Battery Charging Rectifier Control to Prevent Parasitic Diode Heating
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Solution Overview
Problem
In existing battery charging devices, when the main switch is turned off and source power supply is stopped while the power generator is rotating, the switch element is controlled by a parasitic diode with high resistance, leading to potential heating and overcharging of the battery.
Innovation Solution
A battery charging device with a rectification unit and a power supply sustaining switch that maintains control power supply when the main switch is cutoff, and a control unit that switches the negative-electrode MOS transistor to an on-state during rotor rotation, preventing parasitic diode rectification and overcharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the main switch is turned off to stop control electric power supply, then power consumption is reduced, but the switch element is controlled by parasitic diode causing heat generation and potential device abnormality
Solution Approach 1:
The control unit detects rotor rotation in advance and maintains the negative-electrode switch element in an on-state before parasitic diode rectification can occur. By anticipating the harmful condition and acting preemptively, the system prevents heat generation while allowing the main switch to be turned off for power savings.
Solution Approach 2:
The negative-electrode switch element acts as an intermediary component that, when maintained in an on-state, provides a low-resistance path for current flow. This intermediary action prevents current from flowing through the high-resistance parasitic diode, thereby eliminating heat generation while allowing the main switch to be cutoff.
2Loss of energy
If the main switch is turned off to stop control electric power supply, then power consumption is reduced, but the battery may be overcharged
Solution Approach 1:
The control unit continuously monitors rotor rotation status and provides feedback to maintain the negative-electrode switch element in an on-state during rotation. This feedback mechanism ensures reliable prevention of overcharging while allowing the main switch to be turned off, achieving both power savings and charging reliability.
Solution Approach 2:
The system detects rotor rotation in advance and preemptively maintains the negative-electrode switch element conductive. This preliminary action ensures that proper rectification is established before any overcharging condition can develop, maintaining reliability while enabling power savings through main switch cutoff.
3Device complexity
If parasitic diode rectification occurs, then the device structure is simple, but the switch element is heated and device abnormality may occur
Solution Approach 1:
The system dynamically adjusts the state of the negative-electrode switch element based on rotor rotation detection. During rotation, the switch element is maintained in an on-state to prevent parasitic diode conduction and heat generation. This dynamic control maintains simple device structure while preventing temperature rise.
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 device curbs heating and overcharging by securing control power supply and maintaining the negative-electrode switch element in an on-state during rotor rotation, effectively preventing parasitic diode rectification and ensuring stable battery charging.
Implementation Method 1
a rectification unit configured to output DC electric power which is obtained by rectifying three-phase AC electric power output from a power generator as charging electric power of a battery
Implementation Method 2
control of the switch element is stopped, and thus AC electric power generated by the power generator may be rectified by a parasitic diode of the switch element. In this case, since rectification is performed by the parasitic diode which has a high resistance, there is a likelihood that the switch element may be heated
Implementation Method 3
three-phase AC electric power output from a power generator as charging electric power of a battery through turning-on of a switch element connected to an output signal line of each phase of the three-phase AC electric power with rotation of a rotor
Data Source
AI summary
A battery charging device includes: a rectification unit configured to output DC electric power which is obtained by rectifying three-phase AC electric power output from a power generator as charging electric power of a battery through turning-on of a switch element connected to an output signal line of each phase of the three-phase AC electric power with rotation of a rotor; a power supply sustaining switch that is able to be sustained in a state in which control electric power of the switch element from the battery is able to be supplied when a main switch is switched to a cutoff state in which supply of the control electric power to the power supply line is stopped; and a control unit configured to control turning-on of the switch element, the control unit sustaining the power supply sustaining switch in a state in which the control electric power of the switch element is able to be supplied when the main switch is switched to the cutoff state and performing control such that the switch element on a negative electrode side connected to a negative electrode terminal of the battery is switched to a turned-on state when the rotor is rotating.