Power Buffer Circuit Segmentation for Pulsating Torque Reduction
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Solution Overview
Problem
Existing power converters with active power buffer circuits require large electrostatic capacitance and power capacity to manage pulsating power, limiting their power capacity and efficiency, especially in applications like household air conditioners where pulsating torque suppression is necessary.
Innovation Solution
A power converter design that includes a DC link, an inverter, and a power buffer circuit with a discharge and charge circuit, where the discharge power is adjusted relative to the charge power to reduce the variation, allowing for a smaller power buffer capacity by using a constant k less than 1/2, thereby reducing the electrostatic capacitance and power capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional power buffer circuit is used to manage pulsating power from a full-wave rectifying circuit, then the power pulsations are reduced, but the electrostatic capacitance and power capacity required become excessively large
Solution Approach 1:
The invention divides the power buffer function into two separate circuits: a first power buffer circuit that handles the pulsating power component, and a second power buffer circuit that handles the average power component. This segmentation allows each circuit to be optimized for its specific function, with the first circuit using a smaller capacitor for ripple suppression and the second circuit handling the bulk power storage, thereby reducing the total power buffer capacity required while maintaining effective pulsation reduction
Solution Approach 2:
The invention dynamically switches between two power buffer circuits based on the operating conditions. The switching element selectively connects either the first or second power buffer circuit to the load, allowing the system to adaptively manage power delivery. This dynamic operation enables the use of smaller capacitors in each circuit while maintaining the overall power buffer performance, as each circuit only needs to handle a portion of the total power requirements at any given time
2Stability of the object's composition
If a large smoothing capacitor is used to buffer power, then voltage ripples are reduced, but the device size and cost increase
Solution Approach 1:
The invention segments the voltage ripple suppression function across two separate capacitor circuits rather than relying on a single large capacitor. The first power buffer circuit uses a smaller capacitor optimized for high-frequency ripple suppression, while the second circuit handles lower-frequency variations. This segmentation achieves effective voltage ripple reduction with significantly reduced total capacitor volume compared to a conventional single large capacitor approach
Solution Approach 2:
The invention changes the operational parameters of the capacitor circuits by using switching elements to dynamically control their connection to the load. By adjusting the switching duty cycles and timing, the system optimizes the ripple suppression performance of each capacitor circuit, allowing smaller capacitors to achieve the same voltage stability as a much larger conventional capacitor would provide
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 reduces the power capacity of the power buffer circuit, allowing for a broader range of power capacity utilization and minimizing pulsating torque, leading to increased efficiency and reduced stress on the compressor support system.
Implementation Method 1
A capacitive element, for example, referred to as a smoothing capacitor is required for buffering of a power
Data Source
Figure 1
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Figure 4
AI summary
A technique for reducing power capacity required for a power buffer circuit is provided. A converter (3) full-wave rectifies a single-phase voltage (Vin), and outputs the rectified voltage (Vrec) across DC power supply lines (LL and LH). An inverter (5) receives the rectified voltage (Vrec), and supplies a three-phase AC current (Iu, Iv and Iw) to an inductive load (6). A power buffer circuit (4) is connected between the DC power supply lines (LL and LH). The power buffer circuit (4) includes a discharge circuit (4a) and a charge circuit (4b). The discharge circuit (4a) includes a capacitor (C4) and a switch (Sc) connected in series to each other. The discharge circuit (4b) is configured, for example, by a boost chopper, and includes a switch (Sl), a reactor (L4), and a diode (D40). The power buffer circuit (4) provides and receives part of pulsations of a power input into the converter (3) to and from the DC power supply lines (LL and LH).