Vehicle Generator Transistor Chopper Circuit Grounding
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Solution Overview
Problem
Vehicle generators equipped with transistor chopper type exciter circuits face reliability and environmental resistance issues due to leakage currents that cause corrosion when exposed to wet conditions, especially in cold climates, leading to limited adoption despite their multifunctionality under normal conditions.
Innovation Solution
A vehicle generator control device with a transistor chopper type exciter circuit featuring a bridge circuit with power transistors and diodes, where one transistor is kept on and the other off when the engine is not operating, ensuring the rotor potential is grounded and preventing corrosion, and using voltage-driven power transistors and diodes to manage leakage currents effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a transistor chopper type exciter circuit is used to supply excitation current to the vehicle generator, then the generator output utilization is improved and regenerative current can be supplied to the battery, but leakage current causes rotor corrosion when the generator is exposed to wet conditions
Solution Approach 1:
The invention applies preliminary action by setting the ground-side transistor to the ON state in advance before wet conditions occur. This proactive measure ensures that the rotor potential is continuously grounded, preventing corrosion from occurring in the first place when the generator is exposed to wet environments with snow-melting agents.
Solution Approach 2:
The invention converts the harmful leakage current into a beneficial protective mechanism. By intentionally grounding the rotor through the transistors, the same electrical pathway that could cause corrosion is instead used to safely dissipate stray currents and maintain potential equality between rotor and stator, thereby protecting against corrosion.
2Device complexity
If both transistors are set to off state when engine is non-operating, then the circuit is simple and power consumption is reduced, but the rotor potential floats and becomes susceptible to leakage current and corrosion
Solution Approach 1:
The invention applies local quality by treating the two transistors differently based on their positions in the bridge circuit. The ground-side transistor is set to ON state to provide protective grounding, while the output-side transistor remains OFF to maintain circuit simplicity. This asymmetric control strategy addresses the specific vulnerability of the rotor to leakage current without over-complicating the overall circuit.
3Reliability
If the ground-side transistor is set to on state continuously, then rotor corrosion is prevented by grounding the potential, but power consumption increases and the transistor operates continuously
Solution Approach 1:
The invention implements periodic action by controlling the ground-side transistor to operate in cycles rather than continuously. The transistor switches between ON and OFF states based on the engine operating condition, being ON only when the engine is non-operating and turning OFF when the engine starts. This periodic control maintains corrosion protection during vulnerable periods while reducing overall power consumption.
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 enhances the environmental resistance and reliability of vehicle generators by preventing rotor corrosion and ensuring efficient operation even in wet conditions, extending the service life of components and improving overall system reliability.
Implementation Method 1
the power transistor on the earth or ground level side of the bridge circuit is positively switched to the on state, it is possible to prevent the electric potential from floating. As a result, even if a leakage current occurs under the condition that the vehicle-mounted electric generator is wet with water from melted snow containing a snow-melting agent, the leakage current is allowed to flow to the ground via the power transistor
Implementation Method 2
a transistor chopper type exciting circuit for supplying an excitation current to a vehicle-mounted electric generator drivable by an engine of the motor vehicle
Data Source
AI summary
A vehicle generator control device includes a transistor chopper type exciting circuit for supplying an excitation current to a vehicle-mounted electric generator drivable by an engine of the motor vehicle. The exciting circuit comprises a bridge circuit having a first pair of opposing arms formed of respective power transistors and a second pair of opposing arms formed of respective diodes. One of the power transistors is connected to a ground potential of the vehicle-mounted electric generator and the other power transistor is connected to an output terminal of the vehicle-mounted electric generator. When the engine is in a non-operating state, the one transistor is set in an on state and the other power transistor is set in an off state.