Energy storage inverter charging and discharging control circuit and control method thereof

Abstract

The present invention provides a charge and discharge control circuit for an energy storage inverter and a control method thereof, wherein the control circuit comprises a bidirectional non-isolated DC-DC converter A, a control circuit, a bidirectional non-isolated DC-DC converter B, a bidirectional isolated DC-DC converter C and a controller. The control circuit has multiple working modes such as isolation, non-isolation, and wide-range conversion, and can meet the requirements of energy storage charging and discharging applications of energy storage inverters under various working conditions. A variety of electric energy functions can be realized through a circuit architecture, and the circuit has good adaptability and practicality. The control method of the control circuit can meet the application requirements of different types of energy storage inverter charging and discharging circuits, and has very good application prospects and extremely high engineering value.

Description

Technical Field

[0001] The present invention belongs to the field of electronic technology, and in particular relates to a charge and discharge control circuit and a control method for an energy storage inverter. Background Art

[0002] As an energy conversion device used in energy storage systems, energy storage inverters can realize the conversion and control management functions of various electric energies. Among them, the energy storage charging and discharging circuit, as the core main conversion circuit, plays an important role in the functional realization and efficient operation of the entire energy storage inverter, especially in new energy storage application projects in solar photovoltaic, wind power generation and other occasions. The charging and discharging control circuit needs to have bidirectional power conversion and can uniformly control and manage the charging and discharging of energy storage batteries. Different circuit methods need to be adopted for different application scenarios of energy storage inverters. For example, some occasions require a high voltage conversion ratio, and some occasions require the charging and discharging circuit to have isolation functions. The existing circuit uses a single conversion circuit architecture that is difficult to meet the needs of various different application scenarios, resulting in the need to reconfigure the design circuit for different application scenarios, and has the disadvantages of poor flexibility and low adaptability. Summary of the invention

[0003] The purpose of the present invention is to make up for the deficiencies of the prior art and provide a charge and discharge control circuit and control method for an energy storage inverter. The charge and discharge circuit of the present invention adopts a modular circuit, and the circuit composition can be flexibly adjusted according to different energy storage charge and discharge requirements to achieve the best circuit matching. The control method of the circuit can achieve efficient control of the circuit of the invention.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A charge and discharge control circuit for an energy storage inverter, comprising a bidirectional non-isolated DC-DC converter A, a control circuit, a bidirectional non-isolated DC-DC converter B, a bidirectional isolated DC-DC converter C and a controller;

[0006] The bidirectional non-isolated DC-DC converter A is respectively connected to the inverter DC bus of the main control circuit of the energy storage inverter and the control terminal b1 of the control circuit; the control circuit comprises switching switches S1 and S2, wherein the common terminals a1 and a2 of the switching switches S1 and S2 are connected, and the control terminals b1 and c1 of the switching switch S1 are respectively connected to the bidirectional non-isolated DC-DC converter A and the inverter DC bus of the main control circuit of the energy storage inverter;

[0007] The control terminals b2, c2 and d2 of the switching switch S2 are respectively connected to the bidirectional non-isolated DC-DC converter B, the DC bus at the energy storage battery end, and the control circuit of the bidirectional isolated DC-DC converter C; the bidirectional non-isolated DC-DC converter B is respectively connected to the b2 terminal of the control circuit and the DC bus at the energy storage battery end; the bidirectional isolated DC-DC converter C is respectively connected to the d2 terminal of the control circuit and the DC bus at the energy storage battery end; the controller is connected to the main control circuit of the energy storage inverter through SPI communication to control the control circuit.

[0008] The bidirectional non-isolated DC-DC converter A, the bidirectional non-isolated DC-DC converter B, and the bidirectional isolated DC-DC converter C can realize different combined operation modes through the control of the control circuit, specifically: (1) when the a1 terminal and the b1 terminal of the switching switch S1 of the control circuit are closed and connected, and the a2 terminal and the b2 terminal of the switching switch S2 are connected, the bidirectional non-isolated DC-DC converter A and the bidirectional non-isolated DC-DC converter B are combined and operated to form a new cascade bidirectional non-isolated converter circuit, thereby improving the voltage conversion and matching of charging and discharging. (2) When the a1 and b1 terminals of the switching switch S1 of the control circuit are closed and connected, and the a2 and c2 terminals of the switching switch S2 are connected, the equivalent bidirectional non-isolated DC-DC converter A works alone, which is suitable for charging and discharging applications with a small voltage conversion range and no isolation required; (3) When the a1 and b1 terminals of the switching switch S1 of the control circuit are closed and connected, and the a2 and d2 terminals of the switching switch S2 are connected, the equivalent bidirectional non-isolated DC-DC converter A and the bidirectional isolated DC-DC converter C work in cascade, which is suitable for applications requiring high voltage conversion and isolation. (4) When the a1 and c1 terminals of the switching switch S1 of the control circuit are closed and connected, and the a2 and b2 terminals of the switching switch S2 are connected, the equivalent bidirectional non-isolated DC-DC converter B works alone. In this mode, it can form an alternating time-sharing operation with the bidirectional non-isolated DC-DC converter A, thereby improving the working reliability of the charging and discharging circuit and extending the service life. It is also suitable for charging and discharging occasions with a small voltage conversion range and no isolation application required; (5) When the a1 and c1 terminals of the switching switch S1 of the control circuit are closed and connected, the switching switch When a2 and c2 of S2 are connected, the inverter DC bus of the energy storage inverter main control circuit is connected to the DC bus of the energy storage battery, which is suitable for discharge applications where the energy storage battery has sufficient power and is greater than the set SOCset value. In this case, there is no need to pass through the converter circuit, and high-efficiency direct discharge can be achieved; (6) When the a1 and c1 terminals of the control circuit's switching switch S1 are closed and connected, and a2 and d2 of the switching switch S2 are connected, the equivalent single bidirectional isolated DC-DC converter C works alone, which is suitable for charging and discharging applications with a small voltage conversion range and requiring isolation.

[0009] The present invention also discloses a control method for a charge and discharge control circuit for an energy storage inverter, and the specific steps are as follows:

[0010] Step 1: Read the controller's set working mode and set value, and analyze whether the working mode is a specific working mode or an automatic working mode;

[0011] Step 2: If the working mode is a specific working mode, the control circuit performs switching control according to the set working mode, and directly goes to step 4; if it is an automatic mode, the control circuit is controlled according to the set value;

[0012] Step 3: Perform control operations on the control circuit according to the read set values, read the energy storage battery bus voltage value UDC_BAT and the energy storage inverter main control circuit inverter DC bus voltage value UDC_INV; and perform control operations according to the preset working mode after determining the working mode and charging mode;

[0013] Step 4: Perform control operations of the control circuit in the corresponding manner of steps 2 and 3.

[0014] Beneficial effects: The present invention provides a charge and discharge control circuit for an energy storage inverter and a control method thereof. The control circuit has multiple working modes such as isolation, non-isolation, and wide-range conversion. It can meet the energy storage charging and discharging application needs of energy storage inverters under various working conditions. A variety of electrical energy functions can be realized through one circuit architecture. It has good adaptability and practicality. The control method of the control circuit can meet the application needs of different types of energy storage inverter charging and discharging circuits. It has very good application prospects and extremely high engineering value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a circuit composition principle block diagram of the control circuit of the present invention;

[0016] Figure 2 is a diagram of an equivalent circuit composition under the control mode described in Example 1 of the present invention;

[0017] Figure 3 is a diagram of an equivalent circuit composition under the control mode described in Example 2 of the present invention;

[0018] Figure 4 is a composition diagram of an equivalent circuit under the control mode described in Example 3 of the present invention;

[0019] Figure 5 is a diagram of an equivalent circuit composition under the control mode described in Example 4 of the present invention;

[0020] Figure 6 is a composition diagram of an equivalent circuit under the control mode described in Example 5 of the present invention;

[0021] Figure 7 is a composition diagram of an equivalent circuit under the control mode described in Example 6 of the present invention;

[0022] Figure 8 It is a flow chart of the control method of the control circuit of the present invention.

[0023] In the figure: 1. Bidirectional non-isolated DC-DC converter A; 2. Control circuit; 3. Bidirectional non-isolated DC-DC converter B; 4. Bidirectional isolated DC-DC converter C; 5. Controller; 6. Energy storage inverter main control circuit; 7. Energy storage battery. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with specific embodiments, but the embodiments are only exemplary and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solution of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the protection scope of the present invention.

[0025] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0026] A charge and discharge control circuit for an energy storage inverter, such as Figure 1 As shown, it includes a bidirectional non-isolated DC-DC converter A1, a control circuit 2, a bidirectional non-isolated DC-DC converter B3, a bidirectional isolated DC-DC converter C4 and a controller 5. The bidirectional non-isolated DC-DC converter A1 is respectively connected to the inverter DC bus of the energy storage inverter main control circuit 6 and the control terminal b1 of the control circuit 2; the control circuit 2 includes switching switches S1 and S2, wherein the common terminals a1 and a2 of the switching switches S1 and S2 are connected, and the control terminals b1 and c1 of the switching switch S1 are respectively connected to the bidirectional non-isolated DC-DC converter A1 and the inverter DC bus of the energy storage inverter main control circuit 6; the control terminals b2, c2 and d2 of the switching switch S2 are respectively connected to the bidirectional non-isolated DC-DC converter B3, the DC bus of the energy storage battery 7, and the control circuit of the bidirectional isolated DC-DC converter C4; the bidirectional non-isolated DC-DC converter B3 is respectively connected to the b2 terminal of the control circuit 2 and the DC bus of the energy storage battery 7; the bidirectional isolated DC-DC converter C4 is respectively connected to the b2 terminal of the control circuit 2 and the DC bus of the energy storage battery 7; 4 is respectively connected to the d2 end of the control circuit 2 and the DC bus of the energy storage battery 7; the controller 2 is connected to the energy storage inverter main control circuit 6 through SPI communication to control the control circuit.

[0027] Figure 2-71 is an equivalent circuit composition diagram of the control circuit of the present invention under different control modes. The bidirectional non-isolated DC-DC converter A1, the bidirectional non-isolated DC-DC converter B3, and the bidirectional isolated DC-DC converter C4 can be controlled by the control circuit 2 to achieve different combined operation modes, as shown in the following embodiments. Example

[0028] like Figure 2 As shown, when the a1 terminal and the b1 terminal of the switching switch S1 of the control circuit 2 are closed and connected, and the a2 and b2 terminals of the switching switch S2 are turned on, the bidirectional non-isolated DC-DC converter A1 and the bidirectional non-isolated DC-DC converter B2 are combined and operated to form a new cascade bidirectional non-isolated converter circuit, thereby improving the voltage conversion and matching capabilities of charging and discharging. Example

[0029] like Figure 3 As shown, when the a1 terminal and the b1 terminal of the switching switch S1 of the control circuit 2 are closed and connected, and the a2 and c2 of the switching switch S2 are turned on, the equivalent bidirectional non-isolated DC-DC converter A1 works alone, which is suitable for charging and discharging occasions with a small voltage conversion range and no isolation application. Example

[0030] like Figure 4 As shown, when the a1 terminal and the b1 terminal of the switching switch S1 of the control circuit 2 are closed and connected, and the a2 and d2 of the switching switch S2 are turned on, the equivalent bidirectional non-isolated DC-DC converter A1 and the bidirectional isolated DC-DC converter C3 work in cascade, which is suitable for charging and discharging occasions requiring high voltage conversion and isolation applications. Example

[0031] like Figure 5 As shown, when the a1 terminal and the c1 terminal of the switching switch S1 of the control circuit 2 are closed and connected, and the a2 and b2 of the switching switch S2 are turned on, the equivalent bidirectional non-isolated DC-DC converter B2 works alone. In this mode, it can form an alternating time-sharing operation with the bidirectional non-isolated DC-DC converter A1, thereby improving the working reliability of the charging and discharging circuit and extending the service life. It is also suitable for charging and discharging occasions with a small voltage conversion range and no isolation application. Example

[0032] like Figure 6 As shown, when the a1 and c1 terminals of the switching switch S1 of the control circuit are closed and connected, and the a2 and c2 terminals of the switching switch S2 are turned on, the inverter DC bus of the energy storage inverter main control circuit is connected to the DC bus of the energy storage battery end, which is suitable for discharge applications where the energy storage battery has sufficient power greater than the set SOCset value. At this time, there is no need to pass through the converter circuit, and high-efficiency direct discharge is achieved. Example

[0033] like Figure 7 As shown, when the a1 and c1 terminals of the switching switch S1 of the control circuit are closed and connected, and a2 and d2 of the switching switch S2 are turned on, the equivalent single bidirectional isolated DC-DC converter C works alone, which is suitable for charging and discharging occasions with a small voltage conversion range and isolated applications.

[0034] Figure 8 : is a flow chart of the control method of the control circuit of the present invention, and the specific steps are as follows:

[0035] Step 1: Read the controller's set working mode and set value, and analyze whether the working mode is a specific working mode or an automatic working mode;

[0036] Step 2: If the working mode is a specific working mode, the control circuit performs switching control according to the set working mode, and directly goes to step 4; if it is an automatic mode, the control circuit is controlled according to the set value;

[0037] Step 3: Perform control operations on the control circuit according to the set value read, and read the bus voltage value of the energy storage battery U DC_BAT And the inverter DC bus voltage value of the energy storage inverter main control circuit U DC_INV ; and after determining the working mode and charging method, perform control operations according to Table 1.

[0038] Table 1

[0039]

[0040] Step 4: Perform control operations of the control circuit in the corresponding manner of steps 2 and 3.

[0041] The above contents are further detailed descriptions of the present invention in combination with specific preferred technical solutions, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A charge and discharge control circuit for an energy storage inverter, characterized in that: It includes a bidirectional non-isolated DC-DC converter A, a control circuit, a bidirectional non-isolated DC-DC converter B, a bidirectional isolated DC-DC converter C and a controller; The bidirectional non-isolated DC-DC converter A is respectively connected to the inverter DC bus of the main control circuit of the energy storage inverter and the control terminal b1 of the control circuit; the control circuit comprises switching switches S1 and S2, wherein the common terminals a1 and a2 of the switching switches S1 and S2 are connected, and the control terminals b1 and c1 of the switching switch S1 are respectively connected to the bidirectional non-isolated DC-DC converter A and the inverter DC bus of the main control circuit of the energy storage inverter; The control terminals b2, c2 and d2 of the switching switch S2 are respectively connected to the bidirectional non-isolated DC-DC converter B, the DC bus at the energy storage battery end, and the control circuit of the bidirectional isolated DC-DC converter C; the bidirectional non-isolated DC-DC converter B is respectively connected to the b2 terminal of the control circuit and the DC bus at the energy storage battery end; the bidirectional isolated DC-DC converter C is respectively connected to the d2 terminal of the control circuit and the DC bus at the energy storage battery end; the controller is connected to the main control circuit of the energy storage inverter through SPI communication to control the control circuit.

2. A charge and discharge control circuit for an energy storage inverter according to claim 1, characterized in that: When the a1 terminal and the b1 terminal of the switching switch S1 of the control circuit are closed and connected, and the a2 and b2 of the switching switch S2 are connected, the bidirectional non-isolated DC-DC converter A and the bidirectional non-isolated DC-DC converter B operate in combination.

3. The charge and discharge control circuit for an energy storage inverter according to claim 1, characterized in that: When the a1 terminal and the b1 terminal of the switching switch S1 of the control circuit are closed and connected, and the a2 and c2 terminals of the switching switch S2 are connected, the equivalent bidirectional non-isolated DC-DC converter A works alone.

4. The charge and discharge control circuit for an energy storage inverter according to claim 1, characterized in that: When the a1 terminal and the b1 terminal of the switching switch S1 of the control circuit are closed and connected, and the a2 and d2 of the switching switch S2 are turned on, the equivalent bidirectional non-isolated DC-DC converter A and the bidirectional isolated DC-DC converter C work in cascade.

5. The charge and discharge control circuit for an energy storage inverter according to claim 1, characterized in that: When the a1 and c1 terminals of the switching switch S1 of the control circuit are closed and connected, and a2 and b2 of the switching switch S2 are turned on, the equivalent bidirectional non-isolated DC-DC converter B works alone. In this mode, it can form an alternating time-sharing operation with the bidirectional non-isolated DC-DC converter A.

6. The charge and discharge control circuit for an energy storage inverter according to claim 1, characterized in that: When the a1 and c1 terminals of the switching switch S1 of the control circuit are closed and connected, and a2 and c2 of the switching switch S2 are connected, the inverter DC bus of the energy storage inverter main control circuit is connected to the DC bus of the energy storage battery end.

7. The charge and discharge control circuit for an energy storage inverter according to claim 1, characterized in that: When the a1 and c1 terminals of the switching switch S1 of the control circuit are closed and connected, and a2 and d2 of the switching switch S2 are turned on, the equivalent single bidirectional isolated DC-DC converter C works alone, which is suitable for charging and discharging occasions with a small voltage conversion range and isolated applications.

8. A control method for a charge and discharge control circuit for an energy storage inverter according to any one of claims 1 to 7, characterized in that: The specific steps are as follows: Step 1: Read the controller's set working mode and set value, and analyze whether the working mode is a specific working mode or an automatic working mode; Step 2: If the working mode is a specific working mode, the control circuit performs switching control according to the set working mode, and directly goes to step 4; if it is an automatic mode, the control circuit is controlled according to the set value; Step 3: Perform control operations on the control circuit according to the read set values, read the energy storage battery bus voltage value UDC_BAT and the energy storage inverter main control circuit inverter DC bus voltage value UDC_INV; and perform control operations according to the preset working mode after determining the working mode and charging mode; Step 4: Perform control operations of the control circuit in the corresponding manner of steps 2 and 3.

Images