Ideal 24VDC-220VDC vehicle switching power supply circuit design

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Overview:
In order to meet the needs of vehicle-mounted electrical equipment, a DC-DC converter with 24VDC input-220VDC output and rated inverter output power of 600W is designed by push-pull inverter-high frequency transformer-full bridge rectification scheme, and AP method is adopted. The design process of the high frequency push-pull transformer is presented. Based on the detailed analysis of the working principle of push-pull inverter, the precautions in the actual design are given. The experimental results show that the scheme is an ideal vehicle DC-DC converter design.

With the increase in the types of electric vehicles used in modern automobiles and the increase in power levels, more and more types of power supplies are required, including AC power and DC power. These power supplies need to use a switching converter to boost the +12VDC or +24VDC DC voltage provided by the battery to +220VDC or +240VDC through the DC-DC converter, and then convert the DC-AC converter to a commercial frequency AC power supply through the DC-AC converter. Frequency conversion voltage supply. For the pre-stage DC-DC converter, the high-frequency DC-AC inverter part, the high-frequency transformer and the AC-DC rectification part are included, and different combinations are adapted to different output power levels, and the conversion performance is also different. Push-pull inverter circuit has been widely used due to its simple structure and high utilization of transformer core, especially in low- and high-current input medium and small power applications. At the same time, full-bridge rectifier circuit also has high voltage utilization and support output power. High-level features, therefore, this paper uses a push-pull inverter-high-frequency transformer-full-bridge rectification scheme to design a DC-DC converter with 24VDC input-220VDC output and rated output power of 600W, and adopts the AP method to design the corresponding push-pull transformer.

The working principle of push-pull inverter Figure 1 shows the basic circuit topology of push-pull inverter-high frequency transformer-full bridge rectifier DC-DC converter. By controlling the two switching tubes S1 and S2 to be alternately turned on at the same switching frequency, and the duty ratio d of each of the switching tubes is less than 50%, a certain dead time is left to avoid simultaneous conduction of S1 and S2. The front-stage push-pull inverter inverts the input DC low voltage into an AC high-frequency low voltage, sends it to the primary side of the high-frequency transformer, and couples it through the transformer to obtain the AC high-frequency high voltage on the secondary side, and then passes the reverse fast The full bridge is rectified and filtered by the recovery diode FRD to obtain the desired DC high voltage. Since the back pressure that the switch can withstand is at least twice the input voltage, that is, 2UI, and the current is the rated current, the push-pull circuit is generally used in low- and medium-power applications where the input voltage is low.

figure 1
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