Vehicle DC Link Power Control for Storage Protection
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Solution Overview
Problem
In vehicles with DC voltage intermediate circuits, excessive power consumption or output due to tolerance-related deviations in motor control can lead to excessive current draw or discharge, overwhelming the storage device and triggering protective device tripping, causing operational disruptions.
Innovation Solution
A power specification device that sets a power limit value and includes a reduction device to adjust this value based on storage current, preventing overload by subtracting a correction value when the current exceeds a maximum threshold, and a power increase device that gradually increases the limit value when conditions allow, ensuring the storage device is not overloaded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the motor control unit operates with high power to compensate for tolerance deviations, then the motor performance is improved, but the storage device is overloaded and protective devices trip
Solution Approach 1:
The power limit value is made dynamically adjustable based on the operating state of the storage device. The reduction device continuously monitors storage current and adjusts the power limit value downward when the storage device approaches its current capacity, preventing overload while allowing maximum power utilization when the storage device has sufficient capacity.
Solution Approach 2:
A feedback mechanism is implemented where the actual storage current is measured and fed back to the reduction device. This feedback loop enables the system to automatically adjust the power limit value based on the real-time state of the storage device, ensuring that the motor can operate at high power when safe and reducing power limits when the storage device is near capacity.
2Productivity
If the power limit value is set high to maximize motor performance, then productivity is improved, but the storage device current exceeds maximum values causing operational disruptions
Solution Approach 1:
The power limit value transitions from a static fixed value to a dynamic variable that adapts to storage device conditions. This allows the system to maximize motor performance when the storage device can handle the current while automatically preventing operational disruptions when the storage device approaches its current limits.
Solution Approach 2:
The reduction device proactively adjusts the power limit value before the storage device becomes overloaded. By monitoring storage current and preemptively reducing the power limit when approaching maximum capacity, the system prevents protective device tripping and maintains continuous operation without waiting for overload conditions to occur.
3Reliability
If the reduction device continuously adjusts the power limit value, then storage device protection is improved, but the control system complexity increases
Solution Approach 1:
The reduction device implements localized adjustment of the power limit value specifically for the motor control unit, without requiring system-wide complexity changes. The adjustment is applied locally at the power limit specification point, keeping the rest of the vehicle control system unchanged and minimizing overall complexity increase.
Solution Approach 2:
The system changes the parameter being controlled from a fixed power limit value to a variable one that depends on storage device state. This parameter change enables adaptive protection while maintaining relatively simple control logic - essentially comparing current measurements against limits and adjusting the power limit accordingly, without requiring complex control algorithms.
Data Source
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AI summary
The invention relates in particular to a vehicle with a DC link, at least one drive motor connected to the DC link, a motor control unit controlling the drive motor, and at least one electrical storage device connected to the DC link, wherein a power control device of the motor control unit specifies a power limit value indicating a maximum motor power, wherein the motor control unit is configured to limit the actual power of the drive motor taking into account the power limit value, and wherein the power control device includes a reduction device, wherein the reduction device specifies a target value as the power limit value as long as the magnitude of a storage current is less than or equal to a predetermined maximum current value.and subtracts a correction value from the target value and specifies the reduced target value as the power limit value if the amount of storage current is greater than the specified maximum current value.