Inverter Phase-Shift Control for LC Filter Harmonic Suppression
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Solution Overview
Problem
Existing inverter systems using two-phase modulation methods generate harmonic waves with amplified amplitudes due to resonance with LC filters, necessitating larger inductors and capacitors to avoid this, which contradicts the demand for downsizing in applications like automobiles and home appliances.
Innovation Solution
A control device that generates a first signal for two-phase modulation, acquires the load's weight, identifies a corresponding phase shift amount, and adjusts this shift to reduce harmonic wave amplitude without altering the filter size by using a control method that includes a first generation unit, acquisition unit, storage unit, and second generation unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inductance of the inductor L and capacitance of the capacitor C are increased to lower the resonance frequency of the LC filter, then the frequency of the harmonic wave generated by the switching of the inverter and the resonance frequency of the LC filter can be kept away from each other, but the size of the inductor L and capacitor C must be increased
Solution Approach 1:
The patent changes the timing parameters of the two-phase modulation method by adjusting the stop period of switching element S1 and the switching periods of switching elements S2 and S3. This parameter adjustment shifts the frequency spectrum of the inverter output, moving the harmonic wave frequencies away from the LC filter's resonance frequency, thereby reducing harmonic amplification without requiring larger filter components
Solution Approach 2:
The patent introduces dynamic control of the switching timing based on the inverter's operating conditions. By dynamically adjusting the stop period and switching periods according to the modulation wave frequency and amplitude, the system adaptively controls the harmonic content to avoid resonance with the fixed-frequency LC filter, achieving effective harmonic suppression across varying operating conditions
2Loss of energy
If the two-phase modulation method is used to reduce switching loss, then the switching efficiency is improved, but harmonic waves with amplified amplitudes are generated due to resonance with the LC filter
Solution Approach 1:
The patent modifies the switching timing parameters within the two-phase modulation framework. By optimizing the stop period of S1 and the switching periods of S2 and S3, the method maintains the low switching loss advantage while reshaping the harmonic spectrum to avoid LC filter resonance, thereby eliminating the harmful harmonic amplification effect
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
Reduces harmonic wave amplitude generated by inverters using two-phase modulation without increasing the size of the LC filter, thus maintaining compactness in devices like vehicles and home appliances.
Implementation Method 1
an LC filter including an inductor L and a capacitor C may be used as means for removing a ripple component thereof
Implementation Method 2
the inverter includes a switching element, and converts the direct current power into the alternating current power by switching the switching element between an ON state and an OFF state
Data Source
AI summary
This control device controls an inverter for driving a load, the control device comprising: a first generation unit for generating a first signal for performing two-phase modulation if a three-phase alternating current voltage for driving the load is generated; an acquisition unit for acquiring the weight of the load; a storage unit for storing corresponding relationships between the weight of the load and a phase shift amount of the first signal; an identification unit for identifying the phase shift amount corresponding to the weight of the load acquired by the acquisition unit in the corresponding relationship; and a second generation unit for generating a second signal in which the phase shift amount has been altered from the first signal on the basis of the phase shift amount identified by the identification unit.