Battery Charger Phase Shift Compensation
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Solution Overview
Problem
Fast charging devices for motor vehicle batteries from three-phase networks face challenges in minimizing phase shift between current and voltage due to RLC filters, leading to reactive power loss and inefficiencies.
Innovation Solution
A fast charging device with a filtering stage, step-down, and step-up stages, incorporating an induction coil and a regulation unit that compensates for phase shift and maintains current amplitude, using cyclic chopping ratios and PID regulators to control switches and ensure optimal energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If an RLC filter is used at the input of the voltage step-down device, then high-frequency harmonics are filtered, but a phase shift between current and voltage is induced, leading to reactive power loss
Solution Approach 1:
The patent implements dynamic regulation of the step-down and step-up converters to actively compensate for the phase shift introduced by the RLC filter. The regulation unit continuously adjusts the switching duty cycles based on real-time current and voltage measurements, enabling the system to dynamically counteract the filter's phase-shifting effect and minimize reactive power loss while maintaining harmonic filtering.
Solution Approach 2:
The patent changes the operating parameters of the converters (switching frequency, duty cycle) to optimize the phase relationship between current and voltage. By adjusting these parameters dynamically, the system can compensate for the RLC filter's phase shift and reduce reactive power consumption while maintaining effective harmonic suppression.
2Power
If the current drawn from the network is chopped at high frequency, then voltage conversion is achieved, but high-frequency harmonics are generated that exceed distribution network standards
Solution Approach 1:
The patent introduces an RLC filter as an intermediary component between the converter and the distribution network. This filter acts as a mediator that allows the converter to operate at high frequency for efficient voltage conversion while blocking and attenuating the high-frequency harmonics from being injected into the distribution network, thus satisfying both conversion efficiency and harmonic emission requirements.
Solution Approach 2:
The patent segments the power conversion system into distinct functional blocks (converter, RLC filter, regulation unit) with clearly defined roles. The converter handles voltage conversion, the RLC filter handles harmonic suppression, and the regulation unit handles control and coordination. This segmentation allows each component to be optimized for its specific function while working together to achieve overall system performance.
3Loss of energy
If the phase shift between current and voltage is minimized, then reactive power loss is reduced, but the presence of the RLC filter makes this difficult to achieve
Solution Approach 1:
The patent implements a feedback control mechanism where the regulation unit continuously monitors the current and voltage phases and adjusts the converter operating parameters to minimize phase shift. The feedback loop measures the actual phase difference and dynamically corrects it by adjusting the switching duty cycles, enabling the system to overcome the RLC filter's inherent phase-shifting effect and reduce reactive power loss.
Solution Approach 2:
The patent dynamically changes the operating parameters of the converters (switching frequency, duty cycle ratio) to compensate for the RLC filter's phase shift. By adjusting these parameters in real-time based on system conditions, the regulation unit can minimize the overall phase difference between input current and voltage, thereby reducing reactive power loss despite the filter's presence.
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 solution effectively minimizes phase difference between current and voltage, reduces reactive power loss, and ensures efficient energy transfer to the battery, meeting battery current setpoints while avoiding undesirable harmonics.
Implementation Method 1
an induction coil interposed between the step-down stage and the step-up voltage stage
Implementation Method 2
a filtering stage of the resistive-inductive-capacitive type intended to be connected to a three-phase network
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
A device (1) for charging a battery (13), comprising: a resistive-inductive-capacitive-type filter stage (2) to be connected to a three-phase network, a voltage buck stage (3), and a voltage boost stage (4) to be connected to the battery (13), as well as an induction coil (Ld) disposed between the buck stage (3) and the boost stage (4). The device (1) comprises a regulating unit (15) which can impose chopping duty cycles on the voltage buck (3) and boost (4) stages. The regulating unit (15) comprises: means (16) for compensating the phase shift induced by the filter stage (12) between the currents (Ie1, Ie2, Ie3) and the voltages (Ve1, Ve2, Ve3) tapped off from each phase (B1, B2, B3) of the three-phase network, and means (16, 17) for maintaining the amplitude value of the current passing through the coil (Ld) above a predefined nonzero threshold.