Energy storage inverter and control method thereof

Abstract

The invention discloses an energy storage inverter and a control method of the energy storage inverter. The energy storage inverter includes: a current sensor; the program processing unit comprises an acquisition subunit; the calculation subunit is configured to execute the following operations: in response to the fact that the load current is greater than or equal to the maximum output current of the energy storage inverter, calculating a voltage regulation coefficient based on a difference value between the load current and the maximum output current; calculating a target voltage value based on the voltage regulation coefficient and a rated output voltage value of the energy storage inverter; calculating a first voltage amplitude based on the target voltage value; calculating a second voltage amplitude based on the rated output voltage value and an output voltage provided by the energy storage inverter to the load; the energy storage inverter is configured to adjust an output voltage provided to the load based on the first voltage amplitude and the second voltage amplitude.

Description

Technical Field

[0001] The present application belongs to the field of power electronics technology, and in particular, relates to an energy storage inverter and a control method for the energy storage inverter. Background Art

[0002] In the current PCS (Power Conversion System, energy storage converter), there are many types of AC side loads, and the energy storage converter needs to adapt to different types of AC loads to improve the load adaptability of the energy storage converter.

[0003] Among the loads on the AC side, some are impact loads, including resistive loads, capacitive loads, inductive loads, etc. Taking the motor load as an example, during the motor load startup process, the instantaneous startup power far exceeds the rated power during normal operation, causing the load current to exceed the overcurrent protection threshold of the energy storage inverter, triggering the protection action of the energy storage inverter, making it impossible for the motor load to start normally. In addition, the large current in a short period of time may cause damage to the components in the energy storage inverter. Summary of the invention

[0004] The embodiments of the present application provide an energy storage inverter and a control method for the energy storage inverter, which improve the technical problem that sudden loading or impact load startup generates large power or large current to trigger the protection of the energy storage inverter.

[0005] In a first aspect, an embodiment of the present application provides an energy storage inverter, the energy storage inverter comprising: a current sensor, configured to collect load current, defining the load current as the current flowing through the load; a program processing unit, comprising: an acquisition subunit, configured to acquire the load current; a calculation subunit, configured to perform the following operations: in response to the load current being greater than or equal to the maximum output current of the energy storage inverter, calculating the difference between the load current and the maximum output current, and calculating a voltage regulation coefficient based on the difference; calculating a target voltage value based on the voltage regulation coefficient and the rated output voltage value of the energy storage inverter, the target voltage value being less than or equal to the rated output voltage value; calculating a first voltage amplitude based on the target voltage value; calculating a second voltage amplitude based on the rated output voltage value and the output voltage provided by the energy storage inverter to the load; the energy storage inverter is configured to adjust the output voltage provided to the load based on the first voltage amplitude and the second voltage amplitude.

[0006] When the energy storage inverter supplies power to the load, the target voltage value and its corresponding first voltage amplitude are calculated according to the voltage regulation coefficient and the rated output voltage value, and the second voltage amplitude is calculated according to the rated output voltage value and the output voltage provided by the energy storage inverter to the load, so that the energy storage inverter adjusts the output voltage provided to the load based on the first voltage amplitude and the second voltage amplitude to achieve output voltage reduction. When the load is suddenly increased during the load startup process, the output voltage of the energy storage inverter decreases, reducing the load current and the risk of overcurrent damage to the device, so that the load starts and runs normally.

[0007] In one or more embodiments of the present application, the calculation subunit is configured to perform the following operations: calculate the difference between the maximum output current and the load current to obtain a first current error value; and calculate a voltage regulation coefficient corresponding to the first current error value based on a preset loop control algorithm.

[0008] The voltage regulation coefficient corresponding to the first current error value is obtained through a preset loop control algorithm, and the output voltage provided to the load is adjusted according to the load current, thereby reducing the load current and the risk of overcurrent damage to the device.

[0009] In one or more embodiments of the present application, the preset loop control algorithm includes: K is the voltage regulation coefficient, Kp is the proportional regulation coefficient, Ki is the integral regulation coefficient, I_Err(t) is the first current error value at time t, and b is a constant.

[0010] The voltage regulation coefficient is generated through proportional-integral control, which eliminates steady-state errors, improves steady-state response speed and accuracy, and enables the energy storage inverter to stably provide output voltage to the load.

[0011] In one or more embodiments of the present application, the calculation subunit is configured to perform the following operations: calculate the difference between the load current and the maximum output current to obtain a second current error value; and calculate a voltage regulation coefficient based on a ratio of the second current error value to the maximum output current.

[0012] The voltage regulation coefficient is calculated by the ratio of the second current error value to the maximum output current, and the output voltage provided to the load is adjusted according to the load current, thereby reducing the load current and the risk of overcurrent damage to the device.

[0013] In one or more embodiments of the present application, the calculation formula of the voltage regulation coefficient includes: K=1-(I_Load-I_Max) / I_Max; K is the voltage regulation coefficient, I_Load is the load current, and I_Max is the maximum output current.

[0014] The voltage regulation coefficient is generated by proportional control. When the load current is too large, the output voltage reduction amplitude is increased, thereby quickly reducing the load current and improving the response speed.

[0015] In one or more embodiments of the present application, the voltage regulation coefficient is K, Kmin≤K≤1; Kmin is the minimum voltage regulation coefficient, and the minimum voltage regulation coefficient is configured so that the product of the minimum voltage regulation coefficient and the rated output voltage value of the energy storage inverter is greater than or equal to the starting voltage of the load.

[0016] The minimum voltage regulation coefficient is determined by the starting voltage of the load and the rated output voltage value, and the value range of the voltage regulation coefficient is determined, so that the output voltage generated by the energy storage inverter based on the voltage regulation coefficient meets the starting requirements of the load, avoiding the load being unable to start due to the output voltage being too low.

[0017] In one or more embodiments of the present application, the rated output voltage value and the target voltage value are defined as the effective value of the AC voltage, and the first voltage amplitude is the product of the target voltage value and the amplitude coefficient; wherein the amplitude coefficient is the ratio of the maximum value of the AC voltage to the effective value of the AC voltage; or, the rated output voltage value and the target voltage value are defined as the maximum value of the AC voltage, and the first voltage amplitude is consistent with the target voltage value.

[0018] When the rated output voltage value and the target voltage value are AC voltage effective values, the first voltage amplitude output by the voltage feedforward control loop is calculated according to the amplitude coefficient, so that the energy storage inverter adjusts the output voltage provided to the load based on the first voltage amplitude.

[0019] In one or more embodiments of the present application, the maximum withstand current of the power switch of the inverter circuit in the energy storage inverter is Icm, and the maximum output current of the energy storage inverter is I_Max; Icm≥2*I_Max.

[0020] The maximum output current of the energy storage inverter is set based on the maximum withstand current parameter of the power switch in the inverter circuit to reduce the risk of overcurrent damage to the device.

[0021] In a second aspect, an embodiment of the present application provides a control method for an energy storage inverter, including: obtaining a load current flowing through a load; in response to the load current being greater than or equal to the maximum output current of the energy storage inverter, calculating a voltage regulation coefficient based on the difference between the load current and the maximum output current; calculating a target voltage value based on the voltage regulation coefficient and the rated output voltage value of the energy storage inverter, the target voltage value being less than or equal to the rated output voltage value; calculating a first voltage amplitude based on the target voltage value; calculating a second voltage amplitude based on the rated output voltage value and the output voltage provided by the energy storage inverter to the load; and adjusting the output voltage provided to the load based on the first voltage amplitude and the second voltage amplitude.

[0022] When the energy storage inverter supplies power to the load, the target voltage value and its corresponding first voltage amplitude are calculated according to the voltage regulation coefficient and the rated output voltage value, and the second voltage amplitude is calculated according to the rated output voltage value and the output voltage provided by the energy storage inverter to the load, so that the energy storage inverter adjusts the output voltage provided to the load based on the first voltage amplitude and the second voltage amplitude to achieve output voltage reduction. During the load startup process or when the load is suddenly increased, the output voltage of the energy storage inverter decreases, reducing the load current and the risk of overcurrent damage to the device, so that the load starts and runs normally.

[0023] In one or more embodiments of the present application, the voltage regulation coefficient is calculated based on the difference between the load current and the maximum output current, including: calculating the difference between the maximum output current and the load current to obtain a first current error value; and calculating the voltage regulation coefficient corresponding to the first current error value based on a preset loop control algorithm; wherein the preset loop control algorithm includes: K is the voltage regulation coefficient, Kp is the proportional regulation coefficient, Ki is the integral regulation coefficient, I_Err(t) is the first current error value at time t, and b is a constant.

[0024] The voltage regulation coefficient is generated by proportional-integral control, which eliminates steady-state errors, improves steady-state response speed and accuracy, and enables the energy storage inverter to stably output the output voltage provided to the load.

[0025] In one or more embodiments of the present application, the voltage regulation coefficient is calculated based on the difference between the load current and the maximum output current, including: calculating the difference between the load current and the maximum output current to obtain a second current error value; calculating the voltage regulation coefficient based on the ratio of the second current error value to the maximum output current; wherein, the calculation formula of the voltage regulation coefficient includes: K=1-(I_Load-I_Max) / I_Max; K is the voltage regulation coefficient, I_Load is the load current, and I_Max is the maximum output current.

[0026] The voltage regulation coefficient is generated by proportional control. When the load current is too large, the output voltage reduction amplitude is increased to quickly reduce the load current and improve the response speed.

[0027] Compared with the prior art, the energy storage inverter and the control method of the energy storage inverter provided in the embodiment of the present application, when the energy storage inverter supplies power to the load, compares the collected load current with the maximum output current of the energy storage inverter, and when the load current is greater than the maximum output current, calculates the voltage regulation coefficient based on the difference between the load current and the maximum output current. The target voltage value and its corresponding first voltage amplitude are calculated according to the voltage regulation coefficient and the rated output voltage value, and the second voltage amplitude is calculated according to the rated output voltage value and the output voltage provided by the energy storage inverter to the load, so that the energy storage inverter adjusts the output voltage provided to the load based on the first voltage amplitude and the second voltage amplitude to achieve output voltage reduction. During the load startup process, the output voltage of the energy storage inverter decreases, the load current is reduced, and the risk of overcurrent damage to the device is reduced, so that the load starts and runs normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application.

[0029] Figure 1 is a structural schematic diagram of an energy storage inverter provided in one embodiment of the present application;

[0030] Figure 2 is a loop control schematic diagram of an energy storage inverter provided in an embodiment of the present application;

[0031] Figure 3 It is a schematic diagram of voltage-current waveforms during the load startup process in the related art;

[0032] Figure 4 1 is a schematic diagram of voltage-current waveforms during a load startup process provided by an embodiment of the present application;

[0033] Figure 5 It is a flow chart of a control method of an energy storage inverter provided in one embodiment of the present application;

[0034] Figure 6 It is a schematic diagram of the structure of an electronic device provided in one embodiment of the present application.

[0035] In the attached figure:

[0036] 10. Current sensor; 20. Program processing unit; 21. Acquisition subunit; 22. Calculation subunit; 30. Load; 40. Inverter circuit. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. The following specific implementation methods are exemplary rather than limiting, and are intended to provide a basic understanding of the present application, and are not intended to confirm the key or decisive elements of the present invention or to limit the scope of protection.

[0038] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating the existence of three relationships. For example, A and / or B means: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0039] In the description of this application, connection can be direct connection, indirect connection through an intermediate medium, or internal connection between two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0040] The embodiment of the present application provides an energy storage inverter and a control method for the energy storage inverter. The specific implementation of the embodiment of the present application is further described below in conjunction with the accompanying drawings.

[0041] Energy storage inverter

[0042] Figure 1 FIG. 1 shows a schematic diagram of the module structure of an energy storage inverter provided by an embodiment of the present application. Figure 1 As shown, the energy storage inverter includes a current sensor 10 and a program processing unit 20. The current sensor 10 is used to collect the load current I_Load. When the energy storage inverter and the load 30 are in working state, the current flowing through the load 30 is collected by the current sensor 10. As an example of the present application, the current sensor is a Hall sensor.

[0043] The program processing unit 20 includes an acquisition subunit 21 and a calculation subunit 22. The acquisition subunit 21 is used to acquire the load current collected by the current sensor 10. Taking the energy storage inverter converting the DC voltage into single-phase AC power as an example, the load 30 connected to the energy storage inverter is a single-phase AC load, and the load current is a single-phase AC current. As an example of the present application, the program processing unit is a digital signal processor (DSP).

[0044] In this embodiment, when the load 30 is started, the program processing unit 20 determines that the load current is greater than or equal to the maximum output current I_max of the energy storage inverter, and the calculation subunit 22 calculates the difference between the maximum output current I_max and the load current I_Load, and calculates the voltage regulation coefficient based on the difference.

[0045] According to some embodiments of the present application, the calculation subunit 22 calculates the difference between the maximum output current I_max and the load current I_Load to obtain a first current error value, and based on a preset loop control algorithm, calculates a voltage regulation coefficient corresponding to the first current error value.

[0046] As an optional implementation, the above preset loop control algorithm includes:

[0047] K is the voltage regulation coefficient, Kp is the proportional regulation coefficient, Ki is the integral regulation coefficient, I_Err(t) is the first current error value at time t, and b is a positive constant.

[0048] As some examples of the present application, the above loop control algorithm includes PI (Proportional-Integral) control. Taking the moment when the load current rises to a value greater than the maximum output current as t0 as an example, is the integral of the first current error value from time (t0-t) to time t0 (current time). At time t0, That is

[0049] If the load current is less than the maximum output current, I_Err(t) is a positive value because it is the difference between the maximum output current and the load current. On the contrary, if the load current is greater than the maximum output current, I_Err(t) is a negative value. In addition, when the load current is equal to the maximum output current, I_Err(t) is 0.

[0050] The integral of all first current error values ​​from time (t0-t) to time t0 is obtained by integration operation. The product of the integral value and the integral adjustment coefficient is the integral error value, that is,

[0051] At time t0, the product of the first current error value I_Err(t0) and the proportional adjustment coefficient is calculated to obtain the proportional error value, that is, Kp*I_Err(t0). The voltage adjustment coefficient at time t0 is obtained by calculating the sum of the integral error value, the proportional error value and the constant b.

[0052] Taking the moment when the load current is greater than the maximum output current as moment t1 as an example, the time interval between moment t1 and moment t0 is t.

[0053] At time t1, That is The voltage regulation factor is:

[0054]

[0055] At any moment, the integral of the first current error value in the time period t before the moment is obtained by integration operation, and the integral error value is generated according to the integral adjustment coefficient Ki and the integral of the first current error value in the time period t. At this moment, the proportional error value is generated according to the proportional adjustment coefficient Kp and the first current error value at this moment. The sum of the integral error value and the proportional error value is the voltage adjustment coefficient. The energy storage inverter provides a stable output voltage to the load 30 through proportional integral control, thereby realizing a smooth startup process of the load 30.

[0056] In the above calculation formula, when the load current I_Load increases and exceeds the maximum output current, the difference between the maximum output current I_max and the load current I_Load, that is, the first current error value, is a negative value, and decreases as the load current I_Load increases. By setting the proportional adjustment coefficient Kp to a positive value, when the load current I_Load increases, the product of the proportional adjustment coefficient Kp and the first current error value, that is, the proportional error value, decreases; by setting the integral adjustment coefficient Ki to a positive value, when the load current I_Load increases, the product of the integral of the first current error value and the integral adjustment coefficient Ki, that is, the integral error value, decreases. Moreover, Kp and Ki are positive values, and when the load current I_Load increases and exceeds the maximum output current I_max, the first current error value is a negative value, so that the product of the proportional adjustment coefficient Kp and the first current error value is a negative value; if the integral value of the first current error value is a negative value, then the product of the integral of the first current error value and the integral adjustment coefficient Ki is also a negative value. By setting the constant b, the voltage adjustment coefficient K decreases as the load current I_Load increases while meeting the numerical range requirements. As a specific example of the present application, the value of the constant b is 1.

[0057] According to some other embodiments of the present application, the calculation subunit 22 calculates the difference between the load current I_Load and the maximum output current I_max to obtain a second current error value, and calculates a voltage regulation coefficient based on a ratio of the second current error value to the maximum output current.

[0058] The calculation formula for calculating the voltage regulation coefficient based on the ratio of the current error value to the maximum output current is:

[0059] K = 1-(I_Load-I_Max) / I_Max, K is the voltage regulation coefficient, I_Load is the load current, and I_Max is the maximum output current.

[0060] In this embodiment, (I_Load-I_Max) is the difference between the load current and the maximum output current, that is, the second current error value, and (I_Load-I_Max) / I_Max is the ratio of the second current error value to the maximum output current. After calculating the ratio of the second current error value to the maximum output current, 1-(I_Load-I_Max) / I_Max is used as the voltage regulation coefficient. That is, the program processing unit 20 determines that the load current is greater than or equal to the maximum output current, and the calculation subunit 22 calculates the voltage regulation coefficient according to the difference between the load current and the maximum output current.

[0061] According to the above calculation formula, when the load current increases, the difference between the load current and the maximum output current, that is, the second current error value, also increases, and accordingly, the ratio of the second current error value to the maximum output current increases, so that the voltage regulation coefficient decreases. Therefore, based on the above calculation formula, when the load current increases, the corresponding voltage regulation coefficient decreases.

[0062] According to some embodiments of the present application, the voltage regulation coefficient K satisfies the following conditions:

[0063] Kmin≤K≤1, Kmin is the minimum voltage regulation coefficient.

[0064] In some embodiments of the present application, the minimum voltage regulation coefficient is calculated based on the rated output voltage value of the energy storage inverter and the starting voltage value of the load 30. The condition satisfied by the minimum voltage regulation coefficient is that the product of the minimum voltage regulation coefficient and the rated output voltage value is greater than or equal to the starting voltage value of the load 30. After the rated output voltage value and the starting voltage value of the load 30 are known, the value range of the minimum voltage regulation coefficient is determined. As a specific example not applied, 0.7≤K≤1.

[0065] In the above embodiment, if the calculated voltage regulation coefficient is less than the minimum voltage regulation coefficient, the program processing unit 20 sets the voltage regulation coefficient to the minimum voltage regulation coefficient.

[0066] As an optional implementation, the starting voltage of the load 30 is lower than the rated output voltage of the energy storage inverter. For example, taking an AC load as an example, the starting voltage of the AC load is the minimum voltage for the AC load to start normally. As a specific example of the present application, the effective value provided by the energy storage inverter is a rated output voltage greater than 200VAC, and the starting voltage of the AC load is lower than the rated output voltage, for example, 140VAC.

[0067] It is understandable that the rated output voltage values ​​of different energy storage inverters are somewhat different, and the starting voltages of different AC loads are not completely consistent. After determining the rated output voltage value of a certain energy storage inverter and the starting voltage of the load 30 electrically connected to the energy storage inverter, the ratio of the starting voltage to the rated output voltage value is calculated, and the minimum voltage adjustment coefficient Kmin is set to be greater than the ratio.

[0068] Taking the rated output voltage of the energy storage inverter as 200VAC and the starting voltage of load 30 as 140VAC as an example, the ratio of the starting voltage to the rated output voltage is 0.7, and the minimum voltage regulation coefficient is selected within the range of [0.7, 1].

[0069] When the minimum voltage regulation coefficient is taken between the ratio of the starting voltage to the rated output voltage and 1, taking the minimum voltage regulation coefficient Kmin as 0.75 as an example, the value range of the voltage regulation coefficient K is 0.75≤K≤1. The product of the voltage regulation coefficient K within this value range and the rated output voltage value of the energy storage inverter is greater than or equal to the starting voltage of the load 30, so that the minimum output voltage provided by the energy storage inverter during the voltage adjustment process meets the voltage required for the normal startup of the load 30.

[0070] According to some embodiments of the present application, the calculation subunit 22 calculates a target voltage value based on the voltage regulation coefficient and the rated output voltage value of the energy storage inverter, and the target voltage value is less than or equal to the rated output voltage value;

[0071] The calculation subunit 22 calculates the difference between the load current and the maximum output current, and then calculates the voltage regulation coefficient based on the difference, and calculates the target voltage value according to the rated output voltage value of the energy storage inverter and the voltage regulation coefficient.

[0072] When the voltage regulation coefficient is taken within the value range obtained in the above embodiment, the voltage regulation coefficient is less than or equal to 1, and the target voltage value obtained by calculating the product of the rated output voltage value of the energy storage inverter and the voltage regulation coefficient is less than or equal to the rated output voltage value of the energy storage inverter. In some embodiments of the present application, when the load current is less than or equal to the maximum output current, the value of the voltage regulation coefficient is 1, and when the load current is greater than the maximum output current, the value of the voltage regulation coefficient is less than 1 and greater than the minimum voltage regulation coefficient Kmin.

[0073] In some embodiments of the present application, the energy storage inverter includes a voltage feedforward control loop and a voltage effective value control loop. The voltage feedforward control loop calculates a first voltage amplitude based on a target voltage value, and the voltage effective value control loop calculates a second voltage amplitude based on a rated output voltage value and an actual output voltage provided by the energy storage inverter to a load.

[0074] The first voltage amplitude output by the voltage feedforward control loop and the second amplitude output by the voltage effective value control loop are superimposed to form a total amplitude. The energy storage inverter adjusts the output voltage provided to the load based on the superimposed total amplitude so that the output voltage provided to the load is close to the target voltage value or remains consistent with the target voltage value.

[0075] like Figure 1 As shown, the calculation subunit 22 of the energy storage inverter generates a corresponding control signal based on the first voltage amplitude through the control loop of the inverter circuit 40 and outputs it to the inverter circuit 40. The inverter circuit 40 adjusts the output voltage provided to the load 30 based on the received control signal.

[0076] When the energy storage inverter calculates the original first voltage amplitude based on the original rated output voltage value, and provides the output voltage to the load 30 according to the original first voltage amplitude, a large instantaneous current will be generated during the startup of the load 30. At this time, the startup power of the load 30 far exceeds the rated power of the load (for example, 3 to 7 times), causing the energy storage inverter to trigger overcurrent and overload protection, so that the load 30 cannot operate normally. In the above-mentioned embodiment of the present application, the energy storage inverter calculates the new first voltage amplitude based on the calculated target voltage value, and the new first voltage amplitude based on the rated output voltage value. and the actual output voltage (U VRMS (s)) calculates the second voltage amplitude. Since the target voltage value is less than or equal to the rated output voltage value, the calculated new first voltage amplitude is also less than or equal to the original first voltage amplitude, so that the superimposed voltage amplitude in this embodiment is smaller than the superimposed voltage amplitude in the original scheme. The output voltage provided to the load 30 by the energy storage inverter based on the superimposed voltage amplitude will also be reduced accordingly. When the output voltage provided to the load 30 is reduced, the corresponding load current will also be reduced, thereby avoiding excessive instantaneous current that causes the load 30 to fail to start and operate normally, and also protecting the electronic devices in the energy storage inverter and reducing the risk of overcurrent damage to the devices.

[0077] According to some embodiments of the present application, in the circuit structure formed by the energy storage inverter and the load 30, the AC voltage output by the energy storage inverter to the load 30 is expressed in the form of an AC voltage effective value. After obtaining the target voltage value, the product of the target voltage value and the amplitude coefficient is calculated to obtain a first voltage amplitude, which is the corresponding AC voltage maximum value, and is used as the output of the voltage feedforward control loop of the energy storage inverter, so that the energy storage inverter adjusts the output voltage provided to the load based on the first voltage amplitude.

[0078] The above amplitude coefficient is the ratio of the maximum value of the AC voltage to the effective value of the AC voltage. For example, in a single-phase AC voltage, the ratio of the maximum value of the voltage to the effective value of the voltage is

[0079] According to some other embodiments of the present application, the AC voltage output by the energy storage inverter to the load 30 is expressed in the form of the maximum value of the AC voltage. If the rated output voltage value and the target voltage value of the energy storage inverter are the maximum values ​​of the AC voltage, the target voltage value is consistent with the first voltage amplitude, and the target voltage value is used as the output of the voltage feedforward control loop of the energy storage inverter. The energy storage inverter adjusts the output voltage provided to the load based on the first voltage amplitude output by the voltage feedforward control loop and the second amplitude output by the voltage effective value control loop.

[0080] Please refer to Figure 2 , Figure 2 A schematic diagram of loop control corresponding to the above embodiment is shown.

[0081] like Figure 2 As shown, the voltage feedforward control loop is a part of the voltage control loop of the energy storage inverter. is the rated output voltage of the energy storage inverter, U VRMS (s) is the output voltage provided by the energy storage inverter to the load 30, I_Load is the load current, and I_Max is the maximum output current.

[0082] G I (s) is a loop controller that generates a voltage regulation coefficient based on the maximum output current I_Max and the load current I_Load. As some optional implementations, G I (s) The voltage regulation coefficient is calculated by the loop control algorithm preset in the above embodiment. As other optional implementations, G I (s) The voltage regulation coefficient is calculated by the voltage regulation coefficient calculation formula, that is, K=1-(I_Load-I_Max) / I_Max.

[0083] It is understandable that in the embodiment based on the preset loop control algorithm, G I (s) calculating the difference between the maximum output current I_Max and the load current I_Load as the first current error value; and in the embodiment based on the calculation formula of the voltage regulation coefficient, G I (s) Calculate the difference between the load current I_Load and the maximum output current I_Max as the second current error value.

[0084] Rated output voltage When used as the effective value of AC voltage, multiply by the amplitude coefficient The corresponding AC voltage maximum value is obtained. It is the ratio of the maximum value of the AC voltage to the effective value of the AC voltage under single-phase AC power.

[0085] To obtain the rated output voltage After the corresponding AC voltage maximum value, calculate the AC voltage maximum value and G I (s) is multiplied by the voltage regulation coefficient outputted by the output to obtain the maximum AC voltage value corresponding to the target voltage value, that is, the first voltage amplitude.

[0086] To obtain the rated output voltage After that, calculate the rated output voltage value The actual output voltage (U VRMS The first voltage amplitude and the second voltage amplitude are superimposed based on the first voltage amplitude output by the voltage feedforward control loop and the second voltage amplitude output by the voltage effective value control loop. The energy storage inverter generates an SPWM (Sine pulse width modulation) signal of the inverter circuit 40 through a subsequent control loop based on the superimposed voltage amplitude, and adjusts the output voltage provided to the load 30 based on the SPWM signal.

[0087] According to some embodiments of the present application, the energy storage inverter includes an inverter circuit 40 composed of a plurality of power switches, wherein the maximum withstand current of the power switches is Icm, and the maximum output current of the energy storage inverter is I_Max.

[0088] When the program processing unit 20 determines that the load current is greater than or equal to the maximum output current I_Max of the energy storage inverter, the calculation subunit 22 calculates the difference between the load current and the maximum output current, and adjusts the output voltage provided to the load 30 based on the difference. In order to reduce the risk of overcurrent damage to the power switch, the corresponding maximum output current I_Max should be set based on the maximum withstand current Icm borne by the power switch, so that when the load current is greater than the maximum output current I_Max, it will not exceed the maximum withstand current Icm of the power switch. That is, after selecting a suitable power switch and determining the maximum withstand current Icm of the power switch, the maximum output current I_Max of the energy storage inverter should be set to be less than the maximum withstand current Icm of the power switch, that is, Icm≥I_Max.

[0089] As an optional implementation, after determining the maximum withstand current Icm of the power switch, the magnitude relationship between the maximum withstand current Icm and the maximum output current I_Max is set to satisfy:

[0090] Icm≥2*I_Max;

[0091] In this embodiment, after determining the maximum withstand current Icm of the power switch based on the device type of the power switch in the energy storage inverter, the maximum output current I_Max of the energy storage inverter is set to be less than half of the maximum withstand current Icm, so that when the load current exceeds the maximum output current I_Max of the energy storage inverter by a large amount, it will not reach the maximum withstand current Icm of the power switch, thereby reducing the risk of overcurrent damage to the power switch.

[0092] It is understandable that in the above-mentioned embodiment of the present application, when the load current is increased to be greater than the maximum output current, the calculation subunit 22 of the energy storage inverter begins to adjust the output voltage provided to the load 30 to reduce the load current. Therefore, compared with the technical solution without output voltage adjustment, the load current is suppressed faster and earlier in the embodiment of the present application, so that the load current does not trigger the overcurrent and overload protection action of the energy storage inverter. That is, the peak value of the load current in this embodiment is lower than the peak value of the load current in the related art. In the case of a lower peak value of the load current, the maximum withstand current of the power switch is correspondingly reduced, thereby expanding the selection range of the device and reducing the cost of the device.

[0093] Please refer to Figure 3 and Figure 4 , Figure 3 The waveform diagram of voltage and current during the startup process of the energy storage inverter supplying power to the load in the related art is shown in FIG. Figure 4 Schematic diagram of voltage and current waveforms during the startup process of the energy storage inverter supplying power to the load in an embodiment of the present application. Figure 3 and Figure 4 The horizontal axis represents time, and the vertical axis represents voltage value / current value.

[0094] like Figure 3 As shown, the green waveform is the output voltage waveform of the energy storage inverter, and the yellow waveform is the load current waveform. When the energy storage inverter is not supplying power to the load, the output voltage of the energy storage inverter is the rated output voltage, that is, a sine waveform, and the load current is 0. When the energy storage inverter supplies power to the load, the instantaneous current of the load during the startup process is large, resulting in the instantaneous power exceeding the load capacity of the energy storage inverter, causing the energy storage inverter to trigger the protection action. Figure 3 The load current eventually remains at 0, indicating that the load cannot start normally and the load stops running.

[0095] like Figure 4 As shown, the green waveform is the output voltage waveform of the energy storage inverter, and the purple waveform is the load current waveform. When the energy storage inverter does not supply power to the load, the load current represented by the purple waveform is 0.

[0096] When the energy storage inverter supplies power to the load, the load current represented by the purple waveform is a sinusoidal waveform, indicating that the load current undergoes a sinusoidal change at this time. Figure 4 In the embodiment, the load current maintains a sinusoidal change and does not become 0 current, indicating that the load maintains normal operation. That is, the instantaneous current of the load during the startup process does not exceed the load capacity of the energy storage inverter, and the energy storage inverter does not trigger a protection action. Therefore, the load starts and runs normally.

[0097] Combination Figure 3 and Figure 4 It can be seen that based on the embodiments of the present application, the technical problem of excessive instantaneous current of the load during startup is improved, and the protection action of the energy storage inverter will not be triggered, thereby achieving normal startup and operation of the load.

[0098] Control method of energy storage inverter

[0099] Based on the energy storage inverter provided in the above embodiment, the present application also provides a control method for the energy storage inverter. Please refer to the following embodiment.

[0100] Please refer to Figure 5 , the control method of the energy storage inverter provided in the embodiment of the present application includes:

[0101] S110, obtaining a load current flowing through the load;

[0102] S120, in response to the load current being greater than or equal to the maximum output current of the energy storage inverter, calculating a voltage regulation coefficient based on a difference between the load current and the maximum output current;

[0103] S130, calculating a target voltage value based on the voltage regulation coefficient and the rated output voltage value of the energy storage inverter, where the target voltage value is less than or equal to the rated output voltage value;

[0104] S140, calculating a first voltage amplitude based on the target voltage value;

[0105] S150, calculating a second voltage amplitude based on a rated output voltage value and an output voltage provided by the energy storage inverter to the load;

[0106] S160, adjusting the output voltage provided to the load based on the first voltage amplitude and the second voltage amplitude.

[0107] The specific implementation methods of the above steps are introduced below.

[0108] In S110, after the energy storage inverter is electrically connected to the load, it provides an output voltage to the load and obtains a load current flowing through the load.

[0109] As an optional implementation, a current sensor is provided between the energy storage inverter and the load, and the energy storage inverter obtains the current collected by the current sensor as the load current.

[0110] In S120, after the load current is acquired, the load current is compared with the maximum output current of the energy storage inverter. The maximum output current is set based on the tolerable current range of each device in the energy storage inverter.

[0111] When it is determined that the load current is greater than or equal to the maximum output current, the voltage regulation coefficient is calculated based on a difference between the load current and the maximum output current.

[0112] As an optional implementation manner, the above S120 includes:

[0113] S210, calculating the difference between the maximum output current and the load current to obtain a first current error value;

[0114] S220: Calculate a voltage regulation coefficient corresponding to the first current error value based on a preset loop control algorithm.

[0115] In S210 , when it is determined that the load current is greater than or equal to the maximum output current, a difference between the maximum output current and the load current is calculated to obtain a first current error value.

[0116] In S220, after obtaining the first current error value at the current moment, a voltage regulation coefficient corresponding to the first current error value is calculated based on a preset loop control algorithm, and the preset loop control algorithm includes:

[0117]

[0118] K is the voltage regulation coefficient, Kp is the proportional regulation coefficient, Ki is the integral regulation coefficient, I_Err(t) is the first current error value at time t, and b is a constant.

[0119] In this embodiment, the environmental control algorithm is PI (Proportional-Integral) control. When it is detected that the load current is greater than the maximum output current at any time, the first current error value at the current moment is calculated, and the product of the first current error value at the current moment and the proportional adjustment coefficient Kp is used as part of the voltage adjustment coefficient. After obtaining the first current error value at the current moment, the first current error value in the time period t from the past to the current moment is integrated, and the product of the integration result and the integral adjustment coefficient Ki is used as another part of the voltage adjustment coefficient. According to the coefficient value obtained by proportional control, the coefficient value obtained by integral control and the sum of the constant term, the final voltage adjustment coefficient is obtained. Through proportional integral control, the energy storage inverter provides a stable output voltage to the load, thereby realizing a smooth start-up process of the load.

[0120] As an optional implementation manner, the above S120 includes:

[0121] S310, calculating the difference between the load current and the maximum output current to obtain a second current error value;

[0122] S320, calculating a voltage regulation coefficient based on a ratio of the second current error value to the maximum output current.

[0123] In S310 , when it is determined that the load current is greater than the maximum output current, a difference between the load current and the maximum output current is calculated to obtain a second current error value.

[0124] In S320, after the second current error value at the current moment is obtained, a voltage regulation coefficient corresponding to the second current error value is calculated based on the ratio of the second current error value to the maximum output current.

[0125] The voltage regulation coefficient calculation formula includes:

[0126] K = 1 - (I_Load - I_Max) / I_Max;

[0127] K is the voltage regulation coefficient, I_Load is the load current, and I_Max is the maximum output current;

[0128] In this embodiment, at any time, if it is detected that the load current is greater than the maximum output current, the corresponding voltage regulation coefficient is calculated using the above calculation formula based on the load current and the maximum output current at the current time.

[0129] In S130, after the voltage regulation coefficient is calculated based on the difference between the load current and the maximum output current, the target voltage value is calculated according to the rated output voltage value of the energy storage inverter and the voltage regulation coefficient.

[0130] When the voltage regulation coefficient is taken within the value range obtained in the above embodiment, since the voltage regulation coefficient is always less than 1, the product of the rated output voltage value of the energy storage inverter and the voltage regulation coefficient, that is, the target voltage value should be less than the rated output voltage value. That is, based on the rated output voltage value and the voltage regulation coefficient, a target voltage value less than the rated output voltage value is obtained.

[0131] In S140, the energy storage inverter includes a voltage feedforward control loop. After the target voltage value is calculated, a first voltage amplitude is calculated based on the target voltage value, and the first voltage amplitude is used as the output of the voltage feedforward control loop of the energy storage inverter.

[0132] In S150, the energy storage inverter further includes a voltage effective value control loop, which calculates a second voltage amplitude based on the rated output voltage value and the output voltage provided by the energy storage inverter to the load. As a specific example of the present application, the second voltage amplitude is the difference between the rated output voltage value and the output voltage provided by the energy storage inverter to the load. After the second voltage amplitude is calculated, it is used as the output of the voltage effective value control loop.

[0133] In S160, the energy storage inverter adjusts the output voltage provided to the load based on the first voltage amplitude and the second voltage amplitude. As a specific example of the present application, the energy storage inverter superimposes the first voltage amplitude and the second voltage amplitude, and adjusts the output voltage provided to the load based on the superimposed voltage amplitude.

[0134] In this embodiment, the energy storage inverter calculates a new first voltage amplitude based on the calculated target voltage value. Since the target voltage value is less than the rated output voltage value, the calculated new first voltage amplitude will also be less than the original first voltage amplitude. The energy storage inverter also calculates the second voltage amplitude based on the rated output voltage value and the output voltage provided by the energy storage inverter to the load. The energy storage inverter is based on the smaller first voltage amplitude, and after superimposing it with the second voltage amplitude, the superimposed voltage amplitude is reduced. The output voltage provided to the load is adjusted based on the superimposed voltage amplitude, so that the output voltage provided to the load will also be reduced accordingly. When the output voltage of the load decreases, the corresponding load current will also decrease, thereby avoiding excessive instantaneous current that causes the load to fail to start and operate normally, and also protecting the electronic devices in the energy storage inverter and reducing the risk of overcurrent damage to the devices.

[0135] Electronic devices

[0136] Figure 6 The hardware structure diagram of the electronic device provided in the embodiment of the present application is shown. The electronic device is at least one of a computer, a server and a document generation dedicated device. The electronic device includes a processor 601 and a memory 602 storing computer program instructions.

[0137] Specifically, the processor 601 includes a central processing unit (CPU), or an application-specific integrated circuit (ASIC), or is configured to implement one or more integrated circuits of the embodiments of the present application.

[0138] Memory 602 includes a large capacity memory for data or instructions. By way of example and not limitation, memory 602 may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive or a combination of two or more of these. Where appropriate, memory 602 may include a removable or non-removable (or fixed) medium. Where appropriate, memory 602 may be inside or outside of an electronic device. In a particular embodiment, memory 602 is a non-volatile solid-state memory.

[0139] The memory 602 may include a read-only memory (ROM), a flash memory device, a random access memory (RAM), a magnetic disk storage medium device, an optical storage medium device, an electrical, optical or other physical / tangible memory storage device. Thus, typically, the memory 602 includes a tangible (non-transitory) computer-readable storage medium (e.g., a memory device) of one or more software that is encoded with computer-executable instructions and that, when executed (e.g., by one or more processors), is operable to perform the operations described with reference to the methods according to the above aspects of the present disclosure.

[0140] The processor 601 implements any one of the energy storage inverter control methods in the above embodiments by reading and executing computer program instructions stored in the memory 602 .

[0141] In one example, the electronic device may further include a communication interface 603 and a bus 610. Figure 6 As shown, the processor 601, the memory 602, and the communication interface 603 are connected via a bus 610 and communicate with each other.

[0142] The communication interface 603 is mainly used to implement communication between various modules, devices, units and / or equipment in the embodiments of the present application.

[0143] Bus 610 includes hardware, software or both, and the parts of electronic equipment are coupled to each other. For example, but not limitation, bus may include accelerated graphics port (AGP) or other graphics bus, enhanced industrial standard architecture (EISA) bus, front side bus (FSB), hypertransport (HT) interconnection, industrial standard architecture (ISA) bus, infinite bandwidth interconnection, low pin count (LPC) bus, memory bus, micro channel architecture (MCA) bus, peripheral component interconnection (PCI) bus, PCI-Express (PCI-X) bus, serial advanced technology attachment (SATA) bus, video electronics standard association local (VLB) bus or other suitable bus or two or more of these combinations. In appropriate cases, bus 610 may include one or more buses. Although the present application embodiment describes and shows a specific bus, the application considers any suitable bus or interconnection.

[0144] The electronic device is based on the control method of the energy storage inverter, thereby realizing the combination of Figure 1 and Figure 5 A control method for an energy storage inverter is described.

[0145] In addition, in combination with the control method of the energy storage inverter in the above embodiment, the embodiment of the present application can provide a computer storage medium for implementation. The computer storage medium stores computer program instructions; when the computer program instructions are executed by the processor, any one of the control methods of the energy storage inverter in the above embodiment is implemented.

[0146] In addition, an embodiment of the present application also provides a computer program product, including a computer program, which can implement the steps and corresponding contents of the aforementioned method embodiment when executed by a processor.

[0147] It should be understood that the terms and expressions used herein are for description only, and one or more embodiments of this specification should not be limited to these terms and expressions. The use of these terms and expressions does not mean to exclude any equivalent features of the schematics and descriptions (or parts thereof), and it should be recognized that various modifications that may exist should also be included in the scope of the claims. Other modifications, changes and substitutions may also exist. Accordingly, the claims should be deemed to cover all such equivalents.

Claims

1. An energy storage inverter, characterized in that: include: A current sensor is configured to collect a load current, wherein the load current is defined as a current flowing through a load; Program processing unit, comprising: an acquisition subunit, configured to acquire the load current; The computing subunit is configured to perform the following operations: In response to the load current being greater than or equal to the maximum output current of the energy storage inverter, calculating a difference between the load current and the maximum output current, and calculating a voltage regulation coefficient based on the difference; Calculating a target voltage value based on the voltage regulation coefficient and the rated output voltage value of the energy storage inverter, wherein the target voltage value is less than or equal to the rated output voltage value; Calculating a first voltage amplitude based on the target voltage value; Calculating a second voltage amplitude based on the rated output voltage value and the output voltage provided by the energy storage inverter to the load; The energy storage inverter is configured to adjust an output voltage provided to the load based on the first voltage amplitude and the second voltage amplitude.

2. The energy storage inverter according to claim 1, characterized in that: The computing subunit is configured to perform the following operations: Calculating a difference between the maximum output current and the load current to obtain a first current error value; A voltage regulation coefficient corresponding to the first current error value is calculated based on a preset loop control algorithm.

3. The energy storage inverter according to claim 2, characterized in that: The preset loop control algorithm includes: K is the voltage regulation coefficient, Kp is the proportional regulation coefficient, Ki is the integral regulation coefficient, I_Err(t) is the first current error value at time t, and b is a positive constant.

4. The energy storage inverter according to claim 1, characterized in that: The computing subunit is configured to perform the following operations: Calculating a difference between the load current and the maximum output current to obtain a second current error value; A voltage regulation coefficient is calculated based on a ratio of the second current error value to the maximum output current.

5. The energy storage inverter according to claim 4, characterized in that: The calculation formula of the voltage regulation coefficient includes: K = 1 - (I_Load - I_Max) / I_Max; K is the voltage regulation coefficient, I_Load is the load current, and I_Max is the maximum output current.

6. The energy storage inverter according to any one of claims 1 to 5, characterized in that: The voltage regulation coefficient is K, Kmin≤K≤1; Kmin is a minimum voltage regulation coefficient, and the minimum voltage regulation coefficient is configured so that the product of the minimum voltage regulation coefficient and the rated output voltage value of the energy storage inverter is greater than or equal to the starting voltage of the load.

7. The energy storage inverter according to any one of claims 1 to 5, characterized in that: The rated output voltage value and the target voltage value are defined as effective values ​​of AC voltages, and the first voltage amplitude is the product of the target voltage value and an amplitude coefficient; wherein the amplitude coefficient is the ratio of the maximum value of the AC voltage to the effective value of the AC voltage; or, The rated output voltage value and the target voltage value are defined as maximum values ​​of the AC voltage, and the first voltage amplitude is consistent with the target voltage value.

8. The energy storage inverter according to any one of claims 1 to 5, characterized in that: The maximum withstand current of the power switch of the inverter circuit in the energy storage inverter is Icm, and the maximum output current of the energy storage inverter is I_Max; Icm≥2*I_Max.

9. A control method for an energy storage inverter, characterized in that: include: Obtain the load current flowing through the load; In response to the load current being greater than or equal to the maximum output current of the energy storage inverter, calculating a voltage regulation coefficient based on a difference between the load current and the maximum output current; Calculate a target voltage value (V_out) based on the voltage regulation coefficient and the rated output voltage value (V_rate) of the energy storage inverter, wherein the target voltage value is less than or equal to the rated output voltage value; Calculating a first voltage amplitude based on the target voltage value; Calculating a second voltage amplitude based on a rated output voltage value and an output voltage provided by the energy storage inverter to the load; An output voltage provided to the load is adjusted based on the first voltage magnitude and the second voltage magnitude.

10. The control method of the energy storage inverter according to claim 9, characterized in that: The calculating the voltage regulation coefficient based on the difference between the load current and the maximum output current includes: Calculating a difference between the maximum output current and the load current to obtain a first current error value; The voltage regulation coefficient corresponding to the first current error value is calculated based on a preset loop control algorithm; wherein the preset loop control algorithm includes: K is the voltage regulation coefficient, Kp is the proportional regulation coefficient, Ki is the integral regulation coefficient, I_Err(t) is the first current error value at time t, and b is a positive constant.

11. The control method of the energy storage inverter according to claim 9, characterized in that: The calculating the voltage regulation coefficient based on the difference between the load current and the maximum output current includes: Calculating a difference between the load current and the maximum output current to obtain a second current error value; Based on the ratio of the second current error value to the maximum output current, a voltage regulation coefficient is calculated; wherein the calculation formula of the voltage regulation coefficient includes: K = 1 - (I_Load - I_Max) / I_Max; K is the voltage regulation coefficient, I_Load is the load current, and I_Max is the maximum output current.

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