Stator Inverter Auxiliary Current Control to Cut Capacitor Heating
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Solution Overview
Problem
The existing electrical systems with stator inverters and auxiliary devices face challenges in reducing the effective current received by the stator inverter and auxiliary electrical device, leading to increased heating and the need for more expensive components due to high current through capacitors.
Innovation Solution
The system controls the auxiliary electrical device to make its current negative or zero when the inverter current is positive, thereby compensating or reducing the total current, which in turn reduces the effective capacity current, using a control device that alternates between different configurations based on the detection of stator inverter current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a capacitor is provided across the inverter terminals to provide variable current, then the current demand on the voltage source is reduced, but the capacitor heats up more and requires more resistant and expensive components
Solution Approach 1:
The patent creates a virtual copy of the capacitor's current-providing function through the auxiliary electrical device controlled by the control unit. Instead of relying solely on the physical capacitor, the system synthesizes an equivalent current contribution through electronic control of the auxiliary device, thereby reducing the actual current burden on the capacitor and its heating effects.
Solution Approach 2:
The control unit dynamically adjusts the operating parameters of the auxiliary electrical device based on the detected inverter current. By changing the control parameters (switching states, duty cycles) of the auxiliary device, the system optimizes the current distribution between the capacitor and auxiliary device, reducing capacitor stress and heating while maintaining overall system performance.
2Stability of the object's composition
If the capacitor provides variable current to reduce the current from the voltage source, then the voltage source delivers more constant current, but the effective current through the capacitor increases causing more heating
Solution Approach 1:
The auxiliary electrical device acts as a virtual copy that shares the current-providing responsibility with the physical capacitor. The control unit coordinates their contributions so that the auxiliary device provides a portion of the variable current that would otherwise fall entirely on the capacitor, reducing capacitor heating while maintaining the constant current characteristic at the voltage source output.
Solution Approach 2:
Instead of the capacitor providing the full variable current component, the auxiliary electrical device provides a partial contribution to the variable current demand. This partial action by the auxiliary device is sufficient to reduce the capacitor's burden and heating effects while the combined system continues to deliver the required constant current to the voltage source.
Data Source
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AI summary
Said electrical system (100) comprises: a stator inverter (108) and an auxiliary electrical device (110) designed for connection to a positive terminal of a DC voltage source (102) for respectively receiving a stator inverter current (iOS) and an auxiliary current (iAUX), the auxiliary electrical device (110) being designed to selectively assume a first configuration in which the auxiliary current (iAUX) is positive and a second configuration in which the auxiliary current (iAUX) is negative or zero. The electrical system (100) further comprises: a sensing device (116) for sensing whether the stator inverter current (iOS) is positive or zero; and a control device (118) for moving the auxiliary electrical device (110) into the first configuration when the stator inverter current (iOS) is detected as zero, and into the second configuration when the stator inverter current (iOS) is detected as positive.