DCDC power supply with wide input voltage range and high output voltage

Abstract

According to the DCDC power supply with the wide input voltage range and the high output voltage, the input series connection and output series connection type double-transistor flyback or double-transistor forward power supply modules are constructed, and the two same power supply modules are connected in an input parallel mode and connected in an output series mode, so that the input and output voltage stress of a single converter is reduced by half, and the output voltage stress of the single converter is reduced by half. And functions of a power supply with a wide input voltage range and a high output voltage are realized. According to the utility model, the voltage division of the two switch tubes in the double-tube flyback or double-tube forward converter is utilized at the same time, so that the single switch tube can select a 600V / 650V conventional withstand voltage model, the model selection of 1200V SiC mos is avoided, and the problems of difficult model selection, high cost and long device purchasing period of a power device are solved. According to the utility model, the conversion efficiency of a wide input voltage range and high output voltage power supply is greatly improved compared with a multi-stage cascade structure power supply, the miniaturization design of the power supply is facilitated, and the design volume of the power supply is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of power supply, and in particular relates to a DCDC power supply with a wide input voltage range and a high output voltage. Background Art

[0002] At present, magnetic levitation centrifugal compressors are widely used in air conditioning systems due to their high operating efficiency, low noise, low maintenance cost, light body and low starting current. In order to ensure the normal operation of the magnetic levitation centrifugal compressor, power is often taken from the DC bus of the frequency converter cabinet, and a 350V DC voltage is provided after the DCDC power supply is converted, and then the magnetic levitation centrifugal compressor bearing suspension is controlled by the controller. When the unit loses power, the DC bus voltage of the frequency converter cabinet will gradually decrease. During this process, the magnetic levitation centrifugal compressor bearing needs to be decelerated from a high speed (tens of thousands of RPM) to a shaft drop speed (500RPM or less), and the DC bus voltage of the frequency converter cabinet at this stage varies from 230VDC to 750VDC. In order to ensure the safe operation of the magnetic levitation centrifugal compressor bearing, the DCDC power supply must operate efficiently and stably under a wide input voltage range (230VDC to 750VDC), and the output voltage is as high as 350VDC. This voltage specification is a very strict challenge for the DCDC power supply design.

[0003] At present, the common practice is to use a multi-stage cascade transformation method. Figure 1 For example, the voltage is first reduced through BUCK conversion, then increased through BOOST, and then through two channels of dual-tube forward + BOOST, and the output is connected in series to obtain a stable 350V high voltage output. This solution uses the input-output voltage ratio of each topology and obtains the required output voltage value after multi-stage conversion, but there are many disadvantages:

[0004] 1. Difficulty in selecting power devices, high costs, and long device procurement cycles. The input voltage of the front-stage BUCK is as high as 750V, which exceeds the conventional MOS 600V / 650V withstand voltage specifications. It is necessary to select SiC MOS with a withstand voltage of 1200V, which leads to difficulty in selection, high costs, and long device procurement cycles. At present, due to the rapid development of the new energy market (wind power, photovoltaics, energy storage, new energy vehicles, etc.), the supply of SiC MOS in the market has been in short supply, the procurement cycle is long, and the cost of high-voltage SiC MOS is much higher than that of conventional withstand voltage MOS.

[0005] 2. Low power conversion efficiency. In a multi-stage cascade conversion structure, the efficiency of each stage is η1, η2, η3, ..., then the total power efficiency η = η1*η2*η3*... For example, assuming that the conversion efficiency of each stage in a four-stage cascade structure is 90%, the total efficiency is η = 90%*90%*90%*90% = 66%, which is very low.

[0006] 3. The power supply is large. The conversion power of each stage in the multi-stage cascade structure is equivalent to the total power. The number of power devices and heat sinks is large, resulting in a large design volume, which is not conducive to product miniaturization. Utility Model Content

[0007] The technical problem to be solved by the utility model is to provide a DCDC power supply with a wide input voltage range and high output voltage.

[0008] The utility model adopts the following technical solution to solve the above technical problems: a DCDC power supply with a wide input voltage range and a high output voltage, comprising two identical power modules, the input ends of the two power modules are connected in parallel, and the output ends of the two power modules are connected in series; the power module comprises two identical converters, the input ends of the two converters are connected in series, and the output ends of the two converters are connected in series.

[0009] According to the above scheme, assuming that the input voltage of the entire power supply is Vin, the input current is Iin, the output voltage is Vo, the output current is Io, the output power is Po, and the conversion efficiency is

[0010] η=Vo*Io / (Vin*Iin);

[0011] The input voltage of a single converter is (1 / 2) Vin, the input current is (1 / 2) Iin, the output voltage is (1 / 4) Vo, the output current is Io, and the conversion efficiency of a single converter is

[0012] η1=((1 / 4)Vo*Io) / ((1 / 2)Vin*(1 / 2)Iin)=Vo*Io / (Vin*Iin)=η,

[0013] The output power of a single converter is

[0014] Po1 = (1 / 4) Vo*Io = (1 / 4) Po.

[0015] According to the above scheme, the power module includes a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a first converter, a second converter, a fifth capacitor C5 and a seventh capacitor diode D7; the first capacitor C1 and the second capacitor C2 are connected in series and respectively connected in parallel to the input ends of the two converters; the first resistor R1 and the second resistor R2 are respectively connected in parallel at both ends of the first capacitor C1 and the second capacitor C2; the fifth capacitor C5 and the seventh capacitor diode D7 are connected in parallel at the output end of the power module.

[0016] According to the above scheme, the first converter and the second converter adopt a double-switch flyback conversion circuit.

[0017] According to the above scheme, the first converter and the second converter adopt a double-transistor forward conversion circuit.

[0018] Furthermore, the first converter includes a first switch tube Q1, a second switch tube Q2, a first diode D1, a second diode D2, a first transformer T1, a fifth diode D5 and a third capacitor C3.

[0019] Furthermore, the second converter includes a third switch tube Q3, a fourth switch tube Q4, a third diode D3, a fourth diode D4, a second transformer T2, a sixth diode D6 and a fourth capacitor C4.

[0020] According to the above scheme, it also includes a first inductor L1 connected in series between the cathode of the fifth diode D5 and the anode of the third capacitor C3, a seventh diode D7 whose cathode is connected to the cathode of the fifth diode D5 and whose anode is connected to the cathode of the third capacitor C3, a second inductor L2 connected in series between the cathode of the sixth diode D6 and the anode of the fourth capacitor C4, and an eighth diode D8 whose cathode is connected to the cathode of the sixth diode D6 and whose anode is connected to the cathode of the fourth capacitor C4.

[0021] According to the above scheme, the input voltage range of the power supply is 230V~750V, and the output voltage is 350V.

[0022] According to the above solution, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4 are MOS tubes or other power tubes.

[0023] The beneficial effects of the utility model are:

[0024] 1. The utility model is a DCDC power supply with a wide input voltage range and high output voltage. By constructing an input series and output series dual-tube flyback or dual-tube forward power supply module, and connecting two identical power supply modules in parallel and in series, the input and output voltage stress of a single converter is reduced by half, thereby realizing the function of a power supply with a wide input voltage range and high output voltage.

[0025] 2. The utility model simultaneously utilizes the voltage division of two switch tubes in a dual-tube flyback or dual-tube forward converter, so that a single switch tube can select a 600V / 650V conventional withstand voltage model, avoiding the selection of 1200V SiC MOS, and solving the problems of difficult selection of power devices, high cost, and long device procurement cycle.

[0026] 3. The utility model makes the conversion power of a single converter only (1 / 4)Po, while the conversion power of a single converter in a multi-stage cascade structure is Po, which greatly improves the conversion efficiency of a power supply with a wide input voltage range and high output voltage compared to a multi-stage cascade structure power supply.

[0027] 4. The conversion power of the utility model is small, which is conducive to the miniaturization design of the power supply and reduces the design volume of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a principle block diagram of an existing multi-stage cascade conversion power supply.

[0029] Figure 2 It is a principle block diagram of embodiment 1 of the utility model.

[0030] Figure 3 It is a principle block diagram of embodiment 2 of the present utility model. DETAILED DESCRIPTION

[0031] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0032] Example 1

[0033] See also Figure 2 , assuming that the power input voltage of the embodiment of the utility model is Vin, the input current is Iin, the output voltage is Vo, the output current is Io, the output power is Po, and the conversion efficiency is η, then

[0034] η=Vo*Io / (Vin*Iin).

[0035] In this embodiment, the inputs of two identical power modules are connected in parallel and the outputs are connected in series, so that the output voltage of a single power module is (1 / 2)Vo and the conversion power is (1 / 2)Po; the inputs of two converters in a single power module are connected in series and the outputs are connected in series, so that the input voltage of a single converter is (1 / 2)Vin, the output voltage is (1 / 4)Vo, and the conversion power is (1 / 4)Po.

[0036] This embodiment includes a completely identical first power module and a second power module; the first power module includes a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a first converter, a second converter, a fifth capacitor C5, and a seventh capacitor diode D7; the first capacitor C1 and the second capacitor C2 are connected in series and are respectively connected to the input ends of the first converter and the second converter; the first resistor R1 and the second resistor R2 are respectively connected in parallel at both ends of the first capacitor C1 and the second capacitor C2, for balancing the voltages at both ends of the first capacitor C1 and the second capacitor C2 at the input end; the first converter includes a first switch tube Q1, a second switch tube Q2, a first diode D1, a second diode D2, a first transformer T1, a fifth diode D5, and a third capacitor C3; the second converter includes a third switch tube Q3, a fourth switch tube Q4, a third diode D3, a fourth diode D4, a second transformer T2, a sixth diode D6, and a fourth capacitor C4.

[0037] When the power input voltage is 230V~750V and the output voltage is 350V, the input voltage of a single converter is 115V~375V and the output voltage is 87.5V. A single converter adopts a dual-tube flyback conversion circuit, and the switch tube of the converter is selected with conventional 600V or 650V withstand voltage specifications.

[0038] According to the above analysis, the input voltage of a single converter is (1 / 2) Vin, the input current is (1 / 2) Iin, the output voltage is (1 / 4) Vo, and the output current is Io. The conversion efficiency of a single converter is

[0039] η1=((1 / 4)Vo*Io) / ((1 / 2)Vin*(1 / 2)Iin)=Vo*Io / (Vin*Iin)=η,

[0040] That is, assuming that the conversion efficiency of a single converter is 90%, the efficiency of the entire power supply is still 90%, and the conversion efficiency is greatly improved compared to the multi-stage cascade structure.

[0041] From the above analysis, the conversion power of a single converter is only 1 / 4 of the total power, which reduces the design power of a single converter and reduces the design volume.

[0042] Example 2

[0043] See also Figure 3 The structure and principle of this embodiment are the same as those of Embodiment 1, except that the first and second converters adopt a double-tube forward conversion circuit, and further include a first inductor L1 connected in series between the cathode of the fifth diode D5 and the anode of the third capacitor C3, a seventh diode D7 whose cathode is connected to the cathode of the fifth diode D5 and whose anode is connected to the cathode of the third capacitor C3, a second inductor L2 connected in series between the cathode of the sixth diode D6 and the anode of the fourth capacitor C4, and an eighth diode D8 whose cathode is connected to the cathode of the sixth diode D6 and whose anode is connected to the cathode of the fourth capacitor C4.

[0044] The above embodiments are only used to illustrate the design ideas and features of the utility model, and their purpose is to enable those skilled in the art to understand the content of the utility model and implement it accordingly. The protection scope of the utility model is not limited to the above embodiments. Therefore, any equivalent changes or modifications made based on the principles and design ideas disclosed by the utility model are within the protection scope of the utility model.

Claims

1. A DCDC power supply with a wide input voltage range and high output voltage, characterized in that: The invention comprises two identical power modules, the input ends of the two power modules are connected in parallel, and the output ends of the two power modules are connected in series; the power module comprises two identical converters, the input ends of the two converters are connected in series, and the output ends of the two converters are connected in series.

2. A DCDC power supply with a wide input voltage range and high output voltage according to claim 1, characterized in that: Assume that the input voltage of the entire power supply is Vin, the input current is Iin, the output voltage is Vo, the output current is Io, the output power is Po, and the conversion efficiency is η=Vo*Io / (Vin*Iin); The input voltage of a single converter is (1 / 2) Vin, the input current is (1 / 2) Iin, the output voltage is (1 / 4) Vo, the output current is Io, and the conversion efficiency of a single converter is η1=((1 / 4)Vo*Io) / ((1 / 2)Vin*(1 / 2)Iin)=Vo*Io / (Vin*Iin)=η, The output power of a single converter is Po1 = (1 / 4) Vo*Io = (1 / 4) Po.

3. A DCDC power supply with a wide input voltage range and high output voltage according to claim 1, characterized in that: The power module includes a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a first converter, a second converter, a fifth capacitor C5 and a seventh capacitor diode D7; the first capacitor C1 and the second capacitor C2 are connected in series and respectively connected in parallel to the input ends of the two converters; the first resistor R1 and the second resistor R2 are respectively connected in parallel at both ends of the first capacitor C1 and the second capacitor C2; the fifth capacitor C5 and the seventh capacitor diode D7 are connected in parallel at the output end of the power module.

4. A DCDC power supply with a wide input voltage range and high output voltage according to claim 1, characterized in that: The first converter and the second converter adopt a double-switch flyback conversion circuit.

5. The DCDC power supply with a wide input voltage range and high output voltage according to claim 1, characterized in that: The first converter and the second converter adopt a double-transistor forward conversion circuit.

6. A DCDC power supply with a wide input voltage range and high output voltage according to claim 4 or 5, characterized in that: The first converter includes a first switch tube Q1, a second switch tube Q2, a first diode D1, a second diode D2, a first transformer T1, a fifth diode D5 and a third capacitor C3.

7. A DCDC power supply with a wide input voltage range and high output voltage according to claim 4 or 5, characterized in that: The second converter includes a third switch tube Q3, a fourth switch tube Q4, a third diode D3, a fourth diode D4, a second transformer T2, a sixth diode D6 and a fourth capacitor C4.

8. The DCDC power supply with a wide input voltage range and high output voltage according to claim 1, characterized in that: It also includes a first inductor L1 connected in series between the cathode of the fifth diode D5 and the anode of the third capacitor C3, a seventh diode D7 having a cathode connected to the cathode of the fifth diode D5 and a cathode connected to the cathode of the third capacitor C3, a second inductor L2 connected in series between the cathode of the sixth diode D6 and the anode of the fourth capacitor C4, and an eighth diode D8 having a cathode connected to the cathode of the sixth diode D6 and a cathode connected to the cathode of the fourth capacitor C4.

9. The DCDC power supply with a wide input voltage range and high output voltage according to claim 1, characterized in that: The input voltage range of the power supply is 230V~750V, and the output voltage is 350V.

10. The DCDC power supply with wide input voltage range and high output voltage according to claim 1, characterized in that: The first switch tube Q1 , the second switch tube Q2 , the third switch tube Q3 , and the fourth switch tube Q4 are MOS tubes or other power tubes.

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