Digitally-controlled biphase BUCK DCDC converter

Abstract

The utility model provides a digital control biphase BUCK DCDC converter, which solves the problem of poor system stability and the like, and comprises two BUCK circuits connected with an LC filter circuit, one BUCK circuit is provided with an MOS tube QH2 and an inductor L1, an MOS tube QS1 is connected between the MOS tube QH2 and the inductor L, the other BUCK circuit is provided with an MOS tube QH2 and an inductor L2, an MOS tube QS2 is connected between the MOS tube QH2 and the inductor L2, and the other BUCK circuit is provided with an MOS tube QS2. The BUCK circuit is connected with a digital control chip through a voltage feedback module, the digital control chip supplies power through a linear voltage regulator LDO, the digital control chip outputs a PWM signal to control on-off of an MOS tube QH1 and an MOS tube QH2 through a half-bridge driving module, the digital control chip controls an MOS tube QS1 and an MOS tube QS2 through an inverter and a half-bridge driver, and the digital control chip is connected with a current sharing circuit. The utility model has the advantages of high power density, good stability and the like.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the electric power electronics technical technical field, concretely relates to a kind of digital control's dual-phase BUCK DCDC converter. BACKGROUND

[0002] Power supply is the energy supply source of electronic equipment. The performance of power supply directly affects the safe and reliable use of electronic equipment. Switching power supply has the advantages of high stability, high power density, light weight, high efficiency, etc. Gradually occupy the market, and with the development of power electronic devices, mainly towards small size, light weight, modularization, digitization direction, applied in industrial, medical, military and other fields of electronic equipment, is the important driving force of industrial development.

[0003] In recent years, designers reduce the size of the device package, device layout, application multilayer circuit board technology, upgrade heat conduction material and other ways to reduce the size of the module power supply. By changing the topology of the circuit to improve conversion efficiency; By optimizing control technology to improve the performance indicators of switching power supply. For example, Chinese patent document discloses BUCK converter circuit [CN201210465056.5], using op amp feedback network to adjust output to realize compensation, using tuning RC time delay to realize loop adjustment, and realizing modulation of switching pulse width through level comparator. Because of its low cost, fast dynamic response speed, simple structure, strong speciality and other advantages. But with the development of power electronics technology and its control technology, the limitations of analog control method are increasingly prominent. Analog control switching power supply has its inherent disadvantages that cannot be overcome: the control circuit design cannot be modified and is difficult to debug after completion; Component parameters change due to changes in use conditions, which easily affects system stability; Control circuit is complex and difficult to miniaturize; Complex control method is difficult to realize; Difficult to realize intelligent monitoring. Due to the above reasons, analog control method has already cannot meet the needs of many applications of electronic technology. SUMMARY

[0004] The utility model aims at the above problem, provide a kind of high power density, high performance's digital control's dual-phase BUCK DCDC converter.

[0005] To achieve the above object, the utility model discloses the following technical scheme is used: a kind of digital control's dual-phase BUCK DCDC converter, including two-way BUCK circuit being connected with LC filter circuit, one-way BUCK circuit has MOS tube QH2 and inductance L1, MOS tube QH2 and inductance L between connection have MOS tube QS1, another way BUCK circuit has MOS tube QH2 and inductance L2, MOS tube QH2 and inductance L2 between connection have MOS tube QS2, BUCK circuit is connected with digital control chip by voltage feedback module, digital control chip is powered by linear voltage stabilizer LDO, digital control chip output PWM signal is controlled MOS tube QH1 and MOS tube QH2 on-off by half-bridge drive module, digital control chip is controlled MOS tube QS1 and MOS tube QS2 by reverser and half-bridge driver, digital control chip is connected with current sharing circuit.

[0006] In the above-mentioned dual-phase BUCK DCDC converter of digital control, the digital control chip includes an asynchronous serial interface UART, and the asynchronous serial interface UART is connected with an analog-to-digital converter ADC through a digital-to-analog converter DAC and a programmable error gain amplifier EA.

[0007] In the above-mentioned dual-phase BUCK DCDC converter of digital control, the asynchronous serial interface UART is connected with a monitoring connector CONMON through a digital compensator DCMP and a dual-path digital pulse width modulator DPWM.

[0008] In the above-mentioned dual-phase BUCK DCDC converter of digital control, the asynchronous serial interface UART is connected with a mean filter CIC through a digital-to-analog converter DAC and a programmable error gain amplifier EA, the mean filter CIC is connected with a digital compensator DCM through an analog-to-digital converter ADC, and the asynchronous serial interface UART is connected with the mean filter CIC.

[0009] In the above-mentioned dual-phase BUCK DCDC converter of digital control, the mean filter CIC adopts a window length of 8.

[0010] In the above-mentioned dual-phase BUCK DCDC converter of digital control, the digital compensator DCMP adopts a PID algorithm.

[0011] In the above-mentioned dual-phase BUCK DCDC converter of digital control, the current sharing circuit includes an amplifier U4A, and the amplifier U4A is connected with a MOS tube Q5 through an amplifier U4B.

[0012] In the above-mentioned digital control dual-phase BUCK DCDC converter, the input end of the amplifier U4A is connected with a resistor R24, the amplifier U4A is connected with a capacitor C28, the amplifier U4A is connected with a resistor R20, a resistor R21 and a capacitor C27, and the resistor R25 is connected between the amplifier U4A and the MOS tube Q5.

[0013] In the above-mentioned digital control dual-phase BUCK DCDC converter, the diode D9 and the resistor R23 are connected between the amplifier U4A and the amplifier U4B, the resistor R27 and the capacitor C30 are connected between the diode D9 and the resistor R23, and the resistor R28, R31, R33, R35 and the capacitor C37, C38 are connected between the resistor R23 and the amplifier U4B.

[0014] In the above-mentioned digital control dual-phase BUCK DCDC converter, the dual-phase BUCK DC / DC converter is wholly packaged in the converter shell, and the converter shell is provided with a support frame.

[0015] Compared with the prior art, the advantages of the utility model are that: realize digital two-way staggered, synchronous rectification BUCK type topology interface switch control, compared with single-phase BUCK, staggered parallel technology can reduce input current ripple and reduce switch loss, improve converter efficiency, the inductance current ripple in two-way Buck topology structure cancels out, the current of the filter capacitor flowing through the output end is reduced, thereby let the output voltage ripple reduce, the loss of the capacitor is reduced, the cross frequency is improved by one time, the low frequency gain of the system is unchanged, the staggered parallel structure signal bandwidth is higher than single road, and the transient response time is less, realize digital control through single-chip microcomputer, multi-bit ADC, DAC analog-digital conversion unit, reduce quantization error, digital compensator adopts PID algorithm, provide programmable compensation adjustment for the system, improve the steady state and transient performance of the loop, and multiple digital pulse width modulator modules simultaneously provide sampling clock for the above-mentioned two digital modules, guarantee the performance of the system. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is the topology structure diagram of the utility model;

[0017] Figure 2 It is the digital control structure block diagram of the utility model;

[0018] Figure 3 It is the parallel expansion current sharing circuit diagram of the utility model;

[0019] Figure 4 It is the structure appearance diagram of the utility model.

[0020] Figure 5 It is another structure appearance diagram of the utility model.

[0021] As shown, the digital control chip 1, the voltage feedback module 2, the half-bridge drive module 3, the current sharing circuit 4, the converter housing 5. DETAILED DESCRIPTION

[0022] The utility model will be made further detailed explanation in combination with the drawings and specific implementation.

[0023] As Figures 1-5 As shown, a kind of digital control's dual-phase BUCK DCDC converter, including two-way BUCK circuit connected with LC filter circuit, one-way BUCK circuit has MOS tube QH2 and inductance L1, MOS tube QH2 and inductance L between connection have MOS tube QS1, another way BUCK circuit has MOS tube QH2 and inductance L2, MOS tube QH2 and inductance L2 between connection have MOS tube QS2, BUCK circuit is connected with digital control chip 1 by voltage feedback module 2, digital control chip 1 is powered by linear regulator LDO, digital control chip 1 output PWM signal controls MOS tube QH1 and MOS tube QH2 on-off by half-bridge drive module 3, digital control chip 1 controls MOS tube QS1 and MOS tube QS2 by reverser and half-bridge drive module 3, digital control chip 1 is connected with current sharing circuit 4.

[0024] MOS tube QH1 and MOS tube QH2 are main power tube, MOS tube QS1 and MOS tube QS2 are synchronous rectification freewheeling tube, linear regulator LDO converts input electric into 5V and powers digital control chip 1.Output voltage is transferred to PWM controller after being handled by output voltage feedback module 2, the current error of current sharing bus, inductance current enters digital control chip 1, and the duty cycle of BUCK circuit switch tube is adjusted by digital control chip 1 finally reaches the purpose of stable output voltage.

[0025] MOS tube adopts small patch package DFN5x6, digital control chip 1 selects patch DFN package of high operation rate, entire circuit board adopts multilayer board technology, reduces power loop, and the entire converter output power is about 1000W.

[0026] Specifically, digital control chip 1 includes asynchronous serial interface UART, and asynchronous serial interface UART is connected with analog-digital converter ADC by digital-analog converter DAC and programmable error gain amplifier EA.

[0027] Further, asynchronous serial interface UART is connected with monitoring connector CONMON by digital compensator DCMP and double-path digital pulse width modulator DPWM.

[0028] Further, the asynchronous serial interface UART is connected with the mean filter CIC through the digital-analog converter DAC and the programmable error gain amplifier EA, the mean filter CIC is connected with the digital compensator DCM through the analog-digital converter ADC, and the asynchronous serial interface UART is connected with the mean filter CIC.

[0029] Further, the mean filter CIC adopts a window length of 8, that is, 8 input values are taken to output the average, the clock adopts the high-frequency sampling clock of the ADC, and the accumulation operation is performed on each ADC high-frequency clock rising edge, the output clock of the mean filter CIC is the special clock of the digital compensator DCM, that is, the special clock of the digital compensator DCM is output after the 8th accumulation operation is completed, the mean operation is implemented by shifting, and the operation is to obtain the mean of 8 inputs, so the result of the operation of 8 inputs is right shifted by 3 bits and output.

[0030] In addition, the digital compensator DCM adopts the PID algorithm. When the output voltage deviates, the proportional adjustment adjusts the output according to the size of the deviation, multiplies the error value by the proportional value to output, and can directly express the size of the deviation. Most systems only need proportional controllers to adjust to basically achieve the expected adjustment result. The integral adjustment adjusts the output according to the integral calculation accumulation of the deviation, multiplies the integral value of the past deviation value by the integral value to output, can reflect the error situation in the past, is used for repairing control, and reduces the static error. The differential adjustment adjusts the output according to the differential of the deviation, multiplies the change slope of the error value by the differential value to output, can express the change trend of the deviation, is used for predicting the change trend of the system, adjusts in advance, reduces the overshoot, and speeds up the system response.

[0031] FB is the voltage signal after the output power supply voltage is divided, and a voltage error signal is generated after being compared with the digital reference voltage generated by the digital-analog converter DAC in the digital control chip 1. After the error signal is synthesized with the current sharing error signal COMP1 and the output current error signal and is quantized into a digital value, the mean filter CIC is used to reduce the generation of random noise, and then the quantized value is sent to the digital compensator DCM to output the compensation signal. Finally, the digital pulse width modulator DPWM outputs a plurality of pulse width modulation signals with a certain time sequence relationship according to the modulation signal, which is used to drive the power switch tube.

[0032] At the same time, the current sharing circuit 4 includes an amplifier U4A connected with a MOS tube Q5 through an amplifier U4B. The current sharing circuit 4 can externally expand the power module and increase the output power. The specific principle is as follows: COUNT1 is the value of the output current of the DC / DC converter after proportional amplification by an operational amplifier. The analog quantity passes through the voltage follower composed of U4 and then is compared with the parallel current sharing bus I_Bus1 to generate an error signal COMP1 which enters the digital controller and participates in the digital compensation module to adjust the PWM duty cycle to adjust the output voltage. When the output current of a certain module increases, the PWM duty cycle decreases, the output voltage decreases, and the output current correspondingly decreases to achieve the purpose of current sharing.

[0033] As can be seen, the amplifier U4A is connected with a resistor R24, the amplifier U4A is connected with a capacitor C28, the amplifier U4A is connected with a resistor R20, a resistor R21 and a capacitor C27, and the amplifier U4A is connected with a resistor R25 between the amplifier U4A and the MOS tube Q5.

[0034] Obviously, the amplifier U4A is connected with a diode D9 and a resistor R23 between the amplifier U4A and the amplifier U4B, the diode D9 and the resistor R23 are connected with a resistor R27 and a capacitor C30, and the resistor R23 is connected with a resistor R28, R31, R33, R35 and a capacitor C37, C38 between the resistor R23 and the amplifier U4B.

[0035] Preferably, the dual-phase BUCK DC / DC converter is integrally packaged in the converter housing 5, and the converter housing 5 is provided with a support frame.

[0036] In summary, the principle of the embodiment is to use the digital control idea to realize the on-off of the switch tube in the main power dual-path interleaved BUCK, so that the energy is orderly transmitted to the output according to the predetermined design. Since the digital circuit is not sensitive to process, voltage and temperature changes, the digital control converter has strong anti-interference performance and strong parameter adjustment flexibility, and can adapt to the use of various types of loads.

[0037] The specific embodiments described herein are merely illustrative of the spirit of the present application. Those skilled in the art of the present application can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, without deviating from the spirit of the present application or exceeding the scope defined by the appended claims.

[0038] Although the terms such as digital control chip 1, voltage feedback module 2, half-bridge drive module 3, current sharing circuit 4, converter housing 5, etc. are used more frequently herein, the possibility of using other terms is not excluded. The use of these terms is only for more convenient description and explanation of the essence of the present application; any kind of additional limitation is contrary to the spirit of the present application.

Claims

1. A digitally controlled two-phase buck DC-DC converter, comprising two buck circuits connected to an LC filter circuit, wherein one buck circuit comprises a MOS transistor QH2 and an inductor L1, with a MOS transistor QS1 connected between the MOS transistor QH2 and the inductor L1; and the other buck circuit comprises a MOS transistor QH2 and an inductor L2, with a MOS transistor QS2 connected between the MOS transistor QH2 and the inductor L2. The invention is characterized in that: The BUCK circuit is connected to the digital control chip (1) via a voltage feedback module (2). The digital control chip (1) is powered by a linear voltage regulator LDO. The digital control chip (1) outputs a PWM signal to control the on / off of the MOS tube QH1 and the MOS tube QH2 via a half-bridge drive module (3). The digital control chip (1) controls the MOS tube QS1 and the MOS tube QS2 via an inverter and the half-bridge drive module (3). The digital control chip (1) is connected to a current sharing circuit (4).

2. The digitally controlled two-phase buck DC-DC converter according to claim 1, wherein: The digital control chip (1) comprises an asynchronous serial interface UART, and the asynchronous serial interface UART is connected to the analog-to-digital converter ADC via a digital-to-analog converter DAC and a programmable error gain amplifier EA.

3. The digitally controlled two-phase buck DC-DC converter according to claim 2, wherein: The asynchronous serial interface UART is connected to the monitoring connector CONMON via a digital compensator DCMP and a dual-channel digital pulse width modulator DPWM.

4. The digitally controlled two-phase buck DC-DC converter according to claim 3, wherein: The asynchronous serial interface UART is connected to the averaging filter CIC through the digital-to-analog converter DAC and the programmable error gain amplifier EA. The averaging filter CIC is connected to the digital compensator DCM through the analog-to-digital converter ADC. The asynchronous serial interface UART is connected to the averaging filter CIC.

5. The digitally controlled two-phase buck DC-DC converter according to claim 4, wherein: The mean filter CIC adopts a window length of 8.

6. The digitally controlled two-phase buck DC-DC converter according to claim 4, wherein: The digital compensator DCMP adopts PID algorithm.

7. The digitally controlled two-phase buck DC-DC converter according to claim 1, wherein: The current balancing circuit (4) includes an amplifier U4A, and the amplifier U4A is connected to the MOS tube Q5 through the amplifier U4B.

8. The digitally controlled two-phase buck DC-DC converter according to claim 7, wherein: The input end of the amplifier U4A is connected to a resistor R24, the amplifier U4A is connected to a capacitor C28, the amplifier U4A is connected to resistors R20, R21 and capacitor C27, and a resistor R25 is connected between the amplifier U4A and the MOS tube Q5.

9. The digitally controlled two-phase buck DC-DC converter according to claim 8, wherein: A diode D9 and a resistor R23 are connected between the amplifier U4A and the amplifier U4B. A resistor R27 and a capacitor C30 are connected between the diode D9 and the resistor R23. Resistors R28, R31, R33, R35 and capacitors C37 and C38 are connected between the resistor R23 and the amplifier U4B.

10. The digitally controlled dual-phase buck DC-DC converter according to claim 1, wherein: The dual-phase BUCK DC / DC converter is entirely encapsulated in a converter housing (5), and the converter housing (5) is equipped with a support frame (6).

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