A charging ripple suppression circuit of an on-board charger and its control method

Abstract

The invention discloses a charging ripple suppression circuit of a vehicle-mounted charger and a control method thereof. The suppression circuit comprises: an AC power supply is used to provide power to a main power circuit of the charger; the main power circuit of the charger is used to pass the AC power through The rectification is converted into DC power, and the converted DC power is charged to the power battery; the bidirectional conversion circuit is used to realize the bidirectional power conversion between the power battery and the low-voltage battery, so as to realize the ripple compensation at the output end of the main power circuit of the charger; A control circuit is used to control the operation of the main power circuit of the charger, the second control circuit is used to control the operation of the bidirectional conversion circuit; the communication circuit is used to realize the communication between the first control circuit and the second control circuit, without increasing the product cost. On the premise, the low-frequency ripple during single-phase operation is suppressed, and the cost of solving the ripple current problem is saved.

Description

technical field [0001] The invention relates to the technical field of chargers, in particular to a charging ripple suppression circuit of a vehicle-mounted charger and a control method thereof. Background technique [0002] At present, most of the on-board chargers are single-phase chargers with a power level of 3.3kW or 6.6kW. The topology circuit usually adopts the front stage PFC (power factor correction unit) and the rear stage LLC (a DC conversion topology). The power factor of the grid needs to be above 0.99, that is, the current is required to be in the same phase as the grid voltage. Affected by this, the DC bus output by the PFC (power factor correction unit) output circuit must have a low-frequency ripple twice the power frequency, which will eventually be reflected in the DC output of the power battery. The above problems will also occur when the three-phase on-board charger works in a phase loss or single-phase state. The ripple will have an impact on the work...

AI Technical Summary

Problems solved by technology

In view of the above two methods to solve the low-frequency ripple, the former, increasing the parallel capacitance of the busbar or adding an active filter device can effectively suppress the low-frequency ripple, but this measure needs to increase the product volume and increase the product cost. The use of capacitors will also reduce the service life of the product. In the latter solution, the introduction of a low-frequency ripple control loop will reduce the system bandwidth, affect the dynamic response speed of the system, and reduce the reliability of the system.

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