A DC power supply system

Abstract

The present application relates to a DC power supply system, which belongs to the field of electric power supply technology, including a DC bus, a charger interconnection circuit, an AC power distribution unit, a bidirectional conversion module and a battery, wherein the charger interconnection circuit is electrically connected to the DC bus, the bidirectional conversion module and the battery, and the bidirectional conversion module includes a rectifier inverter unit and an isolated bidirectional DC / DC unit, wherein the rectifier inverter unit is electrically connected to the AC power distribution unit and the isolated bidirectional DC / DC unit, and the isolated bidirectional DC / DC unit is electrically connected to the charger interconnection circuit. The present application can perform remote capacity control and has the effect of simplifying the circuit and reducing costs.

Description

Technical Field

[0001] The present application relates to the technical field of electric power supply, and in particular to a direct current power supply system. Background Art

[0002] In the power system of the power station, the high-voltage switchgear cannot be powered off. Therefore, a battery is installed on the power system as a backup power source. When the city power is off, the battery supplies power to the high-voltage switchgear. As the last barrier of the high-voltage switchgear, if the battery capacity is insufficient, it will cause a major impact. Therefore, the battery needs to be regularly charged and discharged at full capacity (capacity verification).

[0003] When checking the capacity, workers were initially required to go to the site to check the capacity, which was time-consuming and labor-intensive, and prone to insufficient manpower. In order to solve the problem of time-consuming and labor-intensive, and prone to insufficient manpower, a DC power supply system was proposed in the related art. Figure 1 The DC power supply system includes: a DC bus 10, a charger connection circuit 20, a battery 30, a charging module 40, an AC distribution unit 60 and a charge-discharge circuit 50. The battery 30 is charged and discharged by remotely controlling the charge-discharge circuit 50, and relevant data is uploaded to the host computer to realize remote capacity verification.

[0004] With respect to the above-mentioned related technologies, the inventors have found the following defects: electrical isolation is required between the power grid and the battery, which is generally achieved by installing an industrial frequency transformer at the front end, resulting in high costs and relatively complex circuits. Summary of the invention

[0005] In order to simplify the circuit, the present application provides a DC power supply system.

[0006] The present application provides a DC power supply system, which adopts the following technical solution:

[0007] A DC power supply system comprises a DC bus, a charger interconnection circuit, an AC power distribution unit, a bidirectional conversion module and a battery, wherein the charger interconnection circuit is electrically connected to the DC bus, the bidirectional conversion module and the battery, wherein the bidirectional conversion module comprises a rectifier inverter unit and an isolated bidirectional DC / DC unit, wherein the rectifier inverter unit is electrically connected to the AC power distribution unit and the isolated bidirectional DC / DC unit, and the isolated bidirectional DC / DC unit is electrically connected to the charger interconnection circuit.

[0008] By adopting the above technical solution, the rectifier inverter unit can convert DC and AC, the isolated bidirectional DC / DC unit can isolate the power grid from the battery, and the circuit can be effectively simplified by replacing the charging module and the charging and discharging circuit with a bidirectional conversion module. At the same time, there is no need to set up an industrial frequency transformer at the front end, thereby reducing costs.

[0009] Preferably, the bidirectional conversion module also includes an auxiliary power supply circuit, an MCU, a first amplifying drive circuit, a second amplifying drive circuit, an AC sampling circuit and a DC sampling circuit, wherein the MCU is electrically connected to the first amplifying drive circuit, the second amplifying drive circuit, the AC sampling circuit and the DC sampling circuit; the auxiliary power supply circuit is used to provide electrical energy to the MCU, the first amplifying drive circuit, the second amplifying drive circuit, the AC sampling circuit and the DC sampling circuit; the AC sampling circuit is used to collect current and voltage on the AC side; the DC sampling circuit is used to collect current and voltage on the DC side; the first amplifying drive circuit is electrically connected to the rectifier and inverter unit; and the second amplifying drive circuit is electrically connected to the isolated bidirectional DC / DC unit.

[0010] Preferably, the rectifying and inverting unit comprises a plurality of bidirectional controllable switches, and the plurality of bidirectional controllable switches constitute a bridge circuit.

[0011] Preferably, the bidirectional controllable switch may be a MOS tube, a thyristor, or an insulated gate bipolar transistor.

[0012] By adopting the above technical solution, the sampling circuit collects the voltage and current, and sends the data to the MCU. The MCU calculates and analyzes the data and outputs a control signal according to the analysis result. The control signal is amplified by the amplification drive circuit to drive the rectifier inverter unit and the isolated bidirectional DC / DC unit respectively, which can adjust the voltage in real time to stabilize the output voltage and facilitate the control of the battery charging and discharging.

[0013] Preferably, the bidirectional conversion module also includes an AC protection unit and a DC protection unit, the AC protection unit is connected to the rectifier inverter unit and the MCU, and the AC protection unit is used to control the on and off of the AC side load circuit; the DC protection unit is connected to the MCU and the isolated bidirectional DC / DC unit, and the DC protection unit is used to control the on and off of the DC side load circuit.

[0014] Preferably, the DC protection unit includes a diode D and a control switch K, the anode of the diode D is connected to the isolated bidirectional DC / DC unit, the cathode of the diode D is connected to the DC side, the control switch K is connected in parallel with the diode D, and the control switch K is electrically connected to the MCU.

[0015] Preferably, the AC protection unit adopts a fuse.

[0016] By adopting the above technical solution, usually the bidirectional conversion modules are connected in parallel in multiple stages in the power supply system. If the bidirectional conversion modules are damaged, the AC protection unit and the DC protection unit can be disconnected to reduce the impact on the entire power supply system.

[0017] Preferably, the bidirectional conversion module further includes a temperature sampling circuit and a fan, the temperature sampling circuit is electrically connected to the MCU and the auxiliary power supply circuit, and the fan is electrically connected to the MCU and the auxiliary power supply circuit.

[0018] By adopting the above technical solution, the temperature sampling circuit monitors the temperature of the bidirectional converter. When the temperature rises, the power of the fan can be increased to increase the heat dissipation effect.

[0019] Preferably, the bidirectional conversion module further includes a communication circuit, and the communication circuit is connected to the MCU and the auxiliary power supply circuit.

[0020] By adopting the above technical solution and setting up the communication circuit, it is convenient to communicate with the host computer and to remotely control the system.

[0021] In summary, the present application includes at least one of the following beneficial technical effects:

[0022] 1. By using a bidirectional conversion module to replace the charging module and the charging and discharging circuit, the circuit can be simplified and the cost can be reduced;

[0023] 2. By setting up EMI filters, the electromagnetic compatibility design can be met and the device can work stably even in complex electromagnetic environments;

[0024] 3. The temperature sampling circuit monitors the temperature of the bidirectional converter. When the temperature rises, the power of the fan can be increased to increase the heat dissipation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a system block diagram of a DC power supply system in the related art;

[0026] Figure 2 It is a system block diagram of an offline DC power supply system in the related art;

[0027] Figure 3 is a system block diagram of a DC power supply system in an embodiment of the present application;

[0028] Figure 4 is a system block diagram of an offline DC power supply system in an embodiment of the present application;

[0029] Figure 5 is a structural block diagram of a bidirectional conversion module in an embodiment of the present application;

[0030] Figure 6 It is a circuit diagram of the rectifier inverter unit in the embodiment of the present application.

[0031] Explanation of the reference numerals: 10, DC bus; 11, bus connection circuit; 20, charger connection circuit; 30, battery; 40, charging module; 50, charging and discharging circuit; 60, AC power distribution unit; 70, bidirectional conversion module; 71, rectifier inverter unit; 72, isolated bidirectional DC / DC unit; 73, auxiliary power supply circuit; 74, first amplifier drive circuit; 75, second amplifier drive circuit; 76, AC sampling circuit; 77, DC sampling circuit; 78, communication circuit; 80, AC protection unit; 81, DC protection unit; 82, EMI filter; 83, temperature sampling circuit; 84, fan. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of this application more clear, the following Figure 1-6 It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0033] refer to Figure 1 In the related art, a DC power supply system generally includes: a DC bus 10, a charger interconnection circuit 20, a battery 30, a charging module 40 and a charge-discharge circuit 50, and the charger interconnection circuit 20 is connected to the DC bus 10, the battery 30, the charging module 40, and the charge-discharge circuit 50 respectively.

[0034] refer to Figure 2 For example, the offline DC power supply system in the related art has a switch 1ZK, a switch 2ZK, a switch 3ZK, a switch 4ZK and a switch 5ZK, wherein the switches are all DC circuit breakers, the switches 4ZK and 5ZK are used for switching the charging and discharging of the II group of batteries, the switches 2ZK and 3ZK are switches connected in series to the fuse, and have the function of isolating the battery 30, and the switch 1ZK is a busbar connecting switch.

[0035] When it is necessary to charge or discharge the battery group I, switches 1ZK, 3ZK and 4ZK are all in the closed state, switches 2ZK and 5ZK are in the open state, and the battery group I is completely isolated for charging or discharging. The discharge process is that the bidirectional inverter converts the DC into AC and then feeds it back to the station's three-phase AC power supply system. After the discharge is completed, the bidirectional inverter converts the three-phase AC into DC and then charges the battery group I. After the nuclear capacity is completed, the system automatically disconnects switches 4ZK and 5ZK first, then closes switches 2ZK and 3ZK, and then disconnects switch 1ZK to restore normal operation.

[0036] The present application embodiment discloses a DC power supply system. Figure 3The DC power supply system includes a DC bus 10, a charger interconnection circuit 20, an AC distribution unit 60, a bidirectional conversion module 70 and a battery 30. The charger interconnection circuit 20 is electrically connected to the DC bus 10, the bidirectional conversion module 70 and the battery 30, and the AC distribution unit 60 is connected to the bidirectional conversion module 70.

[0037] refer to Figure 4 In order to facilitate the understanding of the present application, the present application will be described more comprehensively by enumerating an offline DC power supply system. For example, the DC bus 10 includes a bus section I and a bus section II, and the bus section I and the bus section II are connected through a bus interconnection circuit 11; the battery 30 includes a group I battery and a group II battery, and the group I battery is connected to the bus section I through a charger interconnection circuit 20, and the group II battery is connected to the bus section II through a charger interconnection circuit 20. Among them, a switch 1ZK is provided in the bus interconnection circuit 11, a switch 6ZK is provided in the charger interconnection circuit 20 connected to the group I battery, and a switch 7ZK is provided in the charger interconnection circuit 20 connected to the group II battery.

[0038] Normally, switch 1ZK is in the open state, switch 6ZK and switch 7ZK are in the closed state, and the AC power distribution unit 60 supplies power to bus section I and bus section II through the bidirectional conversion module 70. When it is necessary to increase the capacity of group I batteries, switch 1ZK is closed and switch 6ZK is opened, and group I batteries are completely isolated. At this time, electric energy flows from bus section II to bus section I to supply power to the load on bus section I, and group I batteries are charged or discharged through the bidirectional conversion module 70, wherein the discharge process is to invert DC into AC and then feed it back to the AC power supply system.

[0039] refer to Figure 5 In this embodiment, the bidirectional conversion module 70 includes a rectifier inverter unit 71, an isolated bidirectional DC / DC unit 72, an auxiliary power supply circuit 73, an MCU, a first amplifying drive circuit 74, a second amplifying drive circuit 75, an AC sampling circuit 76, a DC sampling circuit 77 and a communication circuit 78, wherein the rectifier inverter unit is electrically connected to the AC power distribution unit 60, the isolated bidirectional DC / DC unit 72, and the first amplifying drive circuit 74, and the isolated bidirectional DC / DC unit 72 is electrically connected to the charger communication circuit 20 and the second amplifying drive circuit 75.

[0040] The MCU is electrically connected to the first amplifying drive circuit 74, the second amplifying drive circuit 75, the AC sampling circuit 76, and the DC sampling circuit 77. The auxiliary power supply circuit 73 is used to provide power to the MCU, the first amplifying drive circuit 74, the second amplifying drive circuit 75, the AC sampling circuit 76, and the DC sampling circuit 77. The AC sampling circuit 76 is used to collect the current and voltage on the AC side, and the DC sampling circuit 77 is used to collect the current and voltage on the DC side.

[0041] Among them, by setting up the communication circuit 78, it is convenient for the MCU to communicate with the host computer, and the system can be remotely controlled by the host computer, which is also convenient for remote core capacity.

[0042] refer to Figure 6 In this embodiment, the rectifier inverter unit 71 includes a plurality of bidirectional controllable switches, and the plurality of bidirectional controllable switches form a bridge circuit. In order to facilitate the understanding of the present application, the present application will be described more comprehensively below by listing the single-phase rectifier inverter unit 71. At this time, the number of bidirectional controllable switches is 4, and the bidirectional controllable switches can be MOS tubes, thyristors, or insulated gate bipolar transistors (IGBTs).

[0043] Among them, the rectifier inverter unit 71 and the isolated bidirectional DC / DC unit 72 form a single channel circuit, that is, when the battery 30 is charged and discharged, the rectifier inverter unit 71 performs rectification and inversion, and the isolated bidirectional DC / DC unit 72 performs isolation. When discharging, the bidirectional conversion module 70 is in the inverter state, by controlling the inverter voltage (set value) on the AC side to be higher than the grid voltage; when charging, the bidirectional conversion module 70 is in the rectifier state, by controlling the rectifier voltage (set value) on the DC side to be higher than the battery 30 voltage, thereby making the charging and discharging effects of the battery 30 better and the core capacity effect better.

[0044] Among them, the AC sampling circuit 76 collects the voltage and current on the AC side, and sends the collected data to the MCU. The MCU performs calculations based on the corresponding data and outputs a first control signal. The first control signal is amplified by the first amplification drive circuit 74. The amplified first control signal is used to drive the rectifier inverter unit 71 to change the duty cycle of the bidirectional controllable switch to maintain the input voltage stable. At the same time, when the core capacity is reached, the MCU can control the rectifier inverter unit 71 so that the voltage on the AC side is greater than the voltage on the DC side, which is convenient for charging the battery 30. The MCU can also control the rectifier inverter unit 71 so that the voltage on the DC side is greater than the voltage on the AC side, which is convenient for discharging the battery 30.

[0045] The DC sampling circuit 77 collects the voltage and current on the AC side and sends the collected data to the MCU. The MCU performs calculations based on the corresponding data and outputs a second control signal. The second control signal is amplified by the second amplification drive circuit 75. The amplified second control signal is used to drive the isolated bidirectional DC / DC unit 72 to stabilize the output voltage.

[0046] refer to Figure 5Optionally, the bidirectional conversion module 70 also includes an AC protection unit 80 and a DC protection unit 81. The AC protection unit 80 is connected to the rectifier inverter unit 71 and the MCU, and the AC protection unit 80 is used to control the on-off of the load circuit on the AC side; the DC protection unit 81 is connected to the MCU and the isolated bidirectional DC / DC unit 72, and the DC protection unit 81 is used to control the on-off of the load circuit on the DC side.

[0047] In this embodiment, the DC protection unit 81 includes a diode D and a control switch K, the anode of the diode D is connected to the isolated bidirectional DC / DC unit 72, the cathode of the diode D is connected to the DC side, the control switch K is connected in parallel with the diode D, the control switch K is electrically connected to the MCU, the control switch K can be a MOS tube or a relay, wherein the AC protection unit 80 can be a fuse or a relay. When a fault occurs in the bidirectional conversion module 70, such as a short circuit, the AC protection unit 80 and the DC protection unit 81 can be disconnected to reduce the impact on the stability of the entire system.

[0048] Optionally, the bidirectional conversion module 70 further includes an EMI filter 82. In the present embodiment, there are three EMI filters 82, one of which is connected to the AC protection unit 80 and the AC side, one of which is connected to the DC protection unit 81 and the DC side, and another EMI filter 82 is connected to the communication circuit 78. By providing the EMI filter 82, the electromagnetic compatibility design can be met, so that the bidirectional conversion module 70 can work stably even in a complex electromagnetic environment.

[0049] Optionally, the bidirectional conversion module 70 further includes a temperature sampling circuit 83 and a fan 84. The temperature sampling circuit 83 is connected to the MCU and the auxiliary power supply circuit 73, and the fan 84 is connected to the MCU and the auxiliary power supply circuit 73. When the bidirectional conversion module 70 is working, the fan 84 is started to dissipate heat from the bidirectional conversion module 70. The temperature sampling circuit 83 collects the temperature of the bidirectional conversion module 70 and sends the temperature data to the MCU. When the temperature of the bidirectional conversion module 70 rises, the MCU increases the power of the fan 84 to improve the heat dissipation effect.

[0050] The implementation principle of a DC power supply system in an embodiment of the present application is as follows: the rectifier inverter unit 71 can perform conversion between DC and AC, and the isolated bidirectional DC / DC unit 72 can isolate the power grid from the battery 30. By using the bidirectional conversion module 70 to replace the charging module 40 and the charging and discharging circuit 50, the circuit can be simplified. At the same time, there is no need to set an industrial frequency transformer at the front end, thereby reducing costs.

[0051] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

Claims

1. A DC power supply system, characterized in that: The invention comprises a DC bus (10), a charger interconnection circuit (20), an AC power distribution unit (60), a bidirectional conversion module (70) and a storage battery (30), wherein the charger interconnection circuit (20) is electrically connected to the DC bus (10), the bidirectional conversion module (70) and the storage battery (30), wherein the bidirectional conversion module (70) comprises a rectifier inverter unit (71) and an isolated bidirectional DC / DC unit (72), wherein the rectifier inverter unit (71) is electrically connected to the AC power distribution unit (60) and the isolated bidirectional DC / DC unit (72), and wherein the isolated bidirectional DC / DC unit (72) is electrically connected to the charger interconnection circuit (20); wherein the bidirectional conversion module (70) further comprises an auxiliary power supply circuit (73), an MCU, a first amplification drive circuit (74), a second amplification drive circuit (75), and a second amplification drive circuit (76). 5), an AC sampling circuit (76) and a DC sampling circuit (77), wherein the MCU is electrically connected to a first amplifying driving circuit (74), a second amplifying driving circuit (75), an AC sampling circuit (76), and a DC sampling circuit (77); the auxiliary power supply circuit (73) is used to provide electric energy to the MCU, the first amplifying driving circuit (74), the second amplifying driving circuit (75), the AC sampling circuit (76), and the DC sampling circuit (77); the AC sampling circuit (76) is used to collect the current and voltage on the AC side; the DC sampling circuit (77) is used to collect the current and voltage on the DC side; the first amplifying driving circuit (74) is electrically connected to a rectifying and inverting unit (71); and the second amplifying driving circuit (75) is electrically connected to an isolated bidirectional DC / DC unit (72); The rectifying and inverting unit (71) comprises a plurality of bidirectional controllable switches, and the plurality of bidirectional controllable switches form a bridge circuit; The AC sampling circuit (76) collects the voltage and current on the AC side and sends the collected data to the MCU. The MCU calculates and outputs a first control signal. The first control signal is amplified by a first amplification drive circuit (74). The amplified first control signal is used to drive the rectifier inverter unit (71) to change the duty cycle of the bidirectional controllable switch. The DC sampling circuit (77) collects the voltage and current on the AC side and sends the collected data to the MCU. The MCU calculates and outputs a second control signal. The second control signal is amplified by the second amplification drive circuit (75). The amplified second control signal is used to drive the isolated bidirectional DC / DC unit (72).

2. The DC power supply system according to claim 1, characterized in that: The bidirectional controllable switch may be a MOS tube, a thyristor, or an insulated gate bipolar transistor.

3. The DC power supply system according to claim 1, characterized in that: The bidirectional conversion module (70) further comprises an AC protection unit (80) and a DC protection unit (81); the AC protection unit (80) is connected to the rectifier inverter unit (71) and the MCU, and the AC protection unit (80) is used to control the on-off of the AC side load circuit; the DC protection unit (81) is connected to the MCU and the isolated bidirectional DC / DC unit (72), and the DC protection unit (81) is used to control the on-off of the DC side load circuit.

4. The DC power supply system according to claim 3, characterized in that: The DC protection unit (81) comprises a diode D and a control switch K, the anode of the diode D is connected to the isolated bidirectional DC / DC unit (72), the cathode of the diode D is connected to the DC side, the control switch K is connected in parallel with the diode D, and the control switch K is electrically connected to the MCU.

5. The DC power supply system according to claim 3, characterized in that: The AC protection unit (80) is a fuse.

6. The DC power supply system according to claim 1, characterized in that: The bidirectional conversion module (70) further comprises a temperature sampling circuit (83) and a fan (84); the temperature sampling circuit (83) is electrically connected to the MCU and the auxiliary power supply circuit (73); and the fan (84) is electrically connected to the MCU and the auxiliary power supply circuit (73).

7. The DC power supply system according to claim 1, characterized in that: The bidirectional conversion module (70) further comprises a communication circuit (78), wherein the communication circuit (78) is connected to the MCU and the auxiliary power supply circuit (73).

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