KR100667844B1 - Pwm controller with phase difference adjustment - Google Patents

Abstract

A multiphase pulse width modulation controller having a phase difference adjustment function is provided to solve a heating problem generated in a switching element by performing a function of a switching frequency of a high frequency through a switching frequency of a low frequency of which phase difference is adjusted. A multiphase pulse width modulation controller having a phase difference adjustment function includes a carrier generator(210), a waveform detector(220), a phase difference adjustor(230), and a pulse width modulator(240). The carrier generator(210) generates a pulse width waveform which has a variable pulse width according to an amplitude of an input signal. The waveform detector(220) detects a change of the waveform of a plurality of carrier signals generated in the carrier generator(210). The phase difference adjustor(230) adjusts to generate a phase difference between the carrier signals based on the waveform change of the detected carrier signal. The pulse width modulator(240) generates a pulse width modulation waveform of which a pulse width is variable according to the amplitude of the input signal.

Description

Multi-Phase Pulse Width Modulation Controller with Phase Difference Adjustment

1 is a diagram illustrating a pulse width modulation switching power converter for converting a conventional direct current power source into a plurality of direct current power sources.

2 is a functional block diagram of a polyphase pulse width modulation controller according to an embodiment of the present invention.

3 is a diagram showing an exemplary waveform used as a carrier signal in pulse width modulation.

4A and 4B are schematic and detailed views of a sawtooth generator as an example of a waveform generator including a phase adjusting input terminal according to an embodiment of the present invention.

4C is a diagram illustrating waveforms of sawtooth waves generated in FIGS. 4A and 4B.

5 is a view showing a power conversion apparatus using a multi-phase pulse width modulation controller according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of current and voltage waveforms in the power converter 500 of FIG. 5.

7 is a diagram illustrating a power conversion apparatus using a polyphase pulse width modulation controller according to another embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control device, and in particular, a multiphase pulse having a phase difference adjustment function to produce a performance when using a high grade power component while using a low grade power component in a power supply such as a DC / DC power converter. A width modulation controller.

BACKGROUND ART Conventional DC / DC converters that convert DC power into DC power generally use a pulse width modulation controller to control the output voltage or current level. When the output voltage or current of the power converter changes higher or lower than the set voltage or current value, it is input to a switching device such as a transistor of the power converter so that the magnitude of the output voltage or output current is equal to the set value. The pulse width of the control signal is changed to be proportional to the magnitude of the change in output voltage or current.

1 is a diagram illustrating a pulse width modulation switching power converter for converting a conventional direct current power source into a plurality of direct current power sources.

1, independent switching circuits are used for each output (voltage or current output) to operate independently without interlocking with each other. Therefore, each converter is determined and implemented based on power supply components and detailed specifications to satisfy each design specification. In general, the design of a DC / DC converter includes (1) regulation, (2) components stress ratio, (3) switching frequency, and (4) input / output capacitors. / Output Capacitor) (5) Inductor and (6) Ripple and noise / transient response / stability. Specifically, the switching frequency includes (1) the equivalent series resistance (ESR) of input / output capacitance and capacitance, (2) magnitude of change in inductance and current flowing through the inductor, (3) output ripple voltage, and (4) heat. (Thermal) It affects various things.

The effect of the switching frequency on the selection of inductance, the change in the current flowing through the inductor, and the change in the output voltage is as follows.

Referring to equation (1), the inductance L is chosen to be inversely proportional to the switching frequency. Therefore, a high switching frequency enables low-cost design using inductors with low inductance values.

Referring to equation (2), the current flowing through the inductor is also inversely proportional to the switching frequency. Therefore, the higher the switching frequency, the smaller the ripple current flowing through the inductor.

Referring to equation (3), the change in output voltage is also inversely related to the switching frequency. Therefore, when the switching frequency is high, the output ripple voltage is reduced, thereby reducing the amount of unnecessary noise components.

Increasing the switching frequency has many advantages, but there are disadvantages such as limitation of rising / falling time of switching device (eg transistor) and heat generation problem due to switching loss. In this case, the switching frequency must be determined by mutually negotiating between them.

Therefore, in order to solve the rise / falling time limitation and heating problem of the switching device, there is a need for a pulse width modulation controller that can obtain a low ripple voltage and current when using a high frequency switching frequency while using a low frequency switching frequency. There is.

The present invention has been devised to solve the above problems, and solves the on / off time constraints and thermal problems of the switching device by using the low frequency switching frequency as the switching frequency of the power conversion device. It is to provide a multi-phase pulse width modulation controller having a phase difference adjustment function to obtain performance.

In order to solve the above technical problem, a multiphase PWM controller having a phase difference adjusting function according to the present invention includes a plurality of carriers for generating a pulse width modulated waveform whose pulse width is varied according to the size of an input signal. carrier generator for generating a signal; A waveform detector for detecting waveform changes of the plurality of carrier signals generated by the carrier generator; A phase difference adjuster that adjusts a predetermined phase difference between the carrier signals based on the detected waveform change of the carrier signal; And a pulse width modulator for generating a pulse width modulated waveform whose pulse width varies according to the magnitude of the input signal.

Preferably, the carrier generator generates a carrier signal which is a sawtooth wave.

Advantageously, said waveform detector detects a falling edge of said sawtooth wave.

Advantageously, said retarder adjusts such that the retardation of carriers produced in said carrier generator maintains the same spacing.

Preferably, the pulse width modulator generates a pulse width modulated waveform proportional to the magnitude of the input signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a functional block diagram of a polyphase pulse width modulation controller according to an embodiment of the present invention.

The polyphase pulse width modulation controller 200 according to an embodiment of the present invention includes a carrier generator 210, a waveform detector 220, a phase difference regulator 230, and a pulse width modulator 240.

Carrier generator 210 generates carrier signals for modulating the input signal. Representative carrier signals used for pulse width modulation include sawtooth wave 310 with positive slope, sawtooth wave 320 with negative slope, and symmetrical triangle wave 330 as shown in FIG. ) And an asymmetrical triangle wave 340. Each carrier signal generated by the carrier generator 210 is a waveform whose period and waveform are the same and differ only in phase. The generated carrier signals are input to the pulse width modulator 240 described below and compared with the output (eg, voltage or current output) of the switching converter to obtain a pulse width modulated signal according to the magnitude of the output of the switching converter. Create

The waveform detector 220 detects a change in the voltage level of each carrier signal so as to know a phase difference between the carrier signals according to the type of the carrier signal generated by the carrier generator 210. For example, a falling edge for a sawtooth wave 310 with a positive slope, a rising edge for a sawtooth wave 320 with a negative slope, a symmetrical triangle wave 330 and an asymmetrical triangle wave 340. ), The phase difference between the respective carriers can be calculated by detecting the maximum or minimum point of the voltage level. The change of the voltage level of the carrier signals may be detected using a comparator using an operational amplifier or an analog-to-digital converter. If the interval of signal change (e.g., falling edge) of each carrier is calculated using, for example, a microprocessor or a timer / counter, etc., the phase difference between the respective carriers can be calculated from the calculated time interval. have.

The phase difference adjuster 230 adjusts the phase difference between the carriers based on the phase difference calculated by the waveform detector 220 to be kept constant. Preferably, when N carriers are generated in the carrier generator 210, the phase difference between each carrier is 360 degrees / N. When the phase difference calculated by the waveform detector 220 is out of an allowable error range, the phase difference adjuster adjusts a trigger time of the carrier generator so that the carrier signals maintain a constant phase difference interval.

The waveform detector 220 and the phase difference adjuster 230 described above may be implemented by generating pulse signals of a constant period using an oscillator and a timer / counter that generate a clock signal of a precise constant frequency. In this case, the generated pulse signals become signals for controlling the phase of the carrier generator 210.

The pulse width modulator 240 compares an output (eg, voltage or current output) of the switching power converter with a carrier generated by the carrier generator 210 to proportionally or inversely proportional to the output of the switching power converter. Generate a pulse width modulated signal. According to the user's selection, when the size of the carrier is larger or smaller than the output of the switching power converter, a pulse signal for driving the switching element of the switching power converter is generated. For example, when generating a pulse signal for driving a switching element of the switching power converter when the size of the carrier is larger than the output of the switching power converter, the size of the carrier is switched when the voltage of the switching power supply is lower than the set voltage. The wider section is wider than the voltage of the power supply, and the width of the pulse driving the switching element is wider. Therefore, since the period in which the switching element is turned on becomes wider, the amount of current supplied to the output side increases, and the amount of charge accumulated in the smoothing (or filter) capacitor on the output side increases, resulting in an increase in the output voltage. Therefore, when the output of the switching power converter is different from the set value, it is controlled to minimize it.

4A and 4B are schematic and detailed views of a sawtooth generator as an example of a waveform generator including a phase adjusting input terminal according to an embodiment of the present invention.

The sawtooth generator 400 according to an embodiment of the present invention includes a current source 410, a charging capacitor 420, a comparator 430, and two switches 440 and 450.

에 의해 조정될 수 있다. 전류원은 일정한 전류(Direct Current)를 공급한다면 다른 토폴로지(topology)의 전류원을 이용할 수도 있다.The current source 410 supplies a constant current and flows through the capacitor 420 connected in series with the current source 210. The magnitude of the current supplied by the current source 410 is a resistance value inside the current source.

Can be adjusted by The current source may use a current source of other topology as long as it supplies a constant current.

)을 생성한다. 따라서, 톱니파 생성기(400)에 전원이 공급되면 커패시터에서의 전압(즉, 출력 전압)은 선형적으로 증가하는 파형을 생성한다. The charging capacitor 420 is proportional to the magnitude of the current supplied from the current source 410 (that is, the flow of charge) and changes linearly with the output voltage (time).

) Thus, when power is applied to the sawtooth generator 400, the voltage at the capacitor (ie, the output voltage) produces a waveform that increases linearly.

The comparator 430 compares the voltage of the capacitor 420 with the set maximum output voltage to limit the maximum value of the voltage at the capacitor 420 so that the voltage of the capacitor 420 becomes larger than the set maximum output voltage. A signal for discharging the electric charge charged in the capacitor 420 is generated. The generated signal is used to control the switch 430 on / off.

The switch 440 serves to bypass the charge charged in the capacitor 420 when the output voltage of the capacitor 420 becomes greater than the set maximum output voltage by using the output of the comparator 430 as an input. The charge charged in the capacitor 420 is instantaneously discharged through the switch 440. After being discharged, the capacitor 420 recharges the charge supplied from the current source 410. As the above process is repeated, the output of the capacitor 420 generates a sawtooth output voltage (FIG. 4C).

The switch 450 is for forcibly discharging the electric charge charged in the capacitor 420 by inputting a phase adjustment control signal. When the switch 450 is turned on, the switch 450 discharges the electric charge of the capacitor 420 ( Or reset) to change the timing at which the capacitor 420 starts charging. It will be described in detail as follows. When the phase adjustment control signal is at a low level, the same operation as that of the conventional sawtooth wave generator is performed. When the phase adjustment control signal is at a high level, the discharge transistor is operated to discharge the charge charged in the charging capacitor. At the point when the phase adjustment control signal goes back to the low level, the sawtooth generator initiates charging and generates a sawtooth wave as when power was first supplied. Therefore, by operating the phase adjustment control signal in the phase adjuster, it is possible to control the timing at which the sawtooth wave is generated, that is, the phase of the sawtooth wave. The input of the switch 450 is connected to the output of the phase difference adjuster 230 described below and used to adjust the phase difference of the carriers generated in the carrier generator 210 of FIG.

Hereinafter, the effects of driving the switching converter using the present invention will be described.

5 is a view showing a power conversion apparatus using a multi-phase pulse width modulation controller according to an embodiment of the present invention.

)을 공통 입력으로 하여 2개의 출력 전압(

및

)을 생성한다. 위와 같이 전원 변환 장치(500)가 2개의 출력 전압을 생성할 때에는 본 발명에 따른 다상 펄스폭 변조 제어기는 위상이 180도(degree) 차이가 나는 캐리어 신호를 생성하여 이에 따라 상기 전원 장치(500)의 스위칭 소자를 구동하는 펄스폭 변조 신호를 생성한다(도 5에서는 편의상 출력 전압을 피드백(feedback)하여 다상 펄스폭 변조 제어기로 입력되는 라인을 생략하였다). 따라서, 상기 전원 변환 장치(500)에 의해 전원 공급을 받는 부하(520)가 정상상태(즉, 스위칭 소자에 구동 펄스가 일정한 듀티비(duty ratio)을 유지하는 상태)에 있다면 각각의 스위칭 소자(510, 520)가 온(on) 되는 시간이 거의 180도(즉, 다상 펄스폭 변조 제어기의 캐리어 신호의 반주기) 정도 차이가 나게 된다(도 6의 610 및 620). 따라서, 입력 직류 전원(

)로부터 최대 전류를 소비하는 순간을 달리한다(도 6의 630 및 640). The power converter 500 of FIG. 5 has one input DC voltage (

) And the two output voltages (

And

) As described above, when the power converter 500 generates two output voltages, the multi-phase pulse width modulation controller according to the present invention generates a carrier signal having a phase difference of 180 degrees, and thus the power supply 500. A pulse width modulated signal for driving the switching element is generated (in FIG. 5, the line input to the polyphase pulse width modulation controller is omitted by feeding back the output voltage for convenience). Therefore, when the load 520 powered by the power converter 500 is in a normal state (that is, a state in which a driving pulse maintains a constant duty ratio to the switching element), each switching element ( The time at which the 510 and 520 are turned on is approximately 180 degrees (i.e., half period of the carrier signal of the multiphase pulse width modulation controller) (steps 610 and 620 of FIG. 6). Therefore, input DC power (

The instant of consuming the maximum current (630 and 640 of FIG. 6).

If the phase-controlled pulse width modulated signal is not used as in the conventional power converter, the instant when the switching elements 510 and 520 are turned on is the same, and at this time, the maximum value of the current flowing through each switching element is generated. The input DC power should be supplied with the added current. That is, a case in which the magnitude of the current to be supplied to the input power becomes instantaneously increases, thereby increasing the capacity of the input capacitor 530 and increasing the cost. When a plurality of power converters are required to receive current from one input DC power supply at the same time, a case may exceed the maximum supply current amount that the input DC power supply can supply.

However, when the phase controlled pulse width modulated signal according to the present invention is used, the time for consuming the maximum current through each switching element is changed, so that the maximum value of the instantaneous current consumption becomes small.

7 is a view showing a power conversion apparatus using a multi-phase pulse width modulation controller according to another embodiment of the present invention.

The power converter 700 of FIG. 7 supplies the current supplied to one load through the two switching elements 710 and the inductor 720 using the polyphase pulse width modulation controller 200 according to the present invention. The current supplied to the load through each switching element is supplied to the load at different times by a phase difference pulse width modulated signal generated by the polyphase pulse width modulation controller 200. It can supply twice as much current as the conventional single phase power converter. In addition, since the path of the current supplied to the load is divided into two switching elements 710 and the inductor 720, the heating problem of the switching element 710 and the inductor 720 is reduced, and thus the switching element 710 and Inductor 720 may be replaced with components of smaller physical size and smaller capacity. When viewed from the capacitor 730 connected to the load side, the power converter 700 has the same effect as operating at a frequency corresponding to twice the carrier frequency of the polyphase pulse width modulation generator. As a result, the output ripple voltage and current are reduced, and the response speed for stabilizing the output voltage or current is increased by increasing the operating frequency.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the appended claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

According to the multi-phase pulse width modulation controller having a phase difference adjusting function according to the present invention, the low frequency switching frequency of the phase difference is adjusted, and the high frequency switching frequency can be used. I can solve it.

Claims (5)

A carrier generator for generating a plurality of carrier signals for generating a pulse width modulated waveform whose pulse width is variable according to the magnitude of the input signal; A waveform detector for detecting waveform changes of the plurality of carrier signals generated by the carrier generator; A phase difference adjuster that adjusts a predetermined phase difference between the carrier signals based on the detected waveform change of the carrier signal; And And a pulse width modulator for generating a pulse width modulated waveform whose pulse width varies according to the magnitude of the input signal. The method of claim 1, wherein the carrier generator, And generating a sawtooth carrier signal. The method of claim 2, wherein the waveform detector, Detecting a falling edge of the sawtooth wave. The method of claim 1, wherein the phase difference regulator, And a phase difference between carriers generated in the carrier generator to maintain the same spacing. The method of claim 1, wherein the pulse width modulator, And generating a pulse width modulation waveform proportional to the magnitude of the input signal.

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