Power Conditioner Anti-Phase Zero Sequence Current Compensation
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Solution Overview
Problem
Conventional power conditioners experience accelerated capacitor aging and malfunction due to non-zero amplitude zero sequence current inputs from unbalanced phase voltages, leading to increased manufacturing costs and bulkier capacitors when attempting to reduce ripple components.
Innovation Solution
A power conditioner with a power converter module, detector module, and control module that generates anti-phase zero sequence currents to compensate for unbalanced inputs, reducing ripple components across capacitors without increasing capacitance or requiring additional power supplies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the capacitance of each capacitor is increased to reduce the ripple component of the voltage across the capacitors, then the ripple component is reduced, but the capacitors become relatively bulky
Solution Approach 1:
The patent introduces a neutral point voltage regulator circuit as an intermediary component between the unbalanced load and the capacitors. This regulator circuit actively compensates for zero-sequence current, preventing it from flowing through the capacitors. By using this intermediary device, the system can maintain small capacitor values while still eliminating the harmful ripple voltage caused by unbalanced loads.
2Object-affected harmful factors
If a power supply is included to provide DC voltages respectively to the capacitors to reduce the ripple component, then the ripple component is reduced, but the device complexity and manufacturing cost increase
Solution Approach 1:
The neutral point voltage regulator circuit is designed to operate autonomously using the existing system resources. It utilizes the DC bus voltage already present in the power converter system and controls the switching elements to generate the necessary compensating currents. The circuit automatically detects zero-sequence current and adjusts its operation accordingly, eliminating the need for external power supplies or additional complex control systems.
3Object-affected harmful factors
If the capacitance of each capacitor is increased to reduce the ripple component of the voltage across the capacitors, then the ripple component is reduced, but the manufacturing cost increases
Solution Approach 1:
The neutral point voltage regulator circuit serves as an intermediary that protects the capacitors from ripple voltage without requiring larger capacitor values. By actively compensating for zero-sequence current, the system can use smaller, less expensive capacitors while still achieving the goal of reducing ripple voltage and preventing capacitor aging.
4Object-affected harmful factors
If a power supply is included to provide DC voltages respectively to the capacitors to reduce the ripple component, then the ripple component is reduced, but the manufacturing cost increases
Solution Approach 1:
The regulator circuit uses the existing DC bus voltage and switching elements already present in the power converter system, eliminating the need for additional power supplies or external components. This self-service approach reduces manufacturing costs while effectively reducing capacitor ripple voltage.
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 solution effectively reduces capacitor ripple, slows aging, and lowers manufacturing costs by eliminating the need for increased capacitance and external power supplies, while maintaining stable power flow between microgrids.
Implementation Method 1
The power converter module is used to be coupled further to the second microgrid, further receives a PWM (pulse width modulation) output, and includes two capacitors that are coupled to each other. The power converter module performs AC to DC (direct current) to AC conversion upon the three-phase AC power input based on the PWM output
Implementation Method 2
The control module generates the PWM output for the power converter module based at least on the first and second detection outputs, such that the common node of the capacitors further receives, from the neutral terminal of the first microgrid, a second zero sequence current input which has a non-zero amplitude and is anti-phase with the first zero sequence current input
Data Source
AI summary
A power conditioner includes a power converter module, a detector module and a control module. The power converter module performs power conversion upon a three-phase AC power input from a first microgrid based on a PWM output to generate a three-phase AC power output for a second microgrid. The detector module detects the three-phase AC power input, and a first zero sequence current input that is received by the power converter module from the second microgrid. The control module generates the PWM output based at least on a result of the detection, such that the power converter module further receives, from the first microgrid, a second zero sequence current input which is anti-phase with the first zero sequence current input.