Control method of power supply system and motor home

Abstract

The application discloses a control method of a power supply system and a motor home. The method comprises the following steps: acquiring the voltage of a battery connection port and the actual voltage of a battery; when the absolute value of the difference between the voltage of the battery connection port and the actual voltage of the battery is less than or equal to a first threshold value, starting a battery compensation function; when the absolute value of the difference between the voltage of the battery connection port and the actual voltage of the battery is greater than a second threshold value, stopping the battery compensation function; and when the absolute value of the difference between the voltage of the battery connection port and the actual voltage of the battery is greater than the first threshold value and less than or equal to the second threshold value, maintaining the current on-off state of the battery compensation function. The battery compensation function is dynamically started to compensate for the line loss voltage drop of a direct-current cable, and problems caused by the line voltage drop between the battery and an inverter-charging integrated machine are solved. Through a hysteresis interval, the battery compensation function is effectively prevented from being dithered due to noise or transient interference, and the system reliability is improved.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more particularly to a control method for a power supply system and a motorhome. Background Technology

[0002] With the widespread application of power supply systems, bidirectional inverters are widely used for energy exchange between batteries and the AC grid or loads. In existing bidirectional inverter systems, the energy management system typically samples the voltage signal at the battery port of the inverter body as the battery voltage feedback value, and uses this battery voltage feedback value to realize functions such as battery charging and discharging control, voltage protection, power regulation, and operating mode switching.

[0003] In the above system structure, the battery pack and the inverter body are usually connected via power cables. Since the power cables and their connectors inevitably have equivalent resistance, when the system is under high current charging or discharging conditions, this equivalent resistance will generate a significant voltage drop in the wires, resulting in a deviation between the battery voltage value sampled at the battery port of the inverter body and the actual voltage across the battery terminals.

[0004] However, in existing technologies, most power supply systems still directly use the voltage at the sampled inverter battery port as the sole basis for battery voltage, without effectively identifying and compensating for voltage deviations caused by power cable voltage drops. As a result, all control decisions based on battery voltage within the system are based on voltage signals with systematic errors. Consequently, in high-power charging and discharging scenarios, the inverter may trigger voltage protection prematurely or delayed, making it difficult to accurately control the charging cut-off voltage and discharging termination voltage. This, in turn, affects the battery's usable capacity, lifespan, and the safety and reliability of system operation. Summary of the Invention

[0005] This invention provides a control method for a power supply system and a motorhome to solve the problem of decreased system reliability caused by the voltage at the battery port of the sampled inverter body deviating from the actual battery voltage.

[0006] According to one aspect of the present invention, a control method for a power supply system is provided, the power supply system including an inverter-charger, an energy management system, and a battery, wherein the battery connection port of the inverter-charger is connected to the battery, and the inverter-charger and the battery are respectively connected to the energy management system; the control method for the power supply system is executed by the energy management system. The control method for the power supply system includes: In each sampling period, the voltage at the battery connection port and the actual voltage of the battery are acquired; When the absolute value of the difference between the voltage at the battery connection port and the actual voltage of the battery is less than or equal to a first threshold for N consecutive sampling periods, the battery compensation function is activated to compensate the battery reference voltage value; N is a positive integer. If, for N consecutive sampling periods, the absolute value of the difference between the voltage at the battery connection port and the actual voltage of the battery is greater than a second threshold, the battery compensation function is turned off so that the voltage at the battery connection port is used as the battery reference voltage value; the second threshold is greater than the first threshold. If, during N consecutive sampling periods, the absolute value of the difference between the voltage at the battery connection port and the actual voltage of the battery is greater than the first threshold and less than or equal to the second threshold, the current on / off state of the battery compensation function is maintained.

[0007] Optionally, enabling the battery compensation function to compensate for the battery reference voltage value includes: The deviation value is the difference between the actual voltage of the battery and the voltage at the battery connection port. A compensation value is generated based on the deviation value; The battery reference voltage value is generated based on the voltage at the battery connection port and the compensation value.

[0008] Optionally, when the deviation value is greater than the first compensation threshold and less than or equal to the second compensation threshold, the compensation value is a compensation value generated based on the deviation value; When the deviation value is less than or equal to the first compensation threshold, the first compensation threshold is used as the compensation value; When the deviation value is greater than the second compensation threshold, the second compensation threshold is used as the compensation value.

[0009] Optionally, generating a compensation value based on the deviation value includes: The product of the deviation value and the compensation coefficient is used as the compensation value; The compensation coefficient is greater than zero and less than or equal to 1.

[0010] Optionally, generating a compensation value based on the deviation value includes: The deviation value is input into a compensation value generation model constructed based on a preset adjustment strategy, and the compensation value generation model is used to process the deviation value to generate the compensation value. The compensation value generation model is configured to determine the compensation value based on at least one of the proportional, integral, and differential characteristics of the deviation value, or based on the weighted relationship between the deviation value of the current sampling period and the compensation value of the previous sampling period.

[0011] Optionally, when the inverter-charger is powered by the mains voltage, before acquiring the voltage at the battery connection port and the actual voltage of the battery in each sampling cycle, the method further includes: Obtain the voltage at the battery connection port; When it is determined that the voltage at the battery connection port is greater than the voltage start-up threshold, the step of acquiring the voltage at the battery connection port and the actual voltage of the battery in each sampling period is performed.

[0012] Optionally, before obtaining the voltage of the battery connection port, the method further includes: Identify the type of battery; When the battery is identified as a lithium battery, the battery is activated to connect the battery to the DC bus. After determining that the voltage of the battery connection port remains within a preset voltage range for a preset time, the function of activating and enabling the battery is deactivated, and then the step of obtaining the voltage of the battery connection port is executed.

[0013] Optionally, the power supply system is applied in the RV, and the DC side nominal voltage level of the inverter-charger includes 12V or 48V, the first threshold is 2V-3V, and the second threshold is 3.5-4.5V.

[0014] Optionally, the voltage between the positive and negative terminals of the battery can be obtained through an external sampling circuit, and the voltage between the positive and negative terminals can be used as the actual voltage of the battery. Alternatively, the actual voltage of the battery can be determined based on the resistance of the cable between the battery connection port and the battery, the current at the battery connection port, and the voltage at the battery connection port. Alternatively, when the battery is a lithium battery, the sampling voltage of each battery cluster in the battery is obtained through the battery management unit, so as to determine the actual voltage of the battery based on the sampling voltage of each battery cluster.

[0015] According to another aspect of the present invention, a motorhome is also provided, including a power supply system, which is controlled using the control method for the power supply system described in the preceding aspect.

[0016] By sampling the actual battery voltage and activating the battery compensation function under certain conditions, the battery reference voltage value is compensated. The battery compensation function is dynamically activated based on the deviation between the voltage at the battery connection port and the actual battery voltage, compensating for line loss and voltage drop in the DC cable. This effectively solves systemic problems such as premature battery protection, incomplete charging, and degraded discharge power quality caused by voltage drop in the line between the battery and the inverter-charger. The hysteresis interval effectively avoids jitter in the battery compensation function caused by noise or transient interference, ensuring the stability of subsequent control logic from the source and further improving system reliability.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart of a control method for a power supply system provided in an embodiment of the present invention; Figure 2 A schematic diagram of a power supply system provided in an embodiment of the present invention; Figure 3 A flowchart of another control method for a power supply system provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of an external sampling circuit provided in an embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] Figure 1 This is a flowchart illustrating a control method for a power supply system provided in an embodiment of the present invention. Figure 2 A schematic diagram of a power supply system provided in an embodiment of the present invention is shown below. Figure 2 As shown, the power supply system includes an inverter / charger 10, an energy management system (EMS), and a battery 11. The battery connection port of the inverter / charger 10 is connected to the battery 11, and both the inverter / charger 11 and the battery are connected to the energy management system. Specifically, the battery connection port includes a positive connection port Vbatt+ and a negative connection port Vbatt-. A DC cable 12 is connected between the positive connection port Vbatt+ and the positive terminal D+ of the battery 11, and a DC cable 12 is connected between the negative connection port Vbatt- and the negative terminal D- of the battery 11. The inverter / charger 10 is also connected to an AC load 13 and a mains power supply 14, respectively. The AC load 13 and the inverter / charger 10, as well as the mains power supply 14 and the inverter / charger 10, are connected via AC cables 15. The control method of the power supply system is executed by the energy management system. (Reference) Figure 1 and Figure 2 The method includes: S110: In each sampling period, acquire the voltage at the battery connection port and the actual voltage of the battery.

[0023] The battery management system and the inverter-charger 10 continuously exchange information. The inverter-charger 10 reads the voltage at its own battery connection port and transmits it to the battery management system so that the battery management system can obtain the voltage at the battery connection port.

[0024] The voltage between the positive terminal D+ and the negative terminal D- of battery 11 is the actual voltage of the battery. In an optional embodiment, the inverter-charger 10 obtains the voltage between the positive terminal D+ and the negative terminal D- of battery 11 through the external sampling cable 16 of the external sampling circuit, thereby obtaining the actual voltage of the battery, and then transmits the actual voltage of the battery to the energy management system. Optionally, the energy management system can be integrated into the inverter-charger 10.

[0025] In each sampling period, the voltage at the battery connection port and the actual battery voltage are acquired. At the first sampling time t1, the voltage at the battery connection port and the actual battery voltage are acquired; at the second sampling time t2, the voltage at the battery connection port and the actual battery voltage are acquired; at the third sampling time t3, the voltage at the battery connection port and the actual battery voltage are acquired; and so on, to acquire the voltage at the battery connection port and the actual battery voltage in each sampling period. The sampling period can be 20ms.

[0026] S120: When the absolute value of the difference between the voltage at the battery connection port and the actual battery voltage is less than or equal to the first threshold for N consecutive sampling periods, the battery compensation function is activated to compensate the battery reference voltage value; N is a positive integer.

[0027] If |Vbatt-VbattCom|≤A is satisfied for N consecutive sampling periods, it is determined that the line loss voltage drop on the DC cable 12 connecting the battery connection port and battery 11 is stable. At this time, the battery compensation function is enabled. Here, Vbatt is the voltage at the battery connection port, VbattCom is the actual battery voltage, and A is the first threshold.

[0028] Under the battery compensation function, the battery reference voltage value is compensated based on the voltage of the battery connection port, and the compensated voltage is used as the battery reference voltage value so that subsequent operations such as battery charging and discharging control, voltage protection, power adjustment and operation mode switching can be performed based on the battery reference voltage value.

[0029] When the battery compensation function is enabled, the voltage at the battery connection port and the actual voltage of the battery are continuously sampled until |Vbatt-VbattCom|>B (the second threshold) is satisfied for N consecutive sampling cycles, at which point the battery compensation function is disabled.

[0030] S130: If the absolute value of the difference between the voltage at the battery connection port and the actual battery voltage is greater than the second threshold for N consecutive sampling periods, the battery compensation function is turned off so that the voltage at the battery connection port is used as the battery reference voltage value; the second threshold is greater than the first threshold.

[0031] If |Vbatt-VbattCom|>B (the second threshold) is satisfied for N consecutive sampling periods, and the deviation between the voltage at the battery connection port and the actual battery voltage is too large, it indicates an anomaly in the sampled actual battery voltage. For example, if the cable connecting the external sampling circuit to the positive terminal D+ or negative terminal D- of battery 11 is loose or disconnected during sampling, it will lead to a large error in the sampled actual battery voltage, further resulting in a large deviation from the voltage at the battery connection port. In this case, since the deviation between the sampled voltage at the battery connection port and the actual battery voltage is inaccurate, enabling the battery compensation function is meaningless. Therefore, the battery compensation function should be disabled, and the system should revert to the local voltage detection mode. In the local voltage detection mode, the voltage at the battery connection port is directly used as the battery reference voltage value.

[0032] If the actual voltage VbattCom of the sampled battery suddenly becomes abnormal (e.g., becomes 0V) due to reasons such as disconnection, (VbattCom-Vbatt) will generate a huge negative difference, which will gradually trigger the condition mentioned above for disabling the battery compensation function (|Vbatt-VbattCom|>B). The system will automatically and smoothly switch back to the mode of using the voltage Vbatt of the battery connection port as the battery reference voltage value, avoiding control instability or malfunction caused by signal sudden changes, realizing seamless backtracking under fault conditions, and ensuring the high availability of the system.

[0033] S140: If, during N consecutive sampling periods, the absolute value of the difference between the voltage at the battery connection port and the actual battery voltage is greater than the first threshold and less than or equal to the second threshold, the current battery compensation function is maintained in its on / off state.

[0034] If, for N consecutive sampling periods, A < |Vbatt - VbattCom| ≤ B (the second threshold), and the battery compensation function is currently enabled, it will remain enabled to compensate the voltage at the battery connection port, and the compensated voltage will be used as the battery reference voltage value. If the battery compensation function is currently disabled, the system will be in local voltage detection mode, using the voltage at the battery connection port as the battery reference voltage value.

[0035] For example, N can be a positive integer such as 1, 2, 3, 4, 5, etc., and can be set according to requirements. The first threshold and the second threshold can also be set according to the voltage level of the power supply system.

[0036] By using hysteresis intervals and delay filtering, the jitter of the battery compensation function caused by noise or transient interference is effectively avoided, ensuring the stability of subsequent control logic from the source. If the battery compensation function is turned off for any reason, and the absolute value of the difference between the voltage at the battery connection port and the actual battery voltage is less than or equal to the first threshold for N consecutive sampling cycles, the battery compensation function will be automatically restarted.

[0037] By sampling the actual battery voltage and activating the battery compensation function under certain conditions, the battery reference voltage value is compensated. The battery compensation function is dynamically activated based on the deviation between the voltage at the battery connection port and the actual battery voltage, compensating for line loss and voltage drop in the DC cable. This effectively solves systemic problems such as premature battery protection, incomplete charging, and degraded discharge power quality caused by voltage drop in the line between the battery and the inverter-charger. The hysteresis interval effectively avoids jitter in the battery compensation function caused by noise or transient interference, ensuring the stability of subsequent control logic from the source and further improving system reliability.

[0038] Figure 3 A flowchart of another control method for a power supply system provided in an embodiment of the present invention is shown below. Figure 2 and Figure 3 The method includes: S111: In each sampling period, acquire the voltage at the battery connection port and the actual voltage of the battery.

[0039] S121: If the absolute value of the difference between the voltage at the battery connection port and the actual voltage of the battery is less than or equal to the first threshold for N consecutive sampling periods, the value of the difference between the actual voltage of the battery and the voltage at the battery connection port is taken as the deviation value.

[0040] The deviation value Err = VbattCom - Vbatt.

[0041] S131: Generate compensation value based on deviation value.

[0042] S141: Generates a battery reference voltage value based on the voltage and compensation value at the battery connection port.

[0043] The deviation value can be processed based on a variety of preset algorithms to generate a compensation value, and the sum of the voltage at the battery connection port and the compensation value is used as the battery reference voltage value.

[0044] In the first embodiment, the product of the deviation value and the compensation coefficient is used as the compensation value. Vb = Vbatt + K·(VbattCom - Vbatt); where Vb is the battery reference voltage value, and K is the compensation coefficient, which is greater than zero and less than or equal to 1.

[0045] Optionally, the compensation coefficient can be a fixed value, K=1. A "difference compensation" strategy is adopted instead of a "signal switching" strategy. The system does not simply replace the battery connection port voltage Vbatt with the actual battery voltage VbattCom as the battery reference voltage value; instead, it calculates the difference for compensation. This makes the compensation process smooth and avoids shocks to the closed-loop control caused by jumps in the battery reference voltage value.

[0046] Alternatively, once the battery compensation function is enabled, the compensation coefficient gradually increases from zero to 1 within a preset number of sampling periods.

[0047] For example, the compensation coefficient increases uniformly from zero to 1 within a preset number of sampling periods according to a preset gradient. For example, the battery compensation function is activated in the Kth sampling period. In the Kth sampling period, the compensation coefficient is 0.2; in the (K+1)th sampling period, it is 0.4; in the (K+2)th sampling period, it is 0.6; in the (K+3)th sampling period, it is 0.8; and in the (K+4)th sampling period, it is 1.0. The compensation coefficient increases from 0 to 1 within 5 sampling periods, meaning the preset gradient is 0.2. In other embodiments, the preset gradient and preset number of sampling periods can be other values, which can be set according to specific needs.

[0048] The compensation coefficient gradually increases from zero to 1 within a preset number of sampling periods to more smoothly compensate the battery reference voltage value to the actual battery voltage, further improving the smoothness of the compensation process.

[0049] In the second embodiment, the deviation value is input into a compensation value generation model constructed based on a preset adjustment strategy. The compensation value generation model processes the deviation value to generate a compensation value. The compensation value generation model is configured to determine the compensation value based on at least one of the proportional, integral, and differential characteristics of the deviation value, or based on the weighted relationship between the deviation value of the current sampling period and the compensation value of the previous sampling period.

[0050] In the second implementation, the preset adjustment strategy can be a PID control strategy, and the compensation value generation model can be a closed-loop model constructed from the PID. It should be noted that the PID control strategy is calculated based on the deviation value of the current sampling period, the deviation value of the previous sampling period, and the historical cumulative deviation value. Specifically, the deviation value of the current sampling period is used to determine the proportional characteristic, the change in deviation value between the current and previous sampling periods is used to determine the derivative characteristic, and the historical cumulative deviation value is used to determine the integral characteristic. Then, the compensation value D satisfies: D = Kp·Err + Ki·∫Errdt + Kd·dErr / dt. Kp·Err is the proportional characteristic of the deviation value, Ki·∫Errdt is the integral characteristic of the deviation value, and Kd·dErr / dt is the differential characteristic of the deviation value. Kp is the proportional coefficient, Ki is the integral coefficient, and Kd is the differential coefficient.

[0051] For example, with Kp=0.6, Ki=0.1, and Kd=0.0 (ignoring for now), for the current sampling period: Vbatt=12.0V, VbattCom=13.0V, Err=1.0V. Kp·Err=0.6×1.0=0.6V; assuming a cumulative error of 2.0 (historical cumulative), then Ki·∫Errdt=0.1·2.0=0.2, and the output D= 0.6+0.2=0.8V; finally, the battery reference voltage value Vb under the current sampling period is Vb=12.0+0.8=12.8V.

[0052] Alternatively, if the preset adjustment strategy is a low-pass filtering strategy, the compensation value generation model is configured to determine the compensation value based on the weighted relationship between the deviation value of the current sampling period and the compensation value of the previous sampling period. Specifically: D(k) = α·Err(k) + (1-α)·D(k-1); D(k) is the compensation value for the k-th sampling period, Err(k) is the deviation value for the k-th sampling period, and D(k-1) is the compensation value for the (k-1)-th sampling period. Where the k-th sampling period is the current sampling period, and the (k-1)-th sampling period is the previous sampling period. α is the filter coefficient, characterizing the response speed, and its value ranges from 0 to 1. The smaller α is, the smoother the compensation process; the larger α is, the more sensitive the compensation.

[0053] Assume Vbatt=12.0V, VbattCom=13.0V, Err=1.0V, α=0.1; Initially, D = 0V. Step 1: D(2) = 0.1 × 1 + 0.9 × 0 = 0.1V; Step2: D(3)=0.1×1+0.9×0.1=0.19V; Step3:D(4)=0.1×1+0.9×0.19=0.271V; Step n: The voltage approaches stability (D→1.0V). This example demonstrates that the sampled voltage at the battery connection port is 12.0V across multiple sampling periods, and the sampled actual battery voltage is 13.0V. When the voltage at the battery connection port changes and / or the actual battery voltage changes across different sampling periods, the sampled values ​​for both in the current sampling period are substituted into the above formula for calculation.

[0054] Optionally, regardless of the method used to generate the compensation value based on the deviation value, the generated compensation value must be greater than the first compensation threshold and less than or equal to the second compensation threshold. In this case, the compensation value used in the compensation calculation is the compensation value generated based on the deviation value. If the deviation value is less than or equal to the first compensation threshold, the first compensation threshold is used as the compensation value, and the sum of the voltage at the battery connection port and the first compensation threshold is used as the battery reference voltage value. If the deviation value is greater than the second compensation threshold, the second compensation threshold is used as the compensation value, and the sum of the voltage at the battery connection port and the second compensation threshold is used as the battery reference voltage value.

[0055] The compensation value is limited to a certain range. When it exceeds this range, the compensation value is fixed to the set value (first compensation threshold or second compensation threshold). This avoids the situation where the cable sampling the actual voltage of the battery comes loose, and the inaccurate sampling data leads to the use of incorrect deviation values ​​to compensate for the battery reference voltage value, resulting in a large control error in the entire system.

[0056] Optionally, when the power supply system is used in the RV, the nominal DC voltage level of the inverter-charger includes 12V or 48V, with a first threshold of 2V-3V and a second threshold of 3.5-4.5V. The first compensation threshold is -3V to -5V, and the second compensation threshold is 3V to 5V. Optionally, the first threshold is 2.5V, the second threshold is 4V, the first compensation threshold is -4V, and the second compensation threshold is 4V.

[0057] S151: If the absolute value of the difference between the voltage at the battery connection port and the actual battery voltage is greater than the second threshold for N consecutive sampling periods, the battery compensation function is turned off so that the voltage at the battery connection port is used as the battery reference voltage value.

[0058] S161: If, during N consecutive sampling periods, the absolute value of the difference between the voltage at the battery connection port and the actual voltage of the battery is greater than the first threshold and less than or equal to the second threshold, the current on / off state of the battery compensation function is maintained.

[0059] In this embodiment, the voltage at the battery connection port is not directly modified. Instead, the battery reference voltage value is compensated based on the voltage at the battery connection port. This approach utilizes the actual battery voltage to improve control accuracy while retaining the sampled value from the battery connection port for overvoltage and undervoltage protection, thus preventing battery connection port protection failure.

[0060] Based on the voltage at the battery connection port, limited compensation is performed by calculating the difference between the voltage at the battery connection port and the actual battery voltage (e.g., setting the maximum compensation value to 4V). Even if the actual battery voltage failure judgment has not been completed, the battery voltage reference value still has the local battery connection port voltage as the basis. This prevents the control from relying entirely on erroneous data due to abnormal sampling of the external actual battery voltage, thus improving the fault tolerance and operational stability of the system.

[0061] After enabling the battery compensation function, in a discharge scenario, assuming the voltage at the battery connection port is 11.1V in a certain sampling period, the battery reference voltage should be slightly higher than the voltage at the battery connection port after compensation, such as 11.5V. When the system determines that the battery still has power based on the compensated battery reference voltage, but the voltage at the battery connection port is low due to line loss, the undervoltage limit at the battery connection port is relaxed, allowing continued discharge until the battery is truly undervoltage, thereby unlocking more usable power.

[0062] In a charging scenario, assuming the battery connection port voltage is 15.8V during a certain sampling period, the battery reference voltage, after compensation, should be slightly lower than the battery connection port voltage. Therefore, after compensation, the battery reference voltage increases from 15.8V to 15.5V. Towards the end of charging, if the battery connection port voltage reaches the original protection point first due to higher line loss, the system determines that the battery is not yet fully charged based on the compensated battery reference voltage. This increases the overvoltage protection threshold of the battery connection port, allowing charging to continue until the battery truly reaches its saturation voltage, ensuring charging capacity.

[0063] For critical switching points such as constant voltage to float charging for lead-acid batteries and constant current to constant voltage charging for lithium batteries, the determination criterion has been changed to the compensated battery reference voltage value, instead of using the voltage at the battery connection port as the battery reference voltage value. This avoids premature switching of charging stages due to artificially high voltage at the battery connection port, allowing the battery to accept energy in a longer constant current (or high voltage constant voltage) stage, significantly shortening charging time and improving the battery's final charge saturation and cycle life.

[0064] The compensation mechanism described in the above embodiment achieves coordination between the actual battery voltage and the local hard protection circuit. It eliminates the "false triggering" of protection points due to line loss, ensuring that the protection action accurately corresponds to the battery's state, and maximizing the charge and discharge capacity range under the premise of absolute safety.

[0065] When the inverter-charger employs an advanced efficiency optimization strategy called "dynamic bus voltage adjustment," its software control strategy, in order to maximize the efficiency of the DC / DC conversion stage, does not use a fixed bus voltage. Instead, it dynamically calculates and sets a theoretically minimum bus voltage reference value, Vbus_ref, based on the real-time collected voltage at the battery connection port. This strategy automatically reduces the bus voltage when the battery voltage is high, reducing unnecessary boost ratios and switching losses, thereby improving overall system efficiency. However, when significant line loss voltage drop exists, the Vbus_ref calculated based on the battery connection port voltage, which is lower than the actual battery voltage, will fall below a safety threshold. This results in an insufficient actual bus voltage to support the subsequent inverter in synthesizing a complete sine wave, ultimately leading to clipping distortion in the AC output voltage and severely degrading power quality. In this embodiment, the battery compensation function is dynamically activated, and the voltage reference Vbus_ref is dynamically calculated. The local port voltage of the inverter-charger (i.e., the battery connection port voltage Vbatt) with line loss errors is replaced with a compensated voltage that approximates or equals the actual battery voltage. Since the compensated battery reference voltage accurately reflects the higher voltage at the battery terminal, the calculated battery reference voltage value is more accurate and sufficient, thus fundamentally eliminating the output voltage clipping problem caused by incorrect bus voltage calculation reference. This ensures high-quality pure sine wave output under any line loss conditions. Furthermore, unlike simply and abruptly switching back to a fixed high-voltage mode to maintain quality, this solution allows the system to continue operating stably in the high-efficiency "dynamic bus voltage adjustment" mode while ensuring output quality. In other words, it preserves and maintains the application value of the original advanced efficiency optimization strategy, making it effective even in complex wiring scenarios.

[0066] Optionally, prior to S110 or S111, the following may also be included: Step a: Obtain the voltage at the battery connection port.

[0067] The voltage at the battery connection port is obtained by interacting with the inverter charger.

[0068] Step b: When it is determined that the voltage at the battery connection port is greater than the voltage start-up threshold, perform the step of acquiring the voltage at the battery connection port and the actual voltage of the battery in each sampling period.

[0069] For a 12V system, the voltage start-up threshold can be 5.5V. If the voltage at the battery connection port is less than or equal to 4V, it indicates that the battery may not be connected, and the steps in the above embodiments are not executed. If the voltage at the battery connection port is greater than 4V and further greater than 5.5V for M sampling cycles (M can be 20), step S110 or S111 is executed.

[0070] Optionally, the method may include the following steps prior to step a: Step c: Identify the battery type.

[0071] The energy management system interacts with the battery management system (BMS) in real time to obtain information about the battery type. Battery types include lithium-ion batteries, lead-acid batteries, and absorbent glass mat (AGM) batteries. Alternatively, the energy management system may obtain battery type information, for example, through user-defined settings via a human-machine interface.

[0072] Step d: When the battery is identified as a lithium battery, activate the enable battery to connect the battery to the DC bus.

[0073] Lithium batteries will trigger their own protection mechanism and disconnect from the DC bus if they are left unused for a long time or if the battery charge is too low. Therefore, before use, the circuit switch must be closed to connect the battery to the DC bus. After the system is powered on, it will recognize the battery as a lithium battery and activate it to close the switch between the battery and the DC bus, thus connecting the battery to the DC bus.

[0074] Step e: After determining that the voltage of the battery connection port remains within a preset voltage range for a preset duration, exit the function of activating and enabling the battery, and then execute the step of obtaining the voltage of the battery connection port.

[0075] After activating the battery, continuously collect the voltage at the battery connection port. When the voltage at the battery connection port remains within the preset voltage range for a preset duration, it is determined that the activation is successful. At this point, exit the battery activation function and proceed to step a.

[0076] Optionally, the actual voltage of the battery can be obtained in several ways, specifically: Method 1: Obtain the voltage between the positive and negative terminals of the battery through an external sampling circuit, and use the voltage between the positive and negative terminals as the actual voltage of the battery.

[0077] An external sampling circuit is constructed to connect the positive and negative terminals of the battery to obtain the actual voltage of the battery. The energy management system is connected to the external sampling circuit, and then obtains the actual voltage of the battery through the external sampling circuit.

[0078] Figure 4 This is a schematic diagram of an external sampling circuit provided in an embodiment of the present invention, with reference to... Figure 4The external sampling circuit includes an input voltage divider unit 17, an isolation amplifier unit 18, and a differential amplifier unit 19. The input voltage divider unit 17 includes a first resistor R1 and a second resistor R2 connected in series between the positive terminal D+ and the negative terminal D- of the battery. The common terminal of the first resistor R1 and the second resistor R2 is connected to the input terminal of the isolation amplifier unit 18. The first output terminal of the isolation amplifier unit 18 is connected to the first differential terminal of the differential amplifier unit 19, and the second output terminal of the isolation amplifier unit 18 is connected to the second differential terminal of the differential amplifier unit 19. The output terminal of the differential amplifier unit 19 is connected to the battery management system via a sixth resistor R6. The negative terminal D- of the battery is connected to the Safety Extra Low Voltage Ground (SELV_GND). A first capacitor C1 is connected in parallel across the second resistor R2 for filtering. The input voltage divider unit 17 attenuates the actual battery voltage to the allowable input range of the isolation amplifier unit 18 and filters out high-frequency interference at the input terminal. The isolation amplifier unit 18 employs an isolation amplifier. Its primary power supply is provided by the safety extra-low voltage side power supply V1 from the isolated DC-DC converter of the inverter-charger, with the safety extra-low voltage ground SELV_GND as the reference ground. Its secondary power supply is provided by the system side power supply V2 from the isolated DC-DC converter, with the system ground GNDD as the reference ground. The two power supplies are mutually isolated and do not share a common ground, achieving electrical isolation between the remote battery and the system. The isolation amplifier unit 18 amplifies its input signal and outputs it in differential form. A third resistor R3 is connected between the first output terminal of the isolation amplifier unit 18 and the first input terminal of the differential amplifier unit 19, and a fourth resistor R4 is connected between the second output terminal of the isolation amplifier unit 18 and the second input terminal of the differential amplifier unit 19. The differential amplifier unit 19, composed of an operational amplifier and a feedback resistor network, forms a differential amplification structure, converting the differential signal output by the isolation amplifier unit 19 into a single-ended signal and further amplifying it to the standard acquisition range of the analog-to-digital converter in the battery management system. The feedback resistor network includes a fifth resistor R5 and a second capacitor C2. The fifth resistor R5 is connected between the second input and output terminals of the differential amplifier unit 19, and the second capacitor C2 is also connected between the second input and output terminals of the differential amplifier unit 19. The second capacitor C2 forms a low-pass filter to limit bandwidth and suppress noise. The signal amplified by the differential amplifier unit 19 is smoothed by a low-pass filter consisting of a sixth resistor R6 connected to the output terminal of the differential amplifier unit 19, and a third capacitor C3 (the first end of the sixth resistor R6 is connected to the output terminal of the differential amplifier unit 19, the first end of the third capacitor C3 is connected to the second end of the sixth resistor R6, and the second end of the third capacitor C3 is connected to system ground GNDD). The final output is the actual battery voltage sampling signal. The battery management system determines the actual battery voltage based on the actual battery voltage sampling signal, where there is a one-to-one correspondence between the actual battery voltage and the actual battery voltage sampling signal.This circuit allows the battery management system to simultaneously monitor the battery's actual voltage.

[0079] Method 2: Determine the actual voltage of the battery based on the resistance of the cable between the battery connection port and the battery, the current at the battery connection port, and the voltage at the battery connection port.

[0080] The resistance of the cable between the positive and negative terminals of the battery can be measured in advance. Then, according to Ohm's law, the actual voltage of the battery can be obtained by adding or subtracting the product of the current and the cable resistance (subtraction when the battery is charging and addition when the battery is discharging) from the voltage at the battery connection port.

[0081] Method 3: When the battery is a lithium battery, the sampling voltage of each battery cluster in the battery is obtained through the battery management unit, so as to determine the actual voltage of the battery based on the sampling voltage of each battery cluster.

[0082] The battery comprises multiple battery clusters connected in parallel. When the energy management system identifies the battery type as a lithium battery, it sends a voltage query command to the battery management unit (BMU). In response to this command, the BMU reads the sampled voltages at the positive and negative terminals of the first to Nth battery clusters. Given the significant voltage change rate of lithium batteries at the end of the charging and discharging process, to improve the robustness of voltage determination, the system performs extreme value averaging (or median filtering) on ​​the acquired cluster sampled voltages and uses the processed result as the actual battery voltage.

[0083] This invention also provides a motorhome, including the aforementioned power supply system, and controlled using the control method of the power supply system in any of the above embodiments.

[0084] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0085] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A control method for a power supply system, characterized in that, The power supply system includes an inverter-charger, an energy management system, and a battery. The battery connection port of the inverter-charger is connected to the battery, and the inverter-charger and the battery are respectively connected to the energy management system. The control method of the power supply system is executed by the energy management system. The control method for the power supply system includes: In each sampling period, the voltage at the battery connection port and the actual voltage of the battery are acquired; When the absolute value of the difference between the voltage at the battery connection port and the actual voltage of the battery is less than or equal to a first threshold for N consecutive sampling periods, the battery compensation function is activated to compensate the battery reference voltage value; N is a positive integer. If, for N consecutive sampling periods, the absolute value of the difference between the voltage at the battery connection port and the actual voltage of the battery is greater than a second threshold, the battery compensation function is turned off so that the voltage at the battery connection port is used as the battery reference voltage value; the second threshold is greater than the first threshold. If, during N consecutive sampling periods, the absolute value of the difference between the voltage at the battery connection port and the actual voltage of the battery is greater than the first threshold and less than or equal to the second threshold, the current on / off state of the battery compensation function is maintained.

2. The control method for a power supply system according to claim 1, characterized in that, Enabling the battery compensation function to compensate for the battery reference voltage value includes: The deviation value is the difference between the actual voltage of the battery and the voltage at the battery connection port. A compensation value is generated based on the deviation value; The battery reference voltage value is generated based on the voltage at the battery connection port and the compensation value.

3. The control method for a power supply system according to claim 2, characterized in that, When the deviation value is greater than the first compensation threshold and less than or equal to the second compensation threshold, the compensation value is a compensation value generated based on the deviation value; When the deviation value is less than or equal to the first compensation threshold, the first compensation threshold is used as the compensation value; When the deviation value is greater than the second compensation threshold, the second compensation threshold is used as the compensation value.

4. The control method for a power supply system according to claim 2 or 3, characterized in that, The step of generating a compensation value based on the deviation value includes: The product of the deviation value and the compensation coefficient is used as the compensation value; The compensation coefficient is greater than zero and less than or equal to 1.

5. The control method for a power supply system according to claim 2 or 3, characterized in that, The step of generating a compensation value based on the deviation value includes: The deviation value is input into a compensation value generation model constructed based on a preset adjustment strategy, and the compensation value generation model is used to process the deviation value to generate the compensation value. The compensation value generation model is configured to determine the compensation value based on at least one of the proportional, integral, and differential characteristics of the deviation value, or based on the weighted relationship between the deviation value of the current sampling period and the compensation value of the previous sampling period.

6. The control method for a power supply system according to claim 1, characterized in that, When the inverter-charger is powered by the mains voltage, before acquiring the voltage at the battery connection port and the actual voltage of the battery in each sampling cycle, the following steps are also included: Obtain the voltage at the battery connection port; When it is determined that the voltage at the battery connection port is greater than the voltage start-up threshold, the step of acquiring the voltage at the battery connection port and the actual voltage of the battery in each sampling period is performed.

7. The control method for a power supply system according to claim 6, characterized in that, Before obtaining the voltage of the battery connection port, the method further includes: Identify the type of battery; When the battery is identified as a lithium battery, the battery is activated to connect the battery to the DC bus. After determining that the voltage of the battery connection port remains within a preset voltage range for a preset time, the function of activating and enabling the battery is deactivated, and then the step of obtaining the voltage of the battery connection port is executed.

8. The control method for a power supply system according to claim 1, characterized in that, The power supply system is used in the RV, and the DC side nominal voltage level of the inverter-charger includes 12V or 48V, the first threshold is 2V-3V, and the second threshold is 3.5-4.5V.

9. The control method for a power supply system according to claim 1, characterized in that, The voltage between the positive and negative terminals of the battery is obtained through an external sampling circuit, and the voltage between the positive and negative terminals is taken as the actual voltage of the battery. Alternatively, the actual voltage of the battery can be determined based on the resistance of the cable between the battery connection port and the battery, the current at the battery connection port, and the voltage at the battery connection port. Alternatively, when the battery is a lithium battery, the sampling voltage of each battery cluster in the battery is obtained through the battery management unit, so as to determine the actual voltage of the battery based on the sampling voltage of each battery cluster.

10. A motorhome, characterized in that, It includes a power supply system, and is controlled using the power supply system control method according to any one of claims 1-9.

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