CN103346684B - Alternating current/direct current (AC/DC) converter adopting active energy-storage capacitance converter - Google Patents

Abstract

The invention provides an alternating current/direct current (AC/DC) converter adopting an active energy-storage capacitor converter. The AC/DC converter comprises an AC/DC converter main power circuit (1), an active energy-storage capacitor converter main power circuit (2) and a control circuit. The control circuit comprises an input voltage difference sampling circuit (3), a phase-shift circuit (4), a rectifying circuit (5), a peak value sampling circuit (6), a signal conditioning circuit (7), a square-root circuit (8), a multiplying unit (9) and a pulse-width modulation (PWM) and switch tube drive circuit (10). The active energy-storage capacitor converter main power circuit (2) and the control circuit are led into the AC/DC converter comprises an AC/DC converter main power circuit (1) and connected onto a direct current bus of the AC/DC converter main power circuit (1), so that under the condition that the input power factor is ensured to be 1, energy-storage capacitor values identical in voltage rating are greatly decreased, a thin-film capacitor or a ceramic capacitor and other small-capacity and long-service-life capacitors can be adopted, the defect that an electrolytic capacitor serving as an energy-storage capacitor is large in volume and short in service life is overcome, and the AC/DC converter has the advantages that the power supply power density is remarkably improved, the service life is prolonged and the like.

Description

AC/DC converter using active energy-storage capacitor converter

Technical Field

The invention relates to the field of alternating current-direct current converters of electric energy conversion devices, in particular to an AC/DC converter adopting an active energy storage capacitor converter.

Background

With the development of power electronics technology, the demand for power conversion devices is higher and higher, and in AC/DC converters, Power Factor Correction (PFC) technology can reduce current harmonics and improve input Power Factor (PF), and has been widely used.

In an AC/DC converter, since the instantaneous input power is pulsating and the output power is constant, an energy storage capacitor is required to balance the difference between the instantaneous input power and the output power. The electrolytic capacitor has the characteristics of high withstand voltage and large capacitance value, and is widely used as an energy storage capacitor of a traditional AC/DC converter. However, the electrolytic capacitor has a large volume and a service life of only thousands of hours, which affects further improvement of power density of the power supply and limits the service life of the power supply.

Disclosure of Invention

The invention aims to provide an AC/DC converter which adopts an active energy storage capacitor converter and has high power density and long service life, can reduce the capacitance value of an energy storage capacitor, and adopts a film capacitor or a ceramic capacitor.

The technical solution for realizing the purpose of the invention is as follows: an AC/DC converter adopting an active energy storage capacitor converter comprises an AC/DC converter main power circuit, an active energy storage capacitor converter main power circuit and a control circuit: the AC/DC converter main power circuit comprises an input voltage source v_inEMI filter, diode rectifier circuit RB, PFC converter, DC/DC converter, load R_Ld(ii) a The main power circuit of the active energy-storage capacitor converter comprises a first switch tube Q₁A second switch tube Q₂Inductor L_sccAnd an energy storage capacitor C_sccWherein the first switch tube Q₁The drain stage of the first switching tube Q is connected with the positive electrode of the DC bus voltage output by the PFC converter₁OfStage and second switch tube Q₂Leakage stage and inductance L_sccIs connected to an inductor L_sccAnother end of the capacitor and an energy storage capacitor C_sccIs connected to the anode of a second switching tube Q₂Source stage and energy storage capacitor C_sccThe cathodes of the two-phase alternating current Power Factor Correction (PFC) converter are connected with the negative electrode of the direct current bus voltage output by the PFC converter; the control circuit adopts a change rule ofThe output signal of the duty ratio drives the first switch tube Q₁By the change rule ofThe output signal of the duty ratio drives the second switch tube Q₂In which P is_oIs the output power of the AC/DC converter, omega_LFor input voltage source v_inAngular frequency of c_sccFor an energy-storage capacitor C_sccCapacitance value of (V)_CBThe direct current bus voltage is output by the PFC converter.

The control circuit comprises an input voltage differential sampling circuit, a phase-shifting circuit, a rectifying circuit, a peak value sampling circuit, a signal conditioning circuit, an squaring circuit, a multiplier, a PWM modulation circuit and a switching tube driving circuit; wherein the output end C of the differential sampling circuit is connected with the input end of the phase-shifting circuit, the output end of the phase-shifting circuit is connected with the input end D of the rectifying circuit, and the output end I of the rectifying circuit is respectively connected with the input end of the peak value sampling circuit and the first input end v of the multiplier_xConnected between the signal output L of the peak sampling circuit and the third input v of the multiplier_zMethod for detecting input direct bus current I of DC/DC converter by current transformer CT in main power circuit of AC/DC converter_BThe output of the current transformer CT is connected with the input end M of the signal conditioning circuit, the output end N of the signal conditioning circuit is connected with the input end of the square circuit, and the output signal of the square circuit is connected with the second input end v of the multiplier_yThe output end of the multiplier is connected with the input end of the PWM modulation and switching tube driving circuit, and one output end of the PWM modulation and switching tube driving circuit is connected with the active storageFirst switch tube Q in main power circuit of energy-capacitance converter₁The other output end of the first switch tube Q is connected with a second switch tube Q in the main power circuit of the active energy storage capacitor converter₂Are connected to each other.

Compared with the prior art, the invention has the following remarkable advantages: (1) under the condition of ensuring that the input power factor is 1, the capacitance value of the energy storage capacitor with the same voltage quota is greatly reduced; (2) the capacitor with small capacity and long service life, such as a thin film capacitor or a ceramic capacitor, can be adopted; (3) the power density of the power supply can be obviously improved, and the service life of the converter can be prolonged.

Drawings

FIG. 1 is a schematic diagram of a conventional two-stage AC/DC converter module.

Fig. 2 is a waveform diagram of the input voltage, the input current, the instantaneous input power and the voltage of the energy storage capacitor of the AC/DC converter of fig. 1 when the input power factor is 1.

Fig. 3 is a schematic diagram of an AC/DC converter after parallel connection of active energy storage capacitive converters.

Fig. 4 is a main circuit structure diagram of an active energy storage capacitor converter, wherein (a) a Buck/Boost bidirectional converter, (b) the Buck/Buck bidirectional converter, and (c) the Buck-Boost bidirectional converter.

Fig. 5 is a waveform diagram of input voltage, input current, instantaneous input power and energy storage capacitor voltage of an AC/DC converter after the Buck/Boost bidirectional converter is introduced when the input power factor is 1.

Fig. 6 is a circuit configuration diagram of an AC/DC converter employing an active energy storage capacitor converter according to the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and the specific embodiments.

1. Conventional PFC converter

The relation between the ripple voltage of the energy storage capacitor and the capacitance value of the capacitor is researched by taking the two-stage AC/DC converter module diagram of FIG. 1 as a black box without paying attention to the internal topology and control mode. For analytical convenience, two assumptions were made:

1) the output voltage ripple is very small compared to its dc amount; 2) all devices are ideal elements and have no loss.

Defining an input voltage v of a PFC converter_in(t) is:

v_in(t)＝V_msinω_Lt (1)

wherein V_mIs the amplitude, omega, of the input AC voltage_LIs the angular frequency of the input ac voltage, and t is time.

When the input power factor is 1, the input current i of the PFC converter_in(t) can be expressed as:

i_in(t)＝I_msinω_Lt (2)

wherein I_mIs the amplitude of the input ac current.

The instantaneous input power P can be derived from the equations (1) and (2)_in(t) is:

<math> <mrow> <msub> <mi>P</mi> <mi>in</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <msub> <mi>v</mi> <mi>in</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mi>in</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mrow> <msub> <mi>V</mi> <mi>m</mi> </msub> <msub> <mi>I</mi> <mi>m</mi> </msub> </mrow> <mn>2</mn> </mfrac> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <mi>cos</mi> <mn>2</mn> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>)</mo> </mrow> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>3</mn> <mo>)</mo> </mrow> </mrow> </math>

average value p of input power in a power frequency period_inComprises the following steps:

<math> <mrow> <msub> <mi>P</mi> <mi>in</mi> </msub> <mo>=</mo> <mfrac> <mn>1</mn> <mi>&pi;</mi> </mfrac> <msubsup> <mo>&Integral;</mo> <mn>0</mn> <mi>&pi;</mi> </msubsup> <msub> <mi>P</mi> <mi>in</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mi>d</mi> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>=</mo> <mfrac> <mn>1</mn> <mi>&pi;</mi> </mfrac> <msubsup> <mo>&Integral;</mo> <mn>0</mn> <mi>&pi;</mi> </msubsup> <mfrac> <mrow> <msub> <mi>V</mi> <mi>m</mi> </msub> <msub> <mi>I</mi> <mi>m</mi> </msub> </mrow> <mn>2</mn> </mfrac> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <mi>cos</mi> <mn>2</mn> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>)</mo> </mrow> <mi>d</mi> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>=</mo> <mfrac> <mrow> <msub> <mi>V</mi> <mi>m</mi> </msub> <msub> <mi>I</mi> <mi>m</mi> </msub> </mrow> <mn>2</mn> </mfrac> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>4</mn> <mo>)</mo> </mrow> </mrow> </math>

assuming that the output voltage ripple is small compared to its DC content, the output power P_oCan be expressed as:

P_o＝V_oI_o (5)

wherein V_oTo output a voltage, I_oTo output a current.

Assuming that the efficiency of the PFC converter is 100%, the average input power in the power frequency period is equal to the output power, which can be obtained from equations (4) and (5):

$\frac{V_m{I}_m}{2}=V_o{I}_o---\left(6\right)$

fig. 2 shows waveforms of input voltage, input current, instantaneous input power and storage capacitor voltage when the input power factor is 1. As can be seen from FIG. 2, during a half of the power frequency cycle, when the instantaneous input power is greater than the output power, the energy storage capacitor C_BCharging; when instantaneous input power P_in(t) less than output power P_oTime, energy storage capacitor C_BAnd (4) discharging. Thus, the energy storage capacitor C_BThe maximum difference Δ E between the stored energy in half the power frequency cycle is:

<math> <mrow> <mi>&Delta;E</mi> <mo>=</mo> <msubsup> <mo>&Integral;</mo> <mrow> <mi>&pi;</mi> <mo>/</mo> <mn>4</mn> </mrow> <mrow> <mn>3</mn> <mi>&pi;</mi> <mo>/</mo> <mn>4</mn> </mrow> </msubsup> <mo>[</mo> <msub> <mi>P</mi> <mi>in</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>-</mo> <msub> <mi>P</mi> <mi>o</mi> </msub> <mo>]</mo> <mi>d</mi> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>=</mo> <mfrac> <msub> <mi>P</mi> <mi>o</mi> </msub> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> </mfrac> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>7</mn> <mo>)</mo> </mrow> </mrow> </math>

according to the relation between the energy of the energy storage capacitor and the voltage thereof, the following steps are carried out:

<math> <mrow> <mi>&Delta;E</mi> <mo>=</mo> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <msub> <mi>c</mi> <mi>B</mi> </msub> <mo>[</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>V</mi> <mi>CB</mi> </msub> <mo>+</mo> <mfrac> <msub> <mi>V</mi> <mi>cpp</mi> </msub> <mn>2</mn> </mfrac> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>-</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>V</mi> <mi>CB</mi> </msub> <mo>-</mo> <mfrac> <msub> <mi>V</mi> <mi>cpp</mi> </msub> <mn>2</mn> </mfrac> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>]</mo> <mo>=</mo> <msub> <mi>c</mi> <mi>B</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>V</mi> <mi>CB</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>V</mi> <mi>cpp</mi> </msub> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>8</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein c is_BFor an energy-storage capacitor C_BCapacitance value of (V)_CBIs the average voltage of the energy storage capacitor, V_cppThe peak value of the voltage of the energy storage capacitor.

The capacitance c of the energy storage capacitor can be obtained from the formulas (7) and (8)_BAnd its ripple voltage peak-to-peak value V_cppVoltage average value V_CBThe relationship of (1) is:

<math> <mrow> <msub> <mi>c</mi> <mi>B</mi> </msub> <mo>=</mo> <mfrac> <mi>&Delta;E</mi> <mrow> <msub> <mi>V</mi> <mi>CB</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>V</mi> <mi>cpp</mi> </msub> </mrow> </mfrac> <mo>=</mo> <mfrac> <msub> <mi>P</mi> <mi>o</mi> </msub> <mrow> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>V</mi> <mi>CB</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>V</mi> <mi>cpp</mi> </msub> </mrow> </mfrac> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>9</mn> <mo>)</mo> </mrow> </mrow> </math>

as can be seen from equation (9), when the angular frequency ω of the AC voltage is inputted_LAnd the average voltage V of the energy storage capacitor_CBA timing, energy storage capacitor c_BAnd peak value V of voltage of energy storage capacitor_cppIn inverse proportion, i.e. peak-to-peak voltage V of the storage capacitor_cppThe smaller the capacitance c of the required energy storage capacitor_BThe larger; capacitance c of energy storage capacitor_BAnd the output power P_oProportional, i.e. output power P_oThe larger the capacitance c of the required energy storage capacitor_BThe larger.

Generally, the average value of the output voltage of the PFC converter is controlled to a certain value. From the equation (9), if the capacitance c of the storage capacitor is reduced_BThen its voltage ripple is the peak-to-peak value V of the voltage of the energy-storage capacitor_cppIt will become large, which will result in increased voltage stress of the power devices of the front and rear stage converters.

2. AC/DC converter using active energy-storage capacitor converter

From the above analysis, it can be seen that the main purpose of the energy storage capacitor is to balance the instantaneous input power and the output power, therefore, if a converter is connected in parallel on the output side of the PFC converter, as shown in fig. 3, and the converter is used to balance the instantaneous pulsating input power and the constant output power, the capacity of the energy storage capacitor can be greatly reduced, and only the current pulsation of the switching frequency needs to be filtered. Since the converter is used to replace the storage capacitor, it can be called a storage capacitor converter.

When the instantaneous input power is larger than the output power, the redundant energy is stored in the energy storage capacitor C through the bidirectional converter of the energy storage capacitor converter_sccAt this time C_sccAnd (6) charging. When the input power is less than the output power, the insufficient energy is formed by C_sccSupplied by a bidirectional converter of the storage capacitor, in which case C_sccAnd (4) discharging. Since the energy storage capacitor converter needs to provide energy bidirectionally, the energy storage capacitor converter is a bidirectional converter, and a Buck/Boost bidirectional converter such as a Buck/Buck bidirectional converter shown in a figure 4(a), a Boost/Buck bidirectional converter shown in a figure 4(b) or a Buck-Boost bidirectional converter shown in a figure 4(c) can be adopted.

3. AC/DC converter using Buck/Boost bidirectional converter as energy storage capacitor converter

In this section, a Buck/Boost bidirectional converter is used as the energy storage capacitor converter. Unlike the energy storage capacitor connected in parallel to the dc bus directly, the energy storage capacitor C_sccCan have large ripple, that is, when the input power of the PFC converter is smaller than the output power, the energy storage capacitor C_sccCan release all the energy stored by the energy storage device, and the voltage of the energy storage device can be reduced from the maximum value to zero; when the input power of the PFC converter is larger than the output power, the energy storage capacitor C_sccEnergy is absorbed and its voltage rises from zero to a maximum value, achieving "full charge".

Instantaneous power P absorbed or released by Buck/Boost bidirectional converter_sccEqual to instantaneous input power P_in(t) and output power P_oThe difference is obtained from the formulae (3), (5) and (6):

P_scc(t)＝P_in(t)-P_o＝-P_ocos2ω_Lt (10)

energy storage capacitor C obtained by combining with figure 1_sccThe stored instantaneous energy is:

<math> <mrow> <mfrac> <mrow> <msub> <mi>c</mi> <mi>scc</mi> </msub> <msubsup> <mi>v</mi> <mi>scc</mi> <mn>2</mn> </msubsup> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </mrow> <mn>2</mn> </mfrac> <mo>=</mo> <mn>0</mn> <mo>+</mo> <msubsup> <mo>&Integral;</mo> <mrow> <mi>&pi;</mi> <mo>/</mo> <mn>4</mn> </mrow> <mrow> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> </mrow> </msubsup> <mrow> <mo>(</mo> <mo>-</mo> <msub> <mi>P</mi> <mi>o</mi> </msub> <mi>cos</mi> <mn>2</mn> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>)</mo> </mrow> <mi>d</mi> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>11</mn> <mo>)</mo> </mrow> </mrow> </math>

c_sccfor an energy-storage capacitor C_sccThe capacitance value of (a);

the voltage expression of the energy storage capacitor obtained from the above equation is:

<math> <mrow> <msub> <mi>v</mi> <mi>scc</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <msqrt> <mfrac> <mrow> <mn>2</mn> <msub> <mi>P</mi> <mi>o</mi> </msub> </mrow> <mrow> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <msub> <mi>c</mi> <mi>scc</mi> </msub> </mrow> </mfrac> </msqrt> <mo>|</mo> <mi>sin</mi> <mrow> <mo>(</mo> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>-</mo> <mfrac> <mi>&pi;</mi> <mn>4</mn> </mfrac> <mo>)</mo> </mrow> <mo>|</mo> <mo>=</mo> <msub> <mi>v</mi> <mrow> <mi>scc</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> <mo>|</mo> <mi>sin</mi> <mrow> <mo>(</mo> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>-</mo> <mfrac> <mi>&pi;</mi> <mn>4</mn> </mfrac> <mo>)</mo> </mrow> <mo>|</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>12</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein,for an energy-storage capacitor C_sccVoltage peak value of (a).

From equation (12), the voltage waveform of the storage capacitor is consistent with the rectified waveform of the input voltage, and the phase is delayed by pi/4, as shown in fig. 5.

From the formula (12)

<math> <mrow> <msub> <mi>c</mi> <mi>scc</mi> </msub> <mo>=</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>P</mi> <mi>o</mi> </msub> </mrow> <mrow> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <msubsup> <mi>v</mi> <mrow> <mi>scc</mi> <mo>,</mo> <mi>m</mi> </mrow> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>13</mn> <mo>)</mo> </mrow> </mrow> </math>

For a Buck/Boost bidirectional converter, an energy storage capacitor C thereof_sccMay have a maximum value of V_CBThus, according to equations (9) and (13) one can obtain:

$\frac{c_{\mathrm{scc}}}{c_B}=\frac{2V_{\mathrm{cpp}}}{V_{\mathrm{CB}}}---\left(14\right)$

if the output power P of the PFC converter_oIs 60W, V_CB=400V, ripple peak-to-peak value V_cppIf 4V, then c_B=120 μ F, and c_scc=2.4 μ F. Therefore, the capacitance can be greatly reduced by adopting the Buck/Boost bidirectional converter, so that the energy storage capacitor C_sccAnd a thin film capacitor or a ceramic capacitor can be adopted, so that the service life of the power supply is prolonged.

4. Control method of Buck/Boost bidirectional converter

From the foregoing analysis, it can be seen that when the energy storage capacitor C is used_sccWhen full-charge discharge is realized, the voltage waveform is consistent with the waveform obtained after input voltage rectification, and the phase lags by pi/4. Therefore, the Buck/Boost bidirectional converter can be controlled by adopting the SPWM, so that the voltage of the Buck/Boost bidirectional converter meets the requirements, namely the instantaneous pulsating input power and the instantaneous pulsating output power of the PFC converter can be balanced.

Referring to FIG. 4(a), the first switch tube Q can be derived from equation (12)₁The duty ratio d of (d) is:

<math> <mrow> <mi>d</mi> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <msub> <mi>v</mi> <mi>scc</mi> </msub> <msub> <mi>V</mi> <mi>CB</mi> </msub> </mfrac> <mo>=</mo> <mfrac> <mrow> <msqrt> <mfrac> <mrow> <mn>2</mn> <msub> <mi>P</mi> <mi>o</mi> </msub> </mrow> <mrow> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <msub> <mi>c</mi> <mi>zcc</mi> </msub> </mrow> </mfrac> </msqrt> <mo>|</mo> <mi>sin</mi> <mrow> <mo>(</mo> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>-</mo> <mfrac> <mi>&pi;</mi> <mn>4</mn> </mfrac> <mo>)</mo> </mrow> <mo>|</mo> </mrow> <msub> <mi>V</mi> <mi>CB</mi> </msub> </mfrac> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>15</mn> <mo>)</mo> </mrow> </mrow> </math>

if the amplitude of the sawtooth wave is V_RAMPThen modulating the wave voltage v_dThe expression of (a) is:

<math> <mrow> <msub> <mi>v</mi> <mi>d</mi> </msub> <mo>=</mo> <mi>d</mi> <mo>&CenterDot;</mo> <msub> <mi>V</mi> <mi>RAMP</mi> </msub> <mo>=</mo> <mfrac> <mrow> <msqrt> <mfrac> <mrow> <mn>2</mn> <msub> <mi>P</mi> <mi>o</mi> </msub> </mrow> <mrow> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <msub> <mi>c</mi> <mi>scc</mi> </msub> </mrow> </mfrac> </msqrt> <mo>|</mo> <mi>sin</mi> <mrow> <mo>(</mo> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>-</mo> <mfrac> <mi>&pi;</mi> <mn>4</mn> </mfrac> <mo>)</mo> </mrow> <mo>|</mo> </mrow> <msub> <mi>V</mi> <mi>CB</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <msub> <mi>V</mi> <mi>RAMP</mi> </msub> </mrow> </math>

<math> <mrow> <mo>=</mo> <mfrac> <mrow> <msqrt> <mfrac> <mrow> <msub> <mrow> <mn>2</mn> <mi>V</mi> </mrow> <mi>CB</mi> </msub> <msub> <mi>I</mi> <mi>B</mi> </msub> </mrow> <mrow> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <msub> <mi>c</mi> <mi>scc</mi> </msub> </mrow> </mfrac> </msqrt> <mo>|</mo> <mi>sin</mi> <mrow> <mo>(</mo> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>-</mo> <mfrac> <mi>&pi;</mi> <mn>4</mn> </mfrac> <mo>)</mo> </mrow> <mo>|</mo> </mrow> <msub> <mi>V</mi> <mi>CB</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <msub> <mi>V</mi> <mi>RAMP</mi> </msub> <mo>=</mo> <msqrt> <mfrac> <mn>2</mn> <mrow> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <msub> <mi>c</mi> <mi>scc</mi> </msub> <msub> <mi>V</mi> <mi>CB</mi> </msub> </mrow> </mfrac> </msqrt> <mo>&CenterDot;</mo> <msub> <mi>V</mi> <mi>RAMP</mi> </msub> <mo>&CenterDot;</mo> <msqrt> <msub> <mi>I</mi> <mi>B</mi> </msub> </msqrt> <mo>&CenterDot;</mo> <mo>|</mo> <mi>sin</mi> <mrow> <mo>(</mo> <msub> <mi>&omega;</mi> <mi>L</mi> </msub> <mi>t</mi> <mo>-</mo> <mfrac> <mi>&pi;</mi> <mn>4</mn> </mfrac> <mo>)</mo> </mrow> <mo>|</mo> </mrow> </math> (16)

in the formula (16) I_BIs the input current of the post-stage DC/DC converter.

In the case of normal operation of the converter, the only variable in equation (16) is I due to load variations_B. The control circuit of the active filter circuit can be designed according to the formula (16), the input voltage is subjected to differential sampling and then subjected to phase shift pi/4 through an RC circuit, the signal is rectified and then divided into two paths, one path is connected with the first input end of the multiplier, the other path is connected with the second input end of the multiplier after voltage division and peak value sampling, and a voltage signal v of the magnitude of the sampled direct current bus current_IBAfter passing through the square-open circuit, the output of the multiplier is connected with the third input end of the multiplier, and the output of the multiplier is intercepted with the sawtooth wave, so that the duty ratio signal shown in the formula (15) can be obtained. Therefore, a method of directly shifting the phase of the input voltage through an RC circuit and then rectifying the input voltage through a bridge circuit is not adopted, and the short circuit with the main power circuit is avoided.

5. The invention adopts the AC/DC converter of the active energy storage capacitor converter

With reference to fig. 6, the AC/DC converter using the active energy storage capacitor converter of the present invention includes an AC/DC converter main power circuit 1, an active energy storage capacitor converter main power circuit 2, and a control circuit: the AC/DC converter main power circuit 1 comprises an input voltage source v_inEMI filter, diode rectifier circuit RB, PFC converter, DC/DC converter, load R_Ld(ii) a The active energy-storage capacitor converter main power circuit 2 comprises a first switch tube Q₁A second switch tube Q₂Inductor L_sccAnd an energy storage capacitor C_sccWherein the first switch tube Q₁Is disclosedA first switch tube Q connected with the positive electrode of the DC bus voltage output by the PFC converter₁Respectively with the second switching tube Q₂Leakage stage and inductance L_sccIs connected to an inductor L_sccAnother end of the capacitor and an energy storage capacitor C_sccIs connected to the anode of a second switching tube Q₂Source stage and energy storage capacitor C_sccThe cathodes of the two-phase alternating current Power Factor Correction (PFC) converter are connected with the negative electrode of the direct current bus voltage output by the PFC converter; the control circuit adopts a change rule ofThe output signal of the duty ratio drives the first switch tube Q₁By the change rule ofThe output signal of the duty ratio drives the second switch tube Q₂In which P is_oIs the output power of the AC/DC converter, omega_LFor input voltage source v_inAngular frequency of c_sccFor an energy-storage capacitor C_sccCapacitance value of (V)_CBThe direct current bus voltage is output by the PFC converter. The energy storage capacitor C_sccThin film capacitors or ceramic chip capacitors.

The control circuit comprises an input voltage differential sampling circuit 3, a phase-shifting circuit 4, a rectifying circuit 5, a peak value sampling circuit 6, a signal conditioning circuit 7, an open square circuit 8, a multiplier 9 and a PWM modulation and switching tube driving circuit 10; wherein the output end C of the differential sampling circuit 3 is connected with the input end of the phase-shifting circuit 4, the output end of the phase-shifting circuit 4 is connected with the input end D of the rectifying circuit 5, and the output end I of the rectifying circuit 5 is respectively connected with the input end of the peak value sampling circuit 6 and the first input end v of the multiplier 9_xConnected to the signal output L of the peak sampling circuit 6 and to a third input v of the multiplier 9_zConnected, current transformer CT in AC/DC converter main power circuit 1 detects input DC bus current I of DC/DC converter_BThe output of the current transformer CT is connected with the input end M of the signal conditioning circuit 7, the output end N of the signal conditioning circuit 7 is connected with the input end of the square circuit 8, and the output signal of the square circuit 8 is multiplied bySecond input v of the device 9_yThe output end of the multiplier 9 is connected with the input end of a PWM modulation and switching tube driving circuit 10, one output end of the PWM modulation and switching tube driving circuit 10 is connected with a first switching tube Q in the active energy storage capacitor converter main power circuit 2₁And the other output end of the first switch tube Q is connected with a second switch tube Q in the main power circuit 2 of the active energy storage capacitor converter₂Are connected to each other.

The input voltage differential sampling circuit 3 comprises a first operational amplifier IC₁A first resistor R₁A second resistor R₂A third resistor R₃A fourth resistor R₄A fifth resistor R₅A sixth resistor R₆A seventh resistor R₇(ii) a Wherein the first resistor R₁A second resistor R₂A third resistor R₃Is connected in series to an input voltage source v_inTwo ends, a first resistor R₁And a second resistor R₂The connecting end of the resistor passes through a fifth resistor R₅Connected to a first operational amplifier IC₁Non-inverting input terminal of, the first operational amplifier IC₁Is connected to the non-inverting input terminal through a sixth resistor R₆Connected to zero of the reference potential, a second resistor R₂And a third resistor R₃The connection terminal of (2) is connected with a fourth resistor R₄Connected to a first operational amplifier IC₁The first operational amplifier IC₁Through a seventh resistor R₇Connected to a first operational amplifier IC₁To the output terminal C.

The phase shift circuit 4 comprises an eighth resistor R₈And a first capacitor C₁Wherein the eighth resistor R₈One terminal of and the first operational amplifier IC₁Is connected to an eighth resistor R₈And the other end of the first capacitor C₁Connected by a first capacitor C₁Is connected to a reference potential zero point, an eighth resistor R₈And a first capacitor C₁Is connected to the input D of the rectifier circuit 5.

The rectifying circuit 5 includes a second operational amplifier IC₂A third operational amplifier IC₃And a twelfth resistor R₁₂A thirteenth resistor R₁₃A fourteenth resistor R₁₄A first diode D₁A second diode D₂A third diode D₃A fourth diode D₄(ii) a Wherein the thirteenth resistor R₁₃And an input terminal of the rectifying circuit (5), i.e., a third operational amplifier IC₃Is connected with the non-inverting input end D, and the other end is connected with a second operational amplifier IC₂Is connected to the inverting input terminal E of the fourth resistor R₁₂And a first diode D₁Are all connected to a second operational amplifier IC₂The inverting input terminal E of, the first diode D₁And a second diode D₂And the anodes of the first and second operational amplifiers IC₂Is connected to the output terminal F of the twelfth resistor R₁₂And a second diode D₂The cathodes of the two resistors are connected with the output end I of the rectifying circuit 5, and the fourteenth resistor R₁₄And a third diode D₃Are all connected to a third operational amplifier IC₃The inverting input terminal G of the first diode D₃And a fourth diode D₄And the anodes of the first and second operational amplifiers IC₃Is connected to the fourteenth resistor R₁₄And the other end of the fourth diode D₄Are connected with the output terminal I of the rectifying circuit 5.

The peak sampling circuit 6 comprises a fourth operational amplifier IC₄A ninth resistor R₉A tenth resistor R₁₀An eleventh resistor R₁₁A fifth diode D₅A second capacitor C₂(ii) a Wherein the ninth resistor R₉Is an input terminal of the peak value sampling circuit 6, which is connected to the output terminal I of the rectifying circuit 5, and a ninth resistor R₉And the other end of (1) and a tenth resistor R₁₀Are all connected to a fourth operational amplifier IC₄The non-inverting input terminal of (1), the tenth resistor R₁₀Is connected to a reference potential zero point, a fourth operational amplifier IC₄And the fourth operational amplifier IC₄Is connected to the output terminal K of a fourth operational amplifier IC₄Through the eleventh output terminal KResistance R₁₁Is connected into a fifth diode D₅Anode of (2), fifth diode D₅And a second capacitor C₂Is connected to the output terminal L of the peak value sampling circuit 6, and a second capacitor C₂And the other end thereof is connected to a reference potential zero point.

The PWM modulation and switching tube driving circuit 10 includes a PWM integrated IC circuit and two driving circuits, the two signals output by the PWM integrated IC circuit are respectively connected to the two driving circuits, wherein the PWM integrated IC circuit may adopt models of UC3525, UC3825, UC3843 or UC 3844. A first operational amplifier IC₁-fourth operational amplifier IC₄The model of TL074, TL072, LM358 or LM324 can be adopted, the multiplier 9 is formed by an integrated IC circuit or a discrete device, and the square-off circuit 8 is formed by an integrated IC circuit or a discrete device.

In summary, the active energy storage capacitor converter for the AC/DC converter of the present invention can greatly reduce the capacitance value of the energy storage capacitor with the same voltage rating under the condition of ensuring the input power factor to be 1, can adopt a small-capacity and long-life capacitor such as a thin film capacitor or a ceramic capacitor, and overcomes the defects of large volume and short service life of an electrolytic capacitor as the energy storage capacitor, and has the advantages of significantly improving the power density of the power supply and prolonging the service life of the converter.

Claims (7)

1. An AC/DC converter adopting an active energy storage capacitor converter is characterized by comprising an AC/DC converter main power circuit (1), an active energy storage capacitor converter main power circuit (2) and a control circuit: the AC/DC converter main power circuit (1) comprises an input voltage source v_inEMI filter, diode rectifier circuit RB, PFC converter, DC/DC converter, load R_Ld(ii) a The active energy-storage capacitor converter main power circuit (2) comprises a first switching tube Q₁A second switch tube Q₂Inductor L_sccAnd an energy storage capacitor C_sccWherein the firstA switch tube Q₁The drain stage of the first switching tube Q is connected with the positive electrode of the DC bus voltage output by the PFC converter₁Respectively with the second switching tube Q₂Leakage stage and inductance L_sccIs connected to an inductor L_sccAnother end of the capacitor and an energy storage capacitor C_sccIs connected to the anode of a second switching tube Q₂Source stage and energy storage capacitor C_sccThe cathodes of the two-phase alternating current Power Factor Correction (PFC) converter are connected with the negative electrode of the direct current bus voltage output by the PFC converter; the control circuit comprises an input voltage differential sampling circuit (3), a phase-shifting circuit (4), a rectifying circuit (5), a peak value sampling circuit (6), a signal conditioning circuit (7), an open-square circuit (8), a multiplier (9) and a PWM modulation and switching tube driving circuit (10); wherein the output end C of the input voltage differential sampling circuit (3) is connected with the input end of the phase-shifting circuit (4), the output end of the phase-shifting circuit (4) is connected with the input end D of the rectifying circuit (5), and the output end I of the rectifying circuit (5) is respectively connected with the input end of the peak value sampling circuit (6) and the first input end v of the multiplier (9)_xA signal output terminal L of the peak value sampling circuit (6) and a third input terminal v of the multiplier (9) are connected_zA current transformer CT in a main power circuit (1) of an AC/DC converter is connected to detect the input DC bus current I of the DC/DC converter_BThe output of the current transformer CT is connected with the input end M of the signal conditioning circuit (7), the output end N of the signal conditioning circuit (7) is connected with the input end of the open-square circuit (8), the output signal of the open-square circuit (8) is connected with the second input end v of the multiplier (9)_yThe output end of the multiplier (9) is connected with the input end of a PWM modulation and switching tube driving circuit (10), one output end of the PWM modulation and switching tube driving circuit (10) is connected with a first switching tube Q in the active energy storage capacitor converter main power circuit (2)₁Is connected with the grid of the active energy-storage capacitor converter, and the other output end of the active energy-storage capacitor converter is connected with a second switching tube Q in the main power circuit (2) of the active energy-storage capacitor converter₂The grid electrodes are connected;

the control circuit adopts a change rule ofThe output signal of the duty ratio drives the first switch tube Q₁By the change rule ofThe output signal of the duty ratio drives the second switch tube Q₂In which P is_oIs the output power of the AC/DC converter, omega_LFor input voltage source v_inAngular frequency of c_sccFor an energy-storage capacitor C_sccCapacitance value of (V)_CBThe direct current bus voltage is output by the PFC converter.

2. The AC/DC converter with active energy-storage capacitor converter according to claim 1, wherein the energy-storage capacitor C_sccIs a thin film capacitor or a ceramic chip capacitor.

3. The AC/DC converter with active energy-storage capacitive converter according to claim 1, characterized in that the input voltage differential sampling circuit (3) comprises a first operational amplifier IC₁A first resistor R₁A second resistor R₂A third resistor R₃A fourth resistor R₄A fifth resistor R₅A sixth resistor R₆A seventh resistor R₇(ii) a Wherein the first resistor R₁A second resistor R₂A third resistor R₃Is connected in series to an input voltage source v_inTwo ends, a first resistor R₁And a second resistor R₂The connecting end of the resistor passes through a fifth resistor R₅Connected to a first operational amplifier IC₁Non-inverting input terminal of, the first operational amplifier IC₁Is connected to the non-inverting input terminal through a sixth resistor R₆Connected to zero of the reference potential, a second resistor R₂And a third resistor R₃The connection terminal of (2) is connected with a fourth resistor R₄Connected to a first operational amplifier IC₁The first operational amplifier IC₁Through a seventh resistor R₇Connected to a first operational amplifier IC₁To the output terminal C.

4. The use of an active reservoir as in claim 1AC/DC converter capable of being used as a capacitive converter, characterized in that said phase-shifting circuit (4) comprises an eighth resistor R₈And a first capacitor C₁Wherein the eighth resistor R₈Is connected with the output end C of the input voltage differential sampling circuit (3), and an eighth resistor R₈And the other end of the first capacitor C₁Connected by a first capacitor C₁Is connected to a reference potential zero point, an eighth resistor R₈And a first capacitor C₁Is connected with the input end D of the rectifying circuit (5).

5. AC/DC converter with active energy-storing capacitive converter according to claim 1, characterized in that the rectifying circuit (5) comprises a second operational amplifier IC₂A third operational amplifier IC₃And a twelfth resistor R₁₂A thirteenth resistor R₁₃A fourteenth resistor R₁₄A first diode D₁A second diode D₂A third diode D₃A fourth diode D₄(ii) a Wherein the thirteenth resistor R₁₃And an input terminal of the rectifying circuit (5), i.e., a third operational amplifier IC₃Is connected with the non-inverting input end D, and the other end is connected with a second operational amplifier IC₂Is connected to the inverting input terminal E of the fourth resistor R₁₂And a first diode D₁Are all connected to a second operational amplifier IC₂The inverting input terminal E of, the first diode D₁And a second diode D₂And the anodes of the first and second operational amplifiers IC₂Is connected to the output terminal F of the twelfth resistor R₁₂And a second diode D₂The cathodes of the two resistors are connected with the output end I of the rectifying circuit (5), and the fourteenth resistor R₁₄And a third diode D₃Are all connected to a third operational amplifier IC₃The inverting input terminal G of the first diode D₃And a fourth diode D₄And the anodes of the first and second operational amplifiers IC₃Is connected to the fourteenth resistor R₁₄And the other end of the fourth diode D₄The cathodes of the two rectifying circuits are connected with the output end I of the rectifying circuit (5).

6. AC/DC converter with active energy-storing capacitive converter according to claim 1, characterized in that the peak-sampling circuit (6) comprises a fourth operational amplifier IC₄A ninth resistor R₉A tenth resistor R₁₀An eleventh resistor R₁₁A fifth diode D₅A second capacitor C₂(ii) a Wherein the ninth resistor R₉One end of the first resistor is an input end of a peak value sampling circuit (6), the input end is connected with an output end I of the rectifying circuit (5), and a ninth resistor R₉And the other end of (1) and a tenth resistor R₁₀Are all connected to a fourth operational amplifier IC₄The non-inverting input terminal of (1), the tenth resistor R₁₀Is connected to a reference potential zero point, a fourth operational amplifier IC₄And the fourth operational amplifier IC₄Is connected to the output terminal K of a fourth operational amplifier IC₄Through an eleventh resistor R₁₁Is connected into a fifth diode D₅Anode of (2), fifth diode D₅And a second capacitor C₂Is connected with the output end L of the peak value sampling circuit (6), and a second capacitor C₂And the other end thereof is connected to a reference potential zero point.

7. The AC/DC converter with an active energy-storage capacitor converter according to claim 1, wherein the PWM modulation and switching tube driving circuit (10) comprises a PWM integrated IC circuit and two driving circuits, wherein the PWM integrated IC circuit is of model number UC3525, UC3825, UC3843 or UC 3844.