Power Converter Test Circuit With Auxiliary Current Circulation
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Solution Overview
Problem
Existing power converter testing systems face challenges with size increase due to the need for multiple converters and unstable circuit operation caused by unbalanced capacitor voltages during initial charging.
Innovation Solution
A testing device and method that includes an auxiliary converter connected to the power converter through a line, with a current output circuit and control circuit to manage the switching elements and power storage elements, ensuring a current path bypasses the power storage elements until the DC component of the test current reaches a predetermined level, stabilizing voltage control and preventing abrupt voltage imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bridge circuit with multiple converters and DC reactors is used for testing, then the testing capability is improved, but the system size increases
Solution Approach 1:
The invention extracts the DC reactor component from the traditional bridge circuit configuration. By removing the DC reactor and using only the auxiliary converter with its integrated capacitor, the system achieves the same current circulation function with reduced size and component count.
Solution Approach 2:
The auxiliary converter serves multiple functions: it provides current circulation during initial charging, enables voltage balancing between capacitors, and facilitates stable operation during testing. This multi-functionality replaces the need for separate DC reactors and multiple converters.
2Productivity
If voltage control is started immediately after test current output, then the testing process is accelerated, but capacitor voltage imbalance occurs causing unstable circuit operation
Solution Approach 1:
The invention implements a preliminary current circulation phase before voltage control is activated. During this phase, the auxiliary converter circulates current to pre-charge the capacitors and establish stable operating conditions, preventing voltage imbalance when voltage control begins.
Solution Approach 2:
The control strategy dynamically transitions from current circulation mode to voltage control mode. The system first establishes current flow to charge capacitors, then activates voltage control once stable conditions are achieved, adapting the control method to the circuit's instantaneous state.
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 stabilizes circuit operation by controlling the active power flow and preventing voltage imbalances between power storage elements, ensuring stable testing of power converters.
Implementation Method 1
a first power storage element connected in parallel with a series connection of the first and second main switching elements
Implementation Method 2
first and second main switching elements connected in series through a first terminal
Data Source
AI summary
A power converter to be tested is supplied with arm current from a hysteresis converter in a state in which it is connected to an auxiliary converter through a line. In the power converter and the auxiliary converter, a circulation operation is performed in which a current path bypassing power storage elements is formed between an output terminal of the power converter and an output terminal of the auxiliary converter, after the start of output of arm current in accordance with a reference current command value in which an AC component and a DC component are superimposed, until a DC component of arm current reaches a predetermined level. After execution of the circulation operation, in the power converter and the auxiliary converter, voltage control of the power storage elements and the output terminals is started.