Automotive Rotary Apparatus Field Current Blocking Circuit
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Solution Overview
Problem
Existing automotive rotary electrical apparatuses fail to effectively block field current in case of short-to-power or short-circuit malfunctions, leading to potential damage to switching control elements.
Innovation Solution
The apparatus employs a field drive circuit with two switching control elements and diode elements, where the field control circuit manages control signals to block field current flow in case of malfunctions, protecting other switching control elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one switching control element and one diode element are used in the field drive circuit, then the device complexity is reduced, but the reliability deteriorates because field current cannot be blocked during short-to-power or short-circuit malfunctions
Solution Approach 1:
The field drive circuit is segmented into two independent switching control elements (first switching control element between battery terminal and positive field terminal, second switching control element between negative field terminal and common potential terminal) with separate control signals. This segmentation allows independent control of each switching element, enabling the circuit to block field current during malfunctions while maintaining simpler structure compared to H-bridge configurations.
2Reliability
If four switching control elements are used in the H-bridge configuration, then the reliability is improved by avoiding malfunctions, but the device complexity increases and control becomes complicated
Solution Approach 1:
The invention extracts only the essential protective function from the complex H-bridge configuration by using merely two switching control elements instead of four. The first switching control element handles the positive field terminal protection, while the second handles the negative field terminal protection. This extraction achieves reliable field current blocking during malfunctions without the complexity of full H-bridge control.
Solution Approach 2:
The control circuit preliminarily detects malfunctions (short-to-power or short-circuit) in the field coil or first switching control element before they cause damage. Upon detecting such malfunctions, the control circuit immediately activates the second switching control element to block field current flow, preventing further damage. This preliminary detection and response mechanism ensures reliability without requiring complex real-time control of multiple switching elements.
3Ease of operation
If the first switching control element is used to control field current, then the ease of operation is improved, but the reliability deteriorates because it cannot protect against short-to-power or short-circuit malfunctions
Solution Approach 1:
The second switching control element acts as an intermediary protective device that monitors and protects against malfunctions in the first switching control element or field coil. When a short-to-power or short-circuit malfunction is detected, the second switching control element interrupts the field current flow, preventing damage to the first switching control element. This intermediary protection mechanism maintains operational simplicity while significantly improving reliability.
Data Source
AI summary
An automotive rotary electrical apparatus with less than four switching control elements capable of blocking a field current while preventing breakage of the switching control elements in response to a malfunction in a feeder circuit for a field coil is proposed. First and second switching control elements controlled by first and second control signals, and first and second diode elements are used. The field control circuit switches the first control signal to the on-level signal while keeping the second control signal as the on-level signal, then switches the second control signal to the off-level signal while keeping the first control signal as the on-level signal, and further switches the first control signal to the off-level signal while keeping the second control signal to the off-level signal, when a short-to-power malfunction of the positive terminal or a short-circuit malfunction of the first switching control element occurs in the feeder circuit for the field coil.