Inverter Testing via Virtual AC Source Simulation
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Solution Overview
Problem
Existing inverter test methods either increase costs by connecting an AC power supply or fail to simulate normal energization conditions, making it difficult to test inverters under actual operational conditions.
Innovation Solution
An inverter test apparatus comprising a test facility inverter, a controller, inductors, a diode rectifier, and an AC power supply, which uses PWM control and phase adjustment to simulate power running and regenerative states, allowing for testing at rated current and voltage with adjustable power factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an AC power supply is connected to the AC side of the inverter, then the inverter can be tested under normal energization condition, but the cost of the test apparatus increases
Solution Approach 1:
The patent creates a virtual AC power supply by using a second inverter to generate a simulated AC voltage that replicates grid conditions. This copying approach allows the first inverter to be tested under normal energization conditions without requiring an actual AC power supply connection, thereby maintaining test accuracy while reducing apparatus cost and complexity
Solution Approach 2:
The patent introduces a reactor as an intermediary component connected between the first and second inverters. This reactor simulates the impedance characteristics of a real AC grid, enabling the first inverter to operate under realistic energization conditions while the second inverter provides the necessary power, thus resolving the contradiction between test realism and cost
2Device complexity
If an AC power supply is not connected to the AC side of the inverter, then the cost of the test apparatus is reduced, but it becomes difficult to test the inverter under normal energization condition
Solution Approach 1:
The second inverter generates a copied AC voltage waveform that mimics real grid conditions, allowing the first inverter to be tested without an actual AC power supply connection. This virtual replication maintains the authenticity of the energization conditions while eliminating the need for expensive external AC power supply equipment
Solution Approach 2:
The second inverter serves multiple functions: it acts as a virtual AC power supply, provides controllable load simulation, and enables both power running and regenerative braking tests. This multi-functionality allows comprehensive inverter testing without external AC power supply equipment, reducing apparatus cost while maintaining test validity
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
Enables testing of inverters under conditions similar to actual operation, reducing costs and improving the accuracy of power factor adjustment and current control.
Implementation Method 1
The inverter is subjected to pulse width modulation (PWM) control, thereby performing a power conversion operation
Implementation Method 2
a reactor 4a, 4b is connected to a load side of a single-phase inverter
Implementation Method 3
a diode rectifier 5, an AC power supply 6
Data Source
Figure 1
Figure 2~3
Figure 4~7
AI summary
An inverter test apparatus (10) which tests a single-phase inverter (1) includes a DC power supply (5) which supplies a DC power to the inverter (1), a test facility inverter (2) which is connected to a DC side of the inverter (1), an inductor (4a) which is connected between an AC side of the inverter (1) and an AC side of the test facility inverter (2), a PWM control module (32) which controls an AC voltage of the inverter (1) to be at a constant amplitude and a constant frequency, a current detector (7) which detects a current (i) that flows through the inductor (4a), a control module (31) which computes a phase command value (θ2r) of the test facility inverter (2) so as to control the current detected by the current detector (7), and a PWM control module (33) which controls a phase of the test facility inverter (2), based on the computed phase command value (θ2r).