Output voltage switching circuit of switching power supply and switching method thereof

Abstract

The invention discloses an output voltage switching circuit, which is used for a secondary output sampling circuit of a switching power supply and comprises a resistor R8, a resistor R9, a resistor R10, a capacitor C7, a switch CN101 and a triode Q1, wherein a connection point of one end of the resistor R8 and one end of the resistor R9 is used for being connected with a cathode of a diode D206 ofthe secondary output sampling circuit; a connection point between the other end of the resistor R8 and the other end of the resistor R9 is connected to the collector of the transistor Q1, the base electrode of the triode Q1 is connected with one end of the resistor R10 and one end of the capacitor C7, the other end of the resistor R10 is connected with one pin of a switch CN101, the other pin ofthe switch CN101 is used for being connected with a control voltage VCC1, and the emitting electrode of the triode Q1 and the other end of the capacitor C7 are used for being connected with the groundGND2 of a secondary output sampling circuit. Whether the switching circuit intervenes in the work of the secondary output sampling circuit or not is controlled by controlling the on and off of the switch CN101, so that the switchable output voltage is realized. The circuit has the advantages of few circuit components, simple circuit, reduction of the cost and the size of a product, and maintenance of the high performance of the switching power supply.

Description

Technical field [0001] The present invention relates to the field of charging pile, and a new energy vehicle switching power source, in particular, to a switching circuit that can switches two or more output voltage currents and its switching method thereof. Background technique [0002] With the rise and continuous development of charging pile technology and new energy automotive technology industry, the market proposes higher requirements for new energy vehicle battery charging and BMS power distribution systems, specific for different battery voltages of battery voltages in terms of 12V and 24V. In order to meet this demand, the existing switching power supply technology is mainly used in the following two programs: [0003] The principle of the first power supply solution is like figure 1 As shown, configure two power modules installed, both power modules are switched power supplies for single-circuit fixed output voltage, which is used to charge the car DC charging pile bat...

AI Technical Summary

Problems solved by technology

This solution not only increases the cost of the system, but also increases its volume

At the same time, when the system switches between different power sources, manual switching operations are required, which not only increases the cost of the equipment system, but also increases the labor cost

This solution is complex and cumbersome to operate, and it is easy to increase the probability of damage to the back-end system due to misoperation by end customers

[0004] The second solution is to use a switching power supply that outputs multiple voltages at the same time. Compared with the first solution, although this switching power supply can reduce the cost and volume of the product, and can meet the charging requirements of different battery voltages, the power supply structure is more complicated. , the secondary circuit of the switching power supply requires two rectification and filtering circuits, and the efficiency of the power supply and the accuracy of each voltage are not high

The biggest disadvantage of option 2 is: the output voltage value of the auxiliary circuit will be affected by the load of the main circuit, resulting in poor voltage accuracy and stability of the auxiliary circuit, and the output voltage of the auxiliary circuit has a relatively large fluctuation range

Moreover, taking a switching power supply with simultaneous output of two voltages (12V and 24V respectively) as an example, when the switching power supply is turned on and working, both output voltages are working, and when one is loaded, the other is working at no load, resulting in The efficiency of switching power supply products is relatively low

Images