Battery Charging Device Thyristor Turn-Off Control
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Solution Overview
Problem
Existing battery charging devices face issues with reliably turning off thyristors when the battery voltage exceeds the set voltage, leading to potential overcharging, especially during transient states in high-speed generator operations, and result in reduced generator output due to phase control requirements.
Innovation Solution
A battery charging device with a controller that applies a trigger signal to three-phase thyristors simultaneously when the battery voltage is below the set voltage and stops the signal after a predetermined trigger stop waiting period has elapsed once the voltage exceeds the set voltage, ensuring reliable thyristor turn-off without phase control, thus preventing overcharging and maintaining generator output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the trigger signal is applied to three-phase thyristors simultaneously when battery voltage is below set voltage, then charging current is supplied to battery, but when trigger signal is eliminated while transient state is ongoing, thyristors cannot be reliably turned off leading to overcharging
Solution Approach 1:
The control device detects whether a transient state is ongoing before eliminating the trigger signal. When a transient state is detected, the control device delays trigger signal elimination until the transient state subsides. This preliminary detection and conditional delay ensures thyristors can be reliably turned off while maintaining precise charging control, resolving the contradiction between turn-off reliability and charging precision.
2Reliability
If phase control is implemented to suppress transient state, then thyristor turn-off reliability improves, but generator output is reduced
Solution Approach 1:
The invention extracts and addresses the root cause of unreliable thyristor turn-off (transient state interference) by detecting transient states and conditionally delaying trigger signal elimination. This approach eliminates the need for phase control measures that would suppress transient states, thereby maintaining full generator output while ensuring reliable thyristor turn-off through selective timing adjustment.
3Productivity
If trigger signal is eliminated immediately when battery voltage exceeds set voltage, then charging stops promptly, but during transient state this causes thyristor commutation failure and overcharging
Solution Approach 1:
The control device performs preliminary detection of transient state conditions before eliminating the trigger signal. When a transient state is detected, the elimination timing is adjusted to occur after the transient state subsides. This preliminary check ensures both rapid charging response (by eliminating the signal as soon as safe to do so) and charging safety (by preventing commutation failure during transient states).
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
This solution effectively prevents overcharging by ensuring thyristors are reliably turned off even during transient states, without reducing the generator's output, by setting an appropriate trigger stop waiting period, allowing for precise control of the charging process.
Implementation Method 1
a three-phase AC generator (1) and a controlled rectifier circuit (2) for rectifying the output of the three-phase AC generator (1)
Implementation Method 2
a controlled rectifier circuit (2) for rectifying the output of the three-phase AC generator (1) and supplying a charging current to a battery (3)
Implementation Method 3
a thyristor that is on at the time the trigger signal is eliminated is held in the on state and turned off once the anode current thereof is less than a holding current
Data Source
AI summary
A battery charging device provided with: a bridge-type controlled rectifier circuit having three-phase thyristors for rectifying the output of a three-phase AC generator and supplying a charging current to a battery; and a controller for controlling the supplying of a trigger signal to the thyristors in accordance with the terminal voltage of the battery; the controller being configured so that the trigger signal is supplied to the thyristors simultaneously when it is detected that the terminal voltage of the battery is equal to or lower than a set voltage, and supplying of the trigger signal is stopped when a certain period has elapsed after the terminal voltage exceeds the set voltage, in order to prevent commutation failure of the thyristors when charging of the battery is stopped, and prevent overcharging of the battery.