Motor Drive Device Shared Relay Control Circuit
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Solution Overview
Problem
Existing motor drive devices have complex circuit constructions and a high number of components due to individual on-off control of MOSFETs in the fail-safe circuit, making cost-saving and reliability challenging.
Innovation Solution
A motor drive device with a shared drive circuit for both phase relays and power supply relays, utilizing semiconductor switching elements and a microcomputer for simultaneous control, simplifying the circuit and reducing component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MOSFETs of the fail-safe circuit are individually on-off controlled, then the fail-safe function is achieved, but the circuit construction of the fail-safe drive unit becomes complicated
Solution Approach 1:
The patent combines the fail-safe drive unit and control unit into a single integrated control unit. This merging eliminates the need for separate drive circuits for each MOSFET, as the control unit directly controls all phase relays and the power supply relay. The integration simplifies the overall circuit construction while maintaining the fail-safe function through centralized control logic.
Solution Approach 2:
The control unit is designed to perform multiple functions: it controls the phase relays for motor phase switching, manages the power supply relay for overall power control, and implements fail-safe monitoring. This multi-functional design eliminates the need for dedicated separate circuits for each function, reducing overall system complexity while maintaining all necessary control capabilities.
2Reliability
If the fail-safe drive unit is provided discretely from the control unit, then the fail-safe function is implemented, but the number of components increases and cost-saving becomes difficult
Solution Approach 1:
The patent merges the fail-safe drive unit and control unit into a single integrated control unit, reducing the total component count. By combining these previously separate units, the patent eliminates redundant components and interconnections while maintaining all necessary control functions including fail-safe monitoring and execution.
Solution Approach 2:
The integrated control unit is designed to handle multiple control tasks simultaneously: phase relay control, power supply relay control, and fail-safe monitoring. This multi-functional approach allows a single component to replace multiple separate components, reducing the overall number of parts in the system.
Data Source
AI summary
The present invention relates to a motor drive device having a drive circuit for driving a power supply relay and a phase relay providing a fail-safe function. The motor drive device includes: an inverter circuit for supplying electric power to an electric motor; a power supply relay provided on a power supply line for supplying electric power from a power supply to the inverter circuit; a phase relay provided on a drive line between the inverter circuit and the electric motor, and constituted by a semiconductor switching element; and a drive circuit connected to the phase relay and the power supply relay. The phase relay and the power supply relay share the same drive circuit, and the phase relay and the power supply relay are driven simultaneously by a drive signal output from the drive circuit.