CN210016405U - Micro-grid double-active full-bridge bidirectional DC-DC converter - Google Patents
Micro-grid double-active full-bridge bidirectional DC-DC converter Download PDFInfo
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Abstract
The embodiment of the utility model provides a two-way DC-DC converter of little electric wire netting double-active full-bridge, including high frequency isolation transformer; the high-frequency inversion rectification circuit comprises a first full-bridge unit and a second full-bridge unit, wherein each bridge arm of the first full-bridge unit and the second full-bridge unit is respectively provided with two MOSFET power switching tubes which are in 180-degree complementary conduction connection, and the two MOSFET power switching tubes at all diagonal angles are set to be in same-switch; a sampling circuit; the driving circuit outputs a PWM control signal to drive the first full-bridge unit and the second full-bridge unit, the driving circuit comprises integrated bridge arm driving chips and peripheral circuits thereof, the integrated bridge arm driving chips are arranged corresponding to each bridge arm, and each integrated bridge arm driving chip drives two MOSFET power switching tubes of the same bridge arm through a high-end output channel and a low-end output channel at the same time; and the protection circuit sends a stop signal to the drive circuit when the circuit is abnormal. The utility model provides a two-way DC-DC converter specially adapted high-power density just requires low-cost, high reliability and efficient occasion.
Description
Technical Field
The embodiment of the utility model provides a little electric wire netting control technical field especially indicates a little two-way DC-DC converter of active full-bridge of electric wire netting.
Background
Currently, renewable energy power generation systems are favored, however, renewable energy has randomness problems, and an energy storage element (energy storage element for short) needs to be introduced to provide clean and safe electric energy for users. A common energy storage element is a battery or a super capacitor. Because the photovoltaic array is greatly influenced by illumination and temperature, the voltage fluctuation on the direct current bus side is obvious. When the energy storage element is used, continuous and stable electric energy can be transmitted to the side of the direct current bus to the load side. In order to enable the energy storage element and the direct current bus side to exchange energy, a junction bridging the energy storage element and the direct current bus side is an isolated bidirectional direct current converter (IBDC), and therefore an energy control center between the direct current bus side and the load side is established. The IBDC regulates the bidirectional flow of energy in the system according to the requirement of a load, and when the load is light, the surplus energy in the system is charged to the energy storage element through the IBDC; when the load is heavy, the energy storage element supplies energy to the load through the IBDC, so that the voltage on the direct current bus side is stabilized. The IBDC controls the charging and discharging of the energy storage element to realize the energy exchange of the energy storage system, so that the system works stably and reliably.
A Dual Active Bridge (DAB) bidirectional DC-DC converter is an IBDC generally used in medium and high power applications, however, at present, there are not many bidirectional DC/DC converters that can meet the requirements of high voltage and high power.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a technical problem that will solve provides a two-way DC-DC converter of active full-bridge of little electric wire netting, can be applicable to the high-power occasion of high pressure.
In order to solve the technical problem, an embodiment of the utility model provides a following technical scheme: a microgrid double-active full-bridge bidirectional DC-DC converter is connected between a photovoltaic simulator and an energy storage device, and comprises:
a high frequency isolation transformer having a high side winding and a low side winding;
the high-frequency inversion rectification circuit comprises a first full-bridge unit which is connected between the high-voltage side winding and the photovoltaic simulator and consists of four MOSFET power switch tubes and a second full-bridge unit which is connected between the low-voltage side winding and the energy storage device and consists of four MOSFET power switch tubes, wherein two MOSFET power switch tubes which are in 180-degree complementary conduction connection are arranged on each bridge arm of the first full-bridge unit and the second full-bridge unit, and the two MOSFET power switch tubes at all diagonal angles are set to be in the same switch and the same switch;
the sampling circuit is used for sampling the output current, the high-voltage side voltage and the low-voltage side voltage;
the driving circuit is connected with the sampling circuit and the first full-bridge unit and the second full-bridge unit, generates and outputs PWM (pulse-width modulation) control signals according to output current, high-voltage side voltage and low-voltage side voltage which are sampled by the sampling circuit so as to drive the first full-bridge unit and the second full-bridge unit, and comprises integrated bridge arm driving chips and peripheral circuits thereof, wherein the integrated bridge arm driving chips are arranged corresponding to each bridge arm of the first full-bridge unit and the second full-bridge unit, each integrated bridge arm driving chip is provided with an independent high-side output channel and an independent low-side output channel, and simultaneously drives two MOSFET (metal-oxide-semiconductor field effect transistor) power switching tubes of the same bridge arm through the high-side output channel and;
and one end of the protection circuit is connected with the output end of the sampling circuit, the other end of the protection circuit is connected with the driving circuit, and when the circuit is abnormal, a stop signal is sent to the driving circuit to enable the driving circuit to stop outputting the PWM control signal.
Further, the integrated bridge arm driving chip is an IR2110 chip.
Further, the floating power supply of the driving chip is a bootstrap circuit, the bootstrap circuit includes a parallel connection body formed by two bootstrap capacitors connected in parallel and a bootstrap diode, two ends of the parallel connection body are respectively connected to a high-side floating ground pin and a high-side power supply voltage pin of the driving chip, a cathode of the bootstrap diode is connected to the high-side power supply voltage pin, and an anode of the bootstrap diode is connected to a low-side power supply voltage pin and a power supply of the driving chip.
Furthermore, the driving circuit comprises an analog-to-digital conversion circuit connected between the sampling circuit and the integrated bridge arm driving chip.
Further, the sampling circuit includes:
a current sampling sub-circuit for sampling the output current; and
and the voltage sampling sub-circuit is used for sampling the voltage of the high-voltage side and the voltage of the low-voltage side.
Further, the current sampling sub-circuit comprises a current sampling chip based on the Hall effect and peripheral circuits thereof.
Furthermore, the voltage sampling sub-circuit is a resistance voltage division sampling circuit.
Furthermore, the microgrid double-active full-bridge bidirectional DC-DC converter also comprises a sampling signal conditioning circuit which is connected between the sampling circuit and the driving circuit and used for filtering the sampling signal, and the sampling signal conditioning circuit is a second-order active low-pass filter circuit.
Further, the protection circuit includes:
an overcurrent protection sub-circuit;
an over-voltage and under-voltage protection sub-circuit;
and the bus undervoltage protection subcircuit.
Further, the magnetic core of the high-frequency isolation transformer is a toroidal magnetic core made of an iron-based nanocrystal material.
After the technical scheme is adopted, the embodiment of the utility model provides an at least, following beneficial effect has: the embodiment of the utility model provides a two MOSFET power switch tubes that are 180 complementary turn-on connections respectively have on every bridge arm of the two-way DC-DC converter of little active full-bridge's of electric wire netting first full-bridge unit and second full-bridge unit, and two MOSFET power switch tubes of all diagonal angles are set up to the same switch with opening, have solved technical problem such as isolation transformer magnetic saturation and low pressure side rectifier diode voltage oscillation, and, set up an integrated bridge arm driver chip and peripheral circuit, and each corresponding each bridge arm integrated bridge arm driver chip has independent high side output channel and low side output channel and simultaneously through two MOSFET power switch tubes of high-end output channel and the same bridge arm of low side output channel drive, can the operating condition of first full-bridge unit of high-efficient control and second full-bridge unit. The utility model discloses two-way DC-DC converter of active full-bridge of little electric wire netting is particularly suitable for being applied to high power density and requires low-cost, high reliability and efficient occasion.
Drawings
Fig. 1 is a schematic block diagram of an alternative embodiment of the microgrid bi-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 2 is a topology flow diagram of an alternative embodiment of the microgrid dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 3 a-3 f are schematic diagrams of equivalent circuits of each switching mode in the forward operation of an alternative embodiment of the dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 4 a-4 f are schematic diagrams of equivalent circuits of each switching mode in reverse operation of an alternative embodiment of the dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 5 is an internal structure diagram of an IR2110 chip of an alternative embodiment of the microgrid dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 6 is a pin function diagram of an IR2110 chip of an alternative embodiment of the microgrid dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 7 is a driving circuit diagram of an IR2110 chip of an alternative embodiment of the microgrid dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 8 is a specific circuit structure diagram of the analog-to-digital conversion circuit employed in an optional embodiment of the microgrid dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 9 is a block diagram of a circuit configuration of a current sampling circuit employed in an alternative embodiment of the microgrid dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 10a and 10b are specific circuit structure diagrams of the current sampling sub-circuit employed in an optional embodiment of the dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 11 is a specific circuit structure diagram of a voltage sampling sub-circuit employed in an optional embodiment of the microgrid dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 12 is a circuit diagram of a sampling signal conditioning circuit according to an alternative embodiment of the microgrid dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 13 is a block diagram of the circuit configuration of the protection circuit according to an alternative embodiment of the microgrid dual-active full-bridge bidirectional DC-DC converter of the present invention.
Fig. 14 is an overcurrent protection schematic diagram of the protection circuit according to an alternative embodiment of the microgrid dual-active full-bridge bidirectional DC-DC converter.
Fig. 15 is an overvoltage/undervoltage protection schematic diagram of the protection circuit according to an optional embodiment of the dual-active full-bridge bidirectional DC-DC converter of the utility model.
Fig. 16 is a circuit structure diagram of the bus under-voltage protection sub-circuit of the protection circuit according to an optional embodiment of the dual-active full-bridge bidirectional DC-DC converter of the utility model.
Detailed Description
The present application will be described in further detail with reference to the following drawings and specific embodiments. It is to be understood that the following illustrative embodiments and description are only intended to illustrate the present invention, and are not intended to limit the present invention, and features in the embodiments and examples may be combined with each other in the present application without conflict.
As shown in fig. 1 and fig. 2, an embodiment of the utility model provides a two-way DC-DC converter of little active full-bridge of electric wire netting is connected between photovoltaic simulator and energy memory, include:
a high frequency isolation transformer T having a high voltage side winding and a low voltage side winding;
the high-frequency inverter rectification circuit 2 comprises a first full-bridge unit 20 which is connected between the high-voltage side winding and the photovoltaic simulator and consists of four MOSFET power switching tubes Q1, Q2, Q3 and Q4, and a second full-bridge unit 22 which is connected between the low-voltage side winding and the energy storage device and consists of four MOSFET power switching tubes Q5, Q6, Q7 and Q8, wherein two MOSFET power switching tubes which are in complementary conduction connection of 180 degrees are arranged on each bridge arm of the first full-bridge unit 20 and the second full-bridge unit 22, and the two MOSFET power switching tubes of all the oblique diagonal angles are arranged to be in the same switch and the same switch;
the sampling circuit 3 is used for sampling the output current, the high-voltage side voltage and the low-voltage side voltage;
a driving circuit 4 connected to the sampling circuit 3 and the first and second full-bridge cells 20 and 22, and generating and outputting PWM control signals according to the output current, the high-side voltage and the low-side voltage sampled by the sampling circuit 3 to drive the first and second full-bridge cells 20 and 22, wherein the driving circuit 4 includes an integrated bridge arm driving chip U11 corresponding to each bridge arm of the first and second full-bridge cells 20 and 22 and peripheral circuits thereof (see fig. 7), each integrated bridge arm driving chip U11 has an independent high-side output channel and low-side output channel and drives two MOSFET power switching tubes of the same bridge arm through the high-side output channel and the low-side output channel;
and one end of the protection circuit 5 is connected with the output end of the sampling circuit 3, the other end of the protection circuit is connected with the driving circuit 4, and when the circuit is abnormal, a stop signal is sent to the driving circuit 4, so that the driving circuit 4 stops outputting the PWM control signal.
The embodiment of the utility model provides a two MOSFET power switch tubes that are 180 complementary turn-on connections respectively have on the two active full-bridge bidirectional DC-DC converter's of microgrid two-way full-bridge unit 20 and every bridge arm of second full-bridge unit 22, for example: q1 and Q2 are on the same arm, Q3 and Q4 are on the same arm, Q5 and Q6 are on the same arm, Q7 and Q8 are on the same arm, and two MOSFET power switching tubes of all diagonal corners are set to be on and off at the same time, for example: q1 and Q4, Q2 and Q3, Q5 and Q8, Q6 and Q7 are two MOSFET power switching tubes respectively located at diagonal angles and are set to be on at the same time, so that technical problems of magnetic saturation of the isolation transformer and voltage oscillation of a low-voltage side rectifier diode are solved, and an integrated bridge arm driving chip U11 and peripheral circuits thereof are arranged corresponding to each bridge arm, each integrated bridge arm driving chip U11 has an independent high-side output channel and a low-side output channel, and drives two MOSFET power switching tubes of the same bridge arm through the high-side output channel and the low-side output channel at the same time, so that the working states of the first full bridge unit 20 and the second full bridge unit 22 can be efficiently controlled. The utility model discloses two-way DC-DC converter of active full-bridge of little electric wire netting is particularly suitable for being applied to high power density and requires low-cost, high reliability and efficient occasion.
The utility model discloses little electric wire netting two-way DC converter of active full-bridge passes through the former vice limit bridge arm mid point voltage V of control14And V58The power is controlled by the magnitude of the phase shift angle, and the ratio of the phase shift angle to 180 degrees is the duty cycle D. As shown in fig. 2, the input and output sides of the microgrid dual-active full-bridge bidirectional DC/DC converter are provided with filter capacitors C9, C10 and a load. The operation of the bi-directional DC/DC converter is similar when transmitting power in the forward and reverse directions, and the operation characteristics of the converter are analyzed below for the forward operation mode and the reverse operation mode, respectively. Prior to analysis, the following assumptions were made: (1) the bidirectional DC/DC converter is in a steady-state working state; (2) all the switch tubes are regarded as ideal switches with one diode and parallel parasitic capacitance; (3) the size of the inductor L is equal to the sum of the leakage inductance and the applied inductance of the high-frequency transformer; (5) the high-frequency transformer is ideal, and the exciting current is zero; (5) v1>KVz, where K is the primary to secondary turns ratio of the transformer.
The forward operation mode of the microgrid dual-active full-bridge bidirectional DC-DC converter provided by the embodiment of the present invention is described in detail with reference to fig. 3a to 3 f.
Mode (a): t is taAt time, corresponding to FIG. 3a, at taBefore time, Q2And Q3、Q6And Q7Conduction, primary side current iLLess than 0, flow through Q2And Q3. Secondary current flows through Q6And Q7ToAnd a forward diode. Power supply V1Output power, power supply V1Absorbing the power.
Mode (b): t is taTo tbAt time, corresponding to FIG. 3b, at taTurn off Q at a moment2And Q3Primary side current iLCapacitor C2And C3Charging, simultaneously, capacitor C1And C4And (4) discharging. Due to the presence of the capacitor C1，C2，C3And C4，Q2And Q3Are all off at zero voltage, so at taIn time, C2And C3Is raised to V1And C is1And C4The voltage drops to zero. Q1And Q4Is connected in parallel with the diode D1And D4And naturally conducts.
Mode (c): to tbTime of day, corresponding to FIGS. 3c, D1And D4After conduction, primary side current iLFlows through D1And D4Can turn on Q at zero voltage1And Q4At this time V14＝-V1，V58＝-V2And V isL＝V1+4.9*V2Thus iLLinearly increasing, the slope is as follows:
diL/dt＝(V1+4.9*V2)/L (1)
since t is reachedcTime, iLGo up to 0, D1And D4Off, in which state the inductor releases energy to a voltage V1And V2。
Mode (d): t is tcTo tdTime of day, corresponding to FIG. 3d, since tcTime of day start, iLIs greater than 0, iLFlow through Q1And Q4，V14＝V1. Secondary current flows through Q6And Q7，V58＝-V2While still being greater than V1+4.9*V2，iLThe linear increase continues. In this state, the power supply V1And V2And simultaneously, energy is stored in the inductor.
Mode (d): t is tdTo teAt time, corresponding to FIG. 3e, at tdTurn off Q at a moment6And Q7Secondary current to Q6And Q7Charging while Q5And Q8And (4) discharging. Because of Q5And Q8Presence of (A), Q6And Q7Are both zero voltage off. At teTime, Q6And Q7Is raised to V2，Q5And Q8Voltage becomes 0, diode D5And D8It is naturally turned on.
Mode (f): t is teTo tfTime of day, corresponding to FIGS. 3f, D5And D8After conduction, a secondary current flows through D5And D8Can turn on Q at zero voltage5And Q8. At the same time, V14＝V1，V58＝V2，VL＝V1-4.9*V2，iLThe linear rise continues, with the following slope:
diL/dt＝(V1-4.9*V2)/L (2)
at tfThereafter, the converter starts another half cycle, which operates similarly to the half cycle described above.
The six forward energy flow modes are the incarnations of different stages of the energy storage system of the bidirectional DC/DC converter. For a battery, modes (a-f) are all in a charged state; for the operation modes with different forward and reverse directions, the charging and discharging control of the photovoltaic power generation energy storage system is different.
The reverse operation mode of the microgrid dual-active full-bridge bidirectional DC-DC converter provided by the embodiments of the present invention is described in detail with reference to fig. 4a to 4 f.
Mode (a): t is taAt time, corresponding to fig. 4a, t equals taTime, Q6And Q7Is turned off when the current-i0Combined capacitor C6And C7Charging and flowing through the low-voltage side of the isolation transformer, the low-voltage side current-iL/n2Gradually rising from zero. Due to the output voltage V1Is converted into a low-side voltage, so that a current-i0And gradually becomes smaller.
Mode(s)(b)：taTo tbAt time, corresponding to fig. 4b, t equals tbTime of day, current-iL/n2Gradually and slowly rise. The rate of rise is the same as mode a; current-i0Continuing to decrease, the capacitance C6And C7Charging is also continued.
Mode (c): t is tbTo tcAt time, corresponding to fig. 4c, t equals tcTime of day, capacitance C6And C7The charging is maximized. At this time-i0Continuing to decrease until there is insufficient load current, capacitor C6And C7The discharge is started.
Mode (d): t is tcTo tdAt time, corresponding to fig. 4d, t equals tdTime of day, capacitance C6And C7Is completely discharged, during which the battery and the stored energy in the filter inductor L0Together, provide energy to the load. And because of the storage in the inductor L0Gradually decrease in energy and because of the output voltage V1Action of, current-i0And current-iL/n2And begins to taper.
Mode (e): t is tdTo teAt time, corresponding to fig. 4e, when t equals teTime of day, switch tube Q6And Q7Switched off again, capacitor C6And C7Cannot mutate, so Q6And Q7Is ZVS off. During this time period Q5To Q8Are simultaneously conducted, the battery voltage V2Added to the filter inductor L0Above, flows through the filter inductor L0Current-i of0But slowly increases. During this time period current-iL/n2Voltage across blocking capacitor and output voltage V1The combined effect of (a) and (b) decreases rapidly.
Mode (f): t is teTo tfAt time, corresponding to fig. 4f, when t equals teTime of day, current-iL/n2And drops to zero. At this stage, the current continues to increase. The equivalent circuit is the same as mode (e). At t ═ tfTime of day, switch tube Q5And Q8Off because of the capacitance C5And C8Can not protrude from both endsVariable, therefore, the switching tube Q5And Q8ZVS turn-off is realized, 6 switching modes are finished in the half period of the circuit, and the current-iL/n2The reverse direction is started. In a complete cycle, the switch tube Q5To Q8Are ZVS switches.
In an optional embodiment of the present invention, the integrated bridge arm driving chip U11 is an IR2110 chip. The utility model discloses a MOSFET power switch pipe is based on the full-bridge circuit drive of IR2110 chip. The IR2110 chip is a high voltage, high speed, high power MOSFET driver, a high voltage integrated circuit with separate high side and low side output channels. Its output driver has a dead time intended to minimize cross conduction of the driver. To simplify use in high frequency applications, the propagation delays are matched. The IR2110 chip is widely used for switching power supplies and motor control speed regulation, and needs to perform energy conversion with medium and small power. The IR2110 chip allows the system to be effectively simplified, fast, 600V tolerant, drive the output current 2A, have under-voltage lockout and have an external over-current detection circuit. The high-end peripheral circuit bearing high voltage adopts a bootstrap mode, so that the number of power channels can be effectively reduced. The IR2110 chip has the advantages of optical coupling isolation (small volume) and electromagnetic isolation (fast), and is the first choice for small and medium power drivers. The internal structure of the IR2110 chip is shown in fig. 5, fig. 6 also shows a pin function diagram of the IR2110 chip, and fig. 7 shows a driving circuit diagram of the IR2110 chip.
In an optional embodiment of the utility model, integrated bridge arm driver chip U11's floating power supply is bootstrap circuit, bootstrap circuit includes the parallelly connected body and bootstrap diode D51 of the parallelly connected formation of two bootstrap capacitors C55, C56, the both ends of parallelly connected body are connected respectively integrated bridge arm driver chip U11's high limit is floated ground pin and high limit mains voltage pin, bootstrap diode D51 negative pole is connected to high limit mains voltage pin and anodal low limit mains voltage pin and the power of being connected to driver chip.
Referring to fig. 5, 6 and 7, the chip for IR2110 is composed of three parts: logic input, level conversion and output protection. The logic power supply voltage of the IR2110 chip is 5-20V, and the chip has two independent high-side output channels and low-side output channels. The floating power supply of the IR2110 chip adopts a bootstrap circuit, the high end of the bootstrap circuit can bear 500V working voltage, and the power consumption is only 116mW at 15V. An IR2110 chip can drive the up and down switches of the same bridge arm through both the high-side output channel and the low-side output channel. The IR2110 chip is adopted, so that the size and the power supply of the control device are reduced, the cost is reduced, and the reliability of the system is improved. The working voltage of the IR2110 chip is 5V, and the driving voltage of the MOSFET tube is +15 VCC. The PWM driving signal of the MOSFET of the upper arm is input to the high channel input terminal HIN of the IR2110 chip, and the PWM driving signal of the mos tube of the lower arm is input to the low channel input terminal LIN of the IR2110 chip. Since the on condition of the MOS transistor is that the gate drive voltage Vgs is greater than the threshold voltage, the upper source is not grounded and is floating. When the upper tube is turned on, Vgs is kept larger than the threshold voltage, and the parallel combination of bootstrap capacitors C55 and C56 in cooperation with bootstrap diode D51 may achieve this. The power supply +15VCC charges the bootstrap capacitors C55 and C56, so that the voltages across the capacitors C55 and C56 approach the power supply +15VCC, and the charges on the capacitors C55 and C56 provide power for the high-side drive output. The bootstrap capacitors C55, C56 are switched on or off by the lower tube. The voltage reduction circuit uses the high side driver of the IR2110 chip. When HIN is high, HO output is high relative to the voltage difference +15 vcc.
Bootstrap capacitors C55 and C56 are charged by conduction through the lower tube or through the load ground. The conduction of the lower tube is that when the inductor freewheels, the current of the MOSFET power switch tube is from bottom to top. Therefore, no charging circuit can be provided for the bootstrap capacitors C55 and C56, and the bootstrap capacitors can only be charged by the load. However, in practical debugging, when the load is a resistor, the bootstrap capacitor can realize bootstrap, and the circuit can work normally. When the load is a battery, the bootstrap capacitor is found to be not bootstrapped, i.e. the charging is unsuccessful. The reason is that the battery itself is the power source. When the battery voltage is greater than the charging voltage of the bootstrap capacitor +15VCC, the bootstrap capacitor has no charging circuit, the upper tube cannot be connected, and the circuit cannot work normally. The isolated power supply is therefore connected to + 15V. The positive and negative electrodes are connected to both ends of the bootstrap capacitor, respectively, to solve the attraction problem. When switch Q2 is turned on, the potential of VS is pulled down, and Vcc is charged by bootstrap diode D, bootstrap capacitor C, and switch Q2 to form a closed loop to charge C, so that bootstrap capacitor C forms a floating supply to ensure that when Q2 is off and Q1 is on, the energy stored by bootstrap capacitor C drives the gate of the Q1 tube to achieve bootstrap drive.
Furthermore, the driving circuit comprises an analog-to-digital conversion circuit connected between the sampling circuit and the integrated bridge arm driving chip. Fig. 8 shows a specific circuit structure of an analog-to-digital conversion circuit, which adopts an STM32F4 controller and an AD7606 application circuit thereof. The model of the adopted analog-to-digital conversion chip is AD 7606. Data VOUT acquired by the sampling circuit is converted by an analog-to-digital conversion chip AD7606, the result of AD7606 conversion is input to an integrated bridge arm driving chip, the integrated bridge arm driving chip analyzes and processes the data, and the duty ratio is adjusted by dead time; whether the bus voltage is maintained at 150V or not is judged through output sampling, and when the bus voltage is greater than 150V, the bus voltage is in a discharging mode, and conversely, the bus voltage is in a charging mode. OUT1 is used for judging whether the battery overflows, C1 judges whether the input is too under-voltage, C2 judges whether the battery is too under-voltage. Therefore, the charging and discharging of the storage battery are realized, and the stability of the bus voltage is maintained. The voltage of the photovoltaic cell and the charging and discharging voltage and current of the storage battery can be monitored in real time through the display screen.
In an optional embodiment of the present invention, as shown in fig. 9, the sampling circuit 3 includes:
a current sampling sub-circuit 30 for sampling the output current; and
and the voltage sampling sub-circuit 32 is used for sampling the high-voltage side voltage and the low-voltage side voltage.
Because the converter needs to realize the bidirectional flow of energy, the voltage and the current in the charge-discharge working mode need to be sampled, and the specific sampling objects are as follows: high side voltage V1Low voltage side voltage V2And an output current. Since energy can flow in both directions, the polarity of the high and low voltage sides is constant, and the input and output current directions can be positive or negative.
In an optional embodiment of the present invention, the current sampling sub-circuit 30 includes a current sampling chip based on hall effect and its peripheral circuit. Fig. 10a and 10b show a specific circuit structure of the current sampling sub-circuit. When current sampling is performed, a current signal needs to be converted into a voltage signal, and the conversion method mainly includes current transmission. In the embodiment, the current sampling chip (Hall current sensor) based on the Hall effect is adopted to sample the current, and the method is more accurate and more stable than a sampling resistor mode. The Hall element has small shape, light weight, strong anti-electromagnetic interference capability, accurate sampling and relatively simple off-chip circuit arrangement, and is widely applied to current sampling of power electronic circuits. The embodiment of the utility model provides an adopt ACS712TELC series chip based on hall effect, its leading principle is that when the electric current is from shown pin 1 in fig. 10b, pin 2 flows to pin 3 and pin 4, and hall element produces linear voltage signal based on magnetic field, and voltage signal is through inside enlargiing, and the filtering, chopper and correction circuit output, signal are exported from pin 7 of chip to the electric current of direct reflection copper foil is sampled to current sample. In one implementation, an ACS712telc-30A chip may be used with a good linear relationship between its input and output, with VOUT being 0.5vcc + IP × 0.066.
In an optional embodiment of the present invention, the voltage sampling sub-circuit 32 is a resistance voltage division sampling circuit. Fig. 11 shows a specific circuit configuration of the voltage sampling sub-circuit. By adopting the resistance voltage division sampling circuit, voltage data in the corresponding circuit can be quickly and accurately obtained.
In an optional embodiment of the present invention, the microgrid dual-active full-bridge bidirectional DC-DC converter further includes a sampling signal conditioning circuit connected between the sampling circuit and the driving circuit and used for filtering the sampling signal. Because there is the LC component in the circuit, the PCB overall arrangement can lead to the harmonic in the sampling, leads to the sampling inaccurate and influences the sampling precision, and this embodiment can make the sampling data of transmitting to drive circuit more accurate through still designing the sampling signal conditioning circuit who carries out filtering to the sampling signal.
In an optional embodiment of the present invention, the sampling signal conditioning circuit is a second-order active low pass filter circuit. Fig. 12 shows a specific circuit configuration of the sampling signal conditioning circuit in which a sampling signal is filtered by a second-order active low-pass filter circuit. The low pass filter can only pass low frequency signals below the cut-off frequency or reject high frequency signals. The formula for the cut-off frequency is:
fcut-off＝1/(2.83πRC) (3)
C41＝2C42(4)
R36＝R37(5)
As shown in fig. 12, U9-a forms a second-order active low-pass filter with a resistor and a capacitor, and consists of two RC filter stages and the same phase comparison circuit. The first stage capacitor C is connected to the output and introduces an appropriate amount of positive feedback to improve the amplitude frequency characteristic. U9-b forms a voltage follower making the input and output identical. The second-order active low-pass filter has higher efficiency than a first-order RC low-pass filter, the high-frequency output voltage is reduced more quickly, and the filtering effect is better.
In an optional embodiment of the present invention, as shown in fig. 13, the protection circuit 5 includes:
an overcurrent protection sub-circuit 50;
an over-voltage and under-voltage protection sub-circuit 52;
bus undervoltage protection subcircuit 54.
In the charging mode, the converter load is a battery, which is charged with a constant average current to prevent overcharging and charging. The voltage must have a limit value, so the protection circuit in this mode should have the following functions: output overcurrent protection; output overvoltage protection; and inputting overvoltage protection. In the discharge mode, the converter load is a dissipative resistive load and the power supply is a battery. To prevent the battery from over-discharging, the protection circuit should have the following functions: input undervoltage protection; output overvoltage protection; and outputting overcurrent protection. When the protection circuit operates, the driving signal can be blocked to ensure the safety of the circuit. FIG. 14 shows an overcurrent protection schematic; fig. 15 shows an overvoltage and undervoltage protection schematic diagram, and fig. 16 shows a bus undervoltage protection circuit diagram. As shown in fig. 16, when the voltage value at pin 6 of dual voltage comparator LM393, i.e., the bus voltage sample value, is smaller than the reference value at pin 5, pin 7 outputs a high level. At this time, the LED indicator lamp D20 lights up, the 11 th pin SD of the IR2110 chip is at a high level, the PWM signal output of the IR2110 chip is blocked, the main circuit stops outputting, and the under-voltage protection is realized.
In an alternative embodiment of the present invention, the magnetic core of the high frequency isolation transformer T is a ring-shaped magnetic core made of an iron-based nanocrystal material.
As a core device of the bidirectional DC-DC converter, the working frequency of the high-frequency isolation transformer T is above 20kHz, and the traditional magnetic core materials such as silicon steel cannot meet the high-frequency requirement. Although the ferrite core has low high-frequency loss, saturation magnetic induction (Bs) and curie temperature are low, and thermal stability is poor. In particular, the volume and weight are relatively large, which is contrary to the direction of research into reducing the volume and weight of the entire system by a bidirectional DC/DC converter. In contrast, iron-based nanocrystalline materials have excellent comprehensive magnetic properties, combining the advantages of silicon steel, permalloy and ferrite, namely high saturation magnetic induction, high magnetic permeability, low loss and excellent temperature. Stability is the best material to manufacture the high frequency isolation transformer core of a bi-directional DC-DC converter. The basic magnetic properties of the iron-based nanocrystalline core and ferrite material are shown in table 1 below.
TABLE 1 magnetic Properties of novel iron-based nanocrystalline and ferrite cores
The utility model discloses select for use iron-based nanocrystalline material as high frequency isolation transformer T's annular iron core, can effectively reduce the iron loss of transformer to the conversion efficiency of converter has been improved.
The foregoing description of the embodiments of the present invention has been presented for purposes of illustration and not limitation, and it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. The utility model provides a two active full-bridge two-way DC-DC converter of little electric wire netting, connects between photovoltaic simulator and energy memory, its characterized in that includes:
a high frequency isolation transformer having a high side winding and a low side winding;
the high-frequency inversion rectification circuit comprises a first full-bridge unit which is connected between the high-voltage side winding and the photovoltaic simulator and consists of four MOSFET power switch tubes and a second full-bridge unit which is connected between the low-voltage side winding and the energy storage device and consists of four MOSFET power switch tubes, wherein two MOSFET power switch tubes which are in 180-degree complementary conduction connection are arranged on each bridge arm of the first full-bridge unit and the second full-bridge unit, and the two MOSFET power switch tubes at all diagonal angles are set to be in the same switch and the same switch;
the sampling circuit is used for sampling the output current, the high-voltage side voltage and the low-voltage side voltage;
the driving circuit is connected with the sampling circuit and the first full-bridge unit and the second full-bridge unit, generates and outputs PWM (pulse width modulation) control signals according to output current, high-voltage side voltage and low-voltage side voltage obtained by sampling of the sampling circuit so as to drive the first full-bridge unit and the second full-bridge unit, and comprises integrated bridge arm driving chips and peripheral circuits thereof, wherein the integrated bridge arm driving chips are arranged corresponding to each bridge arm of the first full-bridge unit and the second full-bridge unit, each integrated bridge arm driving chip is provided with an independent high-side output channel and an independent low-side output channel, and simultaneously drives two MOSFET (metal oxide semiconductor field effect transistor) power switching tubes of the same bridge arm through the high-side output channel and the low;
and one end of the protection circuit is connected with the output end of the sampling circuit, the other end of the protection circuit is connected with the driving circuit, and when the circuit is abnormal, a stop signal is sent to the driving circuit to enable the driving circuit to stop outputting the PWM control signal.
2. The microgrid dual-active full-bridge bidirectional DC-DC converter of claim 1, wherein the integrated bridge arm driving chip is an IR2110 chip.
3. The microgrid dual-active full-bridge bidirectional DC-DC converter as claimed in claim 1 or 2, wherein the floating power supply of the integrated bridge arm driving chip is a bootstrap circuit, the bootstrap circuit comprises a parallel connection body formed by two bootstrap capacitors in parallel connection and a bootstrap diode, two ends of the parallel connection body are respectively connected with a high-side floating ground pin and a high-side power supply voltage pin of the driving chip, a cathode of the bootstrap diode is connected to the high-side power supply voltage pin, and an anode of the bootstrap diode is connected to a low-side power supply voltage pin and a power supply of the driving chip.
4. The microgrid dual-active full-bridge bidirectional DC-DC converter of claim 1, wherein the driving circuit comprises an analog-to-digital conversion circuit connected between the sampling circuit and the integrated bridge arm driving chip.
5. The microgrid dual-active full-bridge bidirectional DC-DC converter of claim 1, wherein the sampling circuit comprises:
a current sampling sub-circuit for sampling the output current; and
and the voltage sampling sub-circuit is used for sampling the voltage of the high-voltage side and the voltage of the low-voltage side.
6. The microgrid dual-active full-bridge bidirectional DC-DC converter of claim 5, wherein the current sampling subcircuit comprises a Hall effect based current sampling chip and its peripheral circuits.
7. The microgrid dual-active full-bridge bidirectional DC-DC converter according to claim 5, wherein the voltage sampling sub-circuit is a resistance voltage division sampling circuit.
8. The microgrid dual-active full-bridge bidirectional DC-DC converter according to claim 1, further comprising a sampling signal conditioning circuit connected between the sampling circuit and the driving circuit for filtering a sampling signal, wherein the sampling signal conditioning circuit is a second-order active low-pass filter circuit.
9. The microgrid dual-active full-bridge bidirectional DC-DC converter of claim 1, wherein the protection circuit comprises:
an overcurrent protection sub-circuit;
an over-voltage and under-voltage protection sub-circuit;
and the bus undervoltage protection subcircuit.
10. The microgrid dual-active full-bridge bidirectional DC-DC converter according to claim 1, characterized in that the magnetic core of the high-frequency isolation transformer is a toroidal core made of an iron-based nanocrystalline material.
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| CN201921310389.4U CN210016405U (en) | 2019-08-13 | 2019-08-13 | Micro-grid double-active full-bridge bidirectional DC-DC converter |
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| CN201921310389.4U CN210016405U (en) | 2019-08-13 | 2019-08-13 | Micro-grid double-active full-bridge bidirectional DC-DC converter |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111207864A (en) * | 2020-03-15 | 2020-05-29 | 成都智创利源科技有限公司 | Integrated solar wireless power indicator |
| CN112265451A (en) * | 2020-12-21 | 2021-01-26 | 西南交通大学 | AC380V circuit topological structure of high-speed train emergency self-traveling system |
| CN115864857A (en) * | 2023-02-22 | 2023-03-28 | 江西清华泰豪三波电机有限公司 | Converter and control method thereof |
-
2019
- 2019-08-13 CN CN201921310389.4U patent/CN210016405U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111207864A (en) * | 2020-03-15 | 2020-05-29 | 成都智创利源科技有限公司 | Integrated solar wireless power indicator |
| CN112265451A (en) * | 2020-12-21 | 2021-01-26 | 西南交通大学 | AC380V circuit topological structure of high-speed train emergency self-traveling system |
| CN115864857A (en) * | 2023-02-22 | 2023-03-28 | 江西清华泰豪三波电机有限公司 | Converter and control method thereof |
| CN115864857B (en) * | 2023-02-22 | 2023-05-16 | 江西清华泰豪三波电机有限公司 | Converter and control method thereof |
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