the temperature detection sections with sensors and the current detection sections without sensors. This intermediary processes the available temperature data and current data to generate estimated temperature values for sections lacking direct temperature measurement capability.
2Measurement precision
If temperature compensation is applied to all current detection sections, then current detection accuracy is improved, but computational complexity increases when temperature data is unavailable
Solution Approach 1:
The patent performs preliminary temperature estimation for all current detection sections before compensation is needed. By pre-calculating estimated temperatures using the estimation section, the system prepares compensation data in advance, so that when compensation is applied, it can proceed efficiently without complex real-time calculations for sections lacking temperature sensors.
3Device complexity
If temperature detection sections are omitted to simplify the system, then device complexity is reduced, but current detection accuracy deteriorates due to un补偿ated temperature errors
Solution Approach 1:
The patent enables the system to self-compensate for temperature effects in sections without temperature sensors by using measurements from sections with sensors. The estimation section allows the system to serve its own temperature measurement needs internally, eliminating the requirement for external temperature detection hardware in every section while maintaining compensation capability.
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
Enables high-accuracy detection of phase currents, improving the reliability and accuracy of controlling the electric rotating machine by compensating for temperature-related errors, even in scenarios where temperature detecting functions are absent for some current detection sections.
Implementation Method 1
a temperature detection section provided corresponding to at least one of the current detection sections for detecting temperature of the current detection section
Implementation Method 2
a temperature increase amount estimation section that estimates, for each of all the current detection sections, an amount of temperature increase of the current detection section due to a current flowing through the phase in which the current detection section is provided based on a current flowing through the current detection section
Data Source
AI summary
Upon determining that the absolute value of an electrical angular speed of a motor-generator is smaller than or equal to a threshold value, a control apparatus compensates a current detected by a U-phase current sensor based on a temperature detected by a U-phase temperature sensor and compensates a current detected by a V-phase current sensor based on an estimated temperature of a V-phase current sensor. On the other hand, upon determining that the absolute value of the electrical angular speed is larger than the threshold value, the control apparatus compensates the currents detected by the U-phase and V-phase current sensors based on temperature detected by the U-phase temperature sensor.