EV Charger Current Calibration for AC Half-Cycle Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing on-board chargers for electric vehicles suffer from hardware sampling errors, leading to unbalanced alternating currents due to deviations between positive and negative half-cycle currents.
Innovation Solution
A charger control method that determines a target current value based on present voltage and steady-state target current, calibrates this value using a current calibration amount, and controls the current on the alternating-current side to follow the calibrated target value, ensuring dynamic balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hardware sampling circuit is used to collect voltage and current on alternating-current side, then charging control can be performed, but hardware sampling error causes deviation between positive and negative half-cycle currents leading to alternating-current unbalance
Solution Approach 1:
The patent applies preliminary action by performing zero-point calibration on the sampling circuit before normal charging operation. The calibration process pre-compensates for hardware sampling errors by determining calibration amounts based on initial sampling data, which are then used to correct subsequent current measurements. This preliminary calibration eliminates the deviation between positive and negative half-cycle currents before charging begins, preventing alternating-current unbalance rather than correcting it during operation.
2Manufacturing precision
If current calibration is performed using sampled current data, then alternating-current balance can be improved, but sampling error in the sampling circuit affects the accuracy of calibration
Solution Approach 1:
The patent implements feedback by using the sampled current data to calculate calibration amounts, which are then applied to correct the target current values. The system continuously monitors the alternating-current side current through the sampling circuit and adjusts the calibration amounts based on the detected deviations between positive and negative half-cycles. This closed-loop feedback mechanism compensates for sampling errors by dynamically adjusting calibration parameters to maintain current balance despite hardware imperfections.
Solution Approach 2:
The patent applies parameter changes by modifying the target current values through calibration amounts that adjust the electrical parameters of the charging system. The calibration process changes the current measurement parameters by applying correction factors derived from sampling data, transforming the raw sampled current values into calibrated current values that accurately reflect the actual alternating-current side conditions. This parameter adjustment compensates for hardware errors and achieves current balance.
3Measurement precision
If zero-point calibration is performed on sampling circuit when charger is powered on, then sampling accuracy can be improved, but additional calibration time and processing are required
Solution Approach 1:
The patent performs zero-point calibration as a preliminary action during the charger power-on sequence, before normal charging operations begin. This calibration process is integrated into the startup routine, allowing the system to complete sampling accuracy adjustments in advance. By performing calibration preliminarily during power-on rather than during active charging, the system minimizes the impact on charging time while ensuring accurate measurements from the start of charging operations.
Data Source
AI summary
A method for controlling a charger, includes: determining a target current value on an alternating-current side, according to a present voltage and a steady-state target current on the alternating-current side of the charger; calibrating the target current value by a current calibration amount on the alternating-current side to obtain a calibrated target current value; and controlling a current on the alternating-current side, according to the calibrated target current value, the present voltage, a present current on the alternating-current side, and a voltage of a bus capacitor, to follow the calibrated target current value. The charger comprises an on-board charger or a charging pile charger.