TWI687031B - High step-down ration direct current power converter - Google Patents

Abstract

A high step-down ratio DC power converter is coupled to a DC input source and includes two transformers with the same turn ratio. The two transformers are configured to store energy when they are connected in series, and to release energy when they are connected in parallel. A primary circuit of the converter includes a first switch and a second switch. When the first and second switches are on, the two transformers are connected in series and therefore enable the DC input source to apply energy to magnetizing inductors and primary leakage inductors of the transformers; meanwhile, energy stored in secondary leakage inductors of the transformers is recycled to an output capacitance. When the first and second switches are off, the transformers are connected in parallel and therefore allow the energy stored in the magnetizing inductors of the transformers to be transferred to the output capacitance. Accordingly, the present invention can achieve not only high step-down ratio DC power conversion but also leakage energy recycle, thus improving energy conversion efficiency.

Description

DC power supply high step-down ratio converter

The invention relates to a DC power supply high step-down ratio converter, in particular to a DC power supply high step-down ratio converter with the function of recovering leakage inductance energy.

Republic of China Invention Patent Announcement No. I528696 "Single-stage high step-down ratio DC-DC converter" is a single-stage high step-down ratio DC-DC converter, which includes an input unit and a DC-DC conversion circuit And an output unit, wherein the input unit is used to input direct current, one end of the DC-DC conversion circuit is electrically connected to the input unit, and the output unit is electrically connected to the other end of the DC-DC conversion circuit , Mainly by inputting DC power to the DC-DC conversion circuit through the input unit, and after voltage conversion by the DC-DC conversion circuit, the output unit outputs the stepped down DC power, the DC- The DC conversion circuit is used to change the voltage gain of the input unit and the output unit to D/2(2-D), where D is the duty cycle to achieve a function with a high step-down ratio.

However, the voltage gain of the previous case is D/2(2-D), and there should still be room for improvement.

Therefore, in order to improve the above-mentioned shortcomings, the present inventors are devoted to research, and propose the DC power supply high step-down ratio converter of the present invention, coupled to a DC input source, which includes: a primary side circuit, including a first A diode, a second diode, a first primary winding of a transformer, a second primary winding of another transformer, a first switch and a second switch, wherein the the first The cathode end of the diode is electrically connected to the anode end of the DC input source and one end of the first switch, and the other end of the first switch is electrically connected to the end of the first primary winding and the second diode Cathode end, the other end of the first primary winding is electrically connected to one end of the second primary winding, the other end of the second primary winding is electrically connected to the anode end of the first diode and the second switch One end of the switch, the other end of the second changeover switch is electrically connected to the anode end of the second diode and the cathode end of the DC input source; and a secondary side circuit including a third diode and a fourth diode A pole body, a first secondary winding of the transformer, a second secondary winding of the other transformer, an output capacitor, and a load, wherein the first secondary winding is coupled to the first primary Side winding, the second secondary winding is coupled to the second primary winding, one end of the first secondary winding is electrically connected to the anode end of the third diode, and the cathode end of the third diode The cathode end of the fourth diode, the output capacitor end and the load end are electrically connected, the anode end of the fourth diode is electrically connected to the second secondary winding end, and the second secondary winding The other end is electrically connected to the other end of the output capacitor, the other end of the load, and the other end of the first secondary winding.

Further, the relationship between the first switch and the second switch is controlled by the pulse width modulation technology to be turned on or off.

Further, the turns ratio of the first primary winding to the first secondary winding is equal to the turns ratio of the second primary winding to the second secondary winding.

Further, using the principle of volt-second balance on the first magnetizing inductance of the transformer, the voltage gain of the DC power supply high step-down ratio converter is nD /2(1- D ).

Further, the relationship between the first switch and the second switch is a metal oxide semiconductor field effect transistor.

According to the above technical features, the following effects can be achieved:

1. Using the volt-second balance principle on the first magnetizing inductance of the transformer, when operating at Vin>2Vo/n, the voltage gain of the DC power supply high step-down ratio converter of this embodiment is nD/2(1- D), a higher step-down ratio than the voltage gain nD/(1-D) of the traditional flyback converter.

2. Use two transformers with the same turns ratio to store energy in series and release energy in parallel, and have the effect of electrical isolation.

3. With the function of energy leakage leakage recovery, it can improve the conversion efficiency.

4. Reduce the voltage stress of the first switch and the second switch.

(1): Primary side circuit

(11): The first diode

(12): Second diode

(131): The first primary winding

(132): Second primary winding

(133): First magnetizing inductance

(134): Second magnetizing inductance

(135): The first primary side leakage inductance

(136): Second primary leakage inductance

(14): The first switch

(15): Second switch

(2): Secondary side circuit

(21): Third diode

(22): Fourth diode

(231): first secondary winding

(232): Second secondary winding

(233): First and second side leakage inductance

(234): Second secondary leakage inductance

(24): Output capacitance

(25): load

(A): DC input source

[The first figure] is a circuit diagram of a DC power supply high step-down ratio converter according to an embodiment of the present invention.

[The second figure] is an equivalent circuit diagram of a DC power supply high step-down ratio converter according to an embodiment of the present invention.

[Third figure] is a main waveform diagram of a DC power supply high step-down ratio converter in a single switching cycle according to an embodiment of the present invention.

[Fourth figure] is a current path diagram operating in mode 1 according to an embodiment of the present invention.

[Fifth figure] is a current path diagram of an embodiment of the present invention operating in mode two.

[Sixth figure] is a current path diagram of mode 3 operating in an embodiment of the present invention.

[Seventh figure] is a current path diagram of an embodiment of the present invention operating in mode four.

[FIG Eighth A] based embodiment of the present operating state of the embodiment when the input voltage Vin is 200V, the output voltage Vo is 24V, full output power of 250W and a transformer turns ratio n is 3, the input voltage V _in and the output voltage V _o Analog waveform diagram, the scale value of the waveform diagram is: V _in /V _o : 50V/div, time: 10ms/div, and the duty cycle D is about 0.42.

[Figure 8B] is the operating state of this embodiment when the first magnetizing inductance flows when the input voltage Vin is 200V, the output voltage Vo is 24V, the full-load output power is 250W, and the transformer turns ratio n is 3 133) The simulation waveform of the current i _Lm1 and the current i _Lk11 of the first primary leakage inductance (135), the scale values of the waveform are respectively: i _Lm1 /i _Lk11 : 2.5A/div, time: 5 μs /div, the duty cycle D is about 0.42.

[Figure 8C] is the operation state of this embodiment when the input voltage Vin is 200V, the output voltage Vo is 24V, the full-load output power is 250W, and the transformer turns ratio n is 3. The simulation waveforms of the current i _N11 of the first primary winding (131) and the current i _N12 of the first secondary winding (231), the scale values of the waveforms are: i _N11 /i _N12 : 2.5A /div, time: 5μs/div, the duty cycle D is about 0.42.

[Eighth D] is the operating state of this embodiment when the input voltage Vin is 200V, the output voltage Vo is 24V, the full-load output power is 250W, and the transformer turns ratio n is 3, flowing through the first switch ( 14) The analog waveform of the current of i _{S1 and} the current of the first diode (11) i _D1 , the scale values of the waveform are respectively: i _S1 /i _D1 : 2.5A/div, time: 5μs/div At this time, the duty cycle D is about 0.42.

Based on the above technical features, the main functions of the DC power converter with high step-down ratio of the present invention will be clearly shown in the following embodiments.

Referring to the first figure, the DC power supply high step-down ratio converter (1000) of this embodiment is coupled to a DC input source (A), which includes a primary side circuit (1) and a secondary side circuit (2), wherein: the primary side circuit (1) includes a first diode (11), a second diode (12), a first primary winding (131) of one transformer, another One of the transformer's second primary winding (132), a first A switch (14) and a second switch (15), wherein the cathode terminal of the first diode (11) is electrically connected to the anode terminal of the DC input source (A) and the first switch ( 14) One end, the other end of the first changeover switch (14) is electrically connected to one end of the first primary winding (131) and the cathode end of the second diode (12), the first primary winding ( 131) The other end is electrically connected to one end of the second primary winding (132), and the other end of the second primary winding (132) is electrically connected to the anode end of the first diode (11) and the second One end of the switch (15), the other end of the second switch (15) is electrically connected to the anode end of the second diode (12) and the cathode end of the DC input source (A), and the first switch (14) and the second changeover switch (15) are metal oxide semiconductor field effect transistors.

The secondary circuit (2) includes a third diode (21), a fourth diode (22), a first secondary winding (231) of the transformer, and one of the other transformers A second secondary winding (232), an output capacitor (24) and a load (25), wherein the first secondary winding (231) is coupled to the first primary winding (131), the first The second secondary winding (232) is coupled to the second primary winding (132). One end of the first secondary winding (231) is electrically connected to the anode end of the third diode (21). The cathode terminal of the three diode (21) is electrically connected to the cathode terminal of the fourth diode (22), the output capacitor (24) end and the load (25) end, the fourth diode (22) The anode terminal is electrically connected to one end of the second secondary winding (232), the other end of the second secondary winding (232) is electrically connected to the other end of the output capacitor (24), the other end of the load (25) and The other end of the first secondary winding (231).

Referring to the second figure, it is the equivalent circuit of the DC power supply high step-down ratio converter (1000) of this embodiment, which uses the ideal transformer, magnetizing inductance, primary leakage inductance and secondary The side leakage inductance means that it includes a first magnetizing inductance (133), a second magnetizing inductance (134), a first primary side leakage inductance (135), a second primary side leakage inductance (136), A first secondary side leakage inductance (233) and a second secondary side leakage inductance (234), wherein one end of the first magnetizing inductance (133) is electrically connected to one end of the first primary winding (131), The other end of the first magnetizing inductance (133) is electrically connected to the other end of the first primary winding (131), and the one end of the second magnetizing inductance (134) is electrically connected to one end of the second primary winding (132), The other end of the second magnetizing inductance (134) is electrically connected to the other end of the second primary winding (132). The first primary leakage inductance (135) is connected in series with the first changeover switch (14) and the first Between a primary winding (131), the second primary leakage inductance (136) is connected in series between the second primary winding (132) and the second switch (15), the first two The secondary leakage inductance (233) is connected in series between the third diode (21) and the first secondary winding (231), and the second secondary leakage inductance (234) is connected in series to the fourth diode Between the body (22) and the second secondary winding (232), and, in this embodiment, the turns ratio of the first primary winding (131) to the first secondary winding is equal to the first The turns ratio of the second primary winding to the second secondary winding, that is, the turns ratio n = N ₁₁ / N ₁₂ = N ₂₁ / N ₂₂ .

The DC power supply high step-down ratio converter (1000) of this embodiment uses pulse width modulation technology to synchronously control the on or off of the first switch (14) and the second switch (15).

Referring to the third figure, it is the main waveform diagram of the DC power supply high step-down ratio converter of this embodiment in a single switching cycle, and its operation mode is described as follows:

Mode 1: As shown in the third and fourth figures, in the interval [ t 0, t 1 ], the first switch (14) and the second switch (15) are turned on, and the current path is as shown in the fourth figure The arrow points to the shown. In this interval, the energy stored in the first magnetizing inductance (133), the second magnetizing inductance (134), the first secondary side leakage inductance (233) and the second secondary side leakage inductance (234) Released to the output capacitor (24) and the load (25). Therefore, the energy of the first secondary side leakage inductance (233) and the second secondary side leakage inductance (234) can be recovered. At the same time, the DC input source (A) releases energy to the first primary side leakage inductance (135) and the second primary side leakage inductance (136). Therefore, the current (i _Lm1 ) flowing through the first magnetizing inductance (133), the second magnetizing inductance (134), the first secondary side leakage inductance (233) and the second secondary side leakage inductance (234) , I _Lm2 , i _N12 and i _N22 ) showed a linear decrease, the current (i _Lk11 and i _Lk21 ) flowing through the first primary side leakage inductance (135) and the second primary side leakage inductance (136) was linear rise. At t = t ₁ , the current (i _N12 , i _N22 ) of the first secondary leakage inductance (233) and the second secondary leakage inductance (234) drops to zero, that is, the first secondary leakage The energy recovery of the inductor (233) and the second secondary leakage inductance (234) is completed. At this time, the currents (i _Lm1 and i _Lm2 ) of the first magnetizing inductance (133) and the second magnetizing inductance (134) are equal to the first primary side leakage inductance (135) and the second primary side leakage inductance The current of (136) (i _Lk11 , i _Lk21 ), this operation mode ends.

Mode 2: Refer to the third and fifth figures, in the interval [t1, t2], the first switch (14) and the second switch (15) are continuously turned on, and the current path is shown by the arrow in the fifth figure Point as shown. In this interval, the DC input source (A) releases energy to the first magnetizing inductance (133) and the second magnetizing inductance (134), the first primary side leakage inductance (135) and the second primary Side leakage inductance (136). The energy stored in the output capacitor (24) is released to the load (25). Therefore, the current (i _Lm1 ) flowing through the first magnetizing inductance (133), the second magnetizing inductance (134), the first primary side leakage inductance (135) and the second primary side leakage inductance (136) _, i _Lm2, i Lk11 and _i Lk21) increases linearly. When t=t2, the first change-over switch (14) and the second change-over switch (15) are turned off, and this operation mode ends.

Mode 3: As shown in the third and sixth figures, in the interval [ t ₂ , t ₃ ], the first switch (14) and the second switch (15) are turned off, and the current path is as shown in the sixth figure The arrow points as shown. In this interval, the energy stored in the first primary side leakage inductance (135) and the second primary side leakage inductance (136) passes through the first diode (11) and the second diode ( 12) Recover to the DC input source (A). The energy stored in the first magnetizing inductance (133) and the second magnetizing inductance (134) is transferred to the first secondary side leakage inductance (233), the second secondary side leakage inductance (234), and the output The capacitor (24) and the load (25). Therefore, the current flowing through the first primary side leakage inductance (135), the second primary side leakage inductance (136), the first magnetizing inductance (133) and the current of the second magnetizing inductance (134) ( i _Lk11 , i _Lk21 , i _Lm1 and i _Lm2 ) showed a linear decrease, and the current (i _N12 , i _N22 ) flowing through the first secondary leakage inductance (233) and the second secondary leakage inductance (234) A linear increase. When t = t ₃ , this operating mode ends. At this time, the currents (i _Lk11 and i _Lk21 ) of the first primary side leakage inductance (135) and the second primary side leakage inductance (136) drop to zero, that is, the first primary side leakage inductance (135 ) And the energy recovery of the second primary side leakage inductance (136) is completed.

Mode 4: As shown in the third and seventh figures, in the interval [t3, t4], the first switch (14) and the second switch (15) are continuously turned off, and the current path is as shown by the arrow in the seventh figure Point as shown. In this interval, the energy stored in the first magnetizing inductance (133), the second magnetizing inductance (134), the first secondary side leakage inductance (233) and the second secondary side leakage inductance (234) Transfer to the output capacitor (24) and the load (25). Therefore, the current flowing through the first magnetizing inductance (133), the second magnetizing inductance (134), the first secondary side leakage inductance (233) and the second secondary side leakage inductance (234) current ( i _Lm1 , i _Lm2 , i _N12 and i _N22 ) decreased linearly. When t=t4, the next switching cycle starts, the first switch (14) and the second switch (15) are turned on, and this operation mode ends.

Using the principle of volt-second balance on the first magnetizing inductance (133) of the transformer, the voltage gain of the DC power supply high step-down ratio converter (1000) of this embodiment is nD /2 (1- D ), which can be compared The voltage gain nD /(1- D ) of the traditional flyback converter obtains a higher step-down ratio. The DC converter with high step-down ratio (1000) of this embodiment is limited to V _in > 2V _o / n .

Refer to the eighth figure A to the eighth figure D, which is the operating state of the DC power supply high step-down ratio converter (1000) of this embodiment when the input voltage V _in is 200V, the output voltage V _o is 24V, and the full load output The simulation result of the power is 250W and the transformer turns ratio n is 3, the duty cycle D is about 0.42.

See Figure A eighth, based input voltage V _in FIG analog waveform and output voltage V _o, the scale of values which is a waveform _{diagram: V in / V o: 50V} / div, time: 10ms / div, to see The DC power supply high step-down ratio converter (1000) of this embodiment can achieve the function of high step-down ratio.

Refer to B shown in FIG. Eighth, the first line is passing through the magnetizing inductance (133) and the current i _{Lm1 Lk11} analog waveform diagram of the first primary-side leakage inductance (135) of the current i, the scale of the waveform in FIG. The values are: i _Lm1 /i _Lk11 : 2.5A/div, time: 5μs/div; refer to the eighth figure C, it is the current i flowing through the first primary winding (131) of the ideal transformer The analog waveforms of the current i _N12 of _N11 and the first secondary winding (231), the scale values of the waveforms are: i _N11 /i _N12 : 2.5A/div, time: 5μs/div; refer to the eighth Figure D shows the simulated waveforms of the current flowing through the first switch (14) i _S1 and the current i _D1 of the first diode (11). The scale values of the waveforms are: i _S1 /i _D1 : 2.5A/div, time: 5μs/div. It can be seen from the eighth figure B to the eighth figure above that it is consistent with the aforementioned operation mode analysis.

Based on the description of the above embodiments, the operation, use and effects of the present invention can be fully understood. However, the above-mentioned embodiments are only preferred embodiments of the present invention, and cannot be used to limit the implementation of the present invention. The scope, that is, simple equivalent changes and modifications made in accordance with the scope of the present invention's patent application and the description of the invention, is within the scope of the present invention.

(1): Primary side circuit

(11): The first diode

(12): Second diode

(131): The first primary winding

(132): Second primary winding

(14): The first switch

(15): Second switch

(2): Secondary side circuit

(21): Third diode

(22): Fourth diode

(231): first secondary winding

(232): Second secondary winding

(24): Output capacitance

(25): load

(A): DC input source

Claims (4)

A DC power supply high step-down ratio converter, coupled to a DC input source, includes: a primary side circuit, including a first diode, a second diode, and a transformer Side windings, one of the second primary windings of another transformer, a first changeover switch and a second changeover switch, wherein the cathode end of the first diode is electrically connected to the anode end of the DC input source and the One end of the first switch, the other end of the first switch is electrically connected to one end of the first primary winding and the cathode end of the second diode, and the other end of the first primary winding is electrically connected to the second One end of the primary winding, the other end of the second primary winding is electrically connected to the anode end of the first diode and one end of the second switch, and the other end of the second switch is electrically connected to the second diode The anode terminal of the body and the cathode terminal of the DC input source use the first magnetizing inductance of the transformer using the volt-second balance principle to obtain the voltage gain of the DC power supply high step-down ratio converter as nD/2(1- D); and a secondary side circuit, including a third diode, a fourth diode, a first secondary winding of the transformer, a second secondary winding of the other transformer, a An output capacitor and a load, wherein the first secondary winding is coupled to the first primary winding, the second secondary winding is coupled to the second primary winding, and one end of the first secondary winding Electrically connected to the anode end of the third diode, the cathode end of the third diode is electrically connected to the cathode end of the fourth diode, the output capacitor end and the load end, the fourth diode The anode terminal is electrically connected to one end of the second secondary winding, and the other end of the second secondary winding is electrically connected to the other end of the output capacitor, the other end of the load, and the other end of the first secondary winding. The DC power supply high step-down ratio converter as described in item 1 of the patent application scope, wherein the first switching switch and the second switching on-off relationship are turned on or off synchronously controlled by pulse width modulation technology. The DC power supply high step-down ratio converter as described in item 1 of the patent scope, wherein the turns ratio of the first primary winding and the first secondary winding is equal to the second primary winding and the The turns ratio of the second secondary winding. The DC power supply high step-down ratio converter as described in item 1 of the patent scope, wherein the relationship between the first switch and the second switch is a metal oxide semiconductor field effect transistor.

Images