阅读说明：本技术 一种宽输入范围的双向隔离dcdc变换器 (Bidirectional isolation DCDC converter with wide input range ) 是由 丁庆 赵宇明 艾精文 李艳 梁晖 于 2020-04-27 设计创作，主要内容包括：本发明涉及一种宽输入范围的双向隔离DCDC变换器,包括第一级变换器,包括三电平双向DCDC变换器和第一控制模块,三电平双向DCDC变换器的输入端与第一电源/第一负载对应相连；第二级变换器,包括三电平双向隔离变换器和第二控制模块,三电平双向隔离变换器的输入端与三电平双向DCDC变换器的输出端对应相连,三电平双向隔离变换器的输出端与第二负载/第二电源对应相连；中压模块,包括第一电容和第二电容；主控模块,用于获取中压模块的均衡方式,根据均衡方式选择第一级变换器和/或第二级变换器对中压模块进行中压均衡控制。该变换器能够适应较宽的输入电压范围,且效率高,同时在两级电路的控制上均加入了中压均衡控制,运行更为灵活可靠。(The invention relates to a bidirectional isolation DCDC converter with a wide input range, which comprises a first-stage converter, a second-stage converter and a third-stage converter, wherein the first-stage converter comprises a three-level bidirectional DCDC converter and a first control module; the second-stage converter comprises a three-level bidirectional isolation converter and a second control module, wherein the input end of the three-level bidirectional isolation converter is correspondingly connected with the output end of the three-level bidirectional DCDC converter, and the output end of the three-level bidirectional isolation converter is correspondingly connected with a second load/a second power supply; the medium-voltage module comprises a first capacitor and a second capacitor; and the main control module is used for acquiring the balance mode of the medium-voltage module and selecting the first-stage converter and/or the second-stage converter to perform medium-voltage balance control on the medium-voltage module according to the balance mode. The converter can adapt to a wider input voltage range, is high in efficiency, simultaneously adds medium-voltage balance control on the control of two stages of circuits, and is more flexible and reliable in operation.)

1. A wide input range bi-directional isolated DCDC converter, comprising:

the first-stage converter comprises a three-level bidirectional DCDC converter and a first control module, wherein the input end of the three-level bidirectional DCDC converter is correspondingly connected with a first power supply/a first load, and the first control module is used for controlling the three-level bidirectional DCDC converter to perform voltage conversion;

the second-stage converter comprises a three-level bidirectional isolation converter and a second control module, wherein the input end of the three-level bidirectional isolation converter is correspondingly connected with the output end of the three-level bidirectional DCDC converter, the output end of the three-level bidirectional isolation converter is correspondingly connected with a second load/a second power supply, and the second control module is used for controlling the three-level bidirectional isolation converter to perform voltage conversion;

the medium-voltage module comprises a first capacitor and a second capacitor, one end of the first capacitor is connected with a first output end of the three-level bidirectional DCDC converter and a first input end of the three-level bidirectional isolation converter, one end of the second capacitor is connected with the other end of the first capacitor, a second output end of the three-level bidirectional DCDC converter and a second input end of the three-level bidirectional isolation converter, and the other end of the second capacitor is connected with a third output end of the three-level bidirectional DCDC converter and a third input end of the three-level bidirectional isolation converter and used for filtering an intermediate voltage;

and the main control module is connected with the first-stage converter and the second-stage converter and is used for acquiring the balance mode of the medium-voltage module and selecting the first-stage converter and/or the second-stage converter to perform medium-voltage balance control on the medium-voltage module according to the balance mode.

2. The wide input range bi-directional isolation DCDC converter of claim 1, wherein said equalization manner includes a first coefficient K1 and a second coefficient K2, and K1+ K2 is 1, wherein,

when K1 is equal to 1, selecting the first-stage converter to perform medium-voltage balance control on the medium-voltage module;

when K1 is more than 0 and less than 1, the first-stage converter and the second-stage converter are selected to perform medium-voltage balance control on the medium-voltage module;

and when K1 is equal to 0, selecting the second-stage converter to perform medium-voltage balance control on the medium-voltage module.

3. The wide input range bi-directional isolation DCDC converter of claim 2, wherein the three-level bi-directional DCDC converter comprises:

one end of the first inductor is used as a first input end of the three-level bidirectional DCDC converter, one end of the second inductor is used as a second input end of the three-level bidirectional DCDC converter, and two ends of the input capacitor are correspondingly connected with the first input end and the second input end of the three-level bidirectional DCDC converter;

from last first to fourth switch tube to serial connection in proper order down, and the first end of first switch tube is as the first output of three-level bidirectional DCDC converter, the tie point of first switch tube and second switch tube with the other end of first inductance links to each other, the tie point of second switch tube and third switch tube is as the second output of three-level bidirectional DCDC converter, the tie point of third switch tube and fourth switch tube with the other end of second inductance links to each other, the second end of fourth switch tube is as the third output of three-level bidirectional DCDC converter.

4. The wide input range bi-directional isolation DCDC converter of claim 3, wherein the first control module comprises:

the medium-voltage control unit is used for obtaining a first duty ratio of the three-level bidirectional DCDC converter by adopting a double closed-loop control strategy according to the intermediate voltage, the intermediate voltage target value and the input current;

the first voltage-sharing control unit is used for acquiring a first regulating quantity according to the voltage of the second capacitor, the voltage-sharing target value and the first coefficient;

and the first signal modulation unit is used for generating a control signal of the three-level bidirectional DCDC converter according to the first duty ratio and the first regulating quantity.

5. The wide input range bi-directional isolation DCDC converter of claim 4, wherein the medium voltage control unit comprises: the first subtractor is used for calculating a difference value between the intermediate voltage target value and the intermediate voltage to obtain a first voltage difference value, the first regulator is used for regulating the first voltage difference value to obtain an input current target value, the second subtractor is used for calculating a difference value between the input current target value and the input current to obtain a first current difference value, and the second regulator is used for regulating the first current difference value to obtain the first duty ratio;

the first voltage-sharing control unit includes: the third subtractor is used for calculating a difference value between the voltage-sharing target value and the voltage of the second capacitor to obtain a second voltage difference value, the third adjustor is used for adjusting the second voltage difference value to obtain a second adjustment amount, and the first multiplier is used for calculating a product of the second adjustment amount and the first coefficient to obtain the first adjustment amount;

the first signal modulation unit includes: a first adder, a first comparator, a first inverter, a fourth subtractor, a fifth subtractor, a second comparator and a second inverter, the first adder is used for calculating the sum of the first duty ratio and the first regulating quantity to obtain a second duty ratio, the first comparator is used for obtaining a second control signal according to the second duty ratio and a preset carrier, the first inverter is used for inverting the second control signal to obtain a first control signal, the fourth subtractor is used for calculating the difference between the first duty cycle and the first regulating quantity to obtain a third duty cycle, the fifth subtracter is used for calculating the difference value between the third duty ratio and the preset duty ratio to obtain a fourth duty ratio, the second comparator is configured to obtain a fourth control signal according to the fourth duty cycle and the preset carrier, and the second inverter is configured to invert the fourth control signal to obtain a third control signal.

6. The wide input range bidirectional isolated DCDC converter of claim 2, wherein the three-level bidirectional isolated converter comprises:

the primary side full bridge circuit comprises fifth to eighth switching tubes connected in series from top to bottom, ninth to twelfth switching tubes connected in series from top to bottom, and first to fourth diodes, wherein a first end of the fifth switching tube and a first end of the ninth switching tube are connected and then serve as a first input end of the three-level bidirectional isolating converter, a connecting point of the fifth switching tube and the sixth switching tube is connected with a cathode of the first diode, a connecting point of the sixth switching tube and the seventh switching tube serves as a first output end of the primary side full bridge circuit, a connecting point of the seventh switching tube and the eighth switching tube is connected with an anode of the second diode, a connecting point of the ninth switching tube and the tenth switching tube is connected with a cathode of the third diode, a connecting point of the tenth switching tube and the eleventh switching tube serves as a second output end of the primary side full bridge circuit, and a connecting point of the eleventh switching tube and the twelfth switching tube is connected with an anode of the fourth diode, an anode of the first diode, a cathode of the second diode, an anode of the third diode and a cathode of the fourth diode are connected to serve as a second input end of the three-level bidirectional isolation converter, and a second end of the eighth switch tube and a second end of the twelfth switch tube are connected to serve as a third input end of the three-level bidirectional isolation converter;

the first end of the transformer is connected with the first output end of the primary side full-bridge circuit, and the second end of the transformer is connected with the second output end of the primary side full-bridge circuit;

the secondary side full-bridge circuit comprises thirteenth to sixteenth switching tubes, wherein the first end of the thirteenth switching tube is connected with the first end of the fourteenth switching tube and then connected with the third end of the transformer, the first end of the fifteenth switching tube is connected with the first end of the sixteenth switching tube and then connected with the fourth end of the transformer, the second end of the thirteenth switching tube is connected with the second end of the fifteenth switching tube and then used as the first output end of the three-level bidirectional isolating converter, and the second end of the fourteenth switching tube is connected with the second end of the sixteenth switching tube and then used as the second output end of the three-level bidirectional isolating converter.

7. The wide input range bi-directional isolation DCDC converter of claim 6, wherein the second control module comprises:

the output voltage control unit is used for obtaining a fifth duty ratio of the three-level bidirectional isolation converter by adopting a double closed-loop control strategy according to the output voltage, the output voltage target value and the output current;

the second voltage-sharing control unit is used for acquiring a third regulating quantity according to the voltage of the second capacitor, the voltage-sharing target value and the second coefficient;

the carrier phase shifting unit is used for carrying out phase shifting processing on a preset carrier according to the fifth duty ratio and a preset carrier period to obtain a first carrier;

and the second signal modulation unit is used for obtaining a control signal of the three-level bidirectional isolation converter according to the third regulating quantity, the preset carrier wave, the first carrier wave and a preset modulation wave.

8. The wide input range bidirectional isolation DCDC converter of claim 7, wherein the output voltage control unit comprises: the voltage regulator comprises a sixth subtracter, a fourth regulator, a seventh subtracter and a fifth regulator, wherein the sixth subtracter is used for calculating the difference value between the output voltage target value and the output voltage to obtain a third voltage difference value, the fourth regulator is used for regulating the third voltage difference value to obtain an output current target value, the seventh subtracter is used for calculating the difference value between the output current target value and the output current to obtain a second current difference value, and the fifth regulator is used for regulating the second current difference value to obtain the fifth duty ratio;

the second voltage-sharing control unit includes: the voltage-equalizing control circuit comprises an eighth subtracter, a sixth regulator and a second multiplier, wherein the eighth subtracter is used for calculating a difference value between the voltage-equalizing target value and the voltage of the second capacitor to obtain a fourth voltage difference value, the sixth regulator is used for regulating the fourth voltage difference value to obtain a fourth regulating quantity, and the second multiplier is used for calculating a product of the fourth regulating quantity and the second coefficient to obtain the third regulating quantity;

the carrier phase shift unit includes: the first divider is used for calculating a quotient between the fifth duty cycle and the preset carrier period to obtain a phase shift angle, and the first phase shifter is used for performing phase shift processing on the preset carrier according to the phase shift angle to obtain the first carrier;

the second signal modulation unit includes: a second adder for obtaining a first modulated wave from the third adjustment amount and the preset modulated wave, a ninth subtractor for obtaining a second modulated wave from the third adjustment amount and the preset modulated wave, a third comparator for obtaining a fifth control signal from the first modulated wave and the preset carrier, a fourth comparator for obtaining a sixth control signal from the preset modulated wave and the preset carrier, a third inverter for obtaining a seventh control signal by inverting the sixth control signal, a fifth comparator for obtaining an eighth control signal from the second modulated wave and the preset carrier, a sixth comparator for obtaining a ninth control signal from the first modulated wave and the first carrier, the seventh comparator is configured to obtain a tenth control signal according to the preset modulation wave and the first carrier, the fourth inverter is configured to obtain an eleventh control signal in an inverted manner with respect to the tenth control signal, the eighth comparator is configured to obtain a twelfth control signal according to the second modulation wave and the first carrier, the first or gate is configured to obtain a thirteenth control signal according to the sixth control signal and the eleventh control signal, and the second or gate is configured to obtain a fourteenth control signal according to the seventh control signal and the tenth control signal.

9. The wide input range bi-directional isolation DCDC converter of claim 6, further comprising a clamp circuit, the clamp circuit comprising:

a first end of the clamping switch tube is connected with a first output end of the three-level bidirectional isolation converter;

and one end of the clamping capacitor is connected with the second end of the clamping switch tube, and the other end of the clamping capacitor is connected with the second output end of the three-level bidirectional isolation converter.

10. The wide input range bidirectional isolation DCDC converter according to claim 9, wherein the main control module is further configured to control the clamp switch tube to be turned on at a first preset time after the control signals of the thirteenth switch tube and the sixteenth switch tube are ended, and to control the clamp switch tube to be turned off at a second preset time before the control signals of the thirteenth switch tube and the sixteenth switch tube come; and the clamping switch tube is controlled to be switched on at a first preset time after the control signals of the fourteenth switch tube and the fifteenth switch tube are finished, and the clamping switch tube is controlled to be switched off at a second preset time before the control signals of the fourteenth switch tube and the fifteenth switch tube arrive.

Technical Field

The invention relates to the technical field of power supplies, in particular to a bidirectional isolation DCDC converter with a wide input range.

Background

The bidirectional isolation DCDC converter is more and more widely applied, and the current commonly used bidirectional isolation DCDC converter comprises a double-active full-bridge type (DAB), a resonance conversion type (LL C) and the like, wherein the double-active full-bridge type can adapt to a wider input voltage range, but the efficiency is influenced because of the circulation current existing between the original secondary side and the original secondary side, and the resonance conversion type can effectively improve the efficiency of the converter, but the working point can only change near the resonance point, so the bidirectional isolation DCDC converter cannot adapt to the wider input voltage range.

Disclosure of Invention

Accordingly, there is a need for a wide input range bi-directional isolated DCDC converter that can accommodate a wide input voltage range and is efficient.

A wide input range bi-directional isolated DCDC converter comprising:

the first-stage converter comprises a three-level bidirectional DCDC converter and a first control module, wherein the input end of the three-level bidirectional DCDC converter is correspondingly connected with the first power supply/first load, and the first control module is used for controlling the three-level bidirectional DCDC converter to perform voltage conversion;

the second-stage converter comprises a three-level bidirectional isolation converter and a second control module, wherein the input end of the three-level bidirectional isolation converter is correspondingly connected with the output end of the three-level bidirectional DCDC converter, the output end of the three-level bidirectional isolation converter is correspondingly connected with a second load/a second power supply, and the second control module is used for controlling the three-level bidirectional isolation converter to carry out voltage conversion;

the medium-voltage module comprises a first capacitor and a second capacitor, one end of the first capacitor is connected with a first output end of the three-level bidirectional DCDC converter and a first input end of the three-level bidirectional isolation converter, one end of the second capacitor is connected with the other end of the first capacitor, a second output end of the three-level bidirectional DCDC converter and a second input end of the three-level bidirectional isolation converter, and the other end of the second capacitor is connected with a third output end of the three-level bidirectional DCDC converter and a third input end of the three-level bidirectional isolation converter and used for filtering intermediate voltage;

and the main control module is connected with the first-stage converter and the second-stage converter and is used for acquiring the balance mode of the medium-voltage module and selecting the first-stage converter and/or the second-stage converter to perform medium-voltage balance control on the medium-voltage module according to the balance mode.

In one embodiment, the equalization pattern includes a first coefficient K1 and a second coefficient K2, and K1+ K2 is 1, wherein,

when K1 is equal to 1, selecting a first-stage converter to perform medium-voltage balance control on a medium-voltage module;

when K1 is more than 0 and less than 1, selecting a first-stage converter and a second-stage converter to perform medium-voltage balance control on the medium-voltage module;

when K1 is equal to 0, the second-stage converter is selected to perform medium-voltage balance control on the medium-voltage module.

In one embodiment, a three-level bidirectional DCDC converter includes:

the three-level bidirectional DCDC converter comprises a first inductor, a second inductor and an input capacitor, wherein one end of the first inductor is used as a first input end of the three-level bidirectional DCDC converter, one end of the second inductor is used as a second input end of the three-level bidirectional DCDC converter, and two ends of the input capacitor are correspondingly connected with the first input end and the second input end of the three-level bidirectional DCDC converter;

the first end of the first switch tube is used as the first output end of the three-level bidirectional DCDC converter, the connection point of the first switch tube and the second switch tube is connected with the other end of the first inductor, the connection point of the second switch tube and the third switch tube is used as the second output end of the three-level bidirectional DCDC converter, the connection point of the third switch tube and the fourth switch tube is connected with the other end of the second inductor, and the second end of the fourth switch tube is used as the third output end of the three-level bidirectional DCDC converter.

In one embodiment, the first control module comprises:

the medium-voltage control unit is used for obtaining a first duty ratio of the three-level bidirectional DCDC converter by adopting a double closed-loop control strategy according to the intermediate voltage, the intermediate voltage target value and the input current;

the first voltage-sharing control unit is used for acquiring a first regulating quantity according to the voltage of the second capacitor, a voltage-sharing target value and a first coefficient;

and the first signal modulation unit is used for generating a control signal of the three-level bidirectional DCDC converter according to the first duty ratio and the first regulating quantity.

In one embodiment, the medium voltage control unit comprises: the first subtractor is used for calculating a difference value between an intermediate voltage target value and an intermediate voltage to obtain a first voltage difference value, the first regulator is used for regulating the first voltage difference value to obtain an input current target value, the second subtractor is used for calculating a difference value between the input current target value and an input current to obtain a first current difference value, and the second regulator is used for regulating the first current difference value to obtain a first duty ratio;

the first voltage-sharing control unit includes: the third subtractor is used for calculating a difference value between the voltage-sharing target value and the voltage of the second capacitor to obtain a second voltage difference value, the third adjustor is used for adjusting the second voltage difference value to obtain a second adjustment quantity, and the first multiplier is used for calculating a product of the second adjustment quantity and the first coefficient to obtain a first adjustment quantity;

the first signal modulation unit includes: the first adder is used for calculating the sum of a first duty ratio and a first regulating quantity to obtain a second duty ratio, the first comparator is used for obtaining a second control signal according to the second duty ratio and a preset carrier, the first inverter is used for reversely obtaining the first control signal according to the second duty ratio, the fourth subtractor is used for calculating the difference value between the first duty ratio and the first regulating quantity to obtain a third duty ratio, the fifth subtractor is used for calculating the difference value between the third duty ratio and the preset duty ratio to obtain a fourth duty ratio, the second comparator is used for obtaining a fourth control signal according to the fourth duty ratio and the preset carrier, and the second inverter is used for reversely obtaining a third control signal according to the fourth control signal.

In one embodiment, a three-level bidirectional isolation converter comprises:

the primary side full bridge circuit comprises fifth to eighth switching tubes connected in series from top to bottom, ninth to twelfth switching tubes connected in series from top to bottom, and first to fourth diodes, wherein the first end of the fifth switching tube and the first end of the ninth switching tube are connected to serve as the first input end of the three-level bidirectional isolating converter, the connection point of the fifth switching tube and the sixth switching tube is connected with the cathode of the first diode, the connection point of the sixth switching tube and the seventh switching tube serves as the first output end of the primary side full bridge circuit, the connection point of the seventh switching tube and the eighth switching tube is connected with the anode of the second diode, the connection point of the ninth switching tube and the tenth switching tube is connected with the cathode of the third diode, the connection point of the tenth switching tube and the eleventh switching tube serves as the second output end of the primary side full bridge circuit, the connection point of the eleventh switching tube and the twelfth switching tube is connected with the anode of the fourth diode, the anode of the first diode, the cathode of the second diode, the anode of the third diode and the cathode of the fourth diode are connected and then serve as a second input end of the three-level bidirectional isolation converter, and the second end of the eighth switch tube and the second end of the twelfth switch tube are connected and then serve as a third input end of the three-level bidirectional isolation converter;

the first end of the transformer is connected with the first output end of the primary side full-bridge circuit, and the second end of the transformer is connected with the second output end of the primary side full-bridge circuit;

the secondary side full-bridge circuit comprises thirteenth to sixteenth switching tubes, wherein a first end of the thirteenth switching tube is connected with a third end of the transformer after being connected with a first end of the fourteenth switching tube, a first end of the fifteenth switching tube is connected with a first end of the sixteenth switching tube and then is connected with a fourth end of the transformer, a second end of the thirteenth switching tube is connected with a second end of the fifteenth switching tube and then is used as a first output end of the three-level bidirectional isolation converter, and a second end of the fourteenth switching tube is connected with a second end of the sixteenth switching tube and then is used as a second output end of the three-level bidirectional isolation converter.

In one embodiment, the second control module comprises:

the output voltage control unit is used for obtaining a fifth duty ratio of the three-level bidirectional isolation converter by adopting a double closed-loop control strategy according to the output voltage, the output voltage target value and the output current;

the second voltage-sharing control unit is used for acquiring a third regulating quantity according to the voltage of the second capacitor, the voltage-sharing target value and the second coefficient;

the carrier phase shifting unit is used for performing phase shifting processing on the preset carrier according to the fifth duty ratio and the preset carrier period to obtain a first carrier;

and the second signal modulation unit is used for obtaining a control signal of the three-level bidirectional isolation converter according to the third regulating quantity, the preset carrier wave, the first carrier wave and the preset modulation wave.

In one embodiment, the output voltage control unit includes: the third voltage difference value is calculated to obtain a third voltage difference value, the fourth regulator is used for regulating the third voltage difference value to obtain an output current target value, the seventh subtractor is used for calculating the difference value between the output current target value and the output current to obtain a second current difference value, and the fifth regulator is used for regulating the second current difference value to obtain a fifth duty ratio;

the second voltage-sharing control unit includes: the voltage-sharing control circuit comprises an eighth subtracter, a sixth regulator and a second multiplier, wherein the eighth subtracter is used for calculating the difference between a voltage-sharing target value and the voltage of the second capacitor to obtain a fourth voltage difference value, the sixth regulator is used for regulating the fourth voltage difference value to obtain a fourth regulating quantity, and the second multiplier is used for calculating the product of the fourth regulating quantity and a second coefficient to obtain a third regulating quantity;

the carrier phase shift unit includes: the first divider is used for calculating a quotient between the fifth duty ratio and a preset carrier period to obtain a phase shift angle, and the first phase shifter is used for performing phase shift processing on a preset carrier according to the phase shift angle to obtain a first carrier;

the second signal modulation unit includes: a second adder for obtaining a first modulated wave from a third adjustment amount and a preset modulated wave, a ninth subtractor for obtaining a second modulated wave from the third adjustment amount and the preset modulated wave, a ninth comparator for obtaining a sixth control signal from the preset modulated wave and a preset carrier wave, a third inverter for obtaining a seventh control signal in reverse to the sixth control signal, a fifth comparator for obtaining an eighth control signal from the second modulated wave and the preset carrier wave, a sixth comparator for obtaining a ninth control signal from the first modulated wave and the first carrier wave, a seventh comparator for obtaining a tenth control signal from the preset modulated wave and the first carrier wave, the fourth inverter is used for inverting the tenth control signal to obtain an eleventh control signal, the eighth comparator is used for obtaining a twelfth control signal according to the second modulation wave and the first carrier wave, the first or gate is used for obtaining a thirteenth control signal according to the sixth control signal and the eleventh control signal, and the second or gate is used for obtaining a fourteenth control signal according to the seventh control signal and the tenth control signal.

In one embodiment, the bidirectional isolation DCDC converter further comprises a clamp circuit, the clamp circuit comprising:

the first end of the clamping switch tube is connected with the first output end of the three-level bidirectional isolation converter;

and one end of the clamping capacitor is connected with the second end of the clamping switch tube, and the other end of the clamping capacitor is connected with the second output end of the three-level bidirectional isolation converter.

In one embodiment, the main control module is further configured to control the clamp switching tube to be turned on at a first preset time after the control signals of the thirteenth switching tube and the sixteenth switching tube are ended, and control the clamp switching tube to be turned off at a second preset time before the control signals of the thirteenth switching tube and the sixteenth switching tube arrive; and controlling the clamp switching tube to be switched on at a first preset time after the control signals of the fourteenth switching tube and the fifteenth switching tube are ended, and controlling the clamp switching tube to be switched off at a second preset time before the control signals of the fourteenth switching tube and the fifteenth switching tube arrive.

The wide-input-range bidirectional isolation DCDC converter comprises a first-stage converter, a second-stage converter, a medium-voltage module and a main control module, wherein the first-stage converter further comprises a three-level bidirectional DCDC converter and a first control module, the input end of the three-level bidirectional DCDC converter is correspondingly connected with a first power supply/a first load, the second-stage converter further comprises a three-level bidirectional isolation converter and a second control module, the input end of the three-level bidirectional isolation converter is correspondingly connected with the output end of the three-level bidirectional DCDC converter, the output end of the three-level bidirectional isolation converter is correspondingly connected with a second load/a second power supply, the medium-voltage module comprises a first capacitor and a second capacitor and is used for filtering intermediate voltage, and the main control module is connected with the first-stage converter and the second-stage converter and is used for acquiring a balancing mode of the medium-voltage module, and selecting the first-stage converter and/or the second-stage converter to perform medium-voltage balance control on the medium-voltage module according to the balance mode. The converter adopts a two-stage circuit structure, the first stage is a three-level bidirectional DCDC converter and can adapt to a wider input voltage range, the second stage is a three-level bidirectional isolation converter and can realize the bidirectional flow and isolation functions of power, the efficiency is high, meanwhile, medium-voltage balance control is added to the control of the two-stage circuit, and the operation is more flexible and reliable.

Drawings

FIG. 1 is a topology diagram of a wide input range bi-directional isolated DCDC converter in one embodiment;

FIG. 2 is a control schematic of a first control module in one embodiment;

FIG. 3 is a control schematic of a second control module in one embodiment;

fig. 4 is a timing diagram for control of the clamp circuit in one embodiment.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

Fig. 1 is a topology diagram of a wide input range bidirectional isolation DCDC converter in an embodiment, and referring to fig. 1, the wide input range bidirectional isolation DCDC converter includes: a first stage converter, a second stage converter, a medium voltage module 30 and a master control module 40.

Specifically, the first-stage converter includes a three-level bidirectional DCDC converter 11 and a first control module 12, an input end of the three-level bidirectional DCDC converter 11 is correspondingly connected to the first power supply/the first load, and the first control module 12 is configured to control the three-level bidirectional DCDC converter 11 to perform voltage conversion.

In one embodiment, the three-level bidirectional DCDC converter 11 comprises a first inductor L1, a second inductor L2, an input capacitor CIN and first to fourth switching tubes, wherein one end of the first inductor L1 is connected with one end of a first power supply/first load as a first input end of the three-level bidirectional DCDC converter 11, one end of the second inductor L2 is connected with the other end of the first power supply/first load as a second input end of the three-level bidirectional DCDC converter 11, two ends of the input capacitor CIN are correspondingly connected with the first input end and the second input end of the three-level bidirectional DCDC converter 11, and the first to fourth switching tubes are sequentially connected in series from top to bottomA first end of the first switch tube Q1 is used as a first output end of the three-level bidirectional DCDC converter 11, a connection point of the first switch tube Q1 and the second switch tube Q2 is connected to the other end of the first inductor L1, a connection point of the second switch tube Q2 and the third switch tube Q3 is used as a second output end of the three-level bidirectional DCDC converter 11, a connection point of the third switch tube Q3 and the fourth switch tube Q4 is connected to the other end of the second inductor L2, a second end of the fourth switch tube Q4 is used as a third output end of the three-level bidirectional DCDC converter 11, that is, the switch tubes Q1-Q4, the inductors L1-L2 and the capacitor CIN form a first stage circuit, the inductors L1-L2 are boost inductors, the capacitor CIN is an input filter capacitor, the switch tubes Q1-Q4 may be MOSFETs with antiparallel diodes, the first control module 12 controls the switch tubes Q1-Q4 to turn on and turn off the first stage voltage of the first control module, for providing the first stage voltage conversion for the first stage voltage of the first control module_inVoltage conversion is carried out to obtain an intermediate voltage U_M。

The second-stage converter comprises a three-level bidirectional isolation converter 21 and a second control module 22, an input end of the three-level bidirectional isolation converter 21 is correspondingly connected with an output end of the three-level bidirectional DCDC converter 11, an output end of the three-level bidirectional isolation converter 21 is correspondingly connected with a second load/a second power supply, and the second control module 22 is used for controlling the three-level bidirectional isolation converter 21 to perform voltage conversion.

In one embodiment, the three-level bidirectional isolation converter 21 includes: a primary side full bridge circuit, a transformer T and a secondary side full bridge circuit. The primary side full bridge circuit comprises fifth to eighth switching tubes connected in series from top to bottom, ninth to twelfth switching tubes connected in series from top to bottom and first to fourth diodes, a first end of the fifth switching tube Q5 is connected with a first end of the ninth switching tube Q9 and then serves as a first input end of the three-level bidirectional isolation converter 21, a connection point of the fifth switching tube Q5 and the sixth switching tube Q6 is connected with a cathode of the first diode D1, a connection point of the sixth switching tube Q6 and the seventh switching tube Q7 is used as a first output end of the primary side full bridge circuit, a connection point of the seventh switching tube Q7 and the eighth switching tube Q8 is connected with an anode of the second diode D2, and a connection point of the ninth switching tube Q9 and the tenth switching tube Q10 is connected with the third diode D103, the connection point of the tenth switching tube Q10 and the eleventh switching tube Q11 serves as the second output end of the primary side full bridge circuit, the connection point of the eleventh switching tube Q11 and the twelfth switching tube Q12 is connected with the anode of the fourth diode D4, the anode of the first diode D1, the cathode of the second diode D2, the anode of the third diode D3 and the cathode of the fourth diode D4 are connected and then serve as the second input end of the three-level bidirectional isolation converter 21, and the second end of the eighth switching tube Q8 and the second end of the twelfth switching tube Q12 are connected and then serve as the third input end of the three-level bidirectional isolation converter 21. The first end of the transformer T is connected with the first output end of the primary side full-bridge circuit, and the second end of the transformer T is connected with the second output end of the primary side full-bridge circuit. The secondary side full-bridge circuit comprises thirteenth to sixteenth switching tubes, a first end of the thirteenth switching tube Q13 is connected with a first end of the fourteenth switching tube Q14 and then connected with a third end of the transformer T, a first end of the fifteenth switching tube Q15 is connected with a first end of the sixteenth switching tube Q16 and then connected with a fourth end of the transformer T, a second end of the thirteenth switching tube Q13 is connected with a second end of the fifteenth switching tube Q15 and then connected with one end of the second load/second power source as a first output end of the three-level bidirectional isolation converter 21, and a second end of the fourteenth switching tube Q14 is connected with a second end of the sixteenth switching tube Q16 and then connected with the other end of the second load/second power source as a second output end of the three-level bidirectional isolation converter 21. That is, the switching tubes Q5-Q16, the diodes D1-D4 and the transformer T form a second stage circuit, the current source type three-level bidirectional isolation converter, further, the switching tubes Q5-Q12 and the diodes D1-D4 form a primary side three-level full bridge circuit, the switching tubes Q13-Q16 form a secondary side full bridge circuit, the primary side three-level full bridge circuit and the secondary side full bridge circuit are connected through the transformer T, the transformer T is an isolation transformer, the diodes D1-D4 are diode clamps, the switching tubes Q5-Q16 can be MOSFETs with anti-parallel diodes, the second control module 22 controls the on and off of the switching tubes Q5-Q16 to realize the voltage conversion of the second stage circuit, for example, the intermediate voltage U5-Q16 is switched on and off_MPerforming voltage conversion to obtain output voltage U_O。

The medium voltage module 30 comprises a first capacitor C1 and a second capacitor COne end of a first capacitor C1 is connected with a first output end of the three-level bidirectional DCDC converter 11 and a first input end of the three-level bidirectional isolation converter 21, one end of a second capacitor C2 is connected with the other end of the first capacitor C1, a second output end of the three-level bidirectional DCDC converter 11 and a second input end of the three-level bidirectional isolation converter 21, and the other end of a second capacitor C2 is connected with a third output end of the three-level bidirectional DCDC converter 11 and a third input end of the three-level bidirectional isolation converter 21 for filtering the intermediate voltage. That is, capacitors C1-C2 form a medium voltage module 30 between the first stage circuit and the second stage circuit for centering the intermediate voltage U_MAnd (6) carrying out filtering processing.

The main control module 40 is connected to the first-stage converter and the second-stage converter, and is configured to obtain a balancing manner of the medium-voltage module 30, and select the first-stage converter and/or the second-stage converter to perform medium-voltage balancing control on the medium-voltage module 30 according to the balancing manner. That is to say, this application both can be realized middling pressure balanced control by first order converter, can realize middling pressure balanced control by second order converter again, can also be realized by both jointly, so not only can effectively solve the problem of operation in-process intermediate voltage unbalance, the problem of the both ends voltage unbalance of first electric capacity and the both ends voltage unbalance of second electric capacity promptly, the operation is nimble reliable moreover.

In this embodiment, a two-stage circuit structure is adopted, the first stage is a three-level bidirectional DCDC converter and can adapt to a wider input voltage range, the second stage is a current type three-level bidirectional isolation converter with a primary three-level full bridge structure and a secondary full bridge structure, bidirectional flow and isolation functions of power can be realized, efficiency is high, medium voltage balance control is added to control of two-stage circuits, a certain stage or two stages can be selected to jointly exert force, medium voltage balance control is realized, and work is more flexible and reliable.

In one embodiment, the equalization manner includes a first coefficient K1 and a second coefficient K2, and K1+ K2 is 1, wherein when K1 is 1, the first stage transformer is selected to perform the medium voltage equalization control on the medium voltage module 30; when K1 is more than 0 and less than 1, the first-stage converter and the second-stage converter are selected to perform medium-voltage balance control on the medium-voltage module 30; when K1 is equal to 0, the second-stage converter is selected to perform the medium-voltage equalization control on the medium-voltage module 30.

That is, the two stages can realize the balance control of the intermediate direct-current voltage, and the adjustment coefficients K1 and K2 can select to realize the voltage sharing control of the upper and lower capacitors, namely the first capacitor C1 and the second capacitor C2, by the first-stage converter, when K1 is equal to 1; when K1 is equal to 0, the control is completely carried out by the second-stage converter; when K1 is between 0 ~ 1, accomplish voltage-sharing control by first order converter and second converter in proportion to not only can effectively solve the unbalanced problem of middle voltage among the operation process, the operation is nimble reliable moreover.

In one embodiment, as shown with reference to FIG. 2, the first control module 12 includes: a medium voltage control unit 121, a first voltage-sharing control unit 122 and a first signal modulation unit 123, the medium voltage control unit 121 being configured to control the medium voltage U according to the intermediate voltage U_MIntermediate voltage target valueAnd an input current i_INObtaining a first duty ratio D of the three-level bidirectional DCDC converter 11 by adopting a double closed-loop control strategy₁For example, a double closed loop control strategy of a voltage outer loop and a current inner loop is adopted; the first voltage-sharing control unit 122 is used for controlling the voltage U according to the voltage of the second capacitor_C2Voltage-sharing target valueAnd the first coefficient K1 to obtain a first regulating variable Delta D₁Target value of voltage equalizationIs an intermediate voltage U_MOne half of (a); the first signal modulation unit 123 is configured to modulate the signal according to the first duty ratio D₁And a first regulating quantity DeltaD₁And generating a control signal of the three-level bidirectional DCDC converter 11 to control the on-off of the switching tubes Q1-Q4.

In one embodiment, shown with continued reference to FIG. 2, whereinThe voltage control unit 121 includes: a first subtractor for calculating an intermediate voltage target value, a first regulator, a second subtractor and a second regulatorAnd an intermediate voltage U_MObtaining a first voltage difference value according to the difference value; the first regulator is used for regulating (such as PI regulating) the first voltage difference value to obtain the target value of the input currentThe second subtracter is used for calculating an input current target valueAnd an input current i_INObtaining a first current difference value according to the difference value; the second regulator is used for regulating (such as PI regulating) the first current difference value to obtain a first duty ratio D₁。

The first voltage equalizing control unit 122 includes: a third subtracter for calculating a voltage-sharing target value, a third regulator and a first multiplierVoltage U of the second capacitor_C2Obtaining a second voltage difference value according to the difference value; the third regulator is used for regulating (such as P regulating) the second voltage difference value to obtain a second regulating quantity; the first multiplier is used for calculating the product of the second regulating quantity and the first coefficient K1 to obtain a first regulating quantity delta D₁。

The first signal modulation unit 123 includes: a first adder for calculating a first duty ratio D, a first comparator, a first inverter, a fourth subtractor, a fifth subtractor, a second comparator and a second inverter₁And a first adjustment quantity Delta D₁Summing to obtain a second duty cycle; the first comparator is used for obtaining a second control signal according to the second duty ratio and a preset carrier and is used for controlling the on-off of the second switching tube Q2; the first inverter is used for inverting the second control signal to obtain the first control signal, and is used for inverting the first control signal to the first switch tube Q1Performing on-off control; the fourth subtracter is used for calculating the first duty ratio D₁And a first adjustment quantity Delta D₁The difference between the first duty cycle and the second duty cycle; the fifth subtracter is used for calculating the difference value between the third duty ratio and the preset duty ratio (such as 1) to obtain a fourth duty ratio; the second comparator is used for obtaining a fourth control signal according to the fourth duty cycle and a preset carrier, and is used for controlling the on-off of the fourth switching tube Q4; the second inverter is used for inverting the fourth control signal to obtain a third control signal, and is used for controlling the on-off of the third switching tube Q3. The first to fourth control signals are PWM control signals, and voltage conversion is realized by on-off control of corresponding switch tubes.

In this embodiment, a double closed-loop control strategy of an outer loop and an inner loop of voltage and current is adopted to control the first-stage circuit three-level bidirectional DCDC converter, and upper and lower capacitor voltage-sharing control of an intermediate direct-current link is added, so that the input voltage with wide-range change is converted into a stable intermediate direct-current voltage, namely, the intermediate voltage, and the whole converter can adapt to a higher input voltage and a wider input voltage change range.

In one embodiment, as shown with reference to FIG. 3, the second control module 22 includes: an output voltage control unit 221, a second voltage-sharing control unit 222, a carrier phase-shifting unit 223 and a second signal modulation unit 224, wherein the output voltage control unit 221 is used for controlling the output voltage U according to the output voltage_OTarget value of output voltageAnd an output current i_OObtaining a fifth duty cycle D of the three-level bidirectional isolated converter 21 using a double closed-loop control strategy₅For example, a double closed loop control strategy of a voltage outer loop and a current inner loop is adopted; the second voltage-sharing control unit 222 is used for controlling the voltage U according to the second capacitor_C2Voltage-sharing target valueAnd the second coefficient K2 to obtain a third regulating variable Delta D₃Target value of voltage equalizationIs an intermediate voltage U_MOne half of (a); the carrier phase shift unit 223 is used for shifting the carrier phase according to the fifth duty ratio D₅And a preset carrier period T_SPerforming phase shift processing on a preset carrier to obtain a first carrier; the second signal modulation unit 224 is used for adjusting the third adjustment quantity Δ D₃The preset carrier wave, the first carrier wave and the preset modulation wave obtain a control signal of the three-level bidirectional isolation converter 21 so as to control the on-off of the switching tubes Q5-Q16.

In one embodiment, continuing to refer to fig. 3, the output voltage control unit 221 includes: a sixth subtracter for calculating an output voltage target value, a fourth regulator, a seventh subtracter and a fifth regulatorAnd an output voltage U_OObtaining a third voltage difference value according to the difference value; the fourth regulator is used for regulating (such as PI regulating) the third voltage difference value to obtain the target value of the output currentThe seventh subtracter is used for calculating an output current target valueAnd an output current i_OObtaining a second current difference value according to the difference value; the fifth regulator is used for regulating (such as PI regulating) the second current difference value to obtain a fifth duty ratio D₅And the carrier phase angle adjusting signals are used as carrier phase angle adjusting signals of the whole bridge arm, namely primary side switching tubes Q9-Q12 carrier phase angle adjusting signals.

The second voltage equalization control unit 222 includes: an eighth subtracter, a sixth regulator and a second multiplier, wherein the eighth subtracter is used for calculating a voltage-sharing target valueVoltage U of the second capacitor_C2Obtaining a fourth voltage difference value from the difference value; the sixth regulator is used for regulating (such as P regulating) the fourth voltage difference value to obtain a fourth regulating quantity(ii) a The second multiplier is used for calculating the product of the fourth regulating quantity and the second coefficient K2 to obtain a third regulating quantity delta D₃And the signals are used as the switching-on time adjusting signals of the primary side switching tubes Q5, Q9, Q8 and Q12 (called primary side outer tubes for short).

The carrier phase shift unit 223 includes: a first divider for calculating a fifth duty cycle D and a first phase shifter₅And a predetermined carrier period T_SThe quotient between obtains a phase shift angle phi; the first phase shifter is used for performing phase shifting processing on a preset carrier wave according to a phase shifting angle phi to obtain a first carrier wave. Further, the carrier phase shifting unit 223 further comprises a first limiter for the fifth duty cycle D₅And carrying out amplitude limiting processing.

The second signal modulation unit 224 includes: a second adder, a ninth subtracter, third to eighth comparators, a third inverter, a fourth inverter, a first OR gate and a second OR gate, wherein the second adder is used for adjusting the quantity delta D according to a third adjustment quantity₃Presetting a modulation wave to obtain a first modulation wave, wherein the preset modulation wave is a modulation wave with a duty ratio of 0.5; a ninth subtractor for adjusting the third adjustment amount Δ D₃Presetting a modulation wave to obtain a second modulation wave; the third comparator is used for obtaining a fifth control signal according to the first modulation wave and a preset carrier wave and is used for controlling the on-off of the fifth switching tube Q5; the fourth comparator is used for obtaining a sixth control signal according to the preset modulation wave and the preset carrier wave and is used for controlling the on-off of the sixth switching tube Q6; the third inverter is used for inverting the sixth control signal to obtain a seventh control signal and is used for controlling the on-off of a seventh switching tube Q7; the fifth comparator is used for obtaining an eighth control signal according to the second modulation wave and the preset carrier wave and is used for controlling the on-off of the eighth switching tube Q8; the sixth comparator is used for obtaining a ninth control signal according to the first modulation wave and the first carrier wave, and is used for controlling the on-off of the ninth switching tube Q9; the seventh comparator is configured to obtain a tenth control signal according to the preset modulation wave and the first carrier, and is configured to perform on-off control on the tenth switching tube Q10; the fourth inverter is used for inverting the tenth control signal to obtain an eleventh control signal and is used for controlling the on-off of an eleventh switching tube Q11; an eighth comparator for obtaining the second modulated wave from the first carrier waveA twelfth control signal for controlling the on-off of the twelfth switching tube Q12; the first or gate is used for obtaining a thirteenth control signal according to the sixth control signal and the eleventh control signal and is used for controlling the on-off of the thirteenth switching tube Q13 and the sixteenth switching tube Q16; the second or gate is used for obtaining a fourteenth control signal according to the seventh control signal and the tenth control signal, and is used for performing on-off control on the fourteenth switching tube Q14 and the sixteenth switching tube Q16. The fifth to fourteenth control signals are PWM control signals. Further, the second signal modulation unit 224 further includes: the second amplitude limiter is used for carrying out amplitude limiting processing on the first modulation wave; the third limiter is used for carrying out limiting processing on the second modulation wave.

In this embodiment, a double closed-loop control strategy of an outer voltage loop and an inner current loop is adopted to control a three-level bidirectional isolation converter of a second-stage circuit, and the output voltage of the converter is controlled in a mode of simultaneously shifting the phases of two switching tubes of the same bridge arm as a whole, that is, a modulation mode of carrier phase shifting of the whole bridge arm is adopted to generate a control signal to control the output voltage of the converter, so that the problem of uneven heating of the inner and outer tubes of the same bridge arm due to more switching devices on the primary side of the second-stage circuit is effectively solved, the heating uniformity of all the switching tubes is ensured, and the upper and lower capacitor voltage-sharing control of an intermediate direct-current link is provided.

In one embodiment, referring to fig. 1, the bidirectional isolation DCDC converter further includes a clamping circuit 50, the clamping circuit 50 includes a clamping switch tube Sc and a clamping capacitor Cc, a first end of the clamping switch tube Sc is connected to a first output end of the three-level bidirectional isolation converter 21, one end of the clamping capacitor Cc is connected to a second end of the clamping switch tube Sc, and the other end of the clamping capacitor Cc is connected to a second output end of the three-level bidirectional isolation converter 21.

In one embodiment, the main control module 40 is further configured to control the clamp switching tube Sc to be turned on at a first preset time after the control signals of the thirteenth switching tube Q13 and the sixteenth switching tube Q16 are ended, and to control the clamp switching tube Sc to be turned off at a second preset time before the control signals of the thirteenth switching tube Q13 and the sixteenth switching tube Q16 arrive; and the clamping switching tube Sc is controlled to be turned on at a first preset time after the control signals of the fourteenth switching tube Q14 and the fifteenth switching tube Q15 are ended, and the clamping switching tube Sc is controlled to be turned off at a second preset time before the control signals of the fourteenth switching tube Q14 and the fifteenth switching tube Q15 arrive.

Specifically, referring to fig. 4, the control signal for clamping the switching tube Sc may be generated by delaying a first preset time T1 after the control signals of the fourteenth and fifteenth switching tubes Q14 and Q15 are ended, and ending the control signal for clamping the switching tube Sc by a second preset time T2 before the next control signal of the fourteenth and fifteenth switching tubes Q14 and Q15 arrives, and generating the control signal for clamping the switching tube Sc by delaying the first preset time T1 after the control signals of the thirteenth and sixteenth switching tubes Q13 and Q16 are ended, and ending the control signal for clamping the switching tube Sc by a second preset time T2 before the next control signal of the control signals of the thirteenth and sixteenth switching tubes Q13 and Q16 arrives.

In the embodiment, the active clamping circuit is added to the output part, and the overvoltage problem of the switching tube in the three-level bidirectional isolation converter can be effectively suppressed by matching with the control time sequence of the clamping switching tube.

In summary, the bidirectional isolation DCDC converter with the wide input range can adapt to higher input voltage and wider input voltage variation range through the two-stage topology; the two stages of circuits can realize the intermediate voltage balance control in the control, so that the control is more flexible; the second-stage circuit generates a control signal by adopting a whole bridge arm carrier phase shifting mode, so that the uniform heating of the switching tube is ensured; the overvoltage problem of a switching tube in the second-stage circuit can be effectively restrained by adding the active clamping absorption circuit on the output side.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.