Phase Shift Control for Three-Port Charging Circuit Light Load Stability
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Solution Overview
Problem
Traditional electric vehicle charging systems face challenges in automatic power distribution, where the output power of the main circuit affects the auxiliary circuit, leading to inadequate power supply when the main circuit is at light or no load, resulting in insufficient power for vehicle-mounted electrical appliances.
Innovation Solution
A phase shift control method for a three-port charging circuit that stabilizes magnetic flux in the transformer by adjusting the phase angle difference between switching waveforms of power switches, ensuring consistent output power to both circuits through PWM control and DSP management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the main circuit output is at light load or no load (small duty cycle), then the main circuit power consumption is reduced, but the magnetic flux in the transformer becomes very small or almost zero, causing the auxiliary circuit to be unable to draw power
Solution Approach 1:
The patent applies dynamic control by switching between two operational modes: phase shift control for light load conditions and duty cycle control for heavy load conditions. This dynamic switching ensures that the transformer maintains adequate magnetic flux for auxiliary circuit operation while optimizing main circuit power consumption based on load conditions.
Solution Approach 2:
The patent changes the control parameter from duty cycle alone to a combination of phase shift angle and duty cycle. By introducing phase shift angle as an additional controllable parameter, the system can independently regulate power transfer to maintain transformer flux levels even when the main circuit operates at light load, thereby ensuring auxiliary circuit power availability.
2Device complexity
If traditional transformer integrated multi-port power output is used, then the structure is simple, but automatic power distribution causes output power cross adjustment between circuits
Solution Approach 1:
The patent maintains the simple transformer integrated structure but introduces dynamic control capability through mode switching between phase shift control and duty cycle control. This dynamic control layer adds independence to power regulation without requiring structural changes to the transformer, thus preserving structural simplicity while achieving independent power control adaptability.
Solution Approach 2:
The patent makes the control system multi-functional by implementing both phase shift control and duty cycle control capabilities within a single charging circuit. This allows the system to handle different operating scenarios (light load, heavy load, auxiliary circuit priority, main circuit priority) using the same hardware structure, achieving versatility without increasing device complexity.
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 method ensures stable magnetic flux and consistent power supply to the auxiliary circuit, even at light loads, allowing it to draw energy normally and meet power demands, while conveniently controlling power conversion directions and numbers.
Implementation Method 1
a transformer connecting the three circuits
Implementation Method 2
the controller carries out PWM control on the first and the second groups of power switches in the primary conversion circuit and also carries out PWM control on the third and the fourth groups of power switches in the first secondary conversion circuit at the same time
Data Source
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AI summary
The present invention discloses a phase shift control method for a charging circuit, wherein the charging circuit comprises a primary conversion circuit, a first secondary conversion circuit, and a second secondary conversion circuit; the controller causes a phase angle difference Φ between an ON/OFF waveform of power switches in the primary conversion circuit and an ON/OFF waveform of power switches in the first secondary conversion circuit; the controller collects an output current (Io1) and an output voltage (Vo1) of the first secondary conversion circuit, collected by the first secondary current collector and the first secondary voltage collector, carries out comparison and calculation between the collected output current and output voltage and a preset output current and output voltage, and adjusts the magnitude and positive and negative of the phase angle difference Φ according to the comparison result. The present invention can stabilize the magnetic flux in the transformer when the main circuit output is at a light load and no load, thereby ensuring that the auxiliary circuit can draw electric energy from the transformer normally and supply power to the outside normally, and also can conveniently control the conversion direction of the power in each port and the number of conversions.