WO2020010729A1

WO2020010729A1 - Direct-current power supply and series and parallel circuit

Info

Publication number: WO2020010729A1
Application number: PCT/CN2018/109367
Authority: WO
Inventors: 戴国峰
Original assignee: 深圳驿普乐氏科技有限公司
Priority date: 2018-07-07
Filing date: 2018-10-08
Publication date: 2020-01-16

Abstract

Provided in the present invention are a direct-current power supply and a series and parallel circuit. The circuit comprises a first DC/DC conversion unit and a second DC/DC conversion unit for converting a received direct current and then outputting same; a first unidirectional conduction device, with one end being electrically connected to the first DC/DC conversion unit, and the other end being electrically connected to a positive electrode output end; and a selection unit, with a first end being electrically connected to the first DC/DC conversion unit, a second end being electrically connected to a second unidirectional conduction device, and a third end being electrically connected to a negative electrode output end, wherein the selection unit receives an instruction of a control module and enables the first DC/DC conversion unit and the second DC/DC conversion unit to be in connection in series or in parallel in response to the instruction; the other end of the second unidirectional conduction device is electrically connected to the positive electrode output end; and the second DC/DC conversion unit is electrically connected to an end of the second unidirectional conduction device and the second end, and the second DC/DC conversion unit is electrically connected to the negative electrode output end. The direct-current power supply provided with the circuit meets charging requirements of electric vehicles on the market.

Description

DC power supply and series-parallel circuit

Technical field

The invention relates to a DC power supply for an electric vehicle, and in particular to a DC power supply and a series-parallel circuit.

Background technique

At present, different types of electric vehicles have different charging voltage ranges. For example, the charging range for passenger cars is generally 225 to 500Vdc; the charging voltage range for buses and buses is 500 to 900V; and even for vehicles of the same type, different manufacturers offer electric The charging voltage of car DC fast charge is also not uniform.

At present, the mainstream charging piles on the market have a narrow charging range and often only take into account some vehicles. This has led to the fact that many cars and piles cannot be charged, and the problem of mismatched piles is very prominent. Moreover, with the increasing number of electric vehicles, this contradiction has become increasingly prominent.

Summary of the invention

Based on the above problems, an object of the present invention is to solve at least one of the technical defects. A series-parallel circuit of a DC power supply is proposed, which can greatly increase the output voltage range of the DC voltage and the voltage range of the constant power output, and expand the output voltage range of the DC power supply sampling the circuit to 225-900Vdc; It is compatible with all electric vehicle charging requirements on the market. To achieve the above object, the present invention adopts the following technical solutions:

A series-parallel circuit for a DC power source, comprising: a first DC / DC conversion unit and a second DC / DC conversion unit for converting the received DC power to an output; a first unidirectional conduction device having one end thereof The first terminal is electrically connected to the first DC / DC conversion unit, and the other end is electrically connected to the output positive terminal. The selection unit has a first terminal electrically connected to the first DC / DC conversion unit, and a second terminal electrically connected to the second terminal. One end and the third end of the unidirectional conduction device are electrically connected to the output negative terminal. The selection unit receives a command from the control module and responds to the command to make the first DC / DC conversion unit and the second DC / DC conversion unit electrically conductive. Serial or parallel; the other end of the second unidirectional conducting device is electrically connected to the output positive terminal; the second DC / DC conversion unit is electrically connected to one end of the second unidirectional conducting device and the second end 2. The second DC / DC conversion unit is electrically connected to an output negative terminal.

Preferably, the selection unit includes a single-pole double-throw switch relay; wherein, when the single-pole double-throw switch relay is closed at the second end, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series. ; When the single-pole double-throw switch relay is closed on the third end, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in parallel.

Preferably, the circuit includes that the first unidirectional conducting device is a first diode, an anode terminal thereof is electrically connected to the first output terminal of the first DC / DC conversion unit, and a cathode terminal thereof is electrically connected to the output. Positive terminal; the second unidirectional conducting device is a second diode, whose anode terminal is electrically connected to the second terminal and the first output terminal of the second DC / DC conversion unit, and its cathode terminal is electrically Connect the output positive terminal.

Preferably, the selection unit includes a first switch and a second switch; the first terminal of the first switch is electrically connected to the first terminal of the second switch and the second output of the first DC / DC conversion unit. Terminal, the second terminal of the first switch is electrically connected to the anode terminal of the second diode, and the second terminal of the second switch is electrically connected to the output negative terminal, wherein when the first switch is closed The first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series. When the second switch is closed, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in parallel. .

Preferably, the first switch and the second switch include a relay.

Preferably, the control module is electrically connected to the first DC / DC conversion unit, the second DC / DC conversion unit, and the selection unit; the control module controls the selection unit based on the received voltage information, if The voltage information is less than or equal to a set threshold, the circuit is in a first working mode, and the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series. When the circuit is in a second working mode, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in parallel.

Preferably, when the circuit is in the first working mode, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series, and the second unidirectional conduction device is cut off.

Preferably, the circuit further includes a capacitor, one end of which is electrically connected to the output positive terminal, and the other end of which is electrically connected to the output negative terminal.

An embodiment of the present invention further provides a DC power source, which is characterized in that it includes a first-stage converter and a second-stage converter, and an input terminal of the second-stage converter is electrically connected to an output terminal of the first-stage converter; The first-stage converter is used to convert the input AC power to DC power, and the second-stage converter includes the circuit according to any one of claims 1 to 7.

Preferably, the DC power source further includes a voltage identification module electrically connected to the control module to obtain voltage information of the electric vehicle to be charged and feed it back to the control module. If the voltage information is less than or equal to A threshold is set, and the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in parallel; if the voltage information is greater than a set threshold, the first DC / DC conversion unit is connected to the The second DC / DC conversion units are electrically connected in series. In this way, the operation mode of the circuit is controlled by controlling the selection unit.

Preferably, the DC power supply further includes: a human-machine interaction module for receiving the charging voltage information input by the user and transmitting the charging voltage information to the control module. The control module controls the working mode of the circuit based on the obtained charging voltage information, wherein When the circuit is in the first working mode, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series; when the circuit is in the second working mode, the first DC The / DC conversion unit and the second DC / DC conversion unit are electrically connected in series and electrically in parallel.

Compared with the solutions in the prior art, the advantages of the present invention are:

The circuit provided by the embodiment of the present invention can widen the output voltage range of the DC voltage and the voltage range of the constant power output. This circuit widens the output voltage range of the DC power supply to 225-900Vdc; thus, it can be compatible with all electric vehicle charging on the market. Claim.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described below with reference to the drawings and embodiments:

FIG. 1 is a functional block diagram of an existing DC / DC converter of a charging power source;

FIG. 2-4 is a functional block diagram of a charging power DC / DC converter circuit according to an embodiment of the present invention;

5-7 are functional block diagrams of a charging power DC / DC converter circuit according to another embodiment of the present invention;

8-9 are functional block diagrams of a DC / DC converter connected to a power source according to an embodiment of the present invention.

detailed description

The above solution is further described below with reference to specific embodiments. It should be understood that these examples are intended to illustrate the present invention and not to limit the scope of the present invention. The implementation conditions used in the examples can be further adjusted, such as the conditions of specific manufacturers, and the implementation conditions that are not specified are generally the conditions in conventional experiments.

This application discloses a DC power source whose output voltage can meet the requirements of different types of vehicle charging voltages, which are described in detail below:

Figure 1 shows a functional block diagram of an existing DC / DC converter for a charging power source. The charging power source includes a DC / DC converter. When the output voltage range of the charging power supply is narrow, the topology satisfies the charging requirements well. If it is applied to a wide range of output voltages, the component design redundancy of the topology is large, resulting in high cost of the charging power supply. Assume that the required power of the charging power source is 10KW. According to the topology of Figure 1, a charging power source must meet the output of 10KW within the output voltage range of 225 ～ 900VDC, and the maximum output current is 44.4A under the minimum voltage of 225V; therefore, this The maximum design power of the charging power of the solution topology will be approximately 44.4A * 900V = 40KW; therefore, the cost of this solution is very high, which is not conducive to the application of charging power in many occasions.

Next, an embodiment of the present invention is described. A series-parallel circuit of a DC power supply includes: 2 DC / DC conversion units for converting the received DC power (to a preset voltage) and outputting the output power; a selection unit whose power is The DC / DC conversion unit is electrically connected. The selection unit receives an instruction from the control module and responds to the instruction so that the first DC / DC conversion unit and the second DC / DC conversion unit are electrically combined (electrically in series or electrically in parallel to make the output Voltage-matching load, such as an electric vehicle to be charged). One end of the first unidirectional device is electrically connected to the DC / DC conversion unit, the other end is electrically connected to the positive output terminal, and the other end of the second unidirectional device is electrically connected. The connection terminal is electrically connected to the other end of the output positive terminal. (The unidirectional conduction device is configured such that the current flows to the load side through the unidirectional conduction device, and the load cannot pass from the unidirectional conduction device to the DC / DC conversion unit. Side flow); the circuit has two working modes through this selection unit, that is, two DC / DC conversion units are electrically connected in series or 2 DC / DC conversion units are electrically connected in parallel. In this embodiment, the second unidirectional conduction device provides a unidirectional current path when the DC / DC conversion units are electrically connected in parallel, and it ends when the two DC / DC conversion units are electrically connected in series. The output voltage is the voltage between the positive output terminal and the negative output terminal. The voltage information (and other parameters) is obtained after the DC power source is connected to the electric vehicle. The process of obtaining the information is the prior art and will not be developed in detail here. In this embodiment, the electrical connection between the two DC / DC conversion units refers to the electrical connection between the outputs of the DC / DC conversion. After the electrical connection, the power is supplied to the outside. Each DC / DC conversion unit has a first output terminal (such as a positive electrode) and a second output terminal (such as a negative electrode), and is electrically connected according to the polarity when connected. The series connection can be expressed as the second end of the first DC / DC conversion unit is electrically connected to the first end of the second DC / DC conversion unit, the first end of the first DC / DC conversion unit is connected to the output positive terminal, and the second DC The second end of the / DC conversion unit is connected to the output negative terminal; the parallel connection can be expressed as the first end of the first DC / DC conversion unit is electrically connected to the first end of the second DC / DC conversion unit and is electrically connected to the output positive Extreme; the second end of the first DC / DC conversion unit is electrically connected to the second end of the second DC / DC conversion unit and is electrically connected to the output negative terminal. The two DC / DC conversion units are independent of each other and run according to the instructions of the control module. The control module also controls the selection unit based on the voltage information of the received load, so that the combined output voltage between the DC / DC conversion units meets the requirements of the load. For example, the voltage information of the load is less than or equal to the set threshold and the two DC / DC conversion units are electrically connected in parallel, and the greater than the set threshold is electrically connected in series between the two DC / DC conversion units.

Next, a charging power DC / DC converter circuit according to an embodiment of the present invention is described with reference to FIGS. 2-4. FIG. 2 is a schematic diagram of a functional block of the charging power DC / DC converter circuit. The circuit 10 includes: a first DC / The DC conversion unit 11, the second DC / DC conversion unit 12, the selection unit 13, the first diode 14, and the second diode 15; the first output terminal of the first DC / DC conversion unit 11 is electrically connected to the first An anode terminal of a diode 14, a second output terminal of the first DC / DC conversion unit 11 is electrically connected to the first terminal of the selection unit, and an a terminal of the selection unit is electrically connected to the anode terminal of the second diode 15. The cathode terminal of the second diode 15 is electrically connected to the cathode terminal of the first diode 14 and the output positive terminal, and the b terminal (ie, the third terminal) of the selection unit is electrically connected to the output negative terminal; the second DC / DC The first output terminal of the conversion unit 12 is electrically connected to the anode terminal and the second terminal (a terminal) of the second diode 15, and the second output terminal of the second DC / DC conversion unit 12 is electrically connected to the output negative terminal; When the selection unit is in the first working mode (the second end is closed), the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series (as shown in Figure 3). ), When in the second mode of operation (third end closed), between the first DC / DC conversion unit and the second DC / DC converting means electrically connected in parallel (Figure 4). Through such a design, the output voltage range of the DC voltage and the voltage range of the constant power output can be greatly increased, and the output voltage range of the DC power supply can be expanded to 225 to 900 Vdc while having high cost performance. The power supply using this solution can be compatible with all electric vehicle charging requirements on the market. The solution has a simple topology and is cost-effective. It uses two unidirectional conduction devices, namely two

diodes

14,15; where the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series, the diode 14 is turned on and the diode 15 is turned off, simplifying control Circuit topology (replace the relay switch with a diode to reduce the control complexity of the circuit). When the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in parallel, the diode 14 is turned on and the diode 15 is turned on.

In the above embodiment, the selection unit 13 includes a single-pole double-throw switch, specifically a single-pole double-throw relay.

The power supply adopting the above solution also includes a control module, which is electrically connected to the first DC / DC conversion unit 11, the second DC / DC conversion unit 12, and the selection unit 13; the control module is also electrically connected to an external load (such as Connected to the electric vehicle to be charged) for signaling interaction (for example, to obtain output voltage information), and the control module controls the first DC / DC conversion unit 11, the second DC / DC conversion unit 12, the selection unit 13 to output according to the voltage information Corresponding voltage and current.

Next, a charging power DC / DC converter circuit according to another embodiment of the present invention is described with reference to FIGS. 5-7. FIG. 5 is a schematic diagram of a functional block of the charging power DC / DC converter circuit. The circuit 20 includes: a first DC / DC conversion unit 21, second DC / DC conversion unit 22, first diode 24, second diode 25, and selection unit 23 includes a first switch 23a and a second switch 23b; the first DC / DC conversion The first output terminal of the unit 21 is electrically connected to the anode terminal of the first diode 24, and the second output terminal of the first DC / DC conversion unit 21 is electrically connected to one end of the first switch 23a and the second switch 23b. One end, the other end of the first switch 23a is electrically connected to the anode end of the second diode 24, the cathode end of the second diode 25 is electrically connected to the cathode end of the first diode 24 and the output positive terminal, and the second The other end of the switch 23b is electrically connected to the output negative terminal; the first output terminal of the second DC / DC conversion unit 22 is electrically connected to the other end of the first switch 23a and the anode terminal of the second diode 25, and the second DC The second output terminal of the / DC conversion unit 22 is electrically connected to the output negative terminal; wherein, when the first switch 23a is closed, the first DC / DC converter The switching unit 21 and the second DC / DC conversion unit 22 are electrically connected in series (as shown in FIG. 6). When the second switch 23 b is closed, the first DC / DC conversion unit 21 and the second DC / DC conversion unit 22 are electrically connected. (See Figure 7). The effect of adopting this scheme is the same as that described in the above scheme, and is not repeated here. In this solution, the first switch 23a and the second switch 23b are relays. This solution has a simple topology. It uses two unidirectional conduction devices, that is, two diodes 24,55. In addition to the anti-backflow function, it also has electrical properties between the first DC / DC conversion unit and the second DC / DC conversion unit. When connected in series, the diode 14 is turned on and the diode 25 is turned off. When the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in parallel, the diode 14 is turned on and the diode 15 is turned on. The power supply adopting this solution also includes a control module, and its operation is the same as above and will not be described repeatedly. One end of the first switch 23a and one end of the second switch 23b are electrically connected to the first end of the selection unit in the solution in FIG. 2, and this end is electrically connected to the second output end of the first DC / DC conversion unit. The other end of the switch 23a is equivalent to the second end of the selection unit in the solution in FIG. 2, and the other end of the first switch 23b is equivalent to the third end.

In this solution, assuming that the output voltage of the first DC / DC conversion unit 21 is V1, the second DC / DC conversion unit 22 is V2, and the output voltage (the voltage between the output positive terminal and the output negative terminal) is Vo, the first mode (As shown in Figure 6), the first switch 23a is closed, the second switch 23b is open, and the output voltage Vo = V1 + V2, during its operation, SW1 is closed, Vc = Vb = V2, Va = Vc + V1 = V2 + V1, because Va> Vb, the first diode 21 is turned on and the second diode 22 is turned off; at this time, Vo = Va = V2 + V1, (selected in this scheme, V1 = V2). In the second mode (as shown in FIG. 7), the first switch 23a is opened, the second switch 23b is closed, the first diode 21 is turned on, and the second diode 22 is turned on. At this time, the output voltage Vo = V1 = V2, the output current is the sum of the output currents of the first DC / DC conversion unit 21 and the second DC / DC conversion unit 22. The impedance of the switch is small and its on-state voltage drop is negligible.

The circuit of the above solution includes two DC / DC conversion units. It is assumed that the maximum output voltage of the charging power supply is Vo and the operating current at the maximum output voltage is Io. The maximum output voltage designed by the two DC / DC conversion units is Vo / 2. The minimum output voltage is Vo / 4; in order to ensure full power in the full voltage range, the maximum output current of the 2 DC / DC conversion units is 2Io. Let ’s describe the demand power of the charging power source as 10KW, and the charging power source achieves 10KW output within the output voltage range of 225 ～ 900VDC; according to the embodiment of the present invention, the output voltage range of each DC / DC conversion unit is 225 ～ 450VDC, the maximum current It is 22.2A; the total design power of the entire charging power supply is 2 * 450 * 22.2 = 20KW, which is much lower than the scheme shown in Figure 1 (40KW), which greatly reduces the system cost.

In one embodiment, when the output voltage is less than or equal to a set threshold (for example, 450V), two two DC / DC conversion units are connected in parallel. At this time, the maximum output current of the output of the charging power source is 44.4A. Under the condition of 225V, the output current is 44.4A to achieve 10KW output; under the condition of 450V, the output current is 22.2A to achieve 10KW output.

In one embodiment, when the output voltage is greater than a set threshold (such as 450V, or other values, depending on the application), two DC / DC conversion units are connected in series. At this time, the output of the charging power source has the maximum output. The current is 22.2A. Under the condition of 450V, the output current is 22.2A to achieve 10KW output; under the condition of 900V, the output current is 11.1A to achieve 10KW output.

In one embodiment, two two DC / DC conversion units are connected to the same power source, as shown in FIG. 8.

In one embodiment, two two DC / DC conversion units are connected to independent power sources, as shown in FIG. 9.

In one embodiment, the circuit further includes a capacitor, one end of which is electrically connected to the output positive terminal, and the other end of which is electrically connected to the output negative terminal.

In one embodiment, the control module is electrically connected to the first DC / DC conversion unit, the second DC / DC conversion unit, and the selection unit; the control module responds to the received voltage information (voltage information of the electric vehicle to be charged) and triggers The selection unit (and sends an instruction to the selection unit, and the selection unit responds to the instruction), wherein when the circuit is in the first working mode, the first DC / DC conversion unit and the second DC / DC conversion unit Electrically connected in parallel; in the second working mode, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series.

In an embodiment, the (DC) power supply using the implementation circuit includes a two-stage converter: a first-stage converter and a second-stage converter, and an input end of the second-stage converter is electrically connected to an output of the first-stage converter. Terminal, the first-stage converter is used to convert the input AC power into DC power; the second-stage converter includes the circuit as described above. The alternating current here can be three-phase 220V or 380V alternating current. In a preferred embodiment, the first-stage converter includes a power factor correction circuit. The power factor correction circuit is used to correct the power factor and perform rectification. In a specific embodiment, the power factor correction circuit may include a full-bridge circuit composed of six IGBTs or MOS transistors, and the control pole of each IGBT or MOS transistor is controlled by a pulse width modulation signal. The second-stage converter is used to convert the voltage of the DC power output from the first-stage converter into a DC voltage suitable for charging the electric vehicle.

In one embodiment, the DC power source using the above implementation circuit further includes a voltage identification module electrically connected to the control module. When the DC power source is connected to the electric vehicle to be charged, the charging voltage information of the electric vehicle to be charged is obtained and fed back to the control. Module, the control module receives the information and sends an instruction in response to the voltage information to the selection unit, and the selection unit receives the instruction and responds to the instruction to electrically connect the first DC / DC conversion unit and the second DC / DC conversion unit in series or in parallel. In this embodiment, if the voltage information is less than or equal to a set threshold, the two DC / DC conversion units are electrically connected in parallel, and if the voltage information is greater than the set threshold, the two DC / DC conversion units are electrically connected in series.

In one embodiment, the DC power supply using the circuit of the above embodiment further includes: a human-machine interaction module for receiving information on charging voltage input by a user; a control module receiving the information and issuing an instruction in response to the voltage information to a selection unit The selection unit receives the instruction and responds to the instruction so that the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series or in parallel. In this embodiment, if the voltage information is less than or equal to a set threshold, the two DC / DC conversion units are electrically connected in parallel, and if the voltage information is greater than the set threshold, the two DC / DC conversion units are electrically connected in series.

In one embodiment, using the DC power supply of the above-mentioned implementation circuit, the voltage identification module, the control module, and the human-computer interaction module may be provided and / or integrated in the above-mentioned circuit.

In one embodiment, a method for controlling a DC power supply of a circuit is also provided. The circuit protection includes: a voltage identification module electrically connected to the control module; the method includes the following steps: Charging voltage information of the electric vehicle to be charged when the DC power source is connected;

The control module sends an instruction in response to the voltage information to the selection unit based on the received voltage information;

The selection unit receives and responds to the instruction so that the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series or in parallel. In this control method, if the voltage information is less than or equal to the set threshold, two DC / DC conversion units (the first DC / DC conversion unit and the second DC / DC conversion unit) are electrically connected in parallel. If the voltage information is greater than the set threshold 2 The DC / DC conversion units are electrically connected in series. The parameters for setting the threshold are the same as those in the foregoing embodiment, and will not be repeated here. In the method, the voltage identification module includes a voltage identification circuit (also referred to as a voltage sampling voltage, which uses a conventional identification circuit in the art, which is not described in detail here), and is used to sample the charging voltage information of the connected electric vehicle to be charged, and Information feedback (using the standard communication protocol of electric vehicles) to the control module (also called the main control board). The control module further identifies the charging voltage information based on a preset rule, and compares the information with a set threshold.

The above embodiments are only for explaining the technical concept and features of the present invention, and the purpose thereof is to enable those familiar with the technology to understand the contents of the present invention and implement them accordingly, and shall not limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit and essence of the present invention shall be covered by the protection scope of the present invention.

Claims

A series-parallel circuit for a DC power source, comprising: a first DC / DC conversion unit and a second DC / DC conversion unit, for converting the received DC power to output; a first unidirectional conduction device, one end of which The first terminal is electrically connected to the first DC / DC conversion unit, and the other end is electrically connected to the output positive terminal; the selection unit is electrically connected to the first DC / DC conversion unit at the first terminal and electrically connected to the second terminal at the second terminal. One end and the third end of the unidirectional conduction device are electrically connected to the output negative terminal. The selection unit receives a command from the control module and responds to the command to make the first DC / DC conversion unit and the second DC / DC conversion unit electrically conductive. Serial or parallel; the other end of the second unidirectional conducting device is electrically connected to the output positive terminal; the second DC / DC conversion unit is electrically connected to one end of the second unidirectional conducting device and the second end 2. The second DC / DC conversion unit is electrically connected to an output negative terminal.
The circuit of claim 1, wherein:

The first unidirectional conducting device includes a first diode, an anode terminal of which is electrically connected to a first output terminal of the first DC / DC conversion unit, and a cathode terminal of which is electrically connected to a positive output terminal;

The second unidirectional conducting device includes a second diode, an anode terminal of which is electrically connected to the second terminal and a first output terminal of the second DC / DC conversion unit, and a cathode terminal of which is connected to an output positive terminal. extreme.
The circuit according to claim 2, wherein the selection unit comprises a single-pole double-throw switch relay, and a first terminal thereof is electrically connected to a second output terminal and a second terminal of the first DC / DC conversion unit. The anode terminal and the third terminal of the second diode are electrically connected to the output negative terminal, and the second output terminal of the second DC / DC conversion unit is electrically connected to the output negative terminal, wherein the single-pole double-throw switch relay is closed. At the second end, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series; when the single pole double throw switch relay is closed at the third end, the first DC / DC conversion The unit is electrically connected in parallel with the second DC / DC conversion unit.
The circuit according to claim 2, wherein the selection unit comprises a first switch and a second switch; a first terminal of the first switch is electrically connected to the first terminal of the second switch and the second switch; The second output terminal of the first DC / DC conversion unit and the second terminal of the first switch are electrically connected to the anode terminal of the second diode, and the second terminal of the second switch is electrically connected to the negative output. Extremely, the second output terminal of the second DC / DC conversion unit is electrically connected to the output negative terminal, wherein when the first switch is closed, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected. When the second switch is closed, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in parallel.
The circuit according to claim 4, wherein the first switch and the second switch include a relay.
The circuit according to claim 1, wherein the control module is electrically connected to the first DC / DC conversion unit, the second DC / DC conversion unit, and the selection unit; and the control module is based on The received voltage information controls the selection unit. If the voltage information is less than or equal to a set threshold, the circuit is in a first working mode, and between the first DC / DC conversion unit and the second DC / DC conversion unit. Electrically connected in parallel; if the voltage information is greater than a set threshold and the circuit is in a second operating mode, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series.
The circuit according to claim 6, wherein in the second working mode, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series, and the second Unidirectional devices are off.
The circuit according to any one of claims 2 to 7, further comprising a capacitor, one end of which is electrically connected to the output positive terminal, and the other end of which is electrically connected to the output negative terminal.
A DC power source is characterized in that it comprises a first-stage converter and a second-stage converter, and an input terminal of the second-stage converter is electrically connected to an output terminal of the first-stage converter; The converter is used to convert the input AC power to DC power, and the second-stage converter includes the circuit according to any one of claims 1 to 7.
The DC power supply according to claim 9, further comprising a voltage identification module electrically connected to the control module to obtain voltage information of the electric vehicle to be charged and feed it back to the control module, the control module Controlling the selection unit based on the received voltage information, and if the voltage information is less than or equal to a set threshold, the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in parallel; if the voltage The information is greater than a set threshold, and the first DC / DC conversion unit and the second DC / DC conversion unit are electrically connected in series.