TW200913450A - DC low-voltage power source device - Google Patents

Abstract

There is provided a DC low-voltage power source device having high step-down efficiency by a piezoelectric transformer. The device comprises: a drive circuit 110 which has switching elements 111, 112 and a choke coil 117 and converts a DC input voltage into an AC voltage by means of the operation of the switching elements 111, 112; a piezoelectric transformer 120 which is driven by the input of a converted AC voltage and outputs a stepped-down AC voltage; and a synchronous rectifier circuit 130 which has the switching elements 131, 132 and choke coils 136, 137 and converts an output AC voltage into a DC voltage, wherein the piezoelectric transformer 120 has an output impedance in a predetermined range determined by an output voltage of the piezoelectric transformer 120 required in accordance with the synchronous rectifying action of the synchronous rectifier circuit 130 and an output current of the piezoelectric transformer 120 derived from the electric power conservation law based on the resistance of a load 140.

Description

200913450 VI. Description of the Invention: [Technical Field] The present invention relates to a DC low voltage power supply device using a piezoelectric transformer (piez〇electric-transformer). _ [Prior Art] In the prior art, there is a DC low-voltage power source device that generates a DC voltage of a low-voltage house. For example, 'the DC low-voltage waste power supply device has a configuration of: a driving circuit that converts a DC voltage into an AC voltage by a switching operation; and a piezoelectric transformer that converts an AC voltage into a low AC voltage; The rectifier circuit converts the AC voltage that is turned out as the piezoelectric transformer H into a DC voltage. For such a DC-powered drive circuit, a half-bridge type drive circuit is used in the case of DC-to-AC conversion. In the rectifier circuit that converts the AC voltage outputted from the piezoelectric transformer into a DC voltage, a current doubler type G synchronous rectifier circuit is often used as a rectifier circuit having a step-down function (refer to Patent Document 1). . Patent Document 1 A DC/DC converter (α/DC converter) is a DC-DC converter that uses an electric hunger gain rectification and smoothing circuit instead of a bridge rectifier circuit, so that the power of the diode is gradually reduced by half. In order to achieve low cost, synchronous rectifiers and special gate waveform shaping circuits are used instead of diodes. In this way, the DC/DC converter of the patent document i reduces the loss of the rectification and smoothing circuit of the DC/DC converter using the piezoelectric transformer, and the efficiency of the swash converter. [Patent Document 1] Japanese Patent Laid-Open Publication No. Hei 11-55941 (Draft of the Invention) (The problem to be solved by the invention) is to obtain a low 'voltage' and thus a direct current circuit as in the above (4) current multiplication type. The low voltage power supply unit can efficiently generate a DC low voltage. However, 'only for the circuit for obtaining a low voltage, the efficiency of the power supply device does not necessarily fill the tool|the electric transformer has a load connected to the output of the piezoelectric transformer, and has a step-down efficiency (conversion efficiency) of different piezoelectric transformers. characteristic. Therefore, if a piezoelectric transformer suitable for the specifications of the load is not used, the efficiency of the DC low-voltage power supply is lowered. The present invention has been made in view of such circumstances, and its object is to provide a DC low voltage device having a high voltage reduction efficiency by a piezoelectric device. (Means for Solving the Problem) (1) In order to achieve the above object for the month b, the DC low-voltage power supply device of the present invention has a drive circuit including a drive circuit and a switching element and a choke coil, and the switching element is operated. Converting the DC input voltage into an AC voltage; the piezoelectric transformer is driven by the input of the AC voltage converted as described above, and the output of the voltage is reduced, and the synchronous rectification circuit has a switching element and an anti-voltage The AC voltage outputted in the circle H is converted into a DC voltage; and the piezoelectric transformer has an output of the above-mentioned electric transformer according to the same V action of the synchronous rectification circuit according to the resistance of the load, and is controlled by the power The output of the Shanglong electric transformer (4) derived by the law is (4) and (4) the output impedance of the established range 97132618 200913450. Thus, the DC low voltage power supply device of the present invention is provided with a piezoelectric transformer having an output impedance corresponding to its output voltage and output current. Thus, since the specification of the piezoelectric transformer is suitable for the load specification of the DC low-voltage power supply device, the step-down efficiency of the piezoelectric transformer can be improved, and the power efficiency of the DC low-voltage power supply device can be improved. (2) The DC low-voltage power supply device according to the present invention is characterized by comprising: a drive circuit having a switching element and a choke coil, wherein the DC input voltage is converted into an AC voltage by the operation of the switching element; The piezoelectric transformer is driven by the input of the AC voltage converted by the above, and outputs the stepped AC voltage; and the synchronous rectification circuit has a switching element and a choke coil, and converts the AC voltage outputted by the above into a DC voltage; and the piezoelectric transformer has the above-mentioned voltage required for the synchronous positive action of the synchronous rectification circuit according to the input voltage of the piezoelectric transformer and the resistance of the load converted based on the input voltage via the driving circuit The maximum boost ratio of a given range, depending on the output voltage of the electrical transformer. In the DC low-voltage power supply device of the present invention, the piezoelectric actuator is designed in such a manner that the voltage output from the piezoelectric transformer is input to the piezoelectric transformer and the maximum boost ratio is within a predetermined range. In this way, the step-down efficiency of the neon transformer can be increased, and the power efficiency of the DC low-voltage power supply device can be improved. (3) Further, the DC low-voltage power supply device of the present invention is characterized in that it has a drive circuit, a coffee element, and a flow resistance_, and the DC input voltage is converted by the action of the above-mentioned switch element 97122618 200913450 For the AC voltage, the piezoelectric transformer is driven by the input of the converted AC voltage, and the stepped AC voltage is output; and the current doubler type synchronous rectification circuit has the switching element and the anti-resistance The stream coil converts the AC voltage outputted as described above into a DC voltage; and when the output voltage is set to Vqut', the output current is set to 1_, and the output impedance Zqpt of the piezoelectric transformer satisfies the following equation. (Expression 1) \γ^^Ζορτ^2π^ψΐ- 0 j〇ut As described above, in the DC low-voltage power supply device of the present invention, the above equation is determined in response to the output voltage and output current of the DC low-voltage power supply device. The output impedance of the 'electrical transformer (3) in the range. Since the specification of the piezoelectric transformer is suitable for the load specification of the DC low-voltage power supply device, the efficiency of the piezoelectric (four) device is increased, and the power efficiency of the DC low-voltage power supply device can be improved. (4) The DC low voltage (4) (4) of the present invention, which has a reduced recording, which is provided with: a half-bridge type driving Wei, having 2 _ off elements and i resistance 'by the above-mentioned switching element %, DC input The voltage is converted into an alternating voltage; the piezoelectric transformer is driven by an input of an alternating voltage that is converted by a top turn, a process, and a stepped down alternating current voltage is outputted, and a current multiplier type synchronous rectification circuit has a switch Component and choke coil, makeup & ^ Convert the AC voltage outputted above to DC voltage; and when the input voltage is destroyed by π ^ 尺马丨Ν, the output voltage is set to I, and the output current is set to Ιουτ, The above-mentioned pressure-reducing (4) 冤, spinner connection (^2) (^Γ / Ι (10)) 97192618 7 200913450 load resistance of the maximum boost ratio Av to satisfy the following formula (Formula 2) Ι π1 V,

OUT —Toc/r <. a <r 3 ~ ^ Av ^

J y IN The change of the thermal conductivity of Mil is determined by the piezoelectric transformer and the structure. Although the driving frequency can change the π of the piezoelectric transformer and the resonance frequency of the piezoelectric transformer is greatly deviated, the piezoelectric transformer m is lowered. Therefore, it is necessary to input 1 to the voltage of the piezoelectric transformer and the electric booster tank electric transformer output from the piezoelectric transformer. In the present invention, a DC low-voltage power supply (3) using a half-bridge type driving circuit is required to input a voltage and an output voltage, and a piezoelectric transformer is designed in such a manner that a large boost ratio is within the target rib target. In this way, the efficiency of the piezoelectric transformer + two + 茔 可 can be improved, and the power efficiency of the DC low voltage power supply device can be improved. (5) The low-light energy material of the gamma is characterized in that: the driving circuit has the _ component and the reducing coil, and the operation of the _ component is: converting the DC input voltage into an alternating voltage; the piezoelectric transformer, by means of The input and replacement parent voltages are input (four), and the alternating voltage is output; and the current multiplied 同步 type synchronous rectification circuit has a 卩·element and a choke coil' to exchange the alternating current (four) outputted by the above output into a direct current In the case where the primary side capacitance of the piezoelectric clock is c and the driving frequency of the piezoelectric transformer is f, the inductance L of the choke coil of the drive circuit satisfies the following formula . 97129618 8 200913450 (Equation 3) In this way, the anti-flow coil with the inductance value matching the piezoelectric transformer of the most appropriate specification is manufactured in the Hefei circuit, so the function of the choke coil can also improve the efficiency. The choke coil is a single winding wire and can achieve a small size sufficient to realize a filter function of shaping the applied rectangular wave voltage waveform into a sinusoidal voltage. In this way, it is not necessary to use the magnetic shielding structure in the strong magnetic field environment to maintain the predetermined operation at the time of design and to make the device compact and lightweight. (6) Further, the DC low-voltage power supply device of the present invention includes: a drive circuit having a switching element and a choke coil, wherein the DC input voltage is converted into an AC voltage by the operation of the switching element; and the ink-electric transformer, Driven by the input of the above-mentioned converted AC voltage, and the step-down AC voltage and the current multiplier type rectifier circuit, having a switching element and a choke coil, will turn the AC power to the county DC voltage ;##The output voltage is set to U, and the output current is set to W'. When the driving frequency of the piezoelectric transformer is set to f, the inductance of the anti-current coil of the value synchronous rectifier circuit (Equation 4) 8 //,

OUT V,

OUT //,

The reactance of the anti-current coil used in the OUT step rectifier circuit is equal to the piezoelectric transformer output dirty response, the side rectifier circuit and the voltage efficiency action. Because of the output specifications of the DC voltage power supply and the output impedance of the piezoelectric transformer, the reactance of the anti-current coil is preferably in 2/2) (7W7^iout), and the inductance of the anti-current coil of the synchronous rectification circuit is the most Fortunately, near (TrMfX^^/^T). Therefore, when the inductance-value of the choke coil is in the above range, high power efficiency can be obtained. Further, in the DC low-voltage power supply device of the present invention, the current-carrying coil of the drive circuit is an air-core coil. Such a DC low voltage power supply device can shape the applied rectangular wave voltage to a sine wave voltage by the use of an air core coil. The air core coil is small enough to implement the filter function. (Effect of the Invention) According to the present invention, since the specification of the piezoelectric surface is suitable for the load regulation of the DC low-voltage power supply device, the step-down efficiency of the piezoelectric transformer is improved, and the power supply efficiency of the DC low-voltage power supply device can be improved. [Embodiment] Next, with regard to the actual cynic form of the present invention, reference is made to the figure. For the sake of explanation, the same constituent elements are denoted by the same reference numerals, and the overlapping description will be omitted. (Configuration of DC Low-Voltage Power Supply Device) FIG. 1 shows a configuration of a DC low-voltage power supply device 100. As shown in FIG. 1, the direct low voltage power supply unit 00 is provided with a driving initial circuit 110, a piezoelectric transformer 12A, a synchronous rectification circuit 13A, a load 140, detection resistors 15G and 155, an error amplifier 160, and voltage control oscillation. Circuit 17 Star-flow low-voltage power supply unit 〇〇97129618 10 200913450 For example, it can be used as a 4AC axis (ACadapto) in combination with the rectifier circuit of the input section. The drive circuit 110 generates an AC voltage from a DC voltage, and an AC voltage of the μ is applied to the input portion of the piezoelectric transformer 12A. The AC voltage is generated corresponding to the oscillating signal of the oscillating circuit 170. The drive circuit 11A has two gate elements in, m and i choke coils 117, and is configured as a half bridge type crane circuit. The driving circuit 110 receives the vibration signal from the voltage control oscillation circuit _, and the switching element ln and the switching element 112 are alternately turned on and off to apply: the input voltage of the sine wave is input to the input terminal of the piezoelectric transformer. The switching action converts the DC voltage into an AC voltage on a rectangular wave. Further, each of the switching elements 1 and 112 uses, for example, a MOSFET. In the present invention, it is particularly important to obtain a low voltage with high efficiency. Therefore, it is preferable that the switching elements in, 112 have a switching element which has a small parasitic capacitance and a fast switching speed. Further, in order to reduce power loss, it is preferable that the switching elements 111 and 112 have a smaller on-resistance. Since the piezoelectric transformer i20 utilizes resonance vibration, it is necessary to use a resonance scale attributed to its shape. The mutual fineness is also dependent on the shape of the element but is about 100 to 200 kHz, and the AC voltage of 50 Hz or 60 Hz at the commercial frequency is of course not moving. In view of this, the Bicai switch circuit, after the input AC voltage is DC, it converts the voltage into 100~200kHz AC voltage matching the resonant frequency of the piezoelectric transformer. In the drive circuit 110, an AC voltage is generated by the switching elements 111, 112 of the switching FET or the like for the input DC voltage. The anti-flow line 117 acquisition circuit ^ 97129618 11 200913450 The piezoelectric cross-voltage state 120 matches 'The waveform that is wheeled into the piezoelectric transformer 12 进行 is shaped into a sinusoidal waveform. The anti-flow coil 丨 7 is used to have the characteristics of the primary side capacitance of the piezoelectric transformer 120. The choke coil 7 can be an air core coil. The half-bridge type drive circuit 11 has two fet and one choke coil, which is advantageous for installation area and cost due to the small number of parts. Further, unlike the push-puU type and full-bridge type), the half-bridge has a step-down effect and is a drive circuit 110 suitable for the off circuit. Through the use of a half-bridge type driving circuit, if the voltage is stepped down in the driving circuit, it is not necessary to perform the step-down of the portion in the power transformer. As the drive circuit 11(), in the full bridge type, push-pull type, and half bridge type, it is preferable to have a half bridge type drive circuit 110 having a step-down effect. Further, in the above-described embodiment, a half bridge type driving circuit or a push-pull type driving circuit is used as the driving circuit 110, but other driving circuits may be used. The choke coil 117 is connected to the switching elements lu, 112 and the piezoelectric transformer (10). The rectangular wave voltage passes through the primary side capacitor 117 effect of the choke coil 117 and the piezoelectric transformer 12Q, and (4) is an alternating voltage of a slightly sinusoidal waveform. And input to the piezoelectric transformer 12A. According to the characteristics of the half-bridge type shaft circuit, when the DC voltage input to the drive circuit U0 is ViN, the input power conversion: the effective value vIPT of the AC voltage of 120 is (3/V^)vIN. °° The anti-flow coil m is connected to the piezoelectric transformer ϋ 12G. The choke coil is, for example, a hollow core anti-knuckle ring wound with a bobbin wound on a synthetic resin bobbin, and is suitable for use in a strong magnetic field environment. The choke coil m is a high-efficiency resonance capable of achieving = 97129618 12 200913450, and is matched with the piezoelectric variable _12G. The inductance L of the L coil 117 is based on the primary side electrostatic capacitance C of the piezoelectric transformer 120. And Pisi?夕#, ,式丨,;π > π m廿w _. Because the anti-flow coil is a transformer that supports the boost function, it is a single-winding and realizes the small-size function of shaping the applied rectangular wave voltage waveform into a sine wave electric i. The voltage power supply _ field ring nail 虽 虽 虽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽 遮蔽(Equation 5) ~ L ^ 4^-2/2c _ The piezoelectric transformation H 12G can be closed as a planar shape, and in the thickness direction: two polarizations of the two plates are laminated in the thickness direction. Form. Each piezoelectric ceramic version has electrodes in its surface, which is the input part of the electric ceramics, and the other piezoelectric = board is the output part. Drive circuit! (4) The input electrode provided in the input part of the package. Piezoelectric county 12G makes the AC voltage input to the input electrode drop, and the output electrode set by the unit is used to mix the rugged AC. The output impedance of the relay 12G can be adjusted according to the material's f-factor or electrode shape. The boost ratio can be adjusted according to the number of layers. The piezoelectric transformer (10) is connected to the synchronous Wei f path 130 in order to reduce the size and weight of the liquid crystal panel by miniaturizing and reducing the size of the liquid crystal panel. The piezoelectric wish-120 reduces the input voltage and outputs it through the vibration of the electric body. Piezoelectric 97129618 13 200913450 The pressure-sensing diode 20 can be, for example, a general Rosen Type piezoelectric transformer. The piezoelectric transformer 120 may be of a single layer type or a laminate type. The piezoelectric transformer 120 is preferably designed such that the output impedance thereof is equal to or lower than 2π2 (νουτ/ιουτ), and the maximum boost ratio is equal to or higher than (?/3) (ν·/νΙΝ), (仏2/3). .... ^~) Below. Further, the input voltage of the DC low voltage power supply unit 1 is expressed as ViN', and the output voltage is expressed as ν 〇υ τ. The synchronous rectification circuit 130 is a current multiplier type synchronous rectification circuit, and has two switching elements 131 and 132 and two choke coils 136 and 137. The synchronous rectification circuit 130 switches the current flow and rectifies using the switching elements 131, 132. The switching elements 131, 132 can use FETs. When the output voltage from the piezoelectric transformer 12A, that is, the input voltage effective value to the synchronous rectification circuit 13A is ν〇ρτ, and the output voltage of the synchronous integer/μ circuit 130 is set to v〇UT, the synchronous rectification The input-output relationship of the circuit 130 can theoretically be expressed by the following equation. (Formula 6)

/ ^om=^-V〇PT=〇A5VOPT As shown in the equation, the current multiplier type synchronous rectification circuit has a step-down function, so that it is not necessary to step down in the piezoelectric transformer 12A. In this manner, the AC voltage output from the piezoelectric transformer surface 12G is converted into a DC voltage, and the voltage is reduced. The rectifier circuit generally uses a diode', but the voltage drop caused by the diode in the rectifier circuit using the diode causes the power to be lost. The output voltage of the rectifier circuit is 97129618 14 200913450 is about 10~20V. If there is a drop of the diode of about 2V, the power loss will be caused by the voltage drop. Here, the rectifying circuit of the present invention-synchronous rectification method can use a switching element instead of a diode to switch the flow of the rectified current. Knife >* package muscle load 140 is connected to the output terminal of synchronous rectifier circuit i3〇, with resistance

RL. The detecting resistors 150 and 155 are for detecting the rotation of the DC power source and the electric Z resistance. Thus, the electrical detection circuit can be easily configured by the use of a resistor. The detecting resistors 150, 155 are sent to the error amplifier 160 with the resulting radiance as a detection signal. The error amplifier 160 generates a differential signal 1 corresponding to the detected power a and the reference power κ difference. The difference amplifier (10) is connected to the surface control money = Π 0, and the differential signal is transmitted to the control side circuit 170. The electrical circuit Π0 accepts the differential signal and controls the frequency of the vibration number or the working ratio ty rat10). The eDonkey control oscillator (four) circuit 170 generates an oscillating signal. Zhenying letter =: two: =! and work than rectangular waves. Control_signal m for 16 paste fineness or work (pulsation impedance of piezoelectric transformer) Figure 2 shows the output impedance of DC low voltage, ancient (9)^ 冤 original clothing 100 output and output power ==120 Schematic diagram of the relationship. In (4) change to 120 when the foolish electricity dust 5 §) Chuan Xi 9 ", the virtual animal Gong side has the output impedance " ... "resistance when matching" to operate with high efficiency. When the dust electrostatic breaker 97926618 15 200913450 120 The output voltage is valid for Φ + two A Vdpt' DC low voltage power supply device 100 when the wheel voltage is set to ^, under the condition of ^ ^ officially established VOTT = & / 7 ^ ^ relationship. When the piezoelectric transformer is measured, the current is set to Ιορτ, and the output current of the DC low-voltage power supply device 100 is Iqut, when the synchronous rectifier circuit 130 is assumed to have no loss, ^, , [疋 相互 mutual value will be established 1 ah = (ten thousand) 1 · nww low voltage electrical transposition (10) loss tts electricity county v ·, output ' ^ % machine gain type synchronous rectifier circuit 130 input voltage, ~ The output voltage of the piezoelectric transformer 120 is two mosquitoes and the second is & (π / νΐ) νουτ. And 'in the assumption that the same disk ^ road (2) lost 4 zero ^ ^ when the input voltage of the synchronous money circuit is low The material of the Wei device depends on the electric power to keep the strange one. (10) From the child's style, the piezoelectric transformer 120 can be obtained. The output impedance is the rule of the fertilizer. From the above _, the equivalent load lightning and the war resistance of the pressure of the brain of the pressure brain (10) is 130, which is W2〇PT, ie, 2/2) J. Pressing the cicada and breaking the mountain 1^) /, - - Fruit power is the output impedance of the 120-shaped piezoelectric transformer 12〇. XWi0UT) 10,000 However, the actual high-efficiency piezoelectric waste FI a ancient f and dangerous The output of U is the impedance of Ζορτ === degrees. When considering the experimental results described later, the most electric i-resistance &&"" is set to satisfy the sound of the machine. The device 100 operates at a high efficiency for two years. Further, the following equations are applicable regardless of the type of the drive circuit 110. (Expression 7) 97129618 16 200913450 7Γ2 V〇,

UT ^ ^OPT =

LOUT opt = 2ττ ~~2ί21 Ι〇υτ On the other hand, when the drive frequency is set to f 'the secondary side capacitance of the piezoelectric transformer 120 is set to &, the output impedance of the piezoelectric transformer (10) is represented by z_1/27rfC2 . The turbulent frequency f is the resonant frequency of the LSI transformer 120. For example, in a piezoelectric transformer, when riding a layer, the piezoelectric resonance mode is used, the resonance frequency of the vibration mode is adopted, and in the case of the piezoelectric state of the laminated ceramic plate, the private use is wide. The resonant frequency of the wheel vibration mode. In the case of the second case divided by the half-wavelength vibration "2 mode, there is a λ-mode of vibration at the 丨 wavelength, but the λ/2 mode is generally used as the resonance mode. Therefore, in the design of the domain, and the polarization in the thickness direction of the 2 # piezoelectric ceramic Wei Jing in the thickness of the shape of the (four) transformer just when 'by adjusting the direction perpendicular to the piezoelectric ceramic = polarization axis Size, and can control the above f. Further, the value of the inter-electrode distance and the electrode area of the piezoelectric material _Electrical_Electrical_Electrical_Electrical_Electrical _12_ is determined. Therefore, the capacitance c2 can be controlled by controlling the above. (Boost Ratio of Piezoelectric Transformer) In the half-bridge type drive circuit m, the input differential signal is used to turn off the DC signal to the AC power on the rectangular wave. Further, one or two, through the anti-flow line 117 of the drive circuit HO and the piezoelectric filter (10) 1 , = then the filter and wave effect generated by each of the 'rectangular wave control' is transformed into the parental voltage of the slightly sinusoidal wave 'And was input to the electric cage 12 〇. At this time, when the DC voltage input to the half bridge type driving circuit 110 is set to V1N, the effective value of the parent current voltage VIPT input to the piezoelectric transformer is. On the other hand, when the output voltage of the DC low voltage power supply unit 1 is Vm]T, the output voltage VqPT of the voltage regulator 120 is necessary for outputting the DC voltage of vqut by the characteristics of the synchronous rectification circuit 130. The valid value is (π/Λ^)ν_. Therefore, when the piezoelectric resistor and the stressor 120 are connected with a load resistor of (y/2) (rwr//wr), the maximum boost ratio (π%, ··~) necessary for the piezoelectric transformer 120 is obtained. Fig. 3 is a schematic diagram showing the relationship between the input voltage and the output voltage of the DC low voltage power supply unit 1 and the input voltage and output voltage of the piezoelectric transformer 120. However, the range of the step-up ratio of the piezoelectric transformer 12, which actually maintains high efficiency, has a certain extent. When considering the experimental results described later, it is preferable to design the piezoelectric transformer 120 in a range in which the maximum lift ratio Av of the piezoelectric transformer 120 satisfies the following expression. (Equation 8)

3 Vm 3 vm (impedance capacitance of the anti-current coil) The reactance of the anti-current coil I36, m used by the synchronous rectification circuit 130, etc. = the impedance of the electric transformer m, the synchronous rectification circuit 13 and the piezoelectric transformer 120冋 Efficiency action. Here, when the output voltage of the DC low-voltage power supply device is \W', the output impedance of the piezoelectric transformer (10) is (π/2) "Γ". The reactance of the anti-flow line _ 136, 137 It is preferably around 97122618 18 200913450 (π2/2)(^//〇π). Therefore, the relationship between the inductance of the anti-current coil of the synchronous rectifier circuit can be determined as L=(;r. When the inductance value of the choke coil is changed in the vicinity and the efficiency is measured, the following equation range indicates the power supply efficiency. Further, f is the drive frequency. (Equation 9) 8' '(10) / Τουτ

(Operation of DC Low Voltage Power Supply Device) Next, the operation of the DC low voltage power supply device 100 configured as described above will be described below. First, the oscillation signal is transmitted from the voltage control oscillation circuit 170 to the drive circuit 110. Then, the driving circuit 10 outputs the sinusoidal voltage to the piezoelectric transformer ι2 透过 through the oscillating signal by the switching elements n1, 112 being turned on and off. In general, the frequency of the piezoelectric transformer and 120 is set to the λ/2 mode. The piezoelectric transformer 12 is driven by the sine wave voltage. The synchronous rectification circuit 130 rectifies the AC voltage input from the piezoelectric transformer 12A, and the output is a straight-forward package [outputs a low-voltage DC voltage at the load 140. The detecting resistor 155 detects the output voltage (tube voltage) applied to the load 14Q as a voltage. A difference of $160 is obtained by comparing the difference between the detection voltage and the reference voltage %, and w reading the red difference. The voltage control oscillator circuit 17Q outputs a reverberation number of a word or a ratio corresponding to the differential signal of the error amplifier (10). The material stimuli _ the rectangular wave signal is transmitted to the switch pieces m, 112 of the drive circuit (10). For example, 97122618 19 200913450 This is the DC low voltage power supply device 100 to output the DC voltage to the load 140 with high power efficiency (Embodiment 1) The piezoelectric transformer 120 for high efficiency is obtained for the DC low voltage power supply crack 100 Experiment of output impedance. Use the output power of the DC low-voltage power supply to be set to ιον, the output current Ι〇υτ is set to u, and the output impedance is designed.

For a 5 hm piezoelectric transformer, the resistance of the load 140 was changed to a degree of lohffl to lion's shirt. As a result, a power efficiency of 95% or more (relative value for the maximum point) can be obtained in the range where the resistance of the load 140 is 2.5 hm or more and 4 hm or less. Figure 4 shows the curve of g U . By setting the power supply efficiency to a range of 9 (10) or more, overheating of the piezoelectric transformer 12 can be prevented. In other words, in other words, the resistance l负载ohm of the load 140 shows high efficiency in the range of 1/4 times or more and 4 times or less. Therefore, for the load U-interval verification, it is preferable to use the piezoelectric transformer 120 used in the DC low-voltage power supply device 1 (10) for the turn-off resistance + the output impedance of the box j is counted as the above, 2/(Kwr/Lur) the following. #Example丄 For the output voltage grinding, the output current Μ of the DC low-voltage power supply 乂 ° is best to apply a piezoelectric transformer with a 50 ohm impedance, and to make the DC power supply high efficiency, it is best to use 1/4 times Piezoelectric transformer with a 4-fold output impedance of 12. 5~2GGohin. (Embodiment 2) 97129618 20 200913450 - The low voltage power supply device 1GG is used to obtain a high efficiency piezoelectric transformer. The maximum boost ratio of the pressure gain 120 is given to the test. In the test, a frequency-controlled voltage control circuit (10) is used by the &彳δ#_ from the error amplifier (10). In the synchronous rectification circuit (10), there is a method of having 2 __ 13 bu 132 and two anti-current coils 136, 137. As a set condition, it will lose

The input voltage VlN is set to 48V', and the output voltage V is set to be. Figure 5 shows the curve of the experimental results. In the piezoelectric transformer 12A in which the maximum A boost ratio is less than about Μ, the boost ratio is not; I is operated. Further, in the case of using the piezoelectric booster whose maximum boost ratio is greater than 2 times, the power efficiency is reduced by 5% or more when the time transformer is used as the dust electric transformer 120. This phenomenon is caused by the difference between the frequency at which the piezoelectric transformer 120 is driven and its natural frequency. When the results are summarized, the maximum boost ratio of the electrical transformer 12 表示 indicating the maximum efficiency is about 1.4 to 1.5 times the minimum necessary boost ratio. Further, when the maximum boost ratio of the piezoelectric transformer 120 exceeds the minimum necessary boost ratio by about 2 times, the dust electric power becomes 120. Since the natural frequency is driven on the high frequency side, the power efficiency is lowered. Therefore, in order to realize the DC high-voltage power supply device 100 that can operate at high efficiency, it is best to use the maximum dust-lift ratio above 〇2/3)(^〇ϋΓ/Vw) or (2π2/3) (rwr/D). The following piezoelectric transformer 120. (Embodiment 3) An experiment for determining the inductance value of the choke coils 136 and 137 used in the synchronous rectification circuit 130 is performed for the DC low voltage power supply device 1A. V (w = 10V, output current I (four) = 1A used in the synchronous rectification circuit 13A 97122618 21 200913450 The inductance of the choke coil is measured by the variation of 22uH~270uH. The resonance frequency is a piezoelectric transformer of 130kHz. (relative to υ. Figure β shows the graph of the sinus test results. As shown in Fig. 6, the efficiency is more than 95% above 33uH, and it is known that the DC power supply can be maintained at 4+3⁄4鬲.

_y, 8fT

OUT above

OUT I〇u When the anti-current coils 136, i 6 f used in the synchronous rectification circuit 130 are multiplexed with the output impedance of the piezoelectric transformer 120, the synchronous rectification electric power iou and the piezoelectric transformer 120 operate with high efficiency. Here, when the specification of the DC voltage power supply is (Vm, Ι〇υτ), the output impedance of the piezoelectric transformer 12〇 is therefore, the reactance of the anti-flow line® 136, 137 is preferably at (?/2). "). Therefore, the relationship between the inductance of the anti-current coil of the synchronous rectification circuit 13 can be determined as L = (; r / 4f) (^W / / wr). In fact, the anti-flow When the inductance value of the coil fluctuates in the vicinity and the efficiency is measured, the high power efficiency is displayed below (W8f) (F_//wr) or (^ / f)cr // wr). [Simplified Schematic] Figure 1 shows BRIEF DESCRIPTION OF THE DRAWINGS Fig. 2 is a schematic view showing the relationship between the output voltage and the output current of the DC low voltage power supply device of the present invention and the output impedance of the piezoelectric transformer 。. Fig. 3 is a view showing the DC low voltage of the present invention. Schematic diagram of the relationship between the input voltage and output % voltage of the power supply unit and the input voltage and output voltage of the piezoelectric transformer. Figure 4 shows the curve of the experimental results. 97129618 22 200913450 Figure 5 shows the curve of the experimental results. Figure 6 shows the experimental results. Curve. [Main component symbol description] 100 DC low voltage power Source device 110 drive circuit 111 ' 112 switching element 117 choke coil 120 piezoelectric transformer 130 synchronous rectification circuit 131 ' 132 switching element 136 , 137 choke coil 140 load 150 , 155 detection resistor 160 error amplifier 170 voltage control oscillation circuit Α ν Maximum boost ratio C Piezoelectric transformer 1st side electrostatic capacitance G Piezoelectric transformer 2nd side electrostatic capacitance f Drive frequency I OPT Input current I OUT Output current L Inductance value 97129618 23 200913450

Rl resistance

VlN input voltage V〇UT output voltage

VlPT input voltage to the piezoelectric transformer V〇PT output voltage from the piezoelectric transformer

Vref reference voltage 输出 Piezoelectric transformer output impedance 97129618 24

Claims (1)

200913450 VII. Patent application scope: 1. - Kind of DC money _ general, the hybrid is that the drive circuit 'has a switching element and a choke coil, and converts the DC input voltage into an AC voltage by the above action. The voltage is repeatedly transformed, and the voltage of the step-down voltage is turned on by the input of the above-mentioned converted current voltage; and the synchronous rectifier circuit has a switching element and a choke coil, and the AC voltage is converted into The DC voltage; the above-mentioned piezoelectric change _ according to the resistance of the load, has the rectification according to the current of the upper circuit _ the above-mentioned (four) the rim of the device, and the above derived by the f-force law (4) The output impedance of the established range of the transformer. A DC low voltage power supply device characterized by comprising: a circuit having a closing element and a current resistance _, wherein the DC input voltage is converted into an AC dust by the operation of the switch ;; piezoelectric Mil 'Driven by the input of the AC voltage converted as described above, and output the stepped AC voltage; and the sub-ring, the synchronous rectification circuit that has been rotated by the above, has a switching element and a anti-current line AC voltage conversion It is a DC voltage; and the inverter is based on the input voltage of the above-mentioned (four) device based on the input power, and the pure resistor, and has the synchronous rectification requirement of the synchronous rectifier circuit. The maximum boost ratio of the established range depends on the output voltage of the current transformer 97122618 25 200913450. 3. A DC low-voltage power supply device, comprising: a driving circuit having a switching element and a choke coil, wherein the DC input voltage is converted into an AC voltage by the operation of the switching element; - Piezoelectric The transformer is driven by the input of the converted AC voltage and outputs the stepped AC voltage; and the current doubler type synchronous rectification circuit has a switch (component and choke coil, which will be The output AC voltage is converted into a DC voltage; and when the output voltage is set to Vqdt and the output current is set to 1, the output impedance z〇PT of the piezoelectric transformer satisfies the following equation: (Formula 1) 0UT huT 4. A type A DC low-voltage power supply device comprising: (a half-bridge type drive circuit having two switching elements and one anti-current coil', wherein a DC input voltage is applied by the operation of the switching element Converted to an alternating voltage; the piezoelectric transformer is driven by the input of the alternating voltage as described above, and outputs the stepped alternating voltage; The current multiplier type synchronous rectification circuit has a switching element and a choke coil, and converts the AC voltage outputted by the above into a DC voltage; and when the input voltage is set to VlN, the output voltage is set, and the output current is set to 97129618 26 200913450 n2l2 ){VOUTll Imrr, the maximum rise in the load resistance of the piezoelectric transformer connected (the pressure ratio Αν is the following formula (Formula 2)) - The present invention includes: a DC low voltage power supply device of the above switching element, characterized in that the driving circuit has a switching element and a choke coil, and the DC input voltage is converted into an AC voltage by operation; The piezoelectric transformer is driven by the above-mentioned converted AC voltage, and the step-down AC voltage is turned off; and the current multiplied H step-down rectifier circuit has a switching element and a choke coil, which will The output AC voltage is converted into a DC voltage; and when the secondary side electrostatic capacitance of the piezoelectric transformer is c and the driving frequency of the piezoelectric transformer is f, the inductance of the anti-current coil of the drive circuit The sensitivity value L is such that the following formula is satisfied. (Expression 3) - ζ C An2f2C 6. A DC low-voltage power supply device, comprising: a drive circuit having a switching element and a choke coil, wherein the DC input voltage is applied by the operation of the switching element Transformed into an AC voltage; a piezoelectric transformer driven by the input of the converted AC voltage and outputting the stepped AC voltage; and 97122618 27 200913450 Current multiplying n-type rectifier circuit 'has a component and anti-flow _ Converting the AC voltage outputted by the above into a DC voltage; and when the output is set to V·, the wheel current is set to w, the drive of the above voltage is set to W, and the field green is multiplied, the rectifier circuit is all The inductance value L of the choke coil is full. (Form 4) π π V〇UT Ι〇υτ f Iουτ 7. As claimed in the patent application, the DC low voltage electric shock pen of any of the above-mentioned driving electric powers 1 to 6 has a choke coil _. And 97129618 28