Switching Element Current Estimation Without Phase Current Sensors
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Solution Overview
Problem
Existing methods for determining phase currents in motor vehicle traction converters rely on costly current sensors, which increase manufacturing costs, complexity, and vulnerability to electromagnetic interference, while also complicating cooling and installation.
Innovation Solution
A method that determines current through switching elements using temperature and voltage sensors, eliminating the need for current sensors by calculating current based on temperature-dependent resistance and voltage drop, integrated with a computing device to simplify the circuit and enhance robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sensors are used to measure phase currents, then current measurement precision is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent extracts the current measurement function from dedicated current sensors and relocates it to the control unit. By measuring voltage across the switching element and combining it with temperature-dependent resistance data, the control unit calculates current internally, eliminating the need for separate current sensors and reducing device complexity.
Solution Approach 2:
The control unit is given multiple functions: it not only controls the switching elements but also measures temperature, measures voltage, and calculates current. This multi-functionality eliminates the need for separate dedicated sensors, reducing overall device complexity while maintaining measurement capabilities.
2Measurement precision
If current sensors are installed in the electrical circuit arrangement, then current determination accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The current measurement capability is extracted from expensive external current sensors and integrated into the control unit's computational functions. The system uses readily available voltage sensors and temperature sensors combined with mathematical calculation, eliminating the need for costly current sensors while maintaining measurement accuracy.
Solution Approach 2:
The patent replaces expensive, complex current sensors with cheaper alternative components: standard voltage sensors and temperature sensors combined with computational processing. This substitution significantly reduces manufacturing cost while achieving the same functional outcome.
3Measurement precision
If current sensors are used for phase current measurement, then current measurement capability is improved, but vulnerability to electromagnetic interference increases
Solution Approach 1:
The current measurement function is extracted from physical current sensors that are vulnerable to electromagnetic interference and relocated to the control unit. By performing current determination through voltage measurement and mathematical calculation of resistance-based relationships, the system eliminates the vulnerability to electromagnetic interference while maintaining measurement capability.
4Measurement precision
If current sensors are installed, then current measurement is enabled, but cooling and installation complexity increase
Solution Approach 1:
The current measurement functionality is extracted from separate current sensors and integrated into the control unit. This eliminates the need for additional sensor installations and associated cooling requirements, simplifying both installation and thermal management while maintaining current measurement 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
Reduces manufacturing costs, simplifies construction, enhances robustness against electromagnetic interference, and improves cooling by eliminating the need for current sensors, while maintaining precise current determination for closed-loop control.
Implementation Method 1
the temperatures of the switching elements of a converter can also be ascertained with the aid of the measured phase currents
Implementation Method 2
the voltage sensor measures a voltage drop across the switchable portion of the switching element
Implementation Method 3
the computing device determines a current value of the current from a temperature measured value of the temperature sensor describing the temperature of the switching element and a voltage measured value of the voltage sensor describing the voltage across the switchable portion
Data Source
AI summary
A method determines a current flowing through at least one switching element of an electrical circuit arrangement. When the switching element is turned on the current flows through a switchable portion of the switching element. The switching element is associated with a temperature sensor and a voltage sensor. The temperature sensor measures a temperature of the switching element and the voltage sensor measures a voltage drop across the switchable portion of the switching element. The temperature sensor and the voltage sensor are connected to a computing device. The computing device determines a current value of the current based on the measured temperature and the measured voltage drop.