Motor Vehicle Charger Control Reducing Switching Losses
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Solution Overview
Problem
High-power battery chargers face inefficiencies and heat dissipation issues due to higher neutral current setpoints, which limit the reduction of power consumption and heat dissipation, necessitating a method to control the neutral current to match the battery current while minimizing losses.
Innovation Solution
A control method for battery chargers involving a series chopper and boost circuit, where the threshold voltage is determined based on battery current measurements, and the series chopper's switches are controlled to maintain constant output voltage, allowing the neutral current to be minimized while ensuring efficient regulation of the load current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the neutral current setpoint is increased to ensure proper current relationship and regulation, then the reliability of current regulation is improved, but the energy losses and heat dissipation increase
Solution Approach 1:
The invention changes the control parameter from neutral current setpoint to direct control of battery current and its derivative. By controlling the battery current directly and using its time derivative, the system achieves proper current relationships without requiring excessive neutral current margin, thereby reducing energy losses while maintaining regulation reliability.
Solution Approach 2:
The invention implements feedback control by using the measured battery current and its time derivative to adjust the switching commands. This feedback mechanism ensures that the current relationships are maintained dynamically without requiring a fixed high neutral current setpoint, thus reducing energy losses while maintaining reliable regulation.
2Loss of energy
If the neutral current setpoint is reduced to improve efficiency, then the energy losses are reduced, but the regulation of load current deteriorates
Solution Approach 1:
The invention changes the control parameters from neutral current setpoint to battery current and its time derivative. This parameter transformation allows the system to achieve effective load current regulation with lower neutral current, thereby reducing energy losses while maintaining or improving regulation quality.
Solution Approach 2:
By implementing feedback control using battery current measurement and its derivative, the system dynamically adjusts to maintain proper current relationships. This eliminates the need for high neutral current setpoints, enabling efficient operation with reduced energy losses while preserving regulation reliability.
3Reliability
If the neutral current setpoint is maintained high to account for model uncertainties, then the reliability under uncertain conditions is improved, but the energy efficiency deteriorates
Solution Approach 1:
The invention uses real-time feedback from battery current measurement and its derivative to adapt to model uncertainties and disturbances. This dynamic feedback control eliminates the need for conservative high neutral current setpoints, achieving reliable regulation under uncertain conditions while significantly reducing energy consumption.
Solution Approach 2:
The control system uses the battery current and its derivative as self-generated signals to regulate the charging process. This self-service approach allows the system to handle uncertainties and disturbances autonomously without requiring excessive neutral current margin, thereby maintaining reliability while reducing energy 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
This approach reduces electrical losses and heat dissipation by optimizing the neutral current to match the battery current, enhancing the overall efficiency of the charger while maintaining effective load current regulation.
Implementation Method 1
the switches of the boost stage so that they are kept open
Implementation Method 2
a boost circuit being connected to on the one hand to the series chopper and on the other hand to the battery
Data Source
Figure 1
Figure 1
Figure 2~4
AI summary
The invention relates to a method for controlling a battery charger for a motor vehicle, the battery charger including an input filter (1) connecting a three-phase power supply circuit to a buck converter (2), a boost circuit (3) being connected to the buck converter (2) and to the battery (BAT). The method includes the following steps: the output threshold voltage of the buck converter (2) is determined on the basis of the difference between a battery-current measurement and a battery-current request; the output voltage of the buck converter (2) is kept constant; and the switches of the boost stage (3) are controlled so as to be kept open.