Inverter Pulsation Compensation for Capacitor Stress and Efficiency
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Solution Overview
Problem
Conventional power converting apparatuses face issues with high current flow to smoothing capacitors, leading to accelerated aging degradation and increased costs, as well as efficiency losses due to pulsation control methods.
Innovation Solution
A power converting apparatus with a rectifier unit, capacitor, inverter, detection unit, and control unit that performs load and power-supply pulsation compensation, adjusting these compensations based on detection values to reduce capacitor degradation and maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a higher capacity smoothing capacitor is used to reduce ripple fluctuation, then the capacitor voltage stability is improved, but the apparatus size and cost increase
Solution Approach 1:
The invention changes the operational parameters of the inverter by superimposing a pulsating current component on the motor driving current. This pulsation compensates for the capacitor voltage ripples without requiring a larger capacitor, thus maintaining voltage stability while avoiding increased apparatus size
Solution Approach 2:
The invention converts the harmful effect of capacitor voltage ripples into a beneficial control signal. By detecting the capacitor voltage and generating a compensating pulsating current, the system transforms the ripple problem into an active compensation mechanism that stabilizes voltage without hardware expansion
2Duration of action of stationary object
If pulsation compensation control is applied to reduce capacitor degradation, then capacitor lifespan is improved, but the root-mean-square values of motor current and inverter current increase, causing efficiency decrease
Solution Approach 1:
The invention applies partial pulsation compensation rather than full compensation. By carefully controlling the amplitude and frequency of the compensating pulsating current, the system reduces capacitor stress while minimizing the increase in RMS current, achieving a balance between capacitor protection and efficiency maintenance
Solution Approach 2:
The invention dynamically adjusts the pulsation compensation parameters based on real-time capacitor voltage detection. The control unit continuously monitors capacitor conditions and modulates the compensating current accordingly, optimizing the balance between capacitor protection and energy efficiency under varying operating conditions
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 apparatus effectively reduces capacitor degradation and maintains high efficiency while avoiding increased size and cost, by controlling pulsations and adjusting compensation levels, thus minimizing losses in semiconductor devices and motor windings.
Implementation Method 1
The rectifier unit rectifies a supply voltage applied from an alternating-current power supply
Implementation Method 2
A power converting apparatus includes a rectifier unit, a capacitor connected to an output end of the rectifier unit
Data Source
AI summary
A power converting apparatus includes a rectifier unit that rectifies a supply voltage applied from a commercial power supply, a capacitor connected to an output end of the rectifier unit, an inverter that converts direct-current power output from the capacitor into alternating-current power and outputs the alternating-current power to a device including a motor, current detection units that detect a power state of the capacitor, and a control unit that performs, by controlling the inverter, load pulsation compensation and power-supply pulsation compensation and adjusts a degree of at least one of the load pulsation compensation and the power-supply pulsation compensation on a basis of detection values of the current detection units. The load pulsation compensation is performed to compensate a load pulsation in a load unit including the inverter and the device. The power-supply pulsation compensation is performed to compensate a power-supply pulsation in the load unit.