CN111987911A - DCDC converter based on gallium nitride - Google Patents

Abstract

The present invention provides a gallium nitride-based DCDC converter, comprising an input filter circuit, a power conversion circuit, a GaN switch tube circuit, a switch drive circuit and an output filter circuit, wherein the input filter circuit is used for filtering the input power supply, The first power supply is obtained; the switch drive circuit is connected to the GaN switch tube circuit, and the switch drive circuit is used to provide a drive control signal for the GaN switch tube circuit, and control the switch of the GaN switch tube in the GaN switch tube circuit with a certain frequency and duty ratio, In order to convert the first power supply to obtain the second power supply; the input side of the power conversion circuit is respectively connected with the output end of the input filter circuit and the GaN switch tube circuit, and the power conversion circuit is used to convert the voltage of the second power supply to obtain the third power supply. The power supply; the input end of the output filter circuit is connected to the output side of the power conversion circuit, and the output filter circuit is used for filtering the third power supply to obtain the output power supply.

Description

A gallium nitride based DCDC converter

technical field

The invention relates to the technical field of switching power supplies, in particular to a DCDC converter based on gallium nitride.

Background technique

At present, 60V to 72V battery packs are becoming more and more popular. For example, they are widely used in electric vehicles. The battery voltage of electric vehicles is generally 60V-72V, while other electrical equipment other than motors on electric vehicles requires 12V. Voltage. Therefore, it is necessary to convert the power supply through a DCDC converter. The traditional DCDC converter of this power has defects such as low frequency and large volume.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention provides a DCDC converter based on gallium nitride, which can greatly increase the switching frequency, reduce the volume, realize lightweight design, and reduce switching loss, thereby reducing heat generation and improving efficiency .

The technical scheme adopted in the present invention is as follows:

A gallium nitride-based DCDC converter includes an input filter circuit, a power conversion circuit, a GaN switch tube circuit, a switch drive circuit and an output filter circuit, wherein the input end of the input filter circuit serves as the input end of the DCDC converter , the input filter circuit is used to filter the input power to obtain the first power supply; the switch drive circuit is connected to the GaN switch tube circuit, and the switch drive circuit is used to provide drive for the GaN switch tube circuit The control signal controls the switch of the GaN switch tube in the GaN switch tube circuit with a certain frequency and duty ratio, so as to convert the first power supply to obtain the second power supply; the input side of the power conversion circuit is respectively connected to the The output end of the input filter circuit is connected to the GaN switch tube circuit, the power conversion circuit is used for voltage conversion of the second power supply to obtain a third power supply; the input end of the output filter circuit is connected to the The output side of the power conversion circuit is connected, the output end of the output filter circuit is used as the output end of the DCDC converter, and the output filter circuit is used for filtering the third power supply to obtain an output power supply.

The gallium nitride-based DCDC converter further includes a current-voltage detection circuit and a voltage-stabilizing current-limiting circuit, wherein the current-voltage detection circuit and the output side of the power conversion circuit or the output end of the output filter circuit The current and voltage detection circuit is used to detect the voltage and current signal of the third power supply; the voltage-stabilizing current-limiting circuit is respectively connected with the current-voltage detection circuit and the switch driving circuit, and the voltage-stabilizing current-limiting circuit is respectively connected The circuit is used to perform voltage regulation and current limiting processing on the voltage and current signals detected by the current and voltage detection circuit and transmit them to the switch driving circuit, so that the switch driving circuit generates the final voltage signal according to the synthesized voltage signal after the voltage regulation and current limiting processing. the drive control signal.

Both the input filter circuit and the output filter circuit include a filter inductor and a filter capacitor.

The power conversion circuit includes a transformer.

The transformer includes an EE core.

The switch driving circuit includes a UC3842 chip, and the GaN switch tube adopts a GaNFast NV6113 chip.

The transformer includes an auxiliary winding, and the auxiliary winding is respectively connected with the UC3842 chip and the GaNFast NV6113 chip to supply power to the UC3842 chip and the GaNFast NV6113 chip.

The voltage-stabilizing and current-limiting circuit includes a TSM103 chip.

An optocoupler is connected between the TSM103 chip and the UC3842 chip, so as to transmit the synthesized voltage signal processed by voltage regulation and current limiting through the optocoupler.

Beneficial effects of the present invention:

The gallium nitride-based DCDC converter of the present invention can greatly increase the switching frequency, reduce the volume, realize lightweight design, and reduce the switching loss by setting the GaN switching tube circuit and the corresponding control and driving circuits, thereby reducing the Generate heat and improve efficiency.

Description of drawings

1 is a schematic block diagram of a gallium nitride-based DCDC converter according to an embodiment of the present invention;

2 is a schematic block diagram of a gallium nitride-based DCDC converter according to an embodiment of the present invention;

3 is a circuit topology diagram of a gallium nitride-based DCDC converter according to an embodiment of the present invention;

4 is a circuit topology diagram of an input filter circuit according to an embodiment of the present invention;

5 is a schematic diagram of the internal structure of a GaNFast NV6113 chip according to an embodiment of the present invention;

6 is a circuit topology diagram of a GaN switch tube circuit according to an embodiment of the present invention;

7 is a circuit topology diagram of a switch driving circuit according to an embodiment of the present invention;

8 is a circuit topology diagram of a power conversion circuit according to an embodiment of the present invention;

9 is a circuit topology diagram of an RC absorption snubber circuit according to an embodiment of the present invention;

10 is a circuit topology diagram of an output filter circuit according to an embodiment of the present invention;

FIG. 11 is a circuit topology diagram of a current-voltage detection circuit and a voltage-stabilizing current-limiting circuit according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

As shown in FIG. 1 , the gallium nitride-based DCDC converter according to the embodiment of the present invention includes an input filter circuit 10 , a power conversion circuit 20 , a GaN switch tube circuit 30 , a switch drive circuit 40 and an output filter circuit 50 . The input terminal of the input filter circuit 10 is used as the input terminal of the DCDC converter, and the input filter circuit 10 is used to filter the input power to obtain the first power supply; the switch drive circuit 40 is connected to the GaN switch tube circuit 30, and the switch drive circuit 40 is used to provide a drive control signal for the GaN switch tube circuit 30, and control the switch of the GaN switch tube in the GaN switch tube circuit 30 with a certain frequency and duty ratio, so as to convert the first power supply to obtain the second power supply; power conversion The input side of the circuit 20 is respectively connected with the output end of the input filter circuit 10 and the GaN switch tube circuit 30. The power conversion circuit 20 is used for voltage conversion of the second power supply to obtain the third power supply; the input end of the output filter circuit 50 is connected to the power The output side of the conversion circuit 20 is connected, the output end of the output filter circuit 50 is used as the output end of the DCDC converter, and the output filter circuit 50 is used for filtering the third power supply to obtain the output power supply.

Further, as shown in FIG. 2 , the gallium nitride-based DCDC converter further includes a current-voltage detection circuit 60 and a voltage-stabilizing current-limiting circuit 70 . The current and voltage detection circuit 60 is connected to the output side of the power conversion circuit 20 or the output end of the output filter circuit 50, that is, the current and voltage detection circuit 60 is connected to the rear stage of the power conversion circuit 20, and the current and voltage detection circuit 60 is used to detect the first The voltage and current signals of the three power sources; the voltage stabilization and current limiting circuit 70 is respectively connected to the current and voltage detection circuit 60 and the switch driving circuit 40 , and the voltage stabilization current limiting circuit 70 is used to stabilize the voltage and current signals detected by the current and voltage detection circuit 60 After the current-limiting processing, it is transmitted to the switch driving circuit 40, so that the switch driving circuit 40 generates a driving control signal according to the synthesized voltage signal after the voltage regulation and current-limiting processing.

In an embodiment of the present invention, both the input filter circuit 10 and the output filter circuit 50 include a filter inductor and a filter capacitor.

Specifically, as shown in FIG. 3 and FIG. 4 , the input filter circuit 10 includes a common mode inductor L1 and an electrolytic capacitor C2, and both ends of the common mode inductor L1 are also connected to the ground through safety capacitors CY01 and CY02, respectively. The input terminal of the input filter circuit 10 is used as the input terminal of the DCDC converter, which is connected to the battery or the grid, and the input range is 60 to 90V DC. The diode D1 connected to the input terminal can prevent the reverse flow of the current. The input filter circuit 10 can suppress the electromagnetic noise and clutter signal of the input power supply and reduce the interference. If the input end is connected to the power grid, it can also prevent the high frequency clutter of the power supply from interfering with the power grid.

In an embodiment of the present invention, the switch driving circuit 40 includes a UC3842 chip, and the GaN switch tube adopts a GaNFast NV6113 chip.

Specifically, the COMP pin of the UC3842 chip is for loop compensation, the FB pin is for voltage feedback, SEN is for current sampling, CT is connected to the reference voltage VREF through resistors R33 and R32, and grounded through capacitor C19 to adjust the difference between the resistor R33 and capacitor C19. The size can change the oscillation rate of the output, as well as the maximum duty cycle. The maximum working frequency of the UC3842 chip is 500kHz. Due to the difference in the manufacturing process of each chip, 450k is used here.

The internal structure of the GaNFast NV6113 chip is shown in Figure 5. It integrates GaN inside and is a gallium nitride power integrated circuit, including a Vcc pin for power supply, with an input voltage range of 10V to 24V, including a PWM pin , used for square wave input, including a Vdd pin, which is the setting pin for gate drive turn-on current, Dz is the gate drive voltage setting pin, D is equivalent to the drain of ordinary MOS, and S is the source. The frequency of the GaNFast NV6113 chip can reach a maximum of 2MHz.

As shown in Figure 3, Figure 6 and Figure 7, the PWM pin of the GaNFast NV6113 chip is connected to the OUT pin of the UC3842 chip to obtain a square wave to control the on-off of the switch. Standard current sensing resistors R29~R31 are connected between the source and ground of the GaNFast NV6113 chip, which can detect the current flowing through the GaNFast NV6113 chip. The PWM, Vdd, Dz pins of the GaNFast NV6113 chip are all connected to a capacitor or a Zener diode to the source and ground. Among them, capacitor C5 can prevent false triggering caused by high frequency voltage spikes. The Sen formed by the anode of the Zener diode D7 and one end of the capacitors C5 and C6 is connected to the sen pin of the GaNFastNV6113 chip.

In an embodiment of the present invention, as shown in FIG. 3 and FIG. 8 , the power conversion circuit 20 includes a transformer, that is, the DCDC converter in the embodiment of the present invention is an isolated converter.

As shown in FIG. 3 and FIG. 8 , the topology of the power conversion circuit 20 according to the embodiment of the present invention is a flyback topology. It can pass the converted DC power through the turns ratio of the winding coil of the transformer, step down and transmit it to the secondary. During the conduction period of the switch tube, the transformer stores energy, and the load current is provided by the output filter capacitor. During the off-time of the switch, the energy stored in the transformer is transferred to the load, providing the load current, charging the output filter capacitor, and compensating for the energy lost during the on-time of the switch.

Specifically, the input voltage of the power conversion circuit 20 is 60 to 90V, and the output voltage is 12.6V. The transformer efficiency η is initially set to 90%. Since the embodiment of the present invention is a high-frequency converter, the transformer frequency is designed to be 450 kHz.

In addition, as shown in Figure 3 and Figure 8, the transformer includes auxiliary windings, which are connected to the UC3842 chip and the GaNFast NV6113 chip, respectively, to provide the VCC1 power output to power the UC3842 chip and the GaNFast NV6113 chip.

The output power of the transformer is:

Due to the loss of the transformer and the voltage drop of the secondary diode, in the actual process, the power design is often larger, so it is designed to be 200W here.

The magnetic flux density is selected as B _w =0.2T, the window utilization rate K _w is initially set to 45%, the temperature rise range of the magnetic core is set to 25 degrees, and X is -0.125. Here, the Ap method is used to select the appropriate magnetic core.

According to the temperature can be calculated:

K _j =70*Δt ^0.545 =70*25 ^0.545 ≈400

Ap represents the product of the effective cross-sectional area of the magnetic core and the window area,

According to this Ap value, an EE magnetic core can be selected, such as an EE10 magnetic core. The magnetic core of this magnetic core has a window area A _w of the wire around which is 23.7cm ² , the effective cross-sectional area of the magnetic core A _e is 12.1cm 2 , and the Ap value is 0.0287.

The current density is:

_J =Kj _{( AwAe} ) ^X =400*(23.7* ^10-2 *12.1* ^10-2 ) ^-0.125 =6.23A/ ^cm2

The number of turns on the primary side is:

_Tomax = _Dmax *T=0.45*2.22=0.999

The secondary turns are:

Since the auxiliary winding mainly supplies power for the UC3842 chip and the GaNFast NV6113 chip, the startup voltage of the UC3842 chip is 16V, and the working voltage of the GaNFast NV6113 chip is 10 to 24V, so the output voltage can be set to 18V.

So the number of turns of the auxiliary winding is:

The primary winding wire diameter is:

The secondary winding wire diameter is:

The wire diameter of the auxiliary winding is 0.2mm ² .

It can be seen that the frequency of the transformer reaches 450kHz, and the volume is significantly reduced. It is a mini transformer with a volume of about 1.5cm ³ , which can reduce the volume of the entire DCDC converter.

As shown in FIG. 3 and FIG. 9 , an RC absorption buffer circuit is also provided between the power conversion circuit 20 and the output filter circuit 50. The RC absorption buffer circuit consists of two resistors R9 and R10 in parallel and a capacitor C7 in series. There is inductance, so the resistance in series with the capacitor can play a damping role. It can prevent the R, L, and C circuits from damaging the components due to the overvoltage at both ends of the capacitor during the transition process, which can protect the lower voltage regulator. Diodes D8, D9.

As shown in FIG. 3 and FIG. 10 , the output filter circuit 50 includes a common mode inductor L2 and electrolytic capacitors C8-C11, and one end of the common mode inductor L2 is also connected to the ground through a safety capacitor CY05. The output end of the output filter circuit 50 is used as the output end of the DCDC converter, is connected to the load, and outputs a direct current of 12V and 6A. Its function and working principle are similar to those of the above-mentioned input filter circuit 10 , which will not be repeated here.

As shown in Figure 3 and Figure 11, the voltage regulator and current limiting circuit includes TSM103 chip. As shown in Figure 3, Figure 11 and Figure 7, an optocoupler is connected between the TSM103 chip and the UC3842 chip to transmit stable voltage through the optocoupler. The synthesized voltage signal after voltage and current limiting processing. The TSM103 chip can achieve constant current and constant voltage. The TSM103 chip integrates two operational amplifiers and a voltage reference device. The VCC pin is the power supply pin and is directly connected to the VCC2 power output provided by the output side of the power conversion circuit 20. IN1+, IN1- The OUT1 pin is an op amp and a voltage reference device to form an ideal voltage controller. The resistors R16 and R22 are connected to the output of the DCDC converter. The IN1-pin provides voltage for the chip, and passes through the chip's internal voltage reference device. The voltage is stabilized at 2.5V, R22 detects the output voltage all the way, and is divided by R24 and R25, and the input from the IN1+ pin is compared with the internal 2.5V reference voltage, so as to adjust the output high and low level of the OUT1 pin, IN2+, IN2-, OUT2 lead The pin is an operational amplifier, which can act as a current limiter in conjunction with the internal integrated voltage reference device and external resistors. The IN2+ pin is divided by resistors R17, R18, and GND to obtain a 2.5V reference voltage from the outside. R16 is the current detection. When the current fluctuates, the voltage of the R16 resistor also changes, so the voltage obtained by IN2- is compared with the 2.5V reference voltage of IN2+ by the internal op amp of the chip, so as to adjust the output level of the OUT2 pin. level. The high and low levels output by the OUT2 pin and the OUT1 pin will change the on-off of the light-emitting diode inside the optocoupler, thereby changing the on-off of the triode. As shown in Figure 7, the internal transistor of the optocoupler is connected to the COMP and FB pins of the UC3842 chip. By whether the transistor is turned on or not, the potential of the COMP pin is changed, thereby changing the duty cycle of the OUT pin, thereby driving the GaN switch. Tube. The SEN pin is connected to the source of the GaN switch, and a voltage proportional to the inductor current is provided to this pin, thereby changing the duty cycle of the output pin OUT pin. Thus, the voltage and current feedback regulation of the DCDC converter is realized.

In addition, it should be noted that the electrolytic capacitor C2 in the above-mentioned input filter circuit 10 is used as the start-up capacitor. When the DCDC converter is turned on, C2 is charged, and then stops after being fully charged, and C2 is discharged from the VCC1 power supply terminal to the UC3842 chip and GaNFast. The NV6113 chip is powered, the switch is turned on, and the DCDC converter is officially working. After that, both the UC3842 chip and the GaNFastNV6113 chip are powered by the auxiliary winding of the transformer.

To sum up, according to the gallium nitride-based DCDC converter according to the embodiment of the present invention, by setting the GaN switch tube circuit and the corresponding control and driving circuits, the switching frequency can be greatly increased, the volume can be reduced, and the lightweight design can be realized. And can reduce switching losses, thereby reducing heat generation and improving efficiency.

In the description of the present invention, the terms "first" and "second" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first", "second" may expressly or implicitly include one or more of that feature. "Plurality" means two or more, unless expressly specifically limited otherwise.

In the present invention, unless otherwise expressly specified and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection , or integrated; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of the two elements or the interaction relationship between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

In the present invention, unless otherwise expressly specified and limited, a first feature "on" or "under" a second feature may be in direct contact between the first and second features, or the first and second features indirectly through an intermediary touch. Also, the first feature being "above", "over" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is level higher than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples, without conflicting each other.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (9)

1. A DCDC converter based on gallium nitride is characterized by comprising an input filter circuit, a power conversion circuit, a GaN switching tube circuit, a switch driving circuit and an output filter circuit,

the input end of the input filter circuit is used as the input end of the DCDC converter, and the input filter circuit is used for filtering an input power supply to obtain a first power supply;

the switch driving circuit is connected with the GaN switch tube circuit and used for providing a driving control signal for the GaN switch tube circuit, and controlling the switch of a GaN switch tube in the GaN switch tube circuit at a certain frequency and duty ratio so as to convert the first power supply and obtain a second power supply;

the input side of the power conversion circuit is respectively connected with the output end of the input filter circuit and the GaN switching tube circuit, and the power conversion circuit is used for performing voltage conversion on the second power supply to obtain a third power supply;

the input end of the output filter circuit is connected with the output side of the power conversion circuit, the output end of the output filter circuit is used as the output end of the DCDC converter, and the output filter circuit is used for filtering the third power supply to obtain an output power supply.

2. The gallium nitride-based DCDC converter according to claim 1, further comprising a current-voltage detection circuit and a regulated current-limiting circuit, wherein,

the current and voltage detection circuit is connected with the output side of the power conversion circuit or the output end of the output filter circuit and is used for detecting a voltage and current signal of the third power supply;

the voltage stabilizing and current limiting circuit is respectively connected with the current and voltage detection circuit and the switch driving circuit, and the voltage stabilizing and current limiting circuit is used for performing voltage stabilizing and current limiting processing on the voltage and current signals detected by the current and voltage detection circuit and then transmitting the voltage and current signals to the switch driving circuit, so that the switch driving circuit can generate the driving control signal according to the synthesized voltage signals after the voltage stabilizing and current limiting processing.

3. The gallium nitride-based DCDC converter according to claim 2, wherein the input filter circuit and the output filter circuit each comprise a filter inductance and a filter capacitance.

4. The gallium nitride-based DCDC converter according to claim 2, wherein the power conversion circuit comprises a transformer.

5. The gallium nitride-based DCDC converter of claim 4, wherein said transformer comprises an EE core.

6. The DCDC converter based on gallium nitride of claim 5, wherein said switch driving circuit comprises a UC3842 chip, and said GaN switch tube is a GaNFast NV6113 chip.

7. The gallium nitride-based DCDC converter of claim 6, wherein said transformer comprises an auxiliary winding, and said auxiliary winding is connected to said UC3842 chip and said GaNFast NV6113 chip respectively, for supplying power to said UC3842 chip and said GaNFast NV6113 chip.

8. The gallium nitride-based DCDC converter of claim 6, wherein said regulated current limiting circuit comprises a TSM103 chip.

9. The DCDC converter based on GaN of claim 8, wherein an opto-coupler is connected between the TSM103 chip and the UC3842 chip, so as to transmit the resultant voltage signal after the voltage stabilization and current limitation processing through the opto-coupler.

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