TW201119196A - A novel variable frequency modulation technique and apparetus for multiphase synchronous rectified VRM - Google Patents

Abstract

A novel variable frequency modulation technique and apparatus for multiphase synchronous rectified voltage regulator module (Voltage Regulator Module, VRM) is proposed in this application. The proposed technique provides zero voltage switching (Zero Voltage Switching, ZVS) for high-side and low-side power switches under both light and heavy load conditions and thereby increasing the efficiency as compared to conventional approach. The dependency of switching frequency on the load condition for the proposed modulation technique and the related conduction loss are analyzed. It will be shown that the frequency increases under light load condition in order to retain ZVS and decrease the conduction loss. Although the switching loss will slightly increase due to the increase of switching frequency, the analysis and experimental results will shown the contribution of frequency increasing can cover this additional loss. Experimental results derived from a single-phase and an eight-phase synchronous rectified VRM show the proposed modulation technique is superior to the conventional one and compared to conventional constant switching frequency techniques, the efficiency can be increased up in the implemented eight-phase VRM under various load conditions.

Description

201119196 VII. Designated representative map·· () The representative representative of this case is ·· (2) 土处-, _ Γ口马. (1) 2) R, R2 R3 Rn Κ·Τ2 SW Imon ViMON Vref

') This represents the Ml component. The non-inverting amplifier's resistance non-inverting amplifier's resistance output current sense resistor determines the switching cheek rate resistance. The switching frequency of the resistor function switch switch controller built-in current source corresponds to The voltage value of the output current is reference voltage. 8. If there is a chemical formula in this case, please disclose the chemical formula which can best show the kidney sign. 9. The invention is in the technical field: The present invention is related to a method of the present application. The new type of variable frequency modulation technology and its device, especially related to the variable frequency control technology applied to the voltage regulation module of various computer motherboards, is used to improve the efficiency of the voltage regulation module. [Prior Art] In industrial applications such as personal computer motherboards, the most widely used vrm circuit architecture is a buck power converter, as shown in Figure 1. A schematic block diagram of the system controlled by the conventional fixed frequency method is illustrated in Figure 2. Since today's motherboards tend to be used for lower voltages and higher currents, various references provide a multi-phase interleaved control structure, which is expected to be full of 201119196. Libo, such as the three-phase VRJVI shown in ® 3, jl. ', Temple. Under interleaved control, the switching drive signals between the two adjacent phases have a complementary phase difference of 4 VRM. For example, the VRM shown in ®3 has a difference of 360 / 3 = 12 两 between the two adjacent phases. . Figure 4 illustrates the measured efficiency curve of the eight-phase plane using the traditional fixed-frequency control method under various loads, where the switching frequency is fixed to the current

“ ^ It is obvious in Figure 4 that the lighter the load, the higher the switching frequency, the more the load is the opposite. The lower the switching frequency, the higher the efficiency. However, this fixed-frequency control method cannot balance the lightness. Recording conditions, and riding need to install additional auxiliary switches or energy storage trees to improve this - shortcomings. This application _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Can touch the good «with wire efficiency, and the output voltage can still control U to adjust βρ. In addition, it only needs to slightly modify the existing (four) se w MGduiati.., PWM) control succeeds to 'effectively reward the lake target, simple [Inventive content] This month's report proposes a new type of variable frequency modulation technology and its device, which is specially related to a voltage regulating module suitable for various computer motherboards (v〇 A Regulator Module (VRM) frequency conversion control (four) surgery, in order to improve the efficiency of the Lai adjustment module. To achieve the above purpose, the present invention discloses a new type of variable frequency modulation technology and its operating principle, the frequency conversion architecture includes - power conversion (p〇wer Stage), a driver circuit or IC (Driver 1C) '- pulse width modulation (pu) se width Modulation, PWM) control cry 201119196 (PWM Corner), - function switch (SW), Output current detection circuit (ι〇Detection Circuit), a switching frequency modulation circuit (3 reading curry f called Modulation C-it) and a function enabling/disabling circuit (4) The PWM (four) device controls the switching of the active power switch in the power conversion circuit to implement the output load power adjustment function. Furthermore, the power conversion circuit can include any-heterogeneous power conversion ^, such as switching the $ (Buek __r ), boost converter (Boost converter) 'half-bridge power converter (secret, converter), etc.' can be used for various circuit configurations of power conversion. The driver ic is based on the enhanced power converter. The driving ability of the wire off; the pwM controller is used for the duty cycle control of the output voltage regulation; the output current_circuit is used to detect the current required by the load; the switching circuit rib is adjusted according to the load current demand to adjust the switching frequency' High efficiency; function enable/disable circuit with function switch to enable or disable the switching frequency modulation circuit. To simplify the description of the preferred embodiment in the description, only the multi-phase vrm architecture is illustrated. - The principle of action of the phase. Further, the present invention is not limited to the eight-phase vrm, and can be applied to any phase number of VRM. [Embodiment] FIG. 5 is a synchronous rectification drop of the preferred embodiment of the present invention. The profiler can represent one of the phases of the phasic VRM, where s丨 and & are the upper and lower arm switches respectively, and ^ and Di〇de2 (4) are the body diodes or the additional Schottky diodes. Clear), while PWM! and P jewel ij are the control signals for the upper and lower arm switches respectively. Here, according to the 119196 current conduction mode of the Inductive Training, the operation of the ® circuit is defined as two states, ie, the state I) and the ι0 <ΙΔζ• at the position 2 L-shaped '15II)' are illustrated in Figures 6(a) and (9), respectively. The account indicates the inductive current; Jjl selects the stomach ^ two forms (four) _ the difference is in the state II due to the inductor current, the Μ 4 phenomenon. Due to the state! The action wire is well known, @this is no longer the capital, the following will be explained for the state 11, divided into four intervals to the interval DC ’

The reduced circuit component waveforms are depicted in Figure 7. It should be emphasized that in order to avoid the two switches Μ 5, guide, and cause secrets, there must be a blank time to fill (10)) control, that is, Figure 7 qingyi d2Tsw, in general, called as. Interval I1叮(10)): + etc. put her as shown in 8(a), at this time, S2#U is discriminated, and S| is turned on, and _ is 跨 across the inductor. The electric_flow increases linearly. Here, the variable (~) of the inductor current can be expressed as A/l1=^V^DiTs L 1 Asw (1) where vin is the wheeled ink, v. For output _, Tsw is the switching period, and L is the inductance value 0 interval II (c^Tsw): The equivalent circuit is as shown in Figure 8(b), this interval is the blank time, the upper and lower arm switches s & Both ends. The secret (4) reliance on the nature of the inductor voltage will drop to a V in an instant. A Vf2' is until the diode Di〇de2 is turned on, where VF2 is the forward turn-on voltage of Diode2. In this _, the upper arm Si voltage vS1 is Vin+VF2. If 201119196 MOSFETs are used as the power switch' then vSI=vDS1, and PWM VGSI and PWM2==VGS2. The voltage on S2 remains at _vF2 before the next drive signal is triggered. This dust is quite low enough to be ignored, so zvs on s2 will be implemented at the beginning of the next interval. Interval III (D2TSW): The equivalent circuit is shown in Figure 8(c). The upper arm switch Si is turned off, the lower arm switch & is turned on, and the inductor current gradually decreases in a negative direction. Because the lower arm switch is still guided

The inductor current negative phenomenon will eventually occur, and the output capacitor will be discharged through the inductor to the ground terminal. The negative current conduction path is shown in Figure 8(d). Interval IX (d2Tsw): The special effect circuit is shown in Figure 8(e). The two switches (10) & once again cut off, which is the second a blank time. In the interval η, due to the continuity of the inductor current f, the inductor power will instantly become V. "V. The axis of the towel-丨 axis_pressure arm switch s2 is Vs2 is Vin+Vn. iGde turns on and on, and the voltage across the upper switch Sd is also sufficient to ignore the lag, % _, the upper arm switch s, zvs can be realized, as shown in the figure. This sense is the current variable (~u) Can be expressed as . ° electric △, L2

Xl±Xfi (2) is shown based on the above analysis 'in the switching cycle _ the overall variation of the inductor current can be listed

AiL=AiLi+ML2 will be obtained in the formula (1) and (2) in the formula (3), available 201119196

V〇

L

DiTsw + V〇

L dTs w

LV,n -V〇 L (D 丨10 d) Tsw(D丨+ d)"_

Sw Eight of Fsw is the switching frequency. In order to operate the VRM in state H, the inductor current changes.

The half of the jade (the jade should be larger than the output load current, to ensure that enough energy can turn Dmde 1 into the same period in the 1st phase), and also increase the efficiency as described above, circuit parameters and load current. The relationship can be written as one of the output load currents. According to the formula __, the circuit can be operated in the state Π, and both the upper arm and the lower arm switches S1 and S2 can have the ZVS effect at the same time. Equation (5) is rewritten as

Sw <—Ί 〇 X(D| +d)x (6) If this reward is applied to the multiphase synchronous rectification VRM, only a slight modification is made to —~ —χ(〇ι +d)xiL (7)

Fen; < where η is her. It can be seen from the formulas (6) and (7) that the cutting rate Fsw is inverse (four) 贞 current ι〇. Therefore, if you want the _, (#) current 丨 of the equation (7) inequality. At the time of delivery, the switching frequency needs to be lowered, and vice versa. For the sake of simplicity of design, the relationship between current and frequency conversion is illustrated in Figure 9. However, for the actual VRM system, the lower the switching frequency, the larger the output voltage slit wave, so the squaring circuit design and the output chopping Wei Fan, the switching frequency is not 201119196 can be reduced without limit, so when the switching frequency is When the load is increased and drops to a predetermined threshold, it is fixed, and even if the load is further increased, a fixed switching frequency is maintained, which is defined as a fixed frequency mode. Therefore, the frequency conversion curve relationship correction for the actual VRM system is as shown in Fig. 10.

Figure 11 illustrates an overall block diagram of the SVRM system of the present invention, including a frequency modulation control mechanism. In the conventional manner of FIG. 2, she simply adds the output load current detecting circuit, the mysterious frequency function enabling/disabling circuit, and a switching frequency modulation control circuit. A more detailed circuit block is shown in FIG. While the VRM becomes lightly loaded, the output load current detecting circuit detects that the output current becomes smaller, and the switching frequency is adjusted to be higher by the female control circuit, so that the upper and lower arm switches can simultaneously reach the ZVS, and the efficiency is improved. Conversely, if the load becomes heavy, the switching frequency will be lowered. When the load is increased to a certain degree, the switching frequency is lowered to the preset value, that is, by the _ Wei Zhilinnengwei (4), the switching side does not continue to be lowered, and the "preset value" is based on such as output voltage ripple, etc. Depending on the specifications. Figure 12 illustrates that the switching frequency modulation control circuit is simply composed of an operational amplifier and two resistors and R2, and the function enabling/disabling circuit is composed of an operational amplifier and a reference voltage Vref. The reference seam is the value corresponding to the value of the transition to the fixed frequency mode. In this real customs, the fine electricity _ _ only use a resistor R3, practice _ light Vi_ 'it is proportional to the wheel out of the (10) controller built-in current source Imon, that is, (8) lm〇n ~ImonXRs 201119196 if the VRM is light In the case, the VlmQn<Vref' function enable/disable circuit will output a month-to-date number, causing the switch SW to be turned on, and actuating the frequency modulation control circuit. When the load is as large as the preset value of 35, VIm()n>Vref, the function enable/disable circuit will cause the switch SW to be closed, and the frequency modulation control circuit is turned off, after which the switching frequency is fixed, and The size is determined by rti+rT2=Rt, in general,

Fsw=^^7 (9) • Where CT is the PWM control 1C internal value or the added capacitance value, depending on the PWM control 1C used. The inspection uses the most widely used eight-phase VRM in the motherboard. The experimental specifications and parameters are listed in Table 1. In order to meet the output voltage chopping 6mV specification at the most heavy load 8〇A, the switching frequency Fsw is adjusted to a minimum of 250kHz, which corresponds to the VRM load 3〇A, and the relationship between the switching frequency and the load current is shown in Fig. 13. The interleaved inductor currents and corresponding switch control signals are illustrated in Figures (8) and (8), where the phase difference between the two adjacent phases is 36 〇. /8=45. . • Figures 15(4) and (9) show the measured waveforms of the upper arm switch S18 and the actual measured waveform of the inductor current at different time bases. At this time, the switch is fresh-55 ,, and the load current is 0A; Subscript! It represents the upper arm switch, and the second subscript 8 represents the "phase of the VRM. Here in the article, the first phase waveform is described, and the waveforms of the adjacent two phases are all related, but the difference is 45. From Fig. 15 It can be seen that before the upper arm switch ^ is turned on, the v-circle has been reduced to 〇V, and zvs is obviously generated. Figure 16 and i7 respectively show the measured waveform of the load current and the withdrawal time, and the switching frequency ^ has been separately from 55. Down to 425kHz and 25th meeting, which makes the switching frequency corresponding to the load core A 2 2 12 201119196 is the preset threshold, and then the switching frequency modulation circuit in Figure u is disabled according to the aforementioned control mechanism If the load is further increased, the fixed frequency switching of 250 kHz is still maintained. Figure 18 illustrates the measured waveform when the load current is increased to 80 A. At this time, the switching frequency is still maintained at 25 kHz, and the upper arm switch S18 obviously has no ZVS effect. The output voltage chopping waveforms measured under the load currents of 3GA and 80A have chopping amplitudes of 5mV and 6mV, respectively, which clearly meet the specifications listed in Table 1. _ Table 1: Eight-phase VRM realized by the preferred embodiment Parameters and specifications

Input Voltage Vin 12V Nominal Output Voltage ^ O.nominal 1.4 V Maximum Output ...Current I0max lOAx 8 Output Inductance 0.51μΗχ8 Switching Frequency Fsw 550kHz ~ 250kHz Output Capacitance 560μΡ x 10 Output Ripple Amplitude 6mV/80A (0.8%) Phase Number n 8 20 describes the switching frequency of the eight-phase synchronous rectification VRM and the actual measurement relationship between the load currents, and the display is quite consistent with the prediction in FIG. Figure 21 shows the efficiency comparison diagram of various loads. The frequency modulation control method, the 550kHz fixed frequency control method and the 250kHz fixed frequency control method are introduced. The frequency modulation method proposed in this paper has high efficiency. Among them, the light load is improved to 8% compared with the fixed frequency control of 250 kHz, and the efficiency is increased by about 3% when the heavy load is compared with the fixed frequency control of 550 kHz. Figures 22(a) and (b) show the output transients between load currents a and 40A, and between 〇A and 8〇A, respectively. It can be seen that even if the frequency modulation control function mentioned in this paper is added, 201119196 Moonlight, the variation of its turn-off voltage is still in the Load Line specification provided by Intel's CPU manufacturer. The technical contents and technical features of the present invention have been disclosed as above, and those skilled in the art can make various substitutions and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should be construed as being limited by the scope of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a conventional step-down power converter, which is a commonly used architecture for multi-phase interleaved synchronous rectification VRM; FIG. 2 shows a conventional control block of multi-phase interleaved synchronous rectification VRM FIG. 3 illustrates a three-phase interleaved synchronous rectification VRM architecture of the prior art; FIG. 4 illustrates an eight-phase interleaved synchronous rectification VRM implemented by the conventional technical control method of FIG. The efficiency diagram 'embrates the efficiency of the operation at a fixed switching frequency (4) and 550 kHz under various loads; Figure 5 illustrates the synchronous rectification VRM circuit, which can be regarded as one of the multiphase Weis to illustrate Figure 6 (4) and (9) illustrate two modes of operation of the inductor current in the circuit of Figure 5; Figure 7 illustrates the waveforms of the components of the circuit of Figure 5 operating in Figure 6 (b) mode; Figure _ to Figure 5 circuit Operation of the equivalent circuit and current conduction in the _) mode 14 201119196 path; Figure 9 illustrates the relationship between the switching frequency and the output load current. Figure 10 illustrates the relationship between the switching frequency and the output load current in the beta system. 11 illustrates the coordinate mentioned frequency modulation control system block diagram of the art; FIG. 12 illustrates a switching circuit architecture proposed method of controlling the frequency modulation;

Figure Lunen eight-phase VRM system is scheduled to solve the problem of ‘with negative Weiliu. Figure 14 (a) and (b) are eight-phase measured interleaved waveforms, where (4) each phase inductor current (5A / div · ' _ / div.) and (b) each phase switch drive signal (1 〇 v/div, broad map l5 (a) and (b) when the load current I 〇 = 〇 A, the measured inductor current and switching waveform at different levels of time 'Chi where is v circle, (5) is / U8, and _ is _, and (4) 400ns/div_ (b) 40ns/div.; Figure 10(a) and (b), output load current i〇=i〇a, at different levels of time The measured inductor current and switching waveform, where Chl is ν_, (5) is ^, and (4) is vGsl8, and (a) 400 ns/div. (b) 4 〇 ns/div.; Figure 17 (a) and (b) When the load current I 〇 = 3 〇 A, the measured inductor current and switching waveform at different horizontal time bases, where (5) is ν_, (5) is -, and (4) is vGSi8, and (8) lps/div. (b 1〇〇ns/div ; Figure 18(a) and (b) show the measured inductor current and switching waveform at different levels of time when the load current I 〇 = 8 〇 A, where Chl is v , Ch3 is, (10), and secret is VGS18 ' and (a) lps/div. (b) i〇〇ns/div ; 15 201119196 Figure 19 (8) and (b) Measure the output voltage chopping of the VRM system, where (8) is the condition of the output load current I〇=30A (10mV/div., 2ps/div.), and (b) the condition of the output load current I〇=80A (10mV/div) .lps/div.); Figure 20 is a diagram showing the relationship between the measured switching frequency Fsw and the load current 1〇 in an eight-phase VRM;

Figure 21 is a comparison of efficiency under various loads; and Figure 22 (a) and (b) are measured output response waveforms, where Chi is V〇 (500mV/div.) and Ch2 is I〇 (20A/div). .), the horizontal time base is 200ps/div. (8) 0AG40A (b) 0ΑΘ80Α. [Main component symbol description] C〇ut ' C〇 output capacitor Diode 1 Diode Diode2 Diode ih Inductor current hi Upper arm switching current lS2 Lower arm switching current L Inductance Load Output load Ri Non-inverting amplifier resistance r2 Non-inverting amplifier Resistor r3 output current sense resistor Rti determines the switching frequency of the resistor Rt2 determines the switching frequency of the resistor S, the upper arm switch s2 lower arm switch sw function switch

16 201119196

Imon controller built-in current source I〇 Output load current ViMON Corresponding to the output current voltage value Vin Input voltage VL Inductor voltage V〇 Output voltage Vref Reference voltage ^Sl Upper arm switching voltage VS2 Lower arm switching voltage

17

Claims (1)

201119196 X. Patent application scope: The new type of frequency conversion modulation technology and its device are mainly used for the frequency conversion control technology of voltage regulator module (VRM) which is applicable to all kinds of computers, and vice versa. In order to improve the efficiency of the voltage regulation module, it comprises: - a power conversion circuit 'to achieve the required power conversion and output load power function; 'drive circuit or 1C' to enhance the drive capability of the active switch in the power converter; The pulse wave modulation controller 'is responsible for the duty cycle control of the output voltage regulation; the function switch is used to switch the fixed frequency and frequency conversion functions; • the output current detection circuit is used to detect the load required Current-switching frequency_variable circuit is used to set the switching frequency according to the load current demand; and a function enabling/disabling circuit for matching the function switching switch to enable the switching frequency modulation circuit or In addition to energy. 2. The novel variable frequency modulation technology and apparatus thereof according to claim 1, wherein the power converter comprises γ for performing power conversion, such as a buck converter, a boost converter, a step-down converter, A flyback converter, a forward converter, a push-pull converter, a half bridge power converter, and a full bridge converter. 3. According to the new type of variable frequency modulation technology and apparatus thereof according to claim 1, the driver sink includes a 1C or circuit capable of enhancing the driving capability of the transistor. 4. The novel variable frequency modulation technique and apparatus thereof according to claim 1, wherein the pulse width modulation controller for performing duty cycle control of the output voltage regulation includes a 1C circuit or a circuit that can be used to implement the PWM function. 5. According to the new type of variable frequency modulation technology and device thereof according to claim 1, wherein the function switching switch with _changing frequency and frequency conversion function includes an electronically controlled type switch capable of switching, such as the following 18 201119196 electrical appliances and various electronic types. A switch, such as a transistor. 6. The novel variable frequency modulation technology and apparatus thereof according to claim 1, wherein the wheel current detecting circuit for detecting the output load current comprises a device or circuit capable of realizing current detection, such as a Hall element sensor (Hall Sensor), resistors, and current comparators. 7. The novel variable frequency modulation technique and apparatus thereof according to claim 1, wherein the switching frequency modulation circuit for adjusting the switching frequency according to the load current demand comprises an operational amplifier and a non-inverting phase formed by two resistors Amplifier. 8. According to the novel variable frequency modulation technology and device thereof according to claim 1, wherein the function enabling/disabling circuit for switching the demodulation (four) path enabling or disabling with the function switching switch comprises an operational amplifier, The operational amplifier is connected to the reference voltage, and the negative terminal of the reference voltage is connected to the ground terminal, wherein the reference voltage is a DC constant voltage source. 9. The new type of variable frequency modulation technology and device of the U-item 7 can replace the reference voltage of the towel with a Zener diode.