CN101521459B - Resonant Switched Capacitor DC Voltage Converter - Google Patents

Abstract

The invention relates to a resonance switch capacitor direct-current voltage converter which comprises a first voltage node, a second voltage node, a first switch, a second switch, a first diode, a second diode and a control circuit, wherein a first voltage is arranged between the first voltage node and a negative line, a second voltage is arranged between the second voltage node and the negative line, the control circuit provides switch gate signals for the first switch and the second switch, the resonance switch capacitor direct-current voltage converter further comprises a center tap inductor and a resonance capacitor, wherein the center tap inductor is connected between the first switch and the second switch, and the resonance capacitor is connected between a common node of the first diode and the second diode and the center node of the center tap inductor. Compared with the traditional switched capacitor direct current voltage converter, the invention has the advantages of reducing complexity, loss and cost, improving speed and avoiding limitation.

Description

Resonant Switched Capacitor DC Voltage Converter

technical field

The invention relates to a resonant switched capacitor DC voltage converter. the

Background technique

In the field of DC power conversion, a conversion circuit combining switches and capacitors is used to convert different voltages. This type of converter uses capacitors to store electrical energy and is called a switched capacitor converter (SwitchedCapacity Converter, SCC). Since this type of converter has no inductor or transformer, it is smaller than other types of converters and can be easily fabricated on an integrated circuit. However, high peak currents typically occur when charging and discharging switched capacitors. Therefore, such converters are usually used in low voltage environments. US Patent Publication No. US20040141345A1 provides a new switched capacitor circuit called a resonant switched capacitor converter (Switched Capacitor Resonant Converter, SCRC), which can work in a high switching frequency and high voltage environment. the

SCRCs are designed based on the removal of the main magnetic energy storage device including the resonant converter. SCRC works in a zero-current switching environment, such as extremely low switching loss and no EMI (Electromagnetic Interference, electromagnetic interference) problems. Also, its efficiency is quite high, possibly higher than 90%. Its structure is simple, and only a small inductance resonant with the switching capacitor is added in the circuit, so the cost of the magnetic components is low. the

While SCRC has many advantages, simple gate drive circuits cannot be applied to this converter, requiring isolation transformers and/or half-bridge gate drives, thus increasing the complexity of the SCRC. Also, the parasitic inductance in the gate drive transformer limits the drive speed, resulting in more switching losses in high frequency applications. Half-bridge gate drives have limitations for high-frequency operation and increased converter cost. the

Contents of the invention

The purpose of the present invention is to provide a resonant switched capacitor DC voltage converter. The DC converter will use a simple gate drive circuit, which reduces the complexity of the SCRC. At the same time, the driving speed is improved by reducing the parasitic inductance, and the high frequency application is reduced. switching loss, and avoid the limitations of high-frequency operation, reducing the cost of the converter. the

In order to achieve the purpose of the above invention, the present invention is a resonant switched capacitor DC voltage converter, comprising a first voltage node, a second voltage node, a first switch, a second switch, a first diode, a second diode, A control circuit, wherein a first voltage is provided between the first voltage node and the negative line, a second voltage is provided between the second voltage node and the negative line, and the control circuit provides switch gate signals for the first switch and the second switch, The resonant switched capacitor DC voltage converter further includes a center tap inductor and a resonance capacitor, wherein the center tap inductor is connected between the first switch and the second switch, and the resonance capacitor is connected between the first diode and the second switch. Between the common node of the diode and the central node of the center tap inductor; the first switch and the second switch are insulated gate bipolar transistors or a pair of complementary metal oxide semiconductor field effect transistor switches; wherein the first When the switch and the second switch are a pair of complementary metal oxide semiconductor field effect transistor switches, the first switch is a P channel metal oxide semiconductor field effect transistor, and the second switch is an N channel metal oxide semiconductor field effect transistor. and the connection relationship between the switch, the voltage node, the diode, and the negative line is one of the following three types: the first type: the first switch and the second switch are connected in series between the first voltage node and the negative line, the The first diode and the second diode are connected in series between the first voltage node and the second voltage node; the second type: the first switch and the second switch are connected in series between the first voltage node and the second voltage node Between the second voltage node, the first diode and the second diode are connected in series between the second voltage node and the negative line; the third type: the first switch and the second switch are connected in series Between the first voltage node and the negative line, the first diode and the second diode are connected in series between the second voltage node and the negative line. the

According to the DC voltage converter described in the preferred embodiment of the present invention, the control circuit is a self-starting gate drive control circuit. the

According to the DC voltage converter described in the preferred specific embodiment of the present invention, when the connection relationship is the second type, the control circuit uses the voltage between the first node and the second node as a self-starting supply Power supply for gate drive

According to the resonant switched capacitor DC voltage converter described in the preferred embodiment of the present invention, when the connection relationship is the third type, the control circuit utilizes the connection between the first voltage node and the negative line The voltage is provided as the power supply for the gate driver for self-starting. the

The advantage of the present invention lies in the application of simple gate drive, which reduces the complexity of SCRC, improves the driving speed by reducing parasitic inductance, reduces the switching loss in high-frequency applications, and avoids the limitations of high-frequency operation, reducing the converter the cost of. the

Description of drawings

Advantage and feature of the present invention are described in detail below with reference to accompanying drawing, wherein

Fig. 1 is the circuit diagram of step-up type resonant switched capacitor DC voltage converter according to a specific embodiment of the present invention;

Fig. 2 and Fig. 3 are schematic diagrams of the working principle of the circuit shown in Fig. 1;

Fig. 4 is the gate pole and current waveform diagram of the circuit shown in Fig. 1;

Fig. 5 is a gate-source voltage and a capacitor current waveform diagram of the circuit shown in Fig. 1;

Fig. 6 is the drain gate voltage of the circuit shown in Fig. 1 and the capacitive current waveform diagram;

7 is a circuit diagram of a step-down resonant switched capacitor DC voltage converter according to a specific embodiment of the present invention; and

FIG. 8 is a circuit diagram of an inverter resonant switched capacitor DC voltage converter according to a specific embodiment of the present invention. the

Detailed ways

FIG. 1 is a circuit diagram of a step-up resonant switched capacitor DC voltage converter 13 . The DC voltage converter 13 includes a pair of complementary metal oxide semiconductor field effect transistor (MOSFET) switches 4 , 5 . Switch 4 is a P-channel MOSFET, and switch 5 is an N-channel MOSFET. In other embodiments, insulated gate bipolar transistors (IGBTs) and other suitable semiconductor switches may also be used. Each switch is equipped with an anti-parallel diode as part of the MOSFET package. A first and a second diode 6,7 are connected in series between the first and the second voltage node 1,2. the

The DC voltage converter 13 has a first voltage V1 between the first voltage node 1 and the ground or negative line 3 and a second voltage V2 between the second voltage node and the ground or negative line 3 . Ground or negative line 3 is at either potential which is lower than the potential of nodes 1,2. Two filter capacitors 8, 11 are connected in parallel with the first and second voltage terminals V1, V2 respectively. the

A center tapped inductor 10 is connected between the first and second MOSFETs 4,5. The resonant capacitor 9 is connected between the common node of the diodes 6 , 7 and the central node 15 of the inductor 10 . In the converter, capacitor 9 provides the main energy storage device. The inductor 10 can be an inductor made of a polymer bonded magnetic core or an air-core inductor that resonates with the capacitor 9 . the

The self-driving gate driving control circuit 12 provides switching gate signals for the MOSFETs 4 and 5 . The gate drive control circuit 12 provides a high voltage between the gate and the source to turn on the N-channel MOSFET5 and turn off the P-channel MOSFET4. Gate drive control circuit 12 provides zero volts or preferably a negative voltage to turn on P-channel MOSFET 4 and turn off N-channel MOSFET 5 . Preferably, the input voltage V1 should be less than or equal to the highest voltage between the gate and source of MOSFETs 4 and 5 . Gate Drive The gate drive circuit 12 may be an integrated circuit or a high-speed crystal oscillator circuit to provide necessary gate drive signals. the

The DC voltage converter 13 is a step-up voltage converter. Voltage V1 is the input and V2 is the output. Ideally, the voltage V2 is equal to twice the voltage V1. the

The DC voltage converter 13 works by charging and discharging the capacitor 9 . Capacitor 9 acts as a resonant capacitor with inductor 10 to obtain a zero current switching environment for the MOSFET. When the MOSFET 4 is turned on, the diode 7 is forward biased and turned on, and the current flows through the series circuit including the MOSFET 4 , the upper inductor of the inductor 10 , the switched capacitor, and the diode 7 . Initially, the current in the inductor is always zero; therefore the current in the series circuit in the on state is zero. Due to the capacitor 9 connected in series and the upper inductance of the inductor 10, the current in the series circuit is

$\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\sqrt{\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; C</span>}}$

is a periodic sine curve, where L is the inductance value of the inductor 10, and C is the capacitance value of the capacitor 9. Assuming a positive current is passed first, at the end of the first half cycle, the diode 7 is reverse biased so as to cancel out the negative half cycle current. A zero current environment is created and MOSFET4 is turned off. The second MOSFET 5 is turned on and the diode 6 is forward biased. Initially the current is zero and the negative half cycle of the resonant current flows. At the end of the negative half cycle, diode 6 is reverse biased, creating a zero current environment. The effect of generating zero-current switching is achieved by a MOSFET switching time that is longer than half a period of the LC resonant current. the

Because the switched capacitor 9 is charged and discharged by the resonant sinusoidal current, there is no current spike problem in the circuit. the

Figures 2 and 3 show the two phases of a boost switching cycle, with the current paths indicated in bold. Figure 4 shows the gate and current waveforms. the

1 and 4, the boost switched capacitor converter of the present invention includes a pair of complementary P-channel/N-channel MOSFETs 4,5. The self-driving gate driving control circuit 12 provides switching gate signals for the MOSFETs 4 and 5 . The gate drive control circuit 12 provides a high voltage between the gate and the source to turn on the N-channel MOSFET5 and turn off the P-channel MOSFET4. Gate driver 12 provides gate and drain voltages to turn on P-channel MOSFET 4 and turn off N-channel MOSFET 5 . When the self-driving control circuit 12 provides a signal higher than 3 for the two complementary switches, the N-channel switch of the half-bridge arm is turned on, and at the same time, the lower inductance of the center-tap inductor is used to generate resonance with the switch inductance. Alternatively, when the self-driven control circuit provides a signal below ground 3 for the two complementary switches, the voltage between the drain and gate of the upper P-channel switch is high, so the upper MOSFET 4 of the half-bridge arm is turned on, using the center The upper inductance of the tapped inductor resonates with the switching inductance. the

Referring to FIGS. 2 and 4 , at time t ₀ , MOSFET5 is turned on and MOSFET4 is turned off. Diode 6 is forward biased. The filter capacitor 11 discharges the load connected to the second voltage node 2 . MOSFET 5 and diode 6 are connected in series with capacitor 9 and the lower inductance of inductor 10 . The sinusoidal current generated by the switched capacitor resonant with the lower inductance of the inductor 10 passes through the series circuit. At the end of the first resonant period, the series current (capacitor 9 current) is zero and the diode 6 is reverse biased to cancel the current in the negative half period. The capacitor is charged to a DC voltage V1.

Referring to Figures 3 and ₄ , at time t1, diode 6 is reverse biased and the current is zero. MOSFET4 is turned on and MOSFET5 is turned off. Diode 7 is forward biased. The input voltage V1 is connected in series with the switched capacitor 9. Under ideal conditions, the voltage V2 is twice the voltage V1, and a negative half cycle of the resonant current is generated. The filter capacitor 11 is charged again. At the end of the negative half cycle, the diode 7 is reverse biased and the current flow stops. At time _t2 , MOSFET5 is turned on again and MOSFET4 is turned off.

Figures 5 and 6 show the waveforms of a resonant switched capacitor DC converter in boost mode with the above parameters and component values. The measured value of the input voltage V1 is 12V, and the measured value of the output voltage V2 is 24V. The power supply (17.1W) has a maximum efficiency of 92.53%. The efficiency of the rated power supply (50W) is 86.38%. The horizontal resolution of the graphs in Figures 5 and 6 is 1 microsecond per unit. At a switching frequency of 200kHz, the switching time of each MOSFET is 2.5 microseconds. The resonance time of capacitor 9 and inductor 10 is 4 microseconds. Therefore, the half-resonant period is 4 microseconds. the

It can be seen that the present invention provides a resonant switched capacitor DC converter with a boost function. In addition to the need for a center-tapped inductor to resonate with the switched capacitor, the DC circuit of the present invention also includes a pair of complementary P-channel/N-channel MOSFETs, so the two complementary switches share the same self-driving control circuit, thereby reducing gate drive costs. The drive signal with dead-time control can be directly applied to the complementary switches, and the current shoot-through of the half-bridge arm can be limited by the center-tapped inductance. the

Fig. 7 is a second specific embodiment of the present invention. The step-down switched capacitor quasi-resonant converter 20 has a first voltage terminal V1 between the first voltage node 1 and the ground or the negative line 3, and a second voltage terminal between the second node 2 and the ground or the negative line 3 V2. Ground or negative line 3 is at any potential below voltage nodes 1 and 2 . Two filter capacitors 8, 11 are connected in parallel with the first and second voltage terminals V1, V2 respectively. Converter 20 includes a pair of complementary metal oxide semiconductor field effect transistor (MOSFET) switches 4,5. Switch 4 is a P-channel MOSFET, and switch 5 is an N-channel MOSFET. The switch 4 and the switch 5 are connected in series between the first node V1 and the second node V2, and the diode 6 and the diode 7 are connected in series between the second node V2 and the negative line 3, forming a step-down resonant switched capacitor DC voltage converter. the

A center tapped inductor 10 is connected between the first and second MOSFETs 4,5. The resonant capacitor 9 is connected between the central node 15 of the inductor 10 and the common node 14 of the diodes 6,7. Capacitor 9 provides the main energy storage device in the converter. The inductor 10 can be an inductor made of a polymer bonded magnetic core or an air-core inductor that resonates with the capacitor 9 . the

The self-driving gate drive control circuit 12 uses the voltage between node 1 and node 2 as the power supply for the gate drive for self-starting. The self-driving gate driving control circuit 12 provides switching gate signals for the MOSFETs 4 and 5 . The DC voltage converter 20 is a step-down DC voltage converter. The voltage V1 is at the input end and V2 is at the load end. Ideally, voltage V2 is equal to half of voltage V1. The DC voltage converter works by charging and discharging the capacitor 9 . Capacitor 9 acts as a resonant capacitor with inductor 10 to obtain a zero current switching environment for the MOSFET. the

Fig. 8 is a third specific embodiment of the present invention. The inverter type switched capacitor quasi-resonant converter 30 has a first voltage terminal V1 between the first voltage node 1 and the ground or the negative line 3, and a second voltage terminal between the second node 2 and the ground or the negative line 3 V2. Ground or negative line 3 may be at any potential below voltage nodes 1 and 2 . Two filter capacitors 8, 11 are connected in parallel with the first and second voltage terminals V1, V2 respectively. Converter 30 includes a pair of complementary metal oxide semiconductor field effect transistor (MOSFET) switches 4,5. Switch 4 is a P-channel MOSFET, and switch 5 is an N-channel MOSFET. The switch 4 and the switch 5 are connected in series between the first node 1 and the negative line 3, and the diode 6 and the diode 7 are connected in series between the second node V2 and the negative line 3, forming an inverter resonant switched capacitor DC voltage converter. the

A center tapped inductor 10 is connected between the first and second MOSFETs 4,5. The resonant capacitor 9 is connected between the central node 15 of the inductor 10 and the common node 14 of the diodes 6,7. Capacitor 9 provides the main energy storage device in the converter. The inductor 10 can be an inductor made of a polymer bonded magnetic core or an air-core inductor that resonates with the capacitor 9 . the

The self-driving gate drive control circuit 12 utilizes the voltage between node 1 and node 3 as the power supply for self-starting gate drive. The self-driving gate driving control circuit 12 provides switching gate signals for the MOSFETs 4 and 5 . The DC converter 30 is an inverter voltage converter. The voltage V1 is at the input end and V2 is at the load end. Ideally, voltage V2 is equal to the negative value of voltage V1. The converter works by charging and discharging the capacitor 9 . Capacitor 9 acts as a capacitor resonant with inductor 10 to obtain a zero-current switching environment for the MOSFET. the

The above is a detailed description of the present invention for those skilled in the art to understand the present invention, but it is conceivable that other changes and modifications can be made without departing from the scope covered by the claims of the present invention. These changes All modifications and modifications are within the protection scope of the present invention. the

Claims (4)

1. A resonant switched capacitor DC voltage converter, comprising a first voltage node, a second voltage node, a first switch, a second switch, a first diode, a second diode, and a control circuit, wherein the first There is a first voltage between the voltage node and the negative line, there is a second voltage between the second voltage node and the negative line, the control circuit provides switching gate signals for the first switch and the second switch, and the characteristic is that the resonant switch The capacitive DC voltage converter further includes a center-tapped inductor and a resonant capacitor, wherein the center-tapped inductor is connected between the first switch and the second switch, and the resonant capacitor is connected between the first diode and the second diode between the common node of and the central node of the center-tapped inductor; The first switch and the second switch are insulated gate bipolar transistors or a pair of complementary metal-oxide-semiconductor field-effect transistor switches; wherein the first switch and the second switch are a pair of complementary metal-oxide-semiconductor field-effect transistors When switching, the first switch is a P-channel MOSFET, and the second switch is an N-channel MOSFET; And the connection relationship between the switch, the voltage node, the diode, and the negative line is one of the following three types: The first type: the first switch and the second switch are connected in series between the first voltage node and the negative line, and the first diode and the second diode are connected in series between the first voltage node and the second voltage between nodes; The second type: the first switch and the second switch are connected in series between the first voltage node and the second voltage node, and the first diode and the second diode are connected in series between the second voltage node and the second voltage node between the negative lines; The third type: the first switch and the second switch are connected in series between the first voltage node and the negative line, and the first diode and the second diode are connected in series between the second voltage node and the negative line between lines. 2. The DC voltage converter according to claim 1, wherein the control circuit is a self-starting gate drive control circuit. 3. The DC voltage converter according to claim 1, wherein when the connection relationship is the second type, the control circuit uses the voltage between the first node and the second node as a self-starting Power supply to the gate drive. 4. The resonant switched capacitor DC voltage converter according to claim 1, wherein when the connection relationship is the third type, the control circuit utilizes the connection between the first voltage node and the negative line The voltage is used as the power supply provided to the gate driver for self-starting.

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