TWI477049B - A power conversion device with a high conversion ratio - Google Patents

Description

Power conversion device with high up conversion ratio

The present invention relates to a booster circuit, and more particularly to a power converter having a high upshift ratio.

Known high-boost circuit designs, such as using a series-connected boost converter to achieve high-boost conversion, or using a coupling inductor (Coupling Inductor), charge pump (Charge Pump), etc. In order to increase the boost ratio, some even combine the above two methods to achieve higher boost conversion. However, the above proposed architectures have their own shortcomings, such as the circuit architecture is too complex, using a large number of passive components such as inductors, capacitors and switches, resulting in poor overall circuit efficiency; or can only be used in low-power applications; or output For floating type, even if there is a good high boost ratio, it limits its application; some circuits, the switching elements are floating rather than grounded, so additional isolation drivers are needed, which not only increases the cost but also increases the cost. The complexity of the entire system design. In addition, many circuit architectures use high-order controllers to increase boost ratios and are difficult to control.

Accordingly, it is an object of the present invention to provide a power conversion apparatus having a high up conversion ratio.

Therefore, the power conversion device of the present invention having a high-up conversion ratio is suitable for boosting an input voltage, and the power conversion device includes a storage inductor, a storage capacitor, a first diode, and a second diode. a third diode, a coupled inductor, a bootband capacitor, a first switching component, and a second switching component.

The energy storage inductor has a first end and a second end receiving the input voltage; the storage capacitor has a first end and a second end coupled to the first end of the energy storage inductor; The diode has an anode coupled to the second end of the energy storage inductor and a cathode coupled to the second end of the storage capacitor; the second diode has a second and a storage capacitor An anode coupled to the terminal and a cathode; the coupled inductor has a primary side coil and a secondary side coil, the secondary side coil and the primary side coil have a turns ratio n, and the primary side coil has a first a first end and a second end of the cathode of the diode, the second side coil having a first end coupled to the cathode of the second diode and the first end of the primary coil a second terminal; the third diode has an anode and a cathode coupled to the second end of the primary side coil.

The shoe strap capacitor has a first end coupled to the second end of the secondary side coil and a second end coupled to the anode of the first diode; the first switching element and the boot capacitor The second end is coupled to and controlled by external control; the second switching element is coupled to the second end of the primary side coil and the anode of the third diode and is electrically controlled by external control.

When the first switching element is non-conducting and the second switching element is non-conducting, the first diode is turned on, the third diode is turned on, and the second diode is turned off, and the voltage across the storage inductor is The energy storage capacitor is biased and the energy storage inductor is demagnetized; when the first switching element is turned on and the second switching element is turned on, the voltage across the energy storage inductor is excited by the input voltage, the first The diode is turned off, the third diode is turned off, and the second diode is turned on, and the input voltage plus the voltage across the storage capacitor and the voltage across the secondary coil charge the shoe capacitor. Let the secondary side coil have a voltage of n times the primary side coil Over the pressure.

Preferably, the first switching element and the second switching element are both grounded non-floating switching elements.

Preferably, the capacitance of the shoe strap capacitor is sufficient to maintain (1 + n) times the input voltage plus (1 + n) times the voltage across the storage capacitor across the steady state.

The power conversion device with high conversion ratio of the present invention has the effect that the designer can adjust the boosting ratio of the secondary side coil and the primary side coil by using the turns ratio n to increase the design flexibility, and the switching element used is Non-floating, the overall drive is simple and practical.

The foregoing and other objects, features, and advantages of the invention are set forth in the <RTIgt;

Referring to FIG. 1, in a preferred embodiment of the present invention, a power conversion device 100 having a high-up conversion ratio is adapted to boost an input voltage v _i , and the power conversion device 100 includes a storage inductor L ₁ and a storage device. Capacitor C ₁ , a first diode D ₁ , a second diode D ₂ , a third diode D ₃ , a first switching element S ₁ , a coupled inductor 15 , and a bootstrap capacitor C ₂ , a second switching element S ₂ , an output capacitor C _o and an output resistor R _o .

The storage inductor L ₁ has a first end 111 and a second end 112 that receive the input voltage v _i ; the storage capacitor C ₁ has a first end 121 coupled to the first end 111 of the storage inductor L ₁ and a second end 122; the first diode D ₁ has an anode 131 coupled to the second end of the storage inductor L ₁ and a cathode 132 coupled to the second end 122 of the storage capacitor C ₁ ; The diode D ₂ has an anode 141 and a cathode 142 coupled to the second end 122 of the storage capacitor C ₁ .

Coupled inductor 15 having a primary side coil N _1, and a secondary winding N _2, N ₂ and the secondary winding side of the primary turns ratio N ₁ n, N ₁ having a primary side coil and a second diode The cathode 142 of the body D ₂ is coupled to the first end 151 (non-tapping end) and a second end (dip end) 152, the secondary side coil N ₂ has a cathode 142 of the second diode D ₂ and the primary The first end 151 of the side coil N ₁ is coupled to the first end (punch end) 161 and the second end (non-tap end) 162; the third diode D ₃ has a second and the second side coil N ₁ end 152 is coupled to the anode 171 and the 172, the other end of the other end of the output capacitor C _o and an output resistor R _o and the end of an end of the output capacitor C _o and an output coupled to resistor R _o of the cathode is grounded.

The shoe strap capacitor C ₂ has a first end 181 coupled to the second end 162 of the secondary side coil N ₂ and a second end 182 coupled to the anode of the first diode D ₁ . Bootstrap capacitance value of the capacitance C ₂ is sufficient such that when the voltage across it is maintained at a steady state (1 + n) times the input voltage plus (1 + n) times the energy storage capacitor voltage across _{C. 1.}

The first switching element S _{1 is} coupled to the second end 182 of the boot band capacitor C ₂ ; the second switching element S ₂ and the second end 152 of the primary side coil N ₁ and the third diode D ₃ The anode 171 is coupled to the anode 171. Preferably, the first switching element S ₁ and the second switching element S ₁ are grounded non-floating switching elements. For example, the n-channel MOS field-effect transistor has a function for controlling conduction and No gate (G), a source (S) and a drain (D), the gate (G) of each switch is used as a control terminal, and the first terminal 201 of the first switching element S ₁ is a source ( S) coupling the second end 182 of the shoe strap capacitor C ₂ and the first end 301 of the second switching element S ₂ to be a source (S) coupled to the second end 152 of the primary side coil N ₁ , the first switching element S the second end 202 is _a drain (D) and a second switching element S ₂ is the second end 302 of the drain (D) and are all grounded.

Referring to FIG. 2, v _i is the input voltage, v _o is the output voltage, i _i is the input current, i _DS1 is the current on the first switching element S ₁ , i _DS2 is the current on the second switching element S ₂ , i _D1 The current on the first diode D ₁ , i _D2 is the current on the second diode D ₂ , i _D3 is the current on the third diode D ₃ , and i _C1 is the storage capacitor C ₁ Current, i _L1 is the current on the storage inductor L ₁ , i ₁ is the current of the primary side coil N ₁ , i ₂ is the current of the secondary side coil N ₂ , and the current flowing through the boot capacitor C ₂ , i _Lm The current on the magnetizing inductance L _m , i ₃ is the sum of the currents on the primary side coil N ₁ and the exciting inductance L _m .

v _gS1 is the gate driving signal of the first switching element S ₁ , v _gS2 is the gate driving signal of the second switching element S ₂ , v _DS1 is the voltage across the first switching element S ₁ , and v _DS2 is the second switching element The voltage across S ₂ , v _L1 is the voltage across the energy storage inductor L ₁ , v _N1 is the voltage across the primary side coil N ₁ or the magnetizing inductance L _m , v _N2 is the voltage across the secondary side coil N ₂ , v _C1 The voltage across the storage capacitor C ₁ and v _C2 are the cross-pressure of the bootstrap capacitor C ₂ .

For the convenience of analysis, the setting conditions are as follows: when the switching period is T _s , the on-time of the first switching element S ₁ and the second switching element S ₂ is DT _s , and the first switching element S ₁ and the second switching element S The cutoff time of ₂ is (1- D ) T _s . The first switching element S ₁ , the two switching elements S ₂ , the first diode D ₁ , the second diode D ₂ and the third diode D ₃ are regarded as ideal components, that is, switching time and on-resistance The reverse recovery time of the diode and the forward voltage drop are negligible. The energy storage inductor L ₁ , the coupled inductor 15, the storage capacitor C ₁ and the boot capacitor C ₂ do not take into account the parasitic resistance, and the shoe capacitor C ₂ is large enough to remain at (1+) when the voltage is across the steady state. n) The input voltage v _{i is} added (1 + n) times the voltage across the storage capacitor C ₁ across the voltage v _C1 . The coupling coefficient of the coupled inductor 15 is one, and the overall circuit operates in the continuous conduction mode.

3 is a timing chart based on current waveforms and voltage waveforms of the above-described respective elements as shown in FIG. 2. Hereinafter, two control modes of the present invention will be described with reference to FIGS. 4 and 5.

Referring to Figure 4, the first mode is the time interval t ₀ t t _1, in this case a first switching element S ₁ is turned on and the second switching element S ₂ is turned on, the voltage across the inductor L ₁ of the two ends of v _i, so energizing the inductor L _1. At the same time, the first diode D _{1 is} turned off and the third diode D _{3 is} turned off, the second diode D _{2 is} turned on, and the voltage across the magnetizing inductance L _m is the input power source v _i plus the storage capacitor C ₁ The magnetizing inductance L _m is excited across the voltage v _C1 .

Further, the input power v _i and v _C1 plus the voltage across the secondary winding N ₁ of the voltage across the energy storage capacitor C ₂ V _N2 of the bootstrap capacitor C ₂ charged, then the voltage across the secondary winding N ₂ It is n times the cross-over voltage V _N1 on the primary side coil N ₁ . Its associated differential equation is Equation 1.

Since the turns ratio n is as in Equation 2.

According to Equation 2 can know a current of the primary side coil N ₁ i N ₁ and the secondary coil of the current i _{2 2} The relationship between N and the primary side coil of _a voltage across the v _N1 and the voltage across the secondary winding N ₂ of the V The relationship of _N2 is as shown in the following formula 3 and formula 4.

i ₁ = n × i ₂ formula 3

v _{N 2} = n × v _{N 1} Equation 4

Put Equation 3 into Equation 1, and after finishing, Equation 5 can be obtained.

In addition, the span voltage v _{C2 of the} shoe strap capacitor C ₂ can be expressed as Equation 6.

v _{C 2} = v _{N 1} + v _{N 2} = (1+ n ) × ( v _i + v _{C 1} ) Equation 6

Referring to Figure 5, the second mode is the time interval t ₁ t t ₀ + T _s, at this time the first switching element S ₁ is turned off and the second switching element S ₂ is turned off, the second diode D ₂ is turned off, the first diode D ₁ is turned on and the third diode D ₃ When turned on, the voltage across the energy storage inductor L ₁ is -v _C1 , so the energy storage inductor L ₁ is demagnetized and the output capacitor C _o is charged, and the voltage across the excitation inductor L _m is v _i + v _C1 +v _C2 -v _N2 -v _o , so the magnetizing inductance L _m is demagnetized, and its associated differential equation is as in Equation 7.

The second mode, the current of the primary side coil N ₁ i _1, the secondary winding N ₂ of the current i ₂ and the magnetizing inductor current relationship of _m L i _Lm Equation 8.

i ₂ =- i ₁ - i _Lm Equation 8

By introducing Equation 3 into Equation 8, the current i _{2 of the} secondary side coil N ₂ can be rewritten to Equation 9.

In addition, the voltage across the primary side coil N ₁ , v _N1 , is obtained by Equation 7 as Equation 10.

v _{N 1} =- v _{N 2} + v _{C 2} + v _{C 1} + v _i - v _o Equation 10

By introducing Equation 4 into Equation 10, the cross-over voltage V _{N1 of the} primary side coil N ₁ can be rewritten into

Equation 3, Equation 6, Equation 9, and Equation 11 are brought into Equation 7, and Equation 12 is obtained.

If <x> represents the average of the variables x, where x can be voltage or current, then Equation 13.

Therefore, the average equation such as Equation 14 can be known from Equation 5 and Equation 12.

Where d is a duty cycle for driving the gate control signals of the first switching element S ₁ and the second switching element S ₂ .

Since it was previously assumed that the shoe strap capacitance C ₂ is large enough to maintain a stable voltage, it can be expressed in terms of ampere-second balance such that <i ₂ 〉 can be expressed by <i _Lm 〉, as in Equation 15.

Therefore, formula 15 is substituted into formula 14, and formula 16 is obtained.

In order to obtain a small signal model for this converter, Equation 16 is perturbed and linearized. First, add <x> to the DC steady-state value X plus an AC disturbance. To show that this AC disturbance is much smaller than the steady-state DC value, as in Equation 17.

Substituting Equation 17 into Equation 16, Equation 18 is obtained.

Equation 19 is obtained by rounding off the high-order term of the DC term and the small perturbation.

According to the formula 19, the small signal model can be obtained, as shown in FIG. 6. In the same way, formula 20 can be obtained by rounding off the high-order term of the alternating term and the small perturbation.

Referring to Figure 7, the inductor is considered to be a short circuit and the capacitor is considered to be an open circuit, and a large signal model can be obtained. According to this large signal model, Equation 21 can be obtained.

Therefore, the voltage conversion of this converter can be obtained as in Equation 22.

Referring to FIG. 8, the power conversion apparatus 100 employs a feedback control system 3, and the specifications of the feedback control system 3 are as shown in Table 1.

The feedback control system 3 is configured to drive the conduction of the first switching element S ₁ and the second switching element S ₂ , and the feedback control system 3 includes a voltage divider circuit (Voltage Divider) 30 , a comparator 31 , and an error An amplifier (Error Amplifier) 32, a pulse width modulator (Pulse-Width Modulator) 33, and a gate driver (Gate Drivers) 34 are combined, and v _ref is a reference voltage.

Referring to Figure 9, at 100% of rated load and the input voltage v _i = 24 volts, the first switching element S ₁ of the gate drive signal V _GS1 waveform, the waveform of the second switching element S ₂ of the gate of the drive signal _v gS2 The waveform of the current i _{L 1} flowing through the storage inductor L ₁ .

Referring to Figure 10, at 100% of rated load and the input voltage v _i = 24 volts, the first switching element S ₁ of the gate drive signal V _GS1 waveform, the waveform of the second switching element S ₂ of the gate of the drive signal _v gS2 The waveform of the current i ₃ flowing through the primary side coil N ₁ of the coupled inductor 15 and the current i ₂ flowing through the secondary side coil N ₂ of the coupled inductor 15 .

Referring to Figure 11, at 100% of rated load and the input voltage v _i = 24 volts, the first switching element S ₁ of the gate drive signal V _GS1 waveform, the waveform of the second switching element S ₂ of the gate of the drive signal _v gS2 , a current flowing through the first switching element on the S ₁ i _DS1, the electric current flowing through the second switching element ₂ S i _DS2 waveform.

Referring to Figure 12, at 100% of rated load and the input voltage v _i = 24 volts, the first switching element S ₁ of the gate drive signal V _GS1 waveform, the waveform of the second switching element S ₂ of the gate of the drive signal _v gS2 The waveform of the voltage across the voltage c _C1 of the storage capacitor C _{1 and} the voltage across the pressure V _C2 of the shoe capacitor C ₂ .

Referring to FIG. 13, when the input voltage v _{i is} 24 volts, the waveform of the gate driving signal v _gS1 of the first switching element S ₁ , the waveform of the voltage v _D1 on the first diode D ₁ , The waveform of the voltage v _D2 on the second diode D ₂ and the waveform of the voltage v _D3 on the third diode D ₃ .

In summary, the power conversion device 100 of the present invention having a high up conversion ratio has the effect that the designer can adjust the boost ratio by using the turns ratio n of the secondary side coil N ₂ and the primary side coil N ₁ to increase the boost ratio thereof. The design flexibility, and the second switching element S _{2 used is} non-floating, and the overall driving method is simple and practical, so that the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

100‧‧‧Power conversion device

111‧‧‧ first end of the energy storage inductor

112‧‧‧The second end of the energy storage inductor

121‧‧‧First end of the storage capacitor

122‧‧‧Second end of the storage capacitor

131‧‧‧Anode of the first diode

132‧‧‧The cathode of the first diode

141‧‧‧Anode of the second diode

142‧‧‧ cathode of the second diode

15‧‧‧Coupled inductor

151‧‧‧First end of the primary side coil

152‧‧‧second end of the primary side coil

161‧‧‧ the first end of the secondary coil

162‧‧‧second end of the secondary coil

171‧‧‧ anode of the third diode

172‧‧‧ cathode of the third diode

181‧‧‧ Boots with the first end of the capacitor

182‧‧‧ Boots with the second end of the capacitor

201‧‧‧First end of the first switching element

202‧‧‧The second end of the first switching element

301‧‧‧ the first end of the second switching element

302‧‧‧second end of the second switching element

C ₁ ‧‧‧ storage capacitor

C ₂ ‧‧‧boot with capacitor

C _o ‧‧‧output capacitor

D ₁ ‧‧‧First Diode

D ₂ ‧‧‧Secondary

D ₃ ‧‧‧third diode

L ₁ ‧‧‧ storage inductor

R _o ‧‧‧ output resistance

S ₁ ‧‧‧first switching element

S ₂ ‧‧‧Second switching element

v _i ‧‧‧ input voltage

v _o ‧‧‧output voltage

1 is a circuit diagram illustrating power conversion of the present invention with a high conversion ratio 2 is a circuit diagram illustrating the current and voltage corresponding to each component of the power conversion device having a high up conversion ratio according to the present invention; FIG. 3 is a waveform timing diagram illustrating the current waveform of each component of FIG. And a voltage waveform; FIG. 4 is a circuit diagram illustrating a conduction path of the power conversion device with a high up conversion ratio in the first mode of the present invention; FIG. 5 is a circuit diagram illustrating the power conversion device with a high conversion ratio of the present invention. FIG. 6 is a circuit diagram illustrating a small signal model of the power conversion device with high rise conversion ratio of the present invention; FIG. 7 is a circuit diagram illustrating a large signal of the power conversion device with high rise conversion ratio of the present invention. FIG. 8 is a circuit block diagram illustrating a feedback control system employed in a preferred embodiment of the power conversion apparatus of the present invention having a high up conversion ratio; and FIGS. 9-13 are waveform diagrams illustrating the present invention having a high up conversion ratio The simulation result of the power conversion device.

100‧‧‧Power conversion device

111‧‧‧ first end of the energy storage inductor

112‧‧‧The second end of the energy storage inductor

121‧‧‧First end of the storage capacitor

122‧‧‧Second end of the storage capacitor

131‧‧‧Anode of the first diode

132‧‧‧The cathode of the first diode

141‧‧‧Anode of the second diode

142‧‧‧ cathode of the second diode

15‧‧‧Coupled inductor

151‧‧‧First end of the primary side coil

152‧‧‧second end of the primary side coil

161‧‧‧ the first end of the secondary coil

162‧‧‧second end of the secondary coil

171‧‧‧ anode of the third diode

172‧‧‧ cathode of the third diode

181‧‧‧ Boots with the first end of the capacitor

182‧‧‧ Boots with the second end of the capacitor

201‧‧‧First end of the first switching element

202‧‧‧The second end of the first switching element

301‧‧‧ the first end of the second switching element

302‧‧‧second end of the second switching element

C ₁ ‧‧‧ storage capacitor

C ₂ ‧‧‧boot with capacitor

C _o ‧‧‧output capacitor

D ₁ ‧‧‧First Diode

D ₂ ‧‧‧Secondary

D ₃ ‧‧‧third diode

S ₁ ‧‧‧first switching element

L ₁ ‧‧‧ storage inductor

R _o ‧‧‧ output resistance

S ₂ ‧‧‧Second switching element

v _i ‧‧‧ input voltage

v _o ‧‧‧output voltage

Claims (3)

A power conversion device with a high-rise conversion ratio, which is suitable for boosting an input voltage, the power conversion device comprising: a storage inductor having a first end and a second end receiving the input voltage; The capacitor has a first end and a second end coupled to the first end of the energy storage inductor; a first diode having an anode coupled to the second end of the energy storage inductor and a a cathode coupled to the second end of the storage capacitor; a second diode having an anode coupled to the second end of the storage capacitor and a cathode; a coupled inductor having a primary coil and a secondary side coil having a turns ratio n of the secondary side coil and the primary side coil, the primary side coil having a first end and a second end coupled to the cathode of the second diode The secondary side coil has a first end and a second end coupled to the cathode of the second diode and the first end of the primary side coil; a third diode having a primary side coil The second end is coupled to the anode and a cathode; a bootband capacitor has a second and the second side coil a first end coupled to the end and a second end coupled to the anode of the first diode; a first switching element coupled to the second end of the strap capacitor and externally controlled to conduct; And a second switching element coupled to the second end of the primary side coil and the anode of the third diode and controlled by external control; When the first switching element is non-conducting and the second switching element is non-conducting, the first diode is turned on, the third diode is turned on, and the second diode is turned off, and the voltage across the storage inductor is The energy storage capacitor is biased and the energy storage inductor is demagnetized; when the first switching element is turned on and the second switching element is turned on, the voltage across the energy storage inductor is excited by the input voltage, the first The diode is turned off, the third diode is turned off, and the second diode is turned on, and the input voltage plus the voltage across the storage capacitor and the voltage across the secondary coil charge the shoe capacitor. The cross-over pressure on the secondary side coil is n times the cross-pressure on the primary side coil. The power conversion device with a high-rise conversion ratio according to claim 1, wherein the first switching element and the second switching element are both grounded non-floating switching elements. A power conversion device with a high-up conversion ratio according to claim 1, wherein the capacitance of the boot band capacitor is sufficient to maintain the input voltage (1+n) times when it is across a steady state. The (1+n) times the voltage across the storage capacitor.