Current control circuit and control method thereof

Abstract

The invention discloses a current control circuit, which acquires current information on the output side of a bidirectional converter by means of a current sampling circuit, uses the outputs of a first voltage regulating circuit and a second voltage regulating circuit as the input of an error amplifier, regards the output of the error amplifier as the input of an optocoupler feedback circuit, feeds back a current signal on the output side into a PWM circuit through conversion processing by means of various levels of circuits, controls a duty ratio of a switching tube on the input side of a main power circuit by means of a control circuit, and realizes constant current of on the output side. The current control circuit can ensure that the bidirectional converter has no current oscillation and current spike when the bidirectional converter switches an operating direction, can realize the constant current on the output side of the bidirectional converter when only using one forward bandgap voltage reference source, and is simple in circuit.

Description

technical field [0001] The invention belongs to the field of electronic technology and relates to a current control circuit for a bidirectional DC-DC converter. Background technique [0002] Because the bidirectional DC-DC converter can work forward or reverse, it can realize the bidirectional transmission of energy, that is, it allows the electric energy to be transferred from the defined input side to the output side, and also allows the electric energy to be transferred from the defined output side to the input side. Functionally equivalent to two unidirectional DC converters, it has a very wide range of applications in uninterruptible power supplies, battery charging and discharging, electric vehicles, energy recovery systems for high-power equipment, and backup power for high-power equipment. [0003] The bidirectional converter can define two working directions. When working in the forward direction, the energy is transferred from the input side to the output side; whe...

AI Technical Summary

Problems solved by technology

However, when this kind of control circuit is applied to a bidirectional converter, there are the following problems: 1. When the converter works in forward and reverse directions, the current direction on the current sampling resistor is opposite: when the converter works in reverse, the voltage obtained by the current sampling resistor When the converter is working in the forward direction, the voltage obtained by the current sampling resistor is negative, which requires a positive and a negative bandgap voltage reference source to make the control circuit of the converter work in the forward or reverse direction. Works well, but it is difficult to implement a negative bandgap voltage reference when the external power supply only has a positive voltage

2. When the converter is switching the working direction, it is necessary to switch the working direction of the bandgap voltage reference source, which will change the control circuit, and the electrical signal oscillation or electrical signal spike generated when the control circuit is changed will affect the error in the converter amplifier input, causing jitter or spikes in the current on the output side of the converter

[0005] In summary, the existing methods are difficult to meet the requirements of bidirectional converter constant current control, which limits its application range

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