CN107565815A - Switching Converter Topologies with preprocessing function - Google Patents

Abstract

The invention discloses a switching converter circuit with a preprocessing function, including a switching device, an output filter circuit, a sampling circuit, a reference voltage circuit, an error amplifier circuit, a PWM generating circuit, a driving circuit and a preprocessing circuit, and the reference voltage generated by the reference voltage circuit. The voltage and the feedback voltage from the sampling circuit are compared and amplified by the error amplifier circuit, and the amplified output voltage signal is compared with the sawtooth wave signal from the internal oscillator to generate a corresponding PWM wave, and then the switching state of the switching device is controlled after passing through the driving circuit , to change the input DC voltage into a pulse voltage, the preprocessing circuit passes through the pulse voltage conditioning circuit and outputs the signal, and the required DC voltage value is obtained after the output filter circuit, the switching converter uses the power semiconductor device as the switching device, periodically Control the on-off of the switch, adjust and stabilize the output voltage by changing the conduction ratio of the switching device, and improve the transient characteristics of the switching converter.

Description

Switching converter circuit with pre-processing function

technical field

The invention belongs to the field of switching converters, and more specifically relates to a switching converter circuit with a preprocessing function.

Background technique

Switching converter circuits have been widely used because of their smaller size and higher work efficiency. A typical switching converter circuit usually adopts PWM mode control. In the traditional PWM mode, the feedback voltage reflecting the output voltage and a reference value are input into the error amplifier to obtain an error amplification signal, and the PWM control signal is generated based on the value of the error amplification signal.

When the load changes suddenly, due to the limitation of the slew rate of the error amplifier, the error amplifier signal cannot quickly follow the change of the output voltage, and the PWM control signal cannot change in time according to the change of the load, so the transient characteristics are relatively poor.

Contents of the invention

The object of the present invention is to provide a switching converter circuit with a pre-processing function to solve the problems raised in the background art above.

To achieve the above object, the present invention provides the following technical solutions:

Switching converter circuits with pre-processing functions, including:

Switching device, which periodically controls the switching on and off of the switch, and adjusts and stabilizes the output voltage by changing the conduction ratio of the switching device;

an output filter circuit, which is used to filter out ripples in the rectified output voltage;

A sampling circuit that tracks level changes of an analog input signal and samples a voltage signal at a specific point in time;

Reference voltage circuit, the reference voltage generated by it and the feedback voltage from the sampling circuit are compared and amplified by the error amplifier circuit, and the amplified output voltage signal is compared with the sawtooth wave signal from the internal oscillator to generate a corresponding PWM wave;

An error amplification circuit, which compares the voltage signal taken by the sampling circuit with the voltage signal at both ends of the reference voltage circuit to generate an error voltage, and amplifies the error voltage;

PWM generating circuit, which adjusts its duty cycle through voltage feedback to stabilize the output voltage;

Drive circuit, the drive circuit is to convert the signal from the circuit into an on or off signal according to the requirements of its control target, control the switching state of the power switching device, change the input DC voltage into a pulse voltage, and pass through the output filter circuit. The required DC voltage value is obtained;

The pre-processing circuit adjusts the signal so that the input signal does not exceed its input threshold and ensures a certain amplitude, thereby improving the pre-processing precision.

Preferably, the switching device is a power semiconductor switching device.

Preferably, the preprocessing circuit utilizes TL084 to complete signal amplification and filtering.

Preferably, when the sampling circuit is in the sampling state, the switch is turned on, and the level change of the input signal is quickly tracked until the arrival of the holding signal. The instantaneous value of the input signal before switching on.

Preferably, the filter inductor electromotive force of the output filter circuit can make the conduction angle of the diode close to π, which reduces the surge current of the diode and prolongs the life of the rectifier diode.

Preferably, slope compensation is used when the duty cycle of the PWM generating circuit is greater than 50%, the peak inductor current and the average inductor current correspond to each other, and the corresponding relationship between the peak inductor current and the average inductor current is accurately corrected.

Compared with the prior art, the beneficial effect of the present invention is: the present invention not only improves the transient characteristics of the PWM mode switching converter in the prior art, but also significantly improves the dynamic response speed to voltage changes, and the input signal does not exceed its Enter the threshold and ensure a certain range to reduce the damage rate of the equipment.

Description of drawings

Fig. 1 is a circuit block diagram of the present invention;

Fig. 2 is a preprocessing circuit diagram of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Example

Switching converter circuits with pre-processing functions, including:

Switching device, which periodically controls the switching on and off of the switch, and adjusts and stabilizes the output voltage by changing the conduction ratio of the switching device;

an output filter circuit, which is used to filter out ripples in the rectified output voltage;

A sampling circuit that tracks level changes of an analog input signal and samples a voltage signal at a specific point in time;

Reference voltage circuit, the reference voltage generated by it and the feedback voltage from the sampling circuit are compared and amplified by the error amplifier circuit, and the amplified output voltage signal is compared with the sawtooth wave signal from the internal oscillator to generate a corresponding PWM wave;

An error amplification circuit, which compares the voltage signal taken by the sampling circuit with the voltage signal at both ends of the reference voltage circuit to generate an error voltage, and amplifies the error voltage;

PWM generating circuit, which adjusts its duty cycle through voltage feedback to stabilize the output voltage;

Drive circuit, the drive circuit is to convert the signal from the circuit into an on or off signal according to the requirements of its control target, control the switching state of the power switching device, change the input DC voltage into a pulse voltage, and pass through the output filter circuit. The required DC voltage value is obtained;

The pre-processing circuit adjusts the signal so that the input signal does not exceed its input threshold and ensures a certain amplitude, thereby improving the pre-processing precision.

Specifically, the switching device is a power semiconductor switching device.

Specifically, the preprocessing circuit uses TL084 to complete signal amplification and filtering.

Specifically, the sampling circuit is in the sampling state, the switch is turned on, and the level change of the input signal is quickly tracked until the arrival of the holding signal. The instantaneous value of the input signal before switching on.

Specifically, the filter inductor electromotive force of the output filter circuit can make the conduction angle of the diode close to π, which reduces the inrush current of the diode and prolongs the life of the rectifier diode.

Specifically, slope compensation is adopted when the duty cycle of the PWM generating circuit is greater than 50%, the peak inductor current and the average inductor current correspond to each other, and the corresponding relationship between the peak inductor current and the average inductor current is accurately corrected.

The reference voltage generated by the reference voltage circuit and the feedback voltage from the sampling circuit are compared and amplified by the error amplifier circuit, and the amplified output voltage signal is compared with the sawtooth wave signal from the internal oscillator to generate a corresponding PWM wave, and then passed through the drive circuit Finally, the switching state of the switching device is controlled, and the input DC voltage is changed into a pulse voltage. The preprocessing circuit passes the pulse voltage conditioning circuit and outputs the signal, and the required DC voltage value is obtained after passing through the output filter circuit. The switching converter uses the power semiconductor As a switching device, the device periodically controls the switching on and off, and adjusts and stabilizes the output voltage by changing the conduction ratio of the switching device to improve the transient characteristics of the switching converter.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical solution of the present invention Any equivalent replacement or change of the inventive concepts thereof shall fall within the protection scope of the present invention.

Claims (6)

1. The switching converter circuit with preprocessing function is characterized in that, comprising: Switching device, which periodically controls the switching on and off of the switch, and adjusts and stabilizes the output voltage by changing the conduction ratio of the switching device; an output filter circuit, which is used to filter out ripples in the rectified output voltage; A sampling circuit that tracks level changes of an analog input signal and samples a voltage signal at a specific point in time; Reference voltage circuit, the reference voltage generated by it and the feedback voltage from the sampling circuit are compared and amplified by the error amplifier circuit, and the amplified output voltage signal is compared with the sawtooth wave signal from the internal oscillator to generate a corresponding PWM wave; An error amplification circuit, which compares the voltage signal taken by the sampling circuit with the voltage signal at both ends of the reference voltage circuit to generate an error voltage, and amplifies the error voltage; PWM generating circuit, which adjusts its duty cycle through voltage feedback to stabilize the output voltage; Drive circuit, the drive circuit is to convert the signal from the circuit into an on or off signal according to the requirements of its control target, control the switching state of the power switching device, change the input DC voltage into a pulse voltage, and pass through the output filter circuit. The required DC voltage value is obtained; The pre-processing circuit adjusts the signal so that the input signal does not exceed its input threshold and ensures a certain amplitude, thereby improving the pre-processing precision. 2. The switching converter circuit with preprocessing function according to claim 1, characterized in that: the switching device is a power semiconductor switching device. 3. The switching converter circuit with pre-processing function according to claim 1, characterized in that: said pre-processing circuit utilizes TL084 to complete signal amplification and filtering. 4. The switching converter circuit with preprocessing function according to claim 1, characterized in that: the sampling circuit is in the sampling state, the switch is turned on, and the level change of the input signal is quickly tracked until the arrival of the hold signal , in the holding state, the switch is turned off, the tracking process stops, and the instantaneous value of the input signal before the switch is turned off has been maintained. 5. The switching converter circuit with preprocessing function according to claim 1, characterized in that: the filter inductance electromotive force of the output filter circuit can make the conduction angle of the diode close to π, which reduces the inrush current of the diode, Extend the life of the rectifier diode. 6. The switching converter circuit with preprocessing function according to claim 1, characterized in that: slope compensation is adopted when the duty cycle in the PWM generating circuit is greater than 50%, and the peak inductor current and the average inductor current are mutually Correspondingly, the corresponding relationship between the peak inductor current and the average inductor current is accurately corrected.