Voltage Converter Control for Overvoltage Switch Stress Relief
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Solution Overview
Problem
Existing control systems for rotating electrical machines in motor vehicles, which use voltage converters, face issues with overvoltage stress on semiconductor switches due to short-circuit currents, leading to reduced reliability and efficiency.
Innovation Solution
A control system that measures voltage and rotational speed to generate commands for short-circuit or open-circuit switch control, reducing stress on switches by interrupting current flow when voltage stabilizes and rotation speed is low, thereby minimizing heat production and extending switch lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all switches are systematically closed when overvoltage is detected to protect the voltage converter and rotating electrical machine, then reliability is improved, but the switches are exposed to high stress due to intense short-circuit currents causing temperature increase and reduced efficiency
Solution Approach 1:
The patent applies local quality by differentiating the control strategy for different groups of switches. Instead of uniformly closing all switches, the control system selectively closes only the low-side switches (first group) while keeping high-side switches (second group) open, or vice versa depending on the fault condition. This localized approach allows protection functionality to be achieved while minimizing the number of switches carrying short-circuit current, thereby reducing overall temperature increase and stress on the switch ensemble.
2Reliability
If all switches are systematically closed when overvoltage is detected to protect the voltage converter and rotating electrical machine, then reliability is improved, but efficiency of the voltage converter is degraded
Solution Approach 1:
The control system implements local quality by applying different control actions to different switch groups based on the specific fault condition. When a fault is detected, only the necessary switches are closed to achieve protection, rather than closing all switches uniformly. This selective approach minimizes the duration and intensity of short-circuit currents, thereby reducing energy losses and maintaining higher voltage converter efficiency while still achieving the protection function.
Solution Approach 2:
The patent employs periodic action through the alternating closure and opening of different switch groups based on the fault condition and system state. The control system periodically switches between different protection configurations (closing low-side switches vs. closing high-side switches) depending on which group is safer to close given the current fault condition. This periodic switching approach allows the system to achieve protection while minimizing continuous exposure to harmful currents, thereby reducing energy losses.
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
The system effectively reduces stress on switches, enhancing the reliability and efficiency of voltage converters by minimizing short-circuit events and heat generation, thus improving overall system performance.
Implementation Method 1
the detector will detect a state fault remained closed for this switch and transmit the detection information of this fault
Implementation Method 2
controllable semiconductor switches are known, such as transistor switches such as a metal-oxide gate field effect transistor (also known as MOSFET) or an insulated gate bipolar transistor (also known as IGBT)
Implementation Method 3
the phases are short-circuited... putting all the phases of the stator at the same potential
Implementation Method 4
the efficiency of the voltage converter is degraded... reducing the stress exerted on the switches... minimizing heat production
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention relates to a control system (2) of a voltage converter (O), the control system (2) comprising: - a first measuring module (20) of a voltage (V) of the DC voltage source (B); - a comparison module (21) of the measured voltage (V) to a first safety threshold (OV1); - a second measuring module (23) for measuring a rotational speed (Ω) of the rotating electrical machine (M); a control module (22) generating an open-circuit control, the open-circuit control consisting of a command to open the first group of switches and a command to open the second group of switches - if a variation over time (dV*) of the measured voltage (V) of the DC voltage source (B) is less than a first safety variation and - if the rotational speed measured (Ω) by the second measuring module (23) is less than a first safety speed.