EV Charger Power Pulsation Absorption for Smaller Capacitors
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Solution Overview
Problem
Existing chargers for electric vehicles face challenges in reducing the size of capacitors required to absorb power pulsation due to single-phase AC power supply, and existing control methods are not applicable to voltage increase operations.
Innovation Solution
A charger design incorporating a rectifier, DC/DC converter, power pulsation absorbing circuit, and controller that controls switchings to absorb power pulsation, allowing for a compact charger by reducing the size of capacitors and inductors through active power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high capacitance capacitor is used to absorb power pulsation, then power pulsation absorption capability is improved, but the size of the capacitor increases
Solution Approach 1:
The power pulsation absorption function is segmented between two components: a capacitor that handles high-frequency pulsation and an inductor that handles low-frequency pulsation. This division allows each component to be optimized for its specific frequency range, enabling the capacitor to be much smaller than a single capacitor would need to be to handle all pulsation frequencies.
Solution Approach 2:
The invention changes the approach by introducing an inductor with specific inductance value (0.1mH to 10mH) in series with the capacitor, creating a resonant circuit that naturally filters different frequency components. This parameter-based solution allows the capacitor to operate at optimal capacitance values without needing excessive capacity.
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 charger effectively absorbs power pulsation, enabling a compact design by limiting the size of capacitors and inductors, and maintaining a constant power input to the DC/DC converter.
Implementation Method 1
a power pulsation absorbing circuit including a first diode, a second diode, a third diode, an inductor, a capacitor, a first switch and a second switch
Implementation Method 2
a power pulsation absorbing circuit including a first diode, a second diode, a third diode, an inductor, a capacitor, a first switch and a second switch
Data Source
AI summary
A charger includes: a rectifier including input terminals, a cathode terminal and an anode terminal, wherein the input terminals are configured for connection to an AC power supply; a DC/DC converter including a first terminal, a second terminal and output terminals, the first terminal being configured to be connected to the cathode terminal of the rectifier, the second terminal being configured to be connected to the anode terminal of the rectifier, wherein the output terminals are configured for connection to a battery; and a power pulsation absorbing circuit including a first to third diodes, an inductor, a capacitor, a first switch and a second switch, wherein the DC/DC converter, the first and second switch are controlled to obtain a constant sum of a power outputted from the AC power supply and a power outputted from the capacitor during increasing a voltage outputted from the AC power supply.