Control circuit and constant current source circuit with same

Abstract

The invention discloses a control circuit used to control a main circuit in a constant current source circuit. The control circuit comprises a controller, a ripple generation circuit and a compensation circuit; the ripple generation circuit is used to obtain a voltage signal which is in a first proportion to the output voltage of a transformer in the main circuit, and separate out a ripple signal in the voltage signal; the compensation circuit is used to acquire the current sample signal of a switch tube in the main circuit, superpose and transmit the ripple signal and the current sample signal to the current sample input terminal of the controller as the current sample input signal of the controller; the controller receives the current sample input signal outputted by the compensation circuit, switches off the switch tube when the current sample input signal reaches a current threshold, and switches on the switch tube when the on-off cycle of the switch tube is in a second proportion to the duration of the current. The control circuit disclosed by the invention can reduce the total harmonic distortion of the constant current source circuit and improve the power factor of the circuit. The invention also discloses a constant current source circuit.

Description

technical field [0001] The invention relates to the technical field of constant current power supply, in particular to a control circuit and a constant current source circuit provided with the control circuit. Background technique [0002] In the field of power electronics technology, the constant current source circuit can provide a stable current for electrical equipment to drive the electrical equipment to operate stably. Due to the higher and higher requirements for power factor and harmonics of electrical equipment, in order to obtain high power factor and reduce the harmonic distortion of input current, power factor correction (PFC) technology is introduced in the constant current source circuit. figure 1 and figure 2 There are two existing constant current source circuits, including a main circuit and a controller, wherein the main circuit includes an input branch and a converter. [0003] exist figure 1 In the shown constant current source circuit, the input bran...

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Problems solved by technology

[0006] However, the applicant found that: figure 1 and figure 2 The shown constant current source circuit has high total harmonic distortion (THD) and low power factor (PF)

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