Control method and controller for output voltage of AC-DC (alternating current-direct current) converter
A technology of output voltage and control method, which is applied in the direction of conversion of DC power input to DC power output, conversion of AC power input into DC power output, output power conversion device, etc., can solve the problems of inaccurate and reliable sampling and holding circuits, and achieve Guaranteed modularity, high sampling accuracy, and reduced cost and overhead
Active Publication Date: 2012-04-25
ZHEJIANG UNIV
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[0005] However, in actual situations, the sample-and-hold circuit is not accurate and reliable, and there is an error between the feedback voltage corresponding to the output feedback amount and the output voltage of the converter, and the error varies with the load conditions of the system and the parameters of off-chip devices. change, this error cannot be compensated on-chip
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[0034] In order to describe the present invention more specifically, the controller and its control method of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.
[0035] Figure 5 It is the basic waveform of the AC-DC converter based on primary side feedback, where Is is the output winding (secondary winding) current, V sense is the auxiliary winding voltage, and PWM is the gate drive signal of the switching tube.
[0036] Such as image 3 and Figure 5 As shown, when the PWM is 1, the switch tube Q1 is turned on, the primary winding current Ip gradually rises, the transformer T1 stores energy on the primary side, and the auxiliary winding voltage is negative, the voltage Vs across the output winding is also a negative voltage, so at this time the diode D1 is turned off, the current Is on the output winding is 0, and the load R L by the output capacitor C L powered by.
[0037] When PWM is 0, t...
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The invention discloses a control method for an output voltage of an AC-DC (alternating current-direct current) converter. The control method comprises the steps of: automatically compensating feedback quantity by acquiring a voltage signal of an auxiliary winding of the converter, automatically compensating the feedback quantity to obtain precise feedback quantity by adopting a breakpoint tracking technique, and outputting a PWM (pulse width modulation) signal according to the feedback quantity to control the on / off of a switching tube in the converter so as to realize the modulation of the output voltage of the converter. At the same time, the invention also discloses a controller for the output voltage of the AC-DC converter. The controller comprises a voltage sampling unit, a digital compensation unit connected with the voltage sampling unit, and a digital pulse modulation unit connected with the digital compensation unit. The control method has high sampling precision, and the sampling precision is not affected by the parameters of the devices outside a chip; and according to the controller, the cost and expense of the converter are lowered and the device modularization is guaranteed.
Description
technical field [0001] The invention belongs to the technical field of converter control, and in particular relates to a method for controlling the output voltage of an AC-DC converter and a controller thereof. Background technique [0002] With the rapid development of portable electronic devices, AC-DC (AC-DC) converter chips have also been developed rapidly. The requirement for modularization of AC-DC converters is gradually increasing, which forces chip designers to use as few off-chip devices as possible to reduce hardware overhead and converter size. [0003] Traditional AC-DC converters based on secondary side feedback such as figure 1 As shown, it adopts the optocoupler isolation feedback mode, the output voltage on the load resistor in the converter is transmitted to the primary side through the optocoupler as the feedback voltage for the controller to adjust the output voltage, this feedback mode requires an additional optocoupler for isolation , which increases ...
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Login to View More IPC IPC(8): H02M7/162H02M3/335
Inventor 邱建平何乐年林玲
Owner ZHEJIANG UNIV