Electric Machine Control via Direct Current Input Calculation
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Solution Overview
Problem
Existing methods for operating electric machines in motor vehicles face challenges due to increased current requirements, leading to overheating and potential damage of electronic components, requiring precise temperature measurements and complex models that are not always accurate.
Innovation Solution
A method using pulse modulated switching of winding phase currents, where the direct current input is calculated based on current values and duty cycles of pulse modulation, eliminating the need for temperature sensors and allowing for more accurate control independent of direct voltage input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors and complex temperature-dependent models are used to control direct current input, then temperature compensation accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the temperature measurement function from the control system by eliminating temperature sensors and temperature-dependent models. Instead of measuring temperature directly, the system calculates an equivalent temperature effect through mathematical transformation of readily available electrical parameters (direct current input, alternating current, duty cycle), thereby removing the complex temperature sensing and compensation subsystem while maintaining control accuracy.
Solution Approach 2:
The patent replaces the physical temperature measurement system (sensors and thermal models) with an electrical parameter-based calculation system. By substituting direct thermal measurement with indirect electrical parameter transformation, the system eliminates mechanical/thermal sensing components and their associated complexity while achieving the same control objective through mathematical relationships between electrical parameters.
2Power
If direct current input is increased to meet power requirements, then power delivery capability is improved, but electronic component heating and damage risk increase
Solution Approach 1:
The patent implements dynamic adjustment of the direct current input threshold based on operating conditions. Instead of using a fixed threshold, the system continuously calculates an adaptive threshold value that accounts for varying load conditions, duty cycle, and alternating current levels. This dynamic approach allows the system to optimize power delivery while preventing overheating by adjusting the threshold in real-time according to actual operating parameters.
Solution Approach 2:
The patent employs feedback control by continuously monitoring electrical parameters (direct current input, alternating current, duty cycle) and using these measurements to adjust the direct current threshold. The control unit calculates the threshold based on feedback from the inverter's operating state, creating a closed-loop system that automatically prevents overheating while maximizing power delivery capability under varying conditions.
3Measurement precision
If temperature sensors are installed for precise temperature measurement, then temperature control accuracy is improved, but system cost and error susceptibility increase
Solution Approach 1:
The patent removes temperature sensors from the system entirely, extracting the temperature measurement function from the physical domain and relocating it to the electrical parameter domain. By calculating temperature effects through mathematical relationships between electrical parameters rather than direct thermal measurement, the system eliminates the need for additional sensors and reduces both cost and error susceptibility.
Solution Approach 2:
The patent creates a virtual model of temperature behavior through electrical parameter relationships. Instead of physically measuring temperature, the system calculates an equivalent temperature state based on the known thermal characteristics of the power electronics and the measured electrical parameters (current, duty cycle). This virtual temperature model provides sufficient control accuracy without requiring physical temperature sensors.
Data Source
AI summary
A method for operating an electric machine, in which a control device assigned to the electric machine is used to switch currents of winding phases of the electric machine in a pulse-modulated manner, provides that a current value of the direct input current of the control device is determined using current values of the winding phases and duty factors of the pulse modulation.