Multi-Motor EV Speed Command Synchronization to Prevent Output Mismatch
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Solution Overview
Problem
In existing electric vehicles with multiple AC motors, inconsistencies in motor outputs can occur due to delays in rotation speed control processing and communication, leading to extra heat generation and efficiency deterioration.
Innovation Solution
An electric vehicle design with a main control unit that transmits rotation speed command signals to a target motor while omitting transmission to other motors, using a driving force merging unit to synchronize motor outputs, and independent processing of command signals to prevent output inconsistencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rotation speed control signals are independently transmitted to each motor, then each motor can operate independently, but calculation errors accumulate and cause output inconsistency
Solution Approach 1:
The patent merges the control signals by having the first command unit transmit its processed rotation speed control signal to the second command unit. This ensures both motors receive the same processed signal, preventing calculation error accumulation while maintaining coordinated operation. The merging occurs at the signal transmission level between command units.
Solution Approach 2:
The first command unit acts as an intermediary that processes the rotation speed control signal from the main control unit and then transmits the processed signal to the second command unit. This intermediary role ensures consistent signal processing and prevents independent calculation errors, while still allowing each command unit to operate with the same reference signal.
2Productivity
If rotation speed control processing is performed separately for each motor, then processing can be parallelized, but minute delays cause output inconsistency and heat generation
Solution Approach 1:
The patent combines the control signal processing by having one command unit (first command unit) process the rotation speed control signal and then transmit the processed result to the other command unit. This eliminates parallel processing delays while maintaining efficient signal distribution, preventing the minute delays that cause output inconsistency and subsequent heat generation.
3Loss of time
If communication delays occur between control unit and command units, then response time increases, but output synchronization is maintained
Solution Approach 1:
The first command unit processes the rotation speed control signal in advance and transmits the processed signal to the second command unit before actual motor execution. This preliminary processing ensures that both motors receive synchronized commands, maintaining output synchronization even when communication delays occur during actual motor operation.
Data Source
AI summary
An electric vehicle includes motors in a state where rotation speeds of output shafts of the motors are interlocked with each other, a main control unit configured to generate a rotation speed command signal based on a target rotation speed and a rotation speed of a target motor, and command units provided to correspond to the motors, and configured to transmit motor command signals to the corresponding motors. The main control unit is configured to transmit the rotation speed command signal to a first command unit corresponding to the target motor, and not to transmit the rotation speed command signal to a second command unit corresponding to the other motor, and the second command unit is configured to generate a second motor command signal transmitted to the motor corresponding to the second command unit based on processing result of the rotation speed command signal received by the first command unit.