Power Converter Active Filter for High-Frequency Disturbance Suppression
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Solution Overview
Problem
Reducing the inductance of reactors and capacitance in power converters increases resonant frequency, leading to high-frequency components in power-supply current waveforms, causing disturbances to AC power supplies, which are not compliant with JIS standards and result in increased switching losses when trying to suppress these disturbances by increasing inverter switching frequency.
Innovation Solution
A power converter design that includes a rectifier circuit, a capacitor, and a switching power-supply circuit that performs switching operations based on current and voltage deviations to supply power to loads from high-frequency components, thereby reducing high-frequency disturbances in the input current and stabilizing output voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the inductance of the reactor and capacitance of the capacitor are reduced to downsize the power converter, then the device size and weight are reduced, but the resonant frequency increases causing high-frequency disturbance to the AC power supply
Solution Approach 1:
The patent extracts and eliminates the reactor and capacitor from the power converter system. By removing these components that cause resonance and high-frequency disturbance, the invention achieves downsizing while avoiding the harmful effects of reduced inductance and capacitance. The active filter compensates for power factor without requiring these traditional components.
Solution Approach 2:
The invention changes the operating parameters by using active power factor correction with switching frequencies in the range of 10-100 kHz, which is significantly higher than traditional approaches. This parameter change allows the system to achieve power factor correction without the resonance issues caused by traditional reactor-capacitor combinations.
2Object-generated harmful factors
If the inverter switching frequency is increased to suppress high-frequency disturbance, then the AC power supply disturbance is reduced, but the switching loss in the inverter increases
Solution Approach 1:
The patent introduces an active filter as an intermediary component that handles the power factor correction and high-frequency disturbance suppression functions. This intermediary takes on the burden of switching operations at high frequencies, allowing the main inverter to operate at lower frequencies and reduce switching losses while still achieving disturbance suppression.
Solution Approach 2:
The power converter system is segmented into separate functional modules: the main inverter for motor drive and an active filter for power factor correction and disturbance suppression. This segmentation allows each module to be optimized independently, with the active filter handling high-frequency switching tasks while the main inverter operates at lower frequencies.
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 approach effectively suppresses high-frequency components in the input current, stabilizes output voltages, reduces switching losses in the inverter, and allows precise control of power consumption, while maintaining low power consumption and rotary control accuracy for air-cooling fans in air conditioners.
Implementation Method 1
a rectifier circuit (2) that rectifies an input current (iu1, iv1, iw1; ic) from an alternating-current power supply (1) and outputs a direct-current voltage
Implementation Method 2
a capacitor (Cd) connected between said first power-supply line and said second power-supply line
Implementation Method 3
a switching power-supply circuit (61; 62; 6) connected between said first power-supply line and said second power-supply line, said switching power-supply circuit performing a switching operation with a duty based on a first current (-iL) flowing in said first power-supply line
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention provides a power converter that suppresses high-frequency disturbance to an alternating-current power supply. A controller (10) includes subtracters (101, 105), a command value corrector (103), and a control block (102). The subtracter (101) obtains a deviation (Δv0) of an output voltage (v0) applied from a switching power-supply circuit (61) to a second load (Cdc+Load) with respect to its command value (v0*). The control block (102) performs PI control on the basis of the deviation (Δv0) to generate a command value (idc*) for a current (idc) flowing in a coil (Ldc). The command value corrector (103) corrects the command value (idc*) such that high-frequency components of a current (iL) flowing in a first power-supply line (21), with respect to the fundamental frequency of an input current (iu1, iv1, iw1), are consumed in the switching power-supply circuit (61). The subtracter (105) obtains a deviation (Δidc) between the corrected command value (idc*) and the current (idc). Commands (r1, r2) for switches are generated on the basis of the deviation (Δidc).