Motor Controller Three-Phase Short Circuit Release
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Solution Overview
Problem
Existing two-wheeled electric vehicles lack a controlled method for releasing a three-phase short circuit, which can lead to unintended battery charging and potential damage, especially when the vehicle is traveling downhill with high speed.
Innovation Solution
A motor controller system that includes a short-circuit control mechanism to initiate a three-phase short circuit based on predetermined conditions, such as high rotation speed and battery voltage, and a release control mechanism to safely end the short circuit when current values meet specific thresholds, preventing inrush currents and protecting the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three-phase short-circuiting is performed to decrease motor speed on a downslope, then the battery is protected from overcharging, but the release of the short circuit may cause large inrush current to flow into the battery
Solution Approach 1:
The patent applies preliminary action by detecting the current flowing through the coils before releasing the short circuit, and only releasing the short circuit when the current is below a predetermined threshold. This preliminary check ensures that the battery is protected from inrush current damage when the short circuit is released, while still allowing the short-circuiting function to protect against overcharging during high-speed downhill operation.
2Ease of operation
If the lower arm switching elements are turned off to release the short circuit, then the battery can charge or normal control can resume, but large inrush current may damage the battery
Solution Approach 1:
The patent implements feedback control by continuously monitoring the current flowing through the coils and using this feedback to determine when it is safe to turn off the lower arm switching elements. The release control means only permits switching element turn-off when the detected current is below the predetermined threshold, creating a closed-loop control system that ensures battery safety while enabling normal operation to resume.
3Speed
If three-phase short-circuiting is used to control motor deceleration, then speed can be reduced on downslope, but there is no controlled method for releasing the short circuit
Solution Approach 1:
The patent applies self-service by designing a release control mechanism that automatically determines when to release the short circuit based on the current condition of the coils. The system monitors its own state and autonomously decides when the short circuit should be released, eliminating the need for complex external control mechanisms while ensuring safe and appropriate release timing.
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
The system effectively manages three-phase short circuits to protect the battery by ensuring controlled initiation and termination, preventing battery overcharging and damage from inrush currents, thereby enhancing the safety and efficiency of the vehicle's operation.
Implementation Method 1
a three-phase AC electric motor, having coils of a first phase, a second phase, and a third phase, for generating a driving force to be transmitted to a drive wheel
Implementation Method 2
a short-circuit control means which turns on all of the lower arm switching elements of the first phase circuit, the second phase circuit, and the third phase circuit to short-circuit the coils of the first phase, second phase, and third phase
Implementation Method 3
a release control means which releases the short-circuited state by turning off the lower arm switching element of a phase circuit in a period in which the current outflowing from the coil of the corresponding phase is equal to or less than a prescribed value
Data Source
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AI summary
A two-wheeled electric vehicle that includes a battery, a three-phase AC electric motor, having coils of a first phase, a second phase, and a third phase, for generating a driving force to be transmitted to a drive wheel, and a motor controller for controlling a supply of current from the battery to the coils of the electric motor. The motor controller includes a drive circuit including a first phase circuit, a second phase circuit, and a third phase circuit, each having a series circuit of an upper arm switching element and a lower arm switching element, a short-circuit control means which turns on all of the lower arm switching elements of the first phase circuit, the second phase circuit, and the third phase circuit to put the electric motor in a short-circuited state in response to meeting of a short-circuiting condition, and a release control means which releases the short-circuited state by turning off the lower arm switching element of a phase circuit, in response to meeting of a release condition when the electric motor is in the short-circuited state, in a period in which the current outflowing from the coil of the corresponding phase is equal to or less than a prescribed value.