Single-Phase Power Conditioner Ripple Control
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Solution Overview
Problem
Existing single-phase power conditioners rely on large and unreliable electrolytic capacitors to manage double-frequency ripple power, leading to limited lifespan and increased costs, as they are prone to failure due to self-heating and thermal stress, which compromises the reliability and longevity of alternative energy systems like solar and fuel cell inverters.
Innovation Solution
A method that senses the AC waveform output of a power conditioner and generates a second AC waveform with the same frequency but shifted by π/4 radians, minimizing double-frequency ripple power by controlling the energy storage device's power flow, allowing for the use of smaller, more reliable film capacitors or inductors, thereby reducing the need for large electrolytic capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large electrolytic capacitors are used to manage double-frequency ripple power, then the power conditioner can operate, but the reliability decreases and lifespan is limited due to self-heating and thermal stress
Solution Approach 1:
The patent changes the operating parameters of the energy storage device by controlling it to operate at a 45-degree phase angle relative to the AC waveform. This parameter change optimizes the division of double-frequency power handling, reducing the burden on capacitors and allowing operation at lower temperatures with extended lifespan
Solution Approach 2:
The patent extracts the double-frequency ripple power management function from the electrolytic capacitors and assigns it to a dedicated energy storage device operating at optimal parameters. This separation allows capacitors to operate within their reliable lifespan ratings while the energy storage device handles the ripple power independently
2Power
If large electrolytic capacitors are used to store energy for double-frequency ripple power, then the power conditioner can function, but the device complexity and cost increase
Solution Approach 1:
The patent changes the operational parameters by introducing a phase-shifted control mode at 45 degrees, which optimizes the energy storage device's operation. This allows smaller, more reliable components to handle the required power management function
Solution Approach 2:
The patent implements dynamic control of the energy storage device's operating parameters, adjusting the phase angle to 45 degrees to optimize performance. This dynamic operation allows the system to maintain power management capability with reduced component size and complexity
3Duration of action of stationary object
If electrolytic capacitors are derated to extend lifespan, then reliability improves, but the operating temperature and voltage are limited
Solution Approach 1:
The patent extracts the double-frequency power handling function from the capacitors and assigns it to a separately controlled energy storage device. This allows capacitors to operate within their rated lifespan parameters while the energy storage device handles the thermal and voltage stresses
Solution Approach 2:
The patent changes the operational parameters by controlling the energy storage device at a 45-degree phase angle, which optimizes the division of power handling. This allows the system to achieve extended warranty periods without derating the capacitors, as the energy storage device absorbs the thermal and voltage stresses
Data Source
AI summary
A method is provided for minimizing a double-frequency ripple power exchanged between a load and an energy source, the energy source delivering electrical power to the load through a single-phase power conditioner, and the power conditioner being coupled to an energy storage device. The method includes determining a phase shift of an AC output signal of the power condition and an average AC output power of the power conditioner. The average AC output power may be a predetermined value or a calculated value based on sensed or measured signals. The method further includes generating an AC signal at an energy storage device. The generated AC signal has an amplitude that is a function of the average AC output power and a phase shift substantially equal to 45 degrees minus an amount that is dependent on the determined phase shift. In some embodiments, the phase shift may be determined to be of a non-zero value.