Method for detecting load connection status of energy storage power supply, energy saving control method therefor, and energy storage power supply

Abstract

A method for detecting a load connection status of an energy storage power supply including an inverter power supply, comprising the steps of: (S1) sampling an output voltage and an output current of the inverter power supply and calculating an output visible power; and (S2) determining whether the visible power is less than a predetermined power threshold, and if the visible power is greater than the predetermined power threshold, detecting that a load is connected to the energy storage power supply; and (S3) executing an active load online detection algorithm to perform secondary detection if the visible power is less than the predetermined power threshold, and determining whether a load is connected based on the result of the secondary detection. This method can automatically recognize the load connection status, and can reduce erroneous determination of the load connection status when the connected load is a small-power load, thereby improving the accuracy of detecting the load connection status of the energy storage power supply, thereby avoiding the inconvenience of turning off the output of the inverter power supply and disconnecting the load due to erroneous determination.

Description

[Technical Field]

[0001] The present invention relates to the field of energy storage power supplies, and more particularly to a method for detecting a load connection state of an energy storage power supply, a method for controlling the same, and an energy storage power supply. [Background technology]

[0002] Advances in lithium battery technology and improvements in processes have increased demand for convenient off-grid power in outdoor and domestic applications, leading to an explosive growth in the portable energy storage market. However, the volume and weight requirements for portable energy storage power sources severely limit the capacity of batteries built into portable energy storage power sources. This has made it urgent to find a way to reduce the no-load loss of energy storage power sources in order to improve the standby time of energy storage power sources, reduce battery consumption, and solve the problem of rapid battery discharge caused by the power source being turned on without load when the user forgets to turn off the output of the energy storage power source or suspends the load.

[0003] There are two main technologies for reducing off-grid no-load losses in conventional inverter power supplies. One technology detects the output power of the inverter power supply, and if the output power remains below a set threshold for a certain period of time, it determines that the inverter power supply is in a no-load state and turns off the output, thereby reducing no-load losses. The other technology aims to reduce battery consumption by designing a dedicated load detection circuit that automatically turns on the power supply output when it detects a load is connected and automatically turns off the power supply output when it detects a load is disconnected.

[0004] One of the above technologies is realized by software logic and does not require additional hardware costs or volume occupancy. However, it has the drawback that it is limited by power sampling accuracy, and when a small power load is connected to the inverter power supply, it will erroneously determine that there is no load and turn off the power supply output, interrupting the power supply to the load. In addition, when the load is reconnected, the inverter power supply cannot automatically recognize the connection of the load and turn on the power supply, and manual operation is required, which reduces the ease of use of the power supply.

[0005] The other technology mentioned above is realized by a hardware function circuit, which can automatically recognize the load connection status and realize automatic on / off of the power supply when loaded. However, the dedicated load detection circuit increases the hardware cost and the volume and weight of the power supply, reducing portability, and the complex circuit introduces more instability and failure rate into the power supply system. Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to solve the problems of improving the accuracy of detecting the load connection state of an energy storage power supply, and of reducing the no-load loss of an energy storage power supply while realizing automatic turn-on of the energy storage power supply under load, and to provide a method for detecting the load connection state of an energy storage power supply, a method for controlling the same, and an energy storage power supply. [Means for solving the problem]

[0007] The technical problems of the present invention are solved by the following technical means.

[0008] A method for detecting a load connection state of an energy storage power supply including an inverter power supply, comprising: S1: sampling the output voltage and output current of the inverter power supply and calculating the output apparent power; S2: Determining whether the present power is smaller than a preset power threshold, and if the present power is larger than the preset power threshold, detecting that a load is connected to the energy storage power source; if the present power is smaller than the preset power threshold, executing an active load online detection algorithm to perform secondary detection, and determining whether a load is connected based on the result of the secondary detection.

[0009] In one embodiment, the active load online detection algorithm includes actively injecting a voltage excitation into an output port of the inverter power supply, then detecting a voltage response at the output port, and determining from the voltage response whether a load is connected or not.

[0010] In one embodiment, the inverter power supply comprises an inverter bridge, a controller, and an AC output filter circuit, the inverter bridge is connected to the AC output filter circuit, the controller is connected to the inverter bridge and the AC output filter circuit, the AC output filter circuit includes a filter capacitor and a discharge resistor connected in parallel therewith, the AC output filter circuit is connected in parallel with the load when the load is connected, and actively injecting a voltage excitation into an output port of the inverter power supply and then detecting a voltage response of the output port, and determining whether a load is connected from the voltage response, A1: The controller drives the inverter bridge to generate a waveform from the zero point of the sine reference wave, and when the waveform is generated up to the peak of the sine reference wave, controls the inverter bridge to block the waveform and cut off the drive signal, so that the voltage across the filter capacitor becomes the rated peak voltage of the inverter power supply; A2: Blocking the waveform and cutting off the drive signal, and simultaneously starting a time measurement, and sampling and monitoring the voltage across the filter capacitor in real time during the time measurement; A3: Stopping the timing when it is detected that the filter capacitor has discharged to a predetermined voltage value, and acquiring a timing value that is a discharge time for the voltage of the filter capacitor to discharge from the rated peak voltage to the predetermined voltage value; A4: The method includes the steps of calculating the rated power of the connected load from the timing value, determining whether the rated power of the load is smaller than a preset load power threshold, and detecting that a load is connected to the energy storage power supply if the rated power of the load is larger than the preset load power threshold, and detecting that no load is connected to the energy storage power supply if the rated power of the load is smaller than the preset load power threshold.

[0011] In one embodiment, the preset voltage value is 3% to 10% of the rated peak voltage of the inverter power supply.

[0012] In one embodiment, the preset voltage value is 5% of the rated peak voltage of the inverter power supply.

[0013] Furthermore, the present invention provides an energy saving control method for an energy storage power source, comprising: B1: Execute the above-mentioned method for detecting the load connection state of the energy storage power supply to detect the load connection state of the energy storage power supply; B2: When it is detected that a load is connected to the energy storage power supply, the controller controls the inverter bridge to start driving and generate a waveform so that the inverter power supply returns to the rated AC sine wave output; B3: When it is detected that no load is connected to the energy storage power supply, after the filter capacitor is discharged to a preset voltage value, the controller controls the inverter bridge to drive and generate a waveform so as to execute the active load online detection algorithm.

[0014] Furthermore, the present invention provides a computer-readable storage medium having a computer program stored thereon, the computer program being capable of implementing the steps of the above-described method for detecting a load connection state of an energy storage power supply when executed by a processor.

[0015] Furthermore, the present invention provides a computer-readable storage medium having a computer program stored thereon, the computer program being capable of implementing the steps of the above-described energy-saving control method for an energy storage power source when executed by a processor.

[0016] Furthermore, the present invention provides an energy storage power supply comprising a computer-readable storage medium on which a computer program is stored and a processor, wherein when the computer program is executed by the processor, the energy storage power supply realizes the steps of the above-mentioned energy saving control method for an energy storage power supply.

[0017] The beneficial effects of the present invention compared with the prior art are as follows: According to the present invention, the output voltage and output current of the inverter power supply are sampled to calculate the output visible power. If the visible power is less than a preset power threshold, an active load online detection algorithm is executed to perform secondary detection, thereby automatically recognizing the load connection status. The secondary detection improves the detection accuracy of the load connection status of the energy storage power supply, reduces erroneous determination of the load connection status, especially when the connected load is a small power load, and avoids the problem of turning off the output of the inverter power supply due to erroneous determination, resulting in load disconnection.

[0018] In some embodiments, the following beneficial effects are achieved: According to the method for detecting the load connection status of an energy storage power supply according to an embodiment of the present invention, by actively injecting voltage excitation into the output port of the inverter power supply and then detecting the voltage response of the output port, it is possible to accurately detect the load connection status of the energy storage power supply without increasing any hardware circuitry or volume occupancy.

[0019] According to the energy saving control method for an energy storage power supply according to an embodiment of the present invention, when it is detected that no load is connected to the energy storage power supply, an active load online detection algorithm is cyclically executed. Furthermore, the active load online detection algorithm drives the inverter bridge to generate a waveform from the zero point of the sine reference wave, and once the sine reference wave is generated up to the peak, it immediately blocks the waveform and cuts off all PWM driving signals. This causes the inverter bridge to generate a waveform with only 0.25 power supply frequency periods within one RC discharge period, thereby reducing the operating time of the inverter power supply. Compared to the inverter power supply continuously generating and outputting waveforms under no load, the no-load loss of the main power circuit of the inverter power supply according to the present invention is significantly reduced.

[0020] According to the energy saving control method for an energy storage power supply of the present invention, when an active load online detection algorithm is executed and it is determined that a load is connected to the energy storage power supply, the inverter bridge starts to drive to generate a waveform and the inverter power supply returns to the rated AC sine wave output, so that the inverter power supply recognizes that a load is connected and can automatically turn on, thereby realizing automatic turn-on of the energy storage power supply under load and reducing no-load loss of the energy storage power supply.

[0021] Other beneficial effects of embodiments of the present invention are further described below. [Brief explanation of the drawings]

[0022] [Figure 1] 2 is a flowchart of a method for detecting a load connection state of an energy storage power supply in an embodiment of the present invention. [Figure 2] FIG. 2 is a circuit diagram of a method for detecting a load connection state of an energy storage power supply according to an embodiment of the present invention. [Figure 3] FIG. 2 is a circuit diagram of a small power load connection state detection of an energy storage power supply in an embodiment of the present invention. [Figure 4]2 is a flowchart of a load connection status detection method and an active load online detection algorithm for an energy storage power supply in an embodiment of the present invention; [Figure 5] 2 is a flowchart of an energy-saving control method for an energy storage power source according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will be further described below by way of preferred embodiments with reference to the accompanying drawings. The examples and features of the examples in this application can be combined with each other as long as they are not inconsistent.

[0024] In response to the demand for reducing off-grid no-load losses of portable energy storage power supplies, an embodiment of the present invention proposes a method for reducing off-grid no-load losses of inverter power supplies, which provides a purely software control algorithm that can automatically recognize the load connection state and realize automatic on / off control of the power supply without adding any hardware circuitry, thereby reducing the no-load losses of the power supply.

[0025] An outline of an embodiment of the present invention is given below.

[0026] An embodiment of the present invention provides a method for detecting a load connection state of an energy storage power supply including an inverter power supply, wherein the inverter power supply comprises an inverter bridge, a controller, and an AC output filter circuit, the inverter bridge is connected to the AC output filter circuit, the controller is connected to the inverter bridge and the AC output filter circuit, the AC output filter circuit includes a filter capacitor and a discharge resistor connected in parallel therewith, and the AC output filter circuit is connected in parallel with the load when the load is connected.

[0027] The load connection status detection method for an energy storage power supply is as shown in Figure 1. S1: Sampling the output voltage and output current of the inverter power supply and calculating the output apparent power; S2: Determine whether the visual power is less than a preset power threshold; If the visible power is greater than a preset power threshold, it is detected that a load is connected to the energy storage power source; If the present power is smaller than the preset power threshold, the method includes a step of executing an active load online detection algorithm to perform secondary detection, and determining whether or not a load is connected based on the result of the secondary detection.

[0028] Here, the active load online detection algorithm includes: actively injecting voltage excitation into the output port of the inverter power supply, and then detecting a voltage response of the output port; and determining whether a load is connected based on the voltage response. Specifically, the active load online detection algorithm includes: A1: The controller drives the inverter bridge to generate a waveform from the zero point of the sine reference wave, and when the waveform is generated up to the peak of the sine reference wave, controls the inverter bridge to block the waveform and cut off the drive signal, so that the voltage across the filter capacitor is the rated peak voltage of the inverter power supply; A2: Blocking the waveform and cutting off the drive signal, and simultaneously starting timing, sampling and monitoring the voltage across the filter capacitor in real time during timing; A3: When it detects that the filter capacitor has discharged to a preset voltage value, it stops timing and acquires the timing value, which is the discharge time it takes for the filter capacitor voltage to discharge from the rated peak voltage to the preset voltage value. wherein the preset voltage value is 3% to 10% of the rated peak voltage of the inverter power supply, and preferably 5% of the rated peak voltage of the inverter power supply; A4: Calculate the rated power of the connected load from the measured value, and determine whether the rated power of the load is smaller than a preset load power threshold; If the rated power of the load is greater than a preset load power threshold, it is detected that a load is connected to the energy storage power source; If the rated power of the load is less than a preset load power threshold, detecting that no load is connected to the energy storage power source.

[0029] Furthermore, the present invention provides an energy saving control method for an energy storage power source, comprising: B1: Execute the above-mentioned method for detecting the load connection state of the energy storage power supply to detect the load connection state of the energy storage power supply; B2: When it is detected that a load is connected to the energy storage power supply, the controller controls the inverter bridge to start driving and generate a waveform so that the inverter power supply returns to the rated AC sine wave output; B3: When it is detected that no load is connected to the energy storage power supply, the filter capacitor is discharged to a preset voltage value, and then the controller controls the inverter bridge to drive the inverter bridge to generate a waveform so as to execute an active load online detection algorithm.

[0030] In one embodiment, in step B1, the load connection state of the energy storage power source is detected at a preset frequency.

[0031] Furthermore, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, the computer program being capable of implementing the steps of the above-described method for detecting a load connection state of an energy storage power supply when executed by a processor.

[0032] Furthermore, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, the computer program being capable of implementing the steps of the above-described energy-saving control method for an energy storage power source when executed by a processor.

[0033] Furthermore, an embodiment of the present invention provides an energy storage power supply including a computer-readable storage medium on which a computer program is stored and a processor, wherein when the computer program is executed by the processor, the energy storage power supply implements the steps of the above-mentioned energy saving control method for the energy storage power supply. [Example]

[0034] The method for detecting a load connection state of an energy storage power supply according to this embodiment is an improvement over the conventional method for detecting a no-load state of an energy storage power supply. As shown in FIG. 2, this embodiment improves the algorithm by utilizing the existing circuit configuration of the energy storage power supply system, and can automatically recognize the load connection state without adding any hardware circuitry.

[0035] As shown in Figure 2, the energy storage power supply includes an inverter power supply, which is a DC-AC inverter circuit consisting of an inverter bridge, a controller, and an AC output filter circuit, and the AC output filter circuit consists of an inductor L and a filter capacitor C, and R' is a discharge resistor for the filter capacitor C, which is connected in parallel with the filter capacitor C in the off state (off means that the IGBTs of the inverter bridge are completely turned off), and the AC output filter circuit is connected in parallel with the load when a load is connected.

[0036] The inverter bridge is connected to the AC output filter circuit, and the controller is connected to the inverter bridge and the AC output filter circuit for drive control of the inverter bridge (waveform generation / blocking) and current / voltage sampling of the AC output filter circuit. The controller is equipped with a sampling circuit, and a differential voltage sampling circuit is used for voltage sampling, and sampling is performed by a Hall sensor for current sampling.

[0037] Specifically, the following steps are included: Sl: Inverter power supply output voltage V out and output current I outBy sampling, the output power P out Calculate JPEG2026505784000002.jpg1354Here, n is the total number of sampling points in one sine wave cycle, and k is the kth sampling point.

[0038] S2: Predetermine a power threshold value of the visual power (for example, 1% of the rated visual power), and determine whether the visual power of the output is smaller than the predetermine power threshold value; If the visible power is greater than a preset power threshold, it is detected that a load is connected to the energy storage power source; When the output apparent power is less than the preset power threshold, the controller of the inverter power supply starts to execute an active load online detection algorithm and outputs a detection result based on the active load online detection algorithm.

[0039] Only when both the condition that the visible power is smaller than a preset power threshold and the output result of the active load online detection algorithm is "no load on the inverter power supply" are met simultaneously, is the inverter power supply judged to be in an unloaded state at this point; if neither condition is met, the inverter power supply is judged to be not in an unloaded state. In this way, the problem of the inverter power supply being erroneously judged to be unloaded and turned off when a small power load is connected is eliminated.

[0040] The mechanism of the active load online detection algorithm of this embodiment is as follows. As shown in Figure 3, the dotted-line area contains an RC discharge circuit consisting of the filter capacitor C of the inverter's own output filter and the impedance R of the external load. Since the filter capacitor's capacitance C is a known quantity, an initial voltage U0 is set for the filter capacitor C. By measuring the quiescent current response curve of the RC discharge circuit—in other words, the discharge time t required for the voltage of capacitor C to drop from its initial value U0 to 0.05U0—the load's R value can be accurately calculated. (R' is a discharge resistor connected in parallel with the filter capacitor C. Its typical resistance is around 200 kΩ. It is used to discharge the residual voltage in the filter capacitor after the inverter power is turned off. However, when the inverter power is turned on under load, the resistance of this resistor is much greater than the load's R, but it can be ignored in this case.) The process for calculating the load's R value is shown below.

[0041] As shown in Figure 3, the voltage on the capacitor is C , the voltage across the load resistor R is U R , the current flowing through the load resistor is i R Then, according to KVL (Kirchhoff's voltage law), JPEG2026505784000003.jpg521 is obtained, and U R =i R *R, Substituting JPEG2026505784000004.jpg1021 into the above equation, we get JPEG2026505784000005.jpg1031 is obtained. As can be seen from the above equation, this equation is a first-order homogeneous differential equation, and the initial condition at time t0 is U C (0+)=U C Since (0-)=U0, the general solution to this equation is U C =Ae pt where A is a constant determined by the initial condition of the first-order homogeneous differential equation, p is the characteristic root of the first-order homogeneous differential equation, t is the time variable, and Ae pt is the general form of the solution of a first-order homogeneous differential equation.

[0042] Substituting the general solution into the above equation, The result is JPEG2026505784000006.jpg632, The characteristic equation is JPEG2026505784000007.jpg520, The characteristic root is JPEG2026505784000008.jpg1016, U C (0+)=U C According to the initial condition of (0-)=U0, U C =Ae pt Substituting, JPEG2026505784000009.jpg640, JPEG2026505784000010.jpg513 is obtained, and thus the solution to this differential equation is JPEG2026505784000011.jpg822, and the initial voltage U C Set (0) = U0 to start discharging the RC discharge circuit, and the real-time voltage U C (t) is detected and U C When (t) = 0.05U0, record the discharge time t.

[0043] In this embodiment, the reason for selecting and recording the discharge time when the amount of power in the capacitor is discharged to 0.05U0 is as follows.

[0044] First, to reduce shock currents, when the following active load online detection algorithm is executed, the inverter bridge must generate a waveform starting from the zero-crossing point of a sine wave. This means that the capacitor voltage must be discharged to the lowest possible voltage value, which is usually less than 10% of the rated AC peak.

[0045] Second, according to the capacitor discharge curve, when the capacitor voltage is discharged to 3% or less of the initial voltage, the voltage drop rate becomes increasingly slow, and the sampling accuracy of the capacitor voltage at low voltages becomes poor. Therefore, to improve the speed and accuracy of the load online detection algorithm, it is necessary to run the active load online detection algorithm again after the capacitor voltage has discharged to at least 3% or more of the initial rated AC peak. Taking these two points into consideration, it is appropriate to record the discharge time when the capacitor voltage is discharged to 3% U0 to 10% U0. Furthermore, to simplify the calculation, it is most preferable to select the intermediate value of 5% U0.

[0046] Let t be a known quantity and R be an unknown quantity. If you substitute JPEG2026505784000012.jpg823, JPEG2026505784000013.jpg945, JPEG2026505784000014.jpg720, JPEG2026505784000015.jpg1037 is obtained, and by organizing the above, JPEG2026505784000016.jpg1014 is obtained, where the RC discharge time t is a measured value and the capacitance C of the capacitor is a known quantity. Therefore, the resistance value R of the connected load can be accurately calculated using the above formula, enabling online automatic load detection.

[0047] As shown in FIG. 4, the specific steps of the active load online detection algorithm in this embodiment implemented in the inverter power supply are as follows: AI: When detecting that the apparent power of the inverter power supply output is less than the preset power threshold, the inverter power supply controller drives the IGBTs (insulated gate bipolar transistors, or other power device switch tubes) of the inverter bridge to generate a waveform from the zero-crossing point of the sine reference wave, and when the sine reference wave peak is generated, it immediately blocks the waveform and controls the pulse width modulation (PWM) drive signal of the IGBTs of the inverter bridge to be cut off, so that the voltage output from the inverter power supply to both ends of the filter capacitor is the rated peak voltage of the inverter power supply, where the rated peak voltage of the inverter power supply is JPEG2026505784000017.jpg610, and timing begins as soon as the inverter power supply drives the blocking waveform.

[0048] A2: When the inverter power supply is driven to block the waveform, timing begins. When the waveform is blocked, the filter capacitor C and the inverter bridge circuit are cut off, providing a zero-input response to the RC discharge circuit formed by the filter capacitor C and the external load R. During timing, the voltage across the filter capacitor is sampled and monitored in real time.

[0049] Specifically, the waveform of the pulse width modulation drive signal is blocked, and at the same time, the on-chip timer of the main control unit MCU of the inverter power supply is started to count time, and the voltage U across the filter capacitor C is c is sampled and monitored in real time.

[0050] A3: When it detects that the filter capacitor has discharged to a preset voltage value, it stops timing and acquires the timing value, which is the discharge time it takes for the filter capacitor voltage to discharge from the rated peak voltage to the preset voltage value.

[0051] Specifically, the filter capacitor C is set to a preset voltage value. When it detects that the filter capacitor C has discharged to JPEG2026505784000018.jpg631, it stops the timer and reads out the timer's timed value to determine whether the voltage of the filter capacitor C has reached the rated peak voltage. Pre-set voltage value from JPEG2026505784000019.jpg610 Obtain the discharge time t when discharging to JPEG2026505784000020.jpg621.

[0052] A4: Calculate the rated power of the connected load from the measured value, and determine whether the rated power of the load is smaller than a preset load power threshold; If the rated power of the load is greater than a preset load power threshold, it is detected that a load is connected to the energy storage power source; If the rated power of the load is less than the preset load power threshold, it is detected that no load is connected to the energy storage power source.

[0053] The specific operations are as follows: When combined with the capacitance C of the inverter power supply output filter capacitor, the resistance value of the connected load is: JPEG2026505784000021.jpg1014, and the rated output voltage of the inverter power supply is U e So the rated power of the connected load is JPEG2026505784000022.jpg1115, and a load power threshold is set in advance (for example, the load power threshold is set in advance to 1 W). If the calculated rated power of the load is less than the preset load power threshold, it is determined that the inverter power supply is unloaded, and if the calculated rated power of the load is greater than or equal to the preset load power threshold, it is determined that a load is connected to the inverter power supply.

[0054] As shown in FIG. 4, the present embodiment further provides an energy-saving control method for an energy storage power supply used for automatic on / off control of a power supply (automatic control of on / off drive of an inverter bridge), B1: Execute the above-mentioned method for detecting the load connection state of the energy storage power supply to detect the load connection state of the energy storage power supply; B2: When it is detected that a load is connected to the energy storage power supply, the controller controls the inverter bridge to generate a waveform so that the inverter power supply returns to the rated AC sine wave output; B3: We have proposed an energy-saving control method for an energy storage power supply, which includes the steps of: when it is detected that no load is connected to the energy storage power supply, discharging the filter capacitor to a preset voltage value, and then the controller controls the inverter bridge to drive the inverter bridge to generate a waveform so as to execute an active load online detection algorithm.

[0055] The specific operations are as follows: The detection result of the method for detecting the load connection state of an energy storage power supply is that the inverter power supply is in a no-load state, i.e., no load is connected to the energy storage power supply. The voltage across the output filter capacitor Pre-set voltage value from JPEG2026505784000023.jpg610 When it is monitored that the voltage has discharged to JPEG2026505784000024.jpg621, the inverter power supply controller drives the IGBTs of the inverter bridge again to generate a waveform from the zero-crossing point of the sine reference wave, and when the waveform is generated up to the peak of the sine reference wave, it controls it to block the waveform, charges the output filter capacitor C up to the rated peak voltage, and again executes the active load online detection algorithm.

[0056] When no load is connected, the discharge resistor R' and the filter capacitor C form an RC discharge circuit. The resistance value of R' is usually about 200kΩ. Assuming that the capacitance of the filter capacitor C is 10uF, the voltage across the filter capacitor is From JPEG2026505784000025.jpg610 Discharge time T required to discharge to JPEG2026505784000026.jpg621 RC The calculation procedure is as follows: JPEG2026505784000027.jpg846, As shown in JPEG2026505784000028.jpg668, the inverter bridge generates a waveform for only 0.25 power supply frequency periods (from the zero crossing point to the peak of the AC reference wave) within one RC discharge period. Assuming the rated output frequency is 50Hz, the waveform generation time of the inverter power supply within one RC discharge period is T INV teeth, JPEG2026505784000029.jpg1045, and therefore, the percentage of operation time of the inverter power supply under no load is JPEG2026505784000030.jpg1238, which means that while the inverter power supply generates and outputs waveforms continuously under no load, the no-load loss of the main power circuit of the inverter power supply adopting this technical solution is only 1 / 1200, which can be said to be almost equivalent to the inverter power supply being in an off state.

[0057] The detection result of the load connection status detection method for the energy storage power supply is that the inverter power supply is not in a no-load state. When a load is connected to the output terminal of the inverter power supply, the R value (load resistance) of the RC discharge circuit becomes much smaller than the resistance value of the discharge resistor R' (e.g., 200 kΩ), and the voltage across the filter capacitor C is rapidly discharged to near 0 V. In this case, if the load rated power is calculated to be greater than the lower threshold, the inverter power supply controller will immediately start driving the inverter bridge to generate a waveform so that the inverter power supply returns to the rated AC sine wave output under load, and the time interval from the connection of the load to the normal output of the inverter power supply will not exceed one power frequency period.

[0058] After the inverter power supply returns to normal output, the load connection status of the energy storage power supply is detected at a preset detection frequency, and when it is detected again that the load's visible power is less than the preset power threshold, the active load online detection algorithm is executed again to detect the load connection status in real time and minimize the no-load loss of the inverter power supply.

[0059] As shown in FIG. 5, by adopting the energy-saving control method for the energy storage power supply of this embodiment, the no-load loss of the power supply can be significantly reduced without any hardware changes, and the no-load on-state loss of the inverter power supply can be brought close to the completely off state.

[0060] Furthermore, the active load online detection algorithm of this embodiment can automatically and quickly recognize the connection and disconnection of a load, and automatically and quickly perform the switching operation of the inverter power supply according to the load connection status, which makes it no different from the power supply being continuously on with no load in use by the user, eliminating the need for manual operation, and solving the problem of the power supply incorrectly determining to turn off when a small power load is connected, thus combining all the advantages of the conventional technical solution for reducing the no-load loss of an inverter power supply when off-grid.

[0061] In this experimental example, the energy-saving control method for energy storage power supplies was applied to a portable energy storage power supply with a battery capacity of 600Wh, output power of 600W, and output voltage of 220V / 50Hz. The battery output power was measured in three cases: power supply to the controller only, output when normally on with no load using alternating current (AC), and when the energy-saving control method for energy storage power supplies was adopted. The results are shown in Table 1.

[0062] JPEG2026505784000031.jpg47148

[0063] "Power supply to controller only" in Table 1 (corresponding to the controller being turned on independently in the circuit diagram) is when the entire inverter power supply supplies power only to the low-voltage controller and human-machine interface, and does not supply power to the main power circuit; in this case, the inverter power supply will not operate normally unless it is turned on manually (by AC output), whereas if the "no-load loss reduction with AC" function is incorporated, the inverter power supply will automatically recognize the connection of a load and turn on automatically, achieving the same functionality under load as "normal no-load on with AC" without human intervention, while consuming only the amount of power equivalent to "power supply to controller only."

[0064] While the battery output power is significantly lower than when using AC with no load, the AC output switching operation can be performed automatically and quickly depending on the load connection status, and the output power is only slightly higher than when "powering the controller only."

[0065] The energy-saving control method for the energy storage power supply in this experimental example is simple, has a significant effect in reducing the no-load loss of the inverter power supply, and is highly versatile, being applicable to single-phase inverter power supply equipment, three-phase inverter power supply equipment, and the entire three-phase inverter system consisting of three single-phase inverter power supplies.

[0066] The above content has described the present invention in more detail by taking specific preferred embodiments, and it is not considered that the specific implementation of the present invention is limited to these descriptions. Those skilled in the art may make some equivalent substitutions or significant modifications without departing from the technical spirit of the present invention, and their performance or application is the same, and they should be considered to fall within the protection scope of the present invention.

Claims

1. A method for detecting a load connection state of an energy storage power supply including an inverter power supply, comprising: S1: sampling the output voltage and output current of the inverter power supply and calculating the output apparent power; S2: determining whether the present power is less than a predetermined power threshold, and if the present power is greater than the predetermined power threshold, detecting that a load is connected to the energy storage power source; and if the present power is less than the predetermined power threshold, executing an active load online detection algorithm to perform secondary detection, and determining whether a load is connected or not from the result of the secondary detection.

2. 2. The method of claim 1, wherein the active load online detection algorithm includes actively injecting a voltage excitation into an output port of an inverter power supply and then detecting a voltage response at the output port, and determining from the voltage response whether a load is connected or not.

3. the inverter power supply includes an inverter bridge, a controller, and an AC output filter circuit, the inverter bridge is connected to the AC output filter circuit, the controller is connected to the inverter bridge and the AC output filter circuit, the AC output filter circuit includes a filter capacitor and a discharge resistor connected in parallel thereto, the AC output filter circuit is connected in parallel with the load when the load is connected, and actively injecting a voltage excitation into an output port of the inverter power supply and then detecting a voltage response of the output port, and determining whether a load is connected from the voltage response, A1: The controller generates a waveform from the zero point of the sine reference wave, and when the waveform is generated to the peak of the sine reference wave, controls the drive signal of the inverter bridge so that the waveform is blocked and the drive signal is cut off, so that the voltage across the filter capacitor becomes the rated peak voltage of the inverter power supply; A2: starting a time measurement at the same time as cutting off the driving signal, and sampling and monitoring the voltage across the filter capacitor in real time during the time measurement; A3: Stopping the timing when it is detected that the filter capacitor has discharged to a predetermined voltage value, and acquiring a timing value that is a discharge time required for the voltage of the filter capacitor to discharge from a rated peak voltage to the predetermined voltage value; A4: The method according to claim 2, further comprising the steps of: calculating a rated power of the connected load from the timing value; determining whether the rated power of the load is smaller than a preset load power threshold; and detecting that a load is connected to the energy storage power supply if the rated power of the load is larger than the preset load power threshold; and detecting that no load is connected to the energy storage power supply if the rated power of the load is smaller than the preset load power threshold.

4. 4. The method of claim 3, wherein the preset voltage value is 3% to 10% of the rated peak voltage of the inverter power supply.

5. 5. The method of claim 4, wherein the preset voltage value is 5% of the rated peak voltage of the inverter power supply.

6. 1. An energy saving control method for an energy storage power source, comprising: B1: Executing the method according to any one of claims 1 to 5 to detect a load connection state of an energy storage power source; B2: When it is detected that a load is connected to the energy storage power supply, the controller controls the inverter bridge to start driving and generate a waveform so that the inverter power supply returns to the rated AC sine wave output; B3: When it is detected that no load is connected to the energy storage power supply, after a filter capacitor is discharged to a preset voltage value, the controller controls the inverter bridge to drive the inverter bridge to generate a waveform so as to execute the active load online detection algorithm.

7. 7. The method according to claim 6, wherein in step B1, the load connection state of the energy storage power supply is detected at a preset detection frequency.

8. A computer-readable storage medium having a computer program stored thereon, the computer program implementing the steps of the method according to any one of claims 1 to 5 when executed by a processor.

9. A computer-readable storage medium having stored thereon a computer program, the computer program implementing the steps of the method according to any one of claims 6 to 7 when executed by a processor.

10. 8. An energy storage power supply comprising: a computer-readable storage medium having a computer program stored thereon; and a processor, wherein the computer program, when executed by the processor, implements the steps of the method according to any one of claims 6 to 7.

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