Load Driver Relay Control Logic
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Solution Overview
Problem
Existing load driver systems require additional ports and wire harnesses to prevent simultaneous ON of relays, increasing complexity and material usage.
Innovation Solution
A load driver configuration that uses a prohibition switch to control the second relay's state based on the first relay's open-close control signal, preventing simultaneous closure without diodes connected to the relays' upstream portions, thus reducing the number of ports and wire harnesses needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diodes are connected to upstream portions of semiconductor relays to prevent simultaneous ON, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the simultaneous-ON prevention function from the upstream relay circuitry and relocates it to the controller. Instead of using diodes at the relay upstream portions, the controller monitors the state of relays and prevents simultaneous activation by controlling the switching signals. This reduces the number of additional ports and wire harnesses needed in the upstream circuit.
Solution Approach 2:
The controller is given a multi-function: it not only controls the normal operation of relays but also performs simultaneous-ON prevention. By integrating the prevention function into the existing controller rather than adding separate hardware components, the patent reduces device complexity while maintaining reliability.
2Reliability
If additional diodes are added to prevent simultaneous relay closure, then reliability is improved, but weight increases
Solution Approach 1:
The patent removes the need for additional diodes and their associated wire harnesses by extracting the prevention function to the controller. This eliminates the extra components and wiring that would contribute to system weight.
Solution Approach 2:
Instead of physically adding diodes to prevent simultaneous closure, the patent uses a virtual/logical copy of the prevention mechanism implemented through controller software/logic. The controller replicates the protection function through control algorithms rather than physical components, thereby avoiding additional weight.
Data Source
AI summary
A load driver includes a microcomputer controlling an ON-OFF switching of a first relay and a second relay. The load driver also includes a fourth switching element performing an ON-OFF drive of the first relay based on a drive signal from the microcomputer, and a fifth switching element performing an ON-OFF drive of the second relay based on a permission signal from the microcomputer. The load driver further includes a third switching element prohibiting the ON drive of the second relay by the fifth switching element to power a motor with power from an accessory battery via the first relay when the microcomputer outputs a “Lo” drive signal.