TWI495239B - Voltage converter combined with one bootstrap capacitor and one coupled inductor - Google Patents

Description

Boost converter with capacitor and coupled inductor

The present invention relates to a boost converter, and more particularly to a boost converter having a bootstrap capacitor and a coupled inductor that can reduce leakage inductance and recover energy.

Boost converters are widely used in applications such as HID optical drives, uninterruptible power systems, solar cell systems, and fuel cell systems. For example, solar cells require a boost converter to convert low voltage to high voltage and then DC. The AC converter is converted to an AC voltage output.

Conventional boost converters are commonly used for boost or flyback. There are other types of boost converters, but each has its own missing. Some boost converters have high conversion efficiency, but the leakage inductance is accompanied. The voltage surge and the circuit are quite complicated. Some boost converters are floating outputs and accompany complex circuits, making circuit analysis difficult.

The inventor has a good voltage conversion performance in the previously proposed boost converter, and in order to reduce the leakage inductance and quickly recover the energy, it is proposed to have a voltage conversion performance different from that previously proposed and more comparable to the aforementioned boost converter. A circuit architecture that reduces leakage inductance and quickly recovers energy.

Accordingly, it is an object of the present invention to provide a boost converter having a bootstrap capacitor and a coupled inductor that reduces leakage inductance and recovers energy.

Therefore, the boost converter of the present invention has a charge pump, a boost circuit and an output circuit.

The charge pump is configured to receive an input voltage, having a first switching element, a second switching element connected in series with the first end of the first switching element, and an anode end connected to the second end of the first switching element The pump diode has a capacitor with a first end and a second end, and the first end of the sleeve is electrically connected to the cathode end of the pump diode, the boot The second end of the capacitor is electrically connected between the first switching element and the second switching element.

The boosting circuit is electrically connected to the charge pump, and has a conductive capacitor and a coupled inductor. The coupled inductor has a primary side winding and a primary side winding. One end of the conductive capacitor is coupled to the input voltage and the conductive capacitor. The first end of the first switching element is coupled to the first end of the first switching element, and the non-injecting end of the primary side winding is coupled to the first end of the first switching element, the secondary side The non-doped end of the winding is coupled to the anode end of the pump diode and the dot end of the secondary side winding is coupled to the second end of the first switching element.

The output circuit has an output inductor, an output capacitor and an output resistor. One end of the output inductor is coupled to the cathode end of the pump diode, and the other end of the output inductor is respectively connected to the output capacitor and the output resistor. And by the control end of the first switching element and the second switching element The control terminal receives the bandwidth adjustment control signal to drive the booster circuit, respectively, and generates an output voltage boosted by the input voltage via the output circuit.

The effect of the invention is that the leakage inductance is recovered and the energy is recovered by the primary side winding and the secondary side winding, and the output current is matched with the output inductor so that the output current is non-pulsating, and as a result, the output current chopping and the output voltage chopping can be significantly reduced. .

100‧‧‧Boost converter

11‧‧‧Charge pump

12‧‧‧Boost circuit

13‧‧‧Output circuit

21‧‧‧Voltage divider

22‧‧‧ Analog Digital Converter

23‧‧‧FPGA Controller

24‧‧‧Half Bridge Gate Driver

C ₁ ‧‧‧conductive capacitor

C ₂ ‧‧‧boot with capacitor

C _o ‧‧‧output capacitor

L _o ‧‧‧Output inductor

D ₁ ‧‧‧ pumping diode

N _p ‧‧‧ primary side winding

N _S ‧‧‧secondary winding

R _o ‧‧‧ output resistance

S ₁ ‧‧‧first switching element

S ₂ ‧‧‧Second switching element

V _i ‧‧‧ input voltage

V _o ‧‧‧output voltage

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: FIG. 1 is a circuit diagram illustrating a preferred embodiment of a boost converter device with a captive capacitor and a coupled inductor of the present invention. 2 is an analog circuit diagram illustrating a preferred embodiment of a boost converter device with a bootstrap capacitor and a coupled inductor in a first state; FIG. 3 is a diagram illustrating a boost of a bootband capacitor and a coupled inductor according to the present invention; FIG. 4 and FIG. 5 are waveform diagrams illustrating the voltage/current timing of the components of the present invention at rated load and light load; FIGS. 6 and 7 are diagrams illustrating the secondary side. A diagram showing the relationship between the current I _{Ns of the} winding and the current I _Lm of the magnetizing inductance; FIG. 8 is a schematic diagram illustrating the boundary condition of the magnetizing inductance Lm; FIG. 9 is a schematic diagram illustrating the boundary condition of the output inductor Lo; A block diagram of a control system of a preferred embodiment of a boost converter having a capacitor with a capacitor and a coupled inductor; and Figs. 11 through 13 are experimental waveforms illustrating an output current Io = 1.25 amps at rated load.

Referring to FIG. 1, in a preferred embodiment of the present invention, a boost converter 100 with a bootstrap capacitor and a coupled inductor includes a charge pump 11, a boost circuit 12, and an output circuit 13.

The charge pump 11 for receiving an input voltage V _i, having a first switching element S _1, a series of the first switching element S ₁ of a first end of the second switching element S _2, an anode terminal connected to the first switching element S ₁ of the second end of the pump diode D _1, and a bootstrap capacitor C _2, the bootstrap capacitor C ₂ having a first end and a second end, the bootstrap capacitor C ₂ a first terminal electrically connected to the cathode terminal to help pump the diode D _1, the second terminal of the bootstrap capacitor C ₂ electrically connected between _two of the first switching element S ₁ and the second switching element S.

The boosting circuit 12 is electrically connected to the charge pump 11 and has a conductive capacitor C ₁ and a coupled inductor. The coupled inductor has a primary side winding N _p and a primary side winding N _S , and one end of the conductive capacitor C ₁ is coupled. The other end of the input voltage V _i and the conductive capacitor C ₁ is coupled to the second end of the first switching element S ₁ , and the dot end of the primary side winding N _p is coupled to the input voltage V _i and the primary winding The non-tapping end of the N _p is coupled to the first end of the first switching element S ₁ , and the non-injecting end of the secondary side winding N _S is coupled to the anode end of the pump diode D ₁ and the secondary winding The dot end of the N _S is coupled to the second end of the first switching element S ₁ .

The output circuit 13 has an output inductor L _o , an output capacitor C _o and an output resistor R _o . One end of the output inductor L _o is coupled to the cathode terminal of the pump diode D ₁ , and the output inductor L _o The other end is connected to the output capacitor C _o and the output resistor R _o , respectively, and the control terminal of the first switching element S _{1 and} the control end of the second switching element S ₂ are respectively driven by the wave width adjustment control signal. The output voltage V _o boosted by the input voltage V _i is output by the output circuit 13.

Referring to Figure 2 and Figure 3, for the convenience of analysis, the relevant setting conditions are as follows: (1) The coupled inductor is an ideal transformer in parallel with a magnetizing inductance (inductor L _m ) in the primary side winding; (2) the circuit architecture operates in a positive current mode. Therefore, the current flowing through the magnetizing inductance L _m and the output inductor L _o is positive; (3) the blanking time between the switching elements is ignored; (4) all switching elements and diodes are ideal components; (5) The capacitance of all capacitors is large enough to keep it at a fixed voltage; (6) Ignore switching chopping.

The preferred embodiment has two states in a continuous conduction mode (CCM). The following analysis includes the power flow direction of each state, and lists the relationship between the DC input voltage Vi and the DC output voltage Vo. The conduction periods of the first switching element S ₁ and the second switching element S ₂ are respectively 1 -D and D, where D represents the DC quiescent duty cycle of the bandwidth adjustment control signal.

I. First state:

Referring to FIG. 2, 4 and 5, in this state, the first switching element S ₁ is not turned on and the second switching element S ₂ is turned on; the primary winding N _p applying an input voltage V _i, Equation 1, resulting in the magnetizing inductance L _m is excited, and the voltage of the secondary side winding N _S is induced by the input voltage V _i multiplied by the turns ratio (N _s /N _p ); meanwhile, the pump diode D ₁ is reverse-biased, and the output The inductance L _o voltage is a negative value: V _C2 -V _o , as Equation 2, such that the output inductance L _{o is} demagnetized, and therefore, the voltage V _{C2 is} supplied to the load.

v _Np = V _i formula 1

v _Lo = V _C2 - V _o Equation 2

II. Second state:

Referring to Figure 3, 4 and 5, in this state, the first switching element S ₁ is turned on and the second switching element S ₂ is not turned on; the primary winding N _p input voltage is applied -V _C1, as shown in equation 3, thereby causing The magnetizing inductance L _m is demagnetized, and the voltage of the secondary side winding N _S is induced to be V _C1 xN _s /N _p ; the pump diode D ₁ is forward-biased, and the voltage of the shoe capacitor C ₂ is charged. For V _i +V _C1 +V _i xN _s /N _p , the voltage of the output inductor L _o is positive: V _i +V _C1 +V _C2 -V _o , as Equation 4, so that the output inductance L _o is magnetized, Therefore, the voltage V _i +V _C1 +V _C2 is supplied together to the load.

v _Np =- V _{C 1} Equation 3

v _Lo = V _i + V _{C 1} + V _{C 2} - V _o Equation 4

The magnetizing inductance L _m applies the voltage-second balance principle in the switching cycle to obtain the formula 5, and the formula 5 can be rewritten as the formula 6.

V _i × D +(- V _{C 1} )×(1- D )=0 Equation 5

Similarly, the output inductor L _o applies the volt-second equilibrium law during the switching cycle to obtain Equation 7, which is the crossover of C ₂ .

( V _{C 2} - V _o )× D +( V _i + V _{C 1} + V _{C 2} - V _o )×(1- D )=0 Equation 7

Finally, according to Equations 6, 7, and 8, the calculation formula of the voltage conversion efficiency (gain) is as shown in Equation 9.

The following describes the boundary condition of the magnetizing inductance L _m operating in the current interval as in Equation 10, wherein the current I _Lm is a direct current component corresponding to the current i _Lm and Δ i _Lm is an alternating current component corresponding to the current i _Lm . The current I _Lm of the magnetizing inductance L _m is expressed by the formulas 11 to 13.

For the convenience of analysis, it is assumed that the input power is equal to the output power. According to the voltage-second balance theorem of the inductor and the ampere-second balance theorem of the capacitor, the DC component of the inductor voltage and the DC component of the capacitor current are both Is 0.

Referring to Figures 6 and 7, the DC components of the currents i _Ns , I _Ns are equal to the DC components of the output current I _o ; similarly, the DC components of the currents i _Lm , I _Lm are equal to the input current I _i entering the primary side of the coupled inductor, plus The DC component of the current i _Np , I _Np . The output current I _o can be expressed as V _o / R _o , and the output current I _{o of} Equation 13 is replaced by V _o / R _o , as in Equation 14. Δ i _Lm can be expressed as Formula 15.

When the boundary condition is 2 I _Lm Δ i _Lm , the magnetizing inductance L _m operates in the positive current region, and therefore, the formula is rewritten as Equation 16, where n is the turns ratio N _s /N _{p of} the secondary side winding and the primary side winding.

among them, And .

Referring to FIG. 8, a relationship diagram in which the duty cycle D and the custom parameter K _{crit 1} ( D ) are set to 3 in Equation 16 shows that K _{1 is} greater than the custom parameter K _{crit 1} ( D ), and the magnetizing inductance L _{m is} operated. In the positive current region; otherwise, part of the current i _Lm enters the negative current region.

The following describes the boundary condition of the output inductor L _o operating in the current interval as in Equation 17, where the current I _Lo is indicative of the DC component corresponding to the current i _Lo and Δ i _Lo is the AC component corresponding to the current i _Lo . The current I _Lo is equal to the output current I _o , which can be expressed as V _o / R _o , as in Equation 18. The current Δ i _Lo can be expressed as Equations 19 and 20.

When the boundary condition is 2 I _Lo Δ i _Lo , the output inductor L _o operates in the positive current region, and therefore, the formula is rewritten as Equation 21.

among them, And .

Referring to FIG. 9, a relationship diagram in which the duty cycle D and the custom parameter K _{crit 2} ( D ) are set to 3 in Equation 16 shows that K _{2 is} greater than the custom parameter K _{crit 2} ( D ), and the output inductor L _{o is} operated. In the positive current region; otherwise, part of the current i _Lm enters the negative current region.

Referring to FIG. 10, a control system of the boost converter device 100 with a bootstrap capacitor and a coupled inductor includes a voltage divider 21, an analog-to-digital converter 22, an FPGA controller 23, and Half bridge gate driver 24, detailed technical principle, FPGA controller 23 is responsible for the timing control and switching control timing of the whole system, processing feedback compensation and calculating control power to perform proportional integral differentiation (referred to as PI) control including The proportional gain gain k _p and the integral gain k _i at the rated load due to the voltage divider 21, the analog-to-digital converter 22, the FPGA controller 23, and the half bridge gate The pole driver 24 is prior art and is not the focus of the present invention, and its principle will not be described in detail herein.

The specifications of the components in the preferred embodiment are as follows: (i) the input voltage V _i is 12 volts; (ii) the nominal output voltage V _o is 48 volts; (iii) the output rated current (I _o,rated ) / power (P _o,rated ) is 1.25A/60W; (iv) minimum output rated current (I _o,min ) / power (P _o,min ) is 0.1A/7.2W; (v) switching frequency f _s is 100kHz; (vi) The output capacitor C _o selects two 470μF/100V shunt capacitors; (vii) the first switching element S ₁ and the second switching element S ₂ are all of the type STP120NF; (viii) the pump diode D ₁ Model V20120C and bootstrap capacitor C ₂ select two 100μF/100V shunt capacitors; (ix) FPGA controller 23 is EP1C3T100; (x) analog digital converter 22 is ADC7476; (xi) half bridge gate The pole driver 24 is of the type IR2011; (xii) the conduction capacitor C ₁ is two series capacitors of 680 μF / 50 V; (xiii) the coupled inductor L _m is Core: PC40EER40-Z; N _p : N _s = 1:3; L _m = 44.8 μH; L _{l 1} =0.498 μH; k ≒ 0.989; and (xiv) the output inductance is Core: PC40EER35-Z; L _o = 136 μH.

Referring to FIGS. 11 to 13, under rated load (rated load), the output current I _o = 1.25 amperes experimental waveforms, it is understood the present invention can stably operate from each waveform; wherein FIG. 11 is a device according to the present invention bootstrap the boost converter and the capacitive means coupled inductor 100. the first switching element S ₁ of the gate electrode drive signal v _{gs 1,} a second switching element S ₂ of the gate electrode drive signal v _{gs 2,} the primary winding N _p and the leakage inductance A waveform diagram of a current i _Ns of the current i _Np + i _Lm and the secondary side winding N _S ; FIG. 12 is a gate driving signal v _{gs 1} of the first switching element S _{1 and} a gate driving signal of the second switching element S ₂ v _{gs 2} , output inductor L _o voltage v _Lo and output inductor L. I _Lo current waveform diagram; and FIG. 13 is a first switching element S gate drive signal v ₁ of _{gs 1,} a second switching element gate drive signal S v ₂ is _{gs 2,} conductive capacitor C ₁ and the voltage V _{C 1} The shoe has a waveform of the capacitor C ₂ voltage V _{C 2} .

The conduction capacitor C ₁ and the shoe strap capacitor C ₂ are charged by the series-connected primary side winding N _p and the secondary side winding N _S , correspondingly causing the conduction capacitance C ₁ voltage V _{C 1} and the boot band capacitance C ₂ voltage V _{C 2} The noise is reduced. In addition, the magnetizing inductance L _m is designed to operate in the positive current region, but the current can be measured as i _Lm + i _Np has a negative current value at some point in time.

In summary, the boost converter 100 with the capacitor and the coupled inductor of the present invention can reduce the leakage inductance and recover the energy by the primary side winding N _p and the secondary side winding N _{S of the} coupled inductor, and cooperate with the output inductor. _Lo makes the output current non-pulsating type, and as a result, the output current chopping and the output voltage chopping can be remarkably reduced, and the leakage inductance can be reduced and the energy can be quickly recovered compared with the conventional boost converter, so that the object of the present invention can be achieved. .

However, the above is only the preferred embodiment of the present invention, and the scope of the present invention cannot be limited thereto, that is, according to the present invention. The simple equivalent changes and modifications made by the scope of the patent application and the contents of the patent specification are still within the scope of the invention.

100‧‧‧Boost converter

11‧‧‧Charge pump

12‧‧‧Boost circuit

13‧‧‧Output circuit

C ₁ ‧‧‧conductive capacitor

C ₂ ‧‧‧boot with capacitor

C _o ‧‧‧output capacitor

L _o ‧‧‧Output inductor

D ₁ ‧‧‧ pumping diode

N _p ‧‧‧ primary side winding

N _S ‧‧‧secondary winding

R _o ‧‧‧ output resistance

S ₁ ‧‧‧first switching element

S ₂ ‧‧‧Second switching element

V _i ‧‧‧ input voltage

V _o ‧‧‧output voltage

Claims (2)

A boost converter device with a capacitor with a capacitor and a coupled inductor, comprising: a charge pump for receiving an input voltage, having a first switching element, and a second connected in series with the first end of the first switching element a switching element, a pump diode connected to the second end of the first switching element with an anode end, and a boot capacitor having a first end and a second end One end is electrically connected to the cathode end of the pump diode, and the second end of the shoe capacitor is electrically connected between the first switching element and the second switching element; a boosting circuit electrically connecting the electric charge The pump has a conductive capacitor-coupled inductor having a primary side winding and a primary side winding. One end of the conductive capacitor is coupled to the input voltage, and the other end of the conductive capacitor is coupled to the first switching element. a second end, the dot end of the primary side winding is coupled to the input voltage, and the non-injecting end of the primary side winding is coupled to the first end of the first switching element, and the non-doping end of the secondary side winding is coupled to the gang The anode end of the diode and the time The dot end of the side winding is coupled to the second end of the first switching element; and an output circuit has an output inductor, an output capacitor and an output resistor, and one end of the output inductor is coupled to the cathode of the pump diode Extremely, the other end of the output inductor is respectively connected to the output capacitor and the output resistor; thereby, the control end of the first switching element and the control end of the second switching element respectively receive a wave width adjustment control signal to drive the liter And compressing the circuit and generating an output voltage boosted by the input voltage via the output circuit. The boost conversion device with a bootstrap capacitor and a coupled inductor according to claim 1 has a voltage conversion performance formula Where V _o is the output voltage, V _i is the input voltage, D is the DC static duty cycle of the wave width adjustment control signal, and N _s /N _{p is} the turns ratio of the secondary side winding and the primary side winding.