Motor Drive Device Regeneration Threshold Control
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Solution Overview
Problem
Existing motor drive devices face challenges in suppressing voltage fluctuation in DC link capacitors, leading to increased production costs and size due to the need for additional components like voltage to ground capacitors and increased motor consumption, which results in greater thermal losses and cooling requirements.
Innovation Solution
A motor drive device with a converter, voltage detection unit, inverter, and motor control unit that dynamically adjusts the regeneration threshold based on the rate of DC voltage increase, using a first threshold for small increases and a second threshold for larger increases, to control voltage fluctuation without the need for additional components or increased cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage to ground capacitors or DC/DC power sources are added to suppress voltage fluctuation, then voltage stability is improved, but production cost increases and device size increases
Solution Approach 1:
The patent extracts the voltage fluctuation suppression function from dedicated hardware components (capacitors, DC/DC power sources) and relocates it to the control unit through software-based threshold adjustment. This removes unnecessary physical components while maintaining the suppression function, thereby reducing device size and cost without compromising voltage stability.
Solution Approach 2:
The patent replaces the mechanical/electrical hardware-based voltage suppression system with a control-based software system. By using the control unit to dynamically adjust regeneration thresholds, the system substitutes physical voltage suppression mechanisms with intelligent control logic, eliminating the need for additional capacitors or power sources.
2Reliability
If motor consumption energy is increased to suppress voltage fluctuation, then voltage stability is improved, but thermal loss increases and cooling requirements increase
Solution Approach 1:
The patent implements dynamic adjustment of the regeneration threshold based on the rate of voltage increase. Instead of continuously operating the motor at high consumption levels, the control unit adaptively sets thresholds (first threshold for slow voltage rise, second threshold for fast voltage rise), allowing the system to suppress voltage fluctuation only when necessary and minimizing unnecessary energy consumption and thermal loss.
Solution Approach 2:
The patent changes the operational parameters of the motor control system by dynamically adjusting the regeneration threshold voltage based on the rate of voltage increase. This parameter change allows the system to optimize between voltage stability and energy efficiency, activating strong suppression only when the voltage rise rate exceeds certain levels, thereby reducing overall thermal loss.
3Reliability
If regeneration threshold is set low to suppress voltage fluctuation, then voltage stability is improved, but unnecessary regeneration occurs reducing efficiency
Solution Approach 1:
The patent makes the regeneration threshold dynamic rather than fixed. The control unit adjusts the threshold based on the rate of voltage increase, setting a first (lower) threshold when voltage rises slowly and a second (higher) threshold when voltage rises rapidly. This dynamic approach ensures regeneration is triggered appropriately without unnecessary activation, maintaining both voltage stability and system efficiency.
Solution Approach 2:
The patent applies partial action by adjusting the regeneration threshold according to the actual voltage rise rate. Instead of always using a low threshold that would cause excessive regeneration, the system uses a higher threshold when the voltage rise rate is low, applying suppression action only to the extent necessary. This prevents unnecessary regeneration while still suppressing voltage fluctuation when needed.
Data Source
AI summary
To provide a motor drive device that suppresses voltage fluctuation of a DC link capacitor, as well as enabling for low cost and size reduction. A motor control unit sets a threshold of voltage at which to start regeneration to a first threshold in a case of an increased amount per unit time of a DC voltage value detected by a voltage detection part being less than a certain amount, and sets the threshold of voltage at which to start regeneration to a second threshold that is larger than the first threshold, in a case of the increased amount per unit time of the DC voltage value detected by the voltage detection part being at least a certain amount.