H-Bridge Switch Tube Temperature Balancing in EV Chargers
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Solution Overview
Problem
Existing methods for controlling vehicle-mounted chargers of electric vehicles, such as dual-polarity and mono-polarity control methods, result in unbalanced heating of switch tubes in the H bridge, leading to reduced service life due to excessive switching losses and overheating.
Innovation Solution
A method that involves obtaining and comparing total charging times for two different control manners of the H bridge to select the optimal control method for each charging cycle, ensuring temperature-balanced control of the switch tubes, thereby prolonging their service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If dual-polarity control method is adopted, then charging function is achieved, but switching loss and heat loss increase due to all four switch tubes being in high frequency ON/OFF state
Solution Approach 1:
The patent applies dynamics by making the control method adjustable rather than fixed. The controller dynamically selects between first and second control methods based on real-time temperature feedback from the switch tubes, allowing the system to adapt its switching strategy to current thermal conditions and minimize both switching loss and heat loss.
Solution Approach 2:
The patent changes the control parameter by switching between two different control methods (first control method and second control method) for the H-bridge circuit. This parameter change allows the system to optimize the balance between switching frequency and heat generation based on temperature conditions, thereby reducing overall energy loss.
2Loss of energy
If mono-polarity control method is adopted, then heat loss from high frequency switching is reduced, but some switch tubes must be switched off with current causing overheat problem
Solution Approach 1:
The patent implements feedback by using temperature detection units to monitor the temperature of each switch tube in real-time. The controller receives this temperature feedback and uses it to determine which control method to apply, ensuring that switch tubes are not operated in conditions that would cause overheating while still minimizing overall heat loss.
Solution Approach 2:
The system dynamically adjusts the control method based on temperature conditions. When temperature feedback indicates safe operating conditions, the system can use the control method that minimizes heat loss; when temperatures approach critical levels, the system switches to the control method that prevents overheating, thus dynamically balancing heat management.
3Ease of operation
If fixing control manner is used during charging process, then control simplicity is maintained, but unbalanced heating of switch tubes occurs reducing service life
Solution Approach 1:
The patent maintains control simplicity through automated feedback-based decision making. Temperature detection units continuously monitor switch tube temperatures and provide feedback to the controller, which automatically selects the appropriate control method without requiring complex manual intervention or complicated control algorithms, thus preserving ease of operation while improving reliability.
Solution Approach 2:
The system performs self-service by automatically monitoring its own thermal state and adjusting its control strategy accordingly. The temperature detection units and controller work together to self-regulate the switching behavior of the H-bridge circuit, ensuring balanced heating and extended service life without requiring external intervention or complex user programming.
Data Source
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AI summary
An electric vehicle, a vehicle-mounted charger and a method for controlling the same. The method includes: obtaining a first total charging period TA for controlling the H bridge in a first manner and a second total charging period TB for controlling the H bridge in a second manner when the vehicle-mounted charger starts to charge a power battery (S1); determining a relation between the first total charging period TA and the second total charging period TB (S2); and selecting a manner for controlling the H bridge according to the relation between the first total charging period TA and the second total charging period TB to perform temperature balanced control over the first switch tube, the second switch tube, the third switch tube and the fourth switch tube (S3).