DC/DC (DC-DC converter) control method of hybrid power vehicle

Abstract

The invention provides a DC / DC (DC-DC converter) control method of a hybrid power vehicle. The DC / DC control method comprises: step one, a vehicle controller detects a current signal of a high-voltage DC bus on the terminal of a power battery, a current signal of a low-voltage DC bus on the terminal of a 12V battery, and a voltage signal on the terminal of the 12V battery; step two, the vehicle controller determines the status of charging and discharging of the power battery; step three, the vehicle controller estimates the state of charge of the 12V battery; step four, the vehicle controller makes DC / DC on / off judgment; step five, the vehicle controller calculates the required output voltage of a DC / DC; and step six, the vehicle controller sends DC / DC on / off command signals and required DC / DC output voltage command signals to the DC / DC, and the DC / DC executes the commands from the vehicle controller. The method eliminates the charge / discharge loss of the power battery during the process of converting the high-voltage electrical energy to the low-voltage electric energy. The DC / DC can be timely turned on for charging the battery to prevent feeding of the battery, so that the transmission loss of electric energy is reduced, the conversion efficiency of electric energy from high voltage to low voltage is improved, and the rate of fuel saving is increased.

Description

technical field [0001] The invention belongs to the field of electric vehicles and relates to a DC / DC control method for a hybrid electric vehicle. Background technique [0002] In today's increasingly serious environmental pollution and energy crisis, electric vehicles, especially hybrid vehicles, have become a hot research topic in the automotive industry. Hybrid electric vehicles generally remove the generator of traditional vehicles, and use DC / DC to convert high-voltage electricity into low-voltage electricity to provide electrical energy for the 12V battery and the low-voltage load of the vehicle. [0003] For a hybrid electric vehicle that cannot be externally charged, or a hybrid electric vehicle that can be externally charged in power balance mode, the source of DC / DC power is only generated by the motor, but there are two power transmission paths: the first is the direct transmission of the power generated by the motor to DC / DC; the second is that the power genera...

AI Technical Summary

Problems solved by technology

[0004] Among the previous patents, patent CN201010103517.5 discloses a DC / DC control method for moderate hybrid electric vehicles. The on-off control of DC / DC is determined by the vehicle system operating mode, power battery SOC and DC / DC fault status. The output voltage level Determined by monitoring the output current, the output voltage has only two levels of 14.5V and 12V. Compared with the present invention, the control method is different, which cannot reduce the power battery charge and discharge energy loss, and cannot rationally use the low-voltage electric energy stored in the battery; patent CN201310121615. 5 discloses a hybrid electric vehicle low-voltage power supply system and its control method. The power supply system retains a low-voltage generator, and the control method focuses on the coordinated power supply between the low-voltage generator and DC / DC. Compared with the present invention, it does not involve DC Automatic turn-on and turn-off control of / DC, and control of DC / DC output voltage level

[0005] At this stage, during the transmission process of the power generated by the motor of the hybrid electric vehicle to the DC / DC, the part with the largest loss is the charge and discharge loss of the power battery, which leads to a decrease in the energy conversion efficiency from high-voltage power to low-voltage power, which is not conducive to fuel saving

Images