Power Conversion Device Ripple Margin Control
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Solution Overview
Problem
Existing power conversion devices struggle to effectively control the operation of loads based on direct-current voltage including ripple voltage, as the methods proposed in prior techniques are either unreliable in determining the recovery time of electrolytic capacitors or cannot be easily applied to systems with variable power supply.
Innovation Solution
A power conversion device that includes a rectifier circuit, a smoothing capacitor, a voltage detection unit, an allowable voltage storage unit, a margin calculation unit, a margin range storage unit, a load limitation decision unit, and a load control unit, which calculates and manages a direct-current voltage margin to stepwise limit and control the operation of loads based on the detected ripple voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed waiting period is used to allow the electrolytic capacitor to warm up and recover smoothing ability, then the capacitor can function properly at low temperatures, but the system experiences unnecessary operational delays and reduced productivity during normal temperature operation
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed waiting period to a dynamic determination method based on actual temperature conditions. The control unit calculates the temperature of the electrolytic capacitor and dynamically adjusts the waiting period duration, allowing the system to adapt to varying thermal conditions rather than applying a uniform delay regardless of actual capacitor temperature state
Solution Approach 2:
The patent implements feedback by using temperature detection to inform control decisions. The control unit receives temperature information about the electrolytic capacitor and uses this feedback to determine whether to apply a waiting period and how long it should last, creating a closed-loop control system that responds to actual capacitor conditions
2Reliability
If the operation of the load is limited during the waiting period to protect against poor smoothing, then capacitor reliability is maintained, but the load cannot operate at full capacity and productivity is reduced
Solution Approach 1:
The patent applies dynamics by making the load operation status dependent on real-time temperature conditions. Instead of a fixed limitation period, the system dynamically adjusts whether load operation should be limited based on the calculated capacitor temperature, allowing full operational capacity when conditions are favorable and applying limitations only when necessary
Solution Approach 2:
The patent changes the parameter of load operation status based on temperature parameter variations. When the electrolytic capacitor temperature is below a predetermined threshold, the system changes the operation parameter to limited mode; when temperature exceeds the threshold, it restores full operation capacity, thereby adapting operational parameters to thermal conditions
3Reliability
If power is supplied to the load based on ripple voltage magnitude, then voltage stability is maintained, but this approach cannot be applied to systems where load power cannot be easily changed
Solution Approach 1:
The patent applies inversion by controlling the power supply unit based on temperature conditions rather than directly controlling the load based on voltage ripple. Instead of adjusting load operation in response to voltage instability, the system inverts the approach by preemptively controlling power supply to the electrolytic capacitor based on temperature, thereby preventing voltage ripple issues before they occur
Solution Approach 2:
The patent introduces the power supply unit as an intermediary between the control unit and the load. The control unit determines operating conditions based on capacitor temperature and instructs the power supply unit to supply or stop power accordingly, using the power supply unit as a mediator to achieve voltage stability without directly controlling the load
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
This solution allows for precise control of load operations based on the magnitude of ripple voltage, maximizing the ripple removal capability of the smoothing capacitor and maintaining the direct-current voltage within a stable range, even in low temperature environments where the smoothing capability is initially low.
Implementation Method 1
a smoothing capacitor 3 that smooths a direct-current voltage that has been rectified by the rectifier circuit 2, the direct-current voltage including a ripple voltage
Implementation Method 2
a rectifier circuit 2 that rectifies an alternating-current voltage supplied from an alternating-current power supply 20
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A power conversion device (1) includes a voltage detection unit (5) that detects a direct-current voltage rectified by a rectifier circuit (2); an allowable voltage storage unit (6) that stores an allowable voltage upper limit value and an allowable voltage lower limit value; a margin calculation unit (7) that calculates an upper limit voltage difference that is a value obtained by subtracting a maximum value of the direct-current voltage detected by the voltage detection unit (5) from the allowable voltage upper limit value, and a lower limit voltage difference that is a value obtained by subtracting the allowable voltage lower limit value from a minimum value of the direct-current voltage detected, and decides that one of the upper limit voltage difference and the lower limit voltage difference that has a smaller value is a direct-current voltage margin; a load limitation decision unit (9) that decides a limitation on an operation of a load (30) depending on a margin range including the direct-current voltage margin decided by the margin calculation unit (7) among a plurality of margin ranges stored in a margin range storage unit (8); and a load control unit (10) that controls the operation of the load (30) depending on the limitation decided by the load limitation decision unit (9).