Heater Controller Circuit for Fail-Safe Current Interruption
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Solution Overview
Problem
Conventional heater controllers in electric and hybrid vehicles face challenges in securely disconnecting heating elements from the power supply, especially when the main switch is damaged, leading to continuous current flow and rapid battery discharge due to the high voltage and power electronic components' limitations.
Innovation Solution
A heater controller with a control unit positioned between the heating element and the output contact, featuring a serial connection of a switching element and a current sensor, allows for secure switching-off by detecting current anomalies and using a second switching element to disconnect power, even if the first switching element fails, thereby preventing continuous current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power electronic switching element is positioned on the high voltage side of the heating element to control current flow, then the ability to interrupt current early in case of defect is improved, but the risk of complete damage to the switching element due to short-circuit causes continuous current flow and battery discharge
Solution Approach 1:
The patent divides the single high-voltage switching function into two separate switching elements: a first switching element on the high-voltage side for normal operation, and a second switching element on the low-voltage side as a safety backup. This segmentation allows the system to maintain current interruption capability while protecting against complete failure, as the second switch can isolate the heating element if the first switch fails short-circuit.
Solution Approach 2:
The control unit acts as an intermediary between the two switching elements, monitoring the operational status of the first switching element and automatically activating the second switching element when a failure is detected. This intermediary function ensures that the safety mechanism is triggered only when necessary, maintaining normal operation during healthy conditions while providing protection during failures.
2Power
If high voltage power electronic components are used to switch power from the battery, then adequate power switching capability is achieved, but the complexity and cost of the switching components increases
Solution Approach 1:
The patent applies different quality requirements to different parts of the switching system: the first switching element handles high voltage and requires full power electronic capabilities, while the second switching element operates at low voltage and can use simpler, less expensive components. This local differentiation of quality requirements reduces overall system complexity and cost while maintaining the necessary high-power switching capability where it is actually needed.
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
This solution provides a more secure and reliable heater controller that prevents unintentional battery discharge and allows for precise switching characteristics using low-voltage components, reducing the risk of damage and enabling efficient power management.
Implementation Method 1
a current sensor (150), in particular an Ohm's law-based current sensor
Implementation Method 2
these heating elements are supplied with power of high voltage networks... continuous drain of current of the heating element
Data Source
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Figure 2
AI summary
The present invention provides a heater controller (100) for supervising a heating element (155) the heater controller (100) having a power connection port (105, 110) for connecting the heater controller (100) with a power source, the power connection port (105, 110) having an input contact (105) and an output contact (110). Furthermore, the heater controller (100) has a heating element connection port (130, 135) for connecting the heater controller (100) with at least one heating element (155), the heating element connection port (130, 135) having a first (130) and a second (135) connection contact. Additionally the heater controller comprises a first switching element (125) being connected between the input contact (105) and the first contact (130) of the heating element connection port, the first switching element (125) being configured for switching power signals having a voltage of at least 100 V. Furthermore the heater controller (100) has a serial connection (140), comprising a second switching element (145) and a current sensor (150), the serial connection (140) being connected between the second contact (135) of the heating element connection port and the output contact (110), the current sensor (150) being configured for providing a current signal representing a current through the current sensor (150). The heater controller (100) comprises furthermore a control element (160) being connected to the first (125) and second (145) switching element as well as the to the current sensor (150), the control element (160) being configured for providing a first control signal to the first switching element (125) to switch first switching element (125) in an on-state or in an off-state, wherein the control element (160) being furthermore configured for receiving the current signal from the current sensor (150) and for providing a second control signal to the second switching element (145) to disconnect an electrical connection between the second connection contact (135) and the output contact (110) in the case the current signal indicates a current through the current sensor (150) while the first switching element (125) is controlled to be in the off-state.