Method for reducing line loss of power supply system and power supply system with reduced line loss

Abstract

A method for reducing line loss of a power supply system and a power supply system with reduced line loss, the power supply system with reduced line loss supplies power to a load through a power line, and comprises: a boost converter, a detection circuit and a control unit. The control unit sets the terminal voltage required by the load, controls the output voltage of the boost converter to be the terminal voltage, and detects the output current corresponding to the terminal voltage as the current current through the detection circuit; the control unit controls the output voltage of the boost converter to be a modulation voltage, and detects the corresponding output current as the modulation current through the detection circuit; the control unit adjusts the output voltage of the boost converter to a first predetermined voltage according to the terminal voltage, the current current, the modulation voltage and the modulation current.

Description

Technical Field

[0001] The present invention relates to a method for reducing line loss of a power supply system and a power supply system with reduced line loss, and in particular to a method for reducing line loss of a power supply system without measuring power line impedance. Background Art

[0002] A base station usually includes a baseband unit (BBU), a radio frequency module (RRU) and one or more antenna modules. In 5G applications, the radio frequency module and the antenna module can also be integrated into an active antenna module (AAU). Whether it is RRU or AAU, it usually needs to be installed in a higher place to facilitate the reception and transmission of signals. Therefore, communication equipment such as RRU / AAU is usually installed at the highest point using an electric tower. At present, there is a certain distance between the power supply system and the load on the tower. This distance will bring a certain degree of power loss and voltage drop in power line transmission, especially in 5G systems. Since the power of the equipment on the tower will increase, the power loss and voltage drop during transmission cannot be ignored. We must think about how to reduce the power transmission loss.

[0003] Using a higher voltage for transmission will reduce power loss, but since it cannot affect the voltage of the base station equipment under the tower, a boost device will be added first, but it must be ensured that the voltage at the load end does not exceed the maximum allowable voltage of the equipment. In the past, one implementation method used a detector installed at the load end of the tower to detect the voltage at the load end, and used a communication device to communicate with the power system of the base station. When the load current is large, the output voltage of the power system is increased to maintain the voltage at the load end. However, this method increases the difficulty and cost of construction, and there is a possibility of communication failure. Another way is to install another step-down device on the tower to convert the voltage transmitted to the tower to the voltage of the equipment on the tower, but its disadvantage is the loss of an extra step-down device, and because the step-down device is located on the tower, it causes maintenance difficulties. There is another possible way, which is to pre-enter the length, thickness and other information of the power line to estimate the power line impedance, and then compensate the voltage according to the output current. However, the problem with this method is that the power line impedance will change due to aging, or the information is not updated in real time when it is reinstalled, which is easy to cause voltage compensation errors and damage the equipment.

[0004] Therefore, how to design a method for reducing line loss of a power supply system and a power supply system with reduced line loss, and use special voltage compensation calculation steps and methods to accurately and quickly calculate the voltage level of the power supply device required to adjust in response to the needs of the communication equipment, is a major issue that the inventors of the present disclosure want to overcome and solve. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for reducing line loss in a power supply system to overcome the problems of the prior art. Therefore, the power supply system of the present invention includes a boost converter, and the boost converter provides a load voltage to the load through a power line. The method for reducing line loss includes the following steps: setting the terminal voltage required by the load, and controlling the output voltage of the boost converter to be the terminal voltage. Detecting the output current corresponding to the terminal voltage as the current current. Controlling the output voltage to be a modulation voltage, and detecting the corresponding output current as the modulation current. Adjusting the output voltage of the boost converter to a first predetermined voltage according to the terminal voltage, the current current, the modulation voltage and the modulation current. Wherein, the load voltage after deducting the power line voltage drop of the power line from the first predetermined voltage satisfies the preset terminal voltage.

[0006] In order to solve the above problems, the present invention provides a power supply system with reduced line loss to overcome the problems of the prior art. Therefore, the power supply system of the present invention provides a load voltage to the load through the power line, and the power supply system includes: a boost converter, which receives an input voltage from the input end and provides an output voltage to the load from the output end. A detection circuit is coupled to the output end. And a control unit is coupled to the boost converter and the detection circuit, and controls the boost converter to convert the input voltage into an output voltage. Among them, the control unit sets the terminal voltage required by the load and controls the voltage at the output end to be the terminal voltage; the control unit detects the output end through the detection circuit and obtains the output current corresponding to the terminal voltage as the current current; the control unit controls the voltage at the output end to be a modulation voltage, and detects the output end through the detection circuit and obtains the output current corresponding to the modulation voltage as the modulation current; the control unit adjusts the output voltage to a first predetermined voltage according to the terminal voltage, the current current, the modulation voltage and the modulation current, so that the load voltage after the predetermined voltage is deducted from the power line voltage drop of the power line meets the terminal voltage preset by the control unit.

[0007] The main purpose and technical effect of the present invention is that, through the above-mentioned special line loss reduction steps and processes disclosed in the present invention, the voltage drop of the power line can be obtained without adding conversion equipment, impedance measurement equipment or additional communication devices, and the technical effect of the voltage size that needs to be adjusted can be quickly calculated, so that the voltage at the load input end can be increased to reduce the power line transmission loss, and it can also be ensured that the voltage at the load input end will not exceed the maximum allowable operating value of the equipment under different load conditions.

[0008] In order to further understand the technology, means and technical effects adopted by the present invention to achieve the predetermined purpose, please refer to the following detailed description and drawings of the present invention. It is believed that the purpose, characteristics and features of the present invention can be deeply and specifically understood thereby. However, the drawings in the specification are only provided for reference and explanation and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A system architecture diagram of a power supply system with reduced line loss according to the present invention;

[0010] Figure 2 A circuit block diagram of a power supply system with reduced line loss according to the present invention;

[0011] Figure 3A A flowchart of the method for reducing line loss of a power supply system of the present invention; and

[0012] Figure 3B This is a flow chart of the steps of subsequent circuit adjustment of the method for reducing line loss of the power supply system of the present invention.

[0013] Description of reference numerals:

[0014] 100…Power supply system

[0015] 10…Rectifier unit

[0016] 20…Boost Converter

[0017] 22…Input

[0018] 24…Output

[0019] 30…Detection circuit

[0020] 40…Control unit

[0021] 50…Bypass switch

[0022] 60…DC converter

[0023] 60-1…Renewable Energy

[0024] 70…Battery

[0025] 200…Power Line

[0026] 300…Load

[0027] A…Electricity Tower

[0028] Vac…AC voltage

[0029] Vin…Input voltage

[0030] Vo…output voltage

[0031] Vr…Power line voltage drop

[0032] Vl…Terminal voltage

[0033] Iin…input current

[0034] Io…output current

[0035] Sin…input signal

[0036] So…output signal

[0037] Sc1…First control signal

[0038] Sc2…Second control signal DETAILED DESCRIPTION

[0039] The technical content and detailed description of the present invention are described as follows with reference to the accompanying drawings:

[0040] See also Figure 1 The power supply system 100 is mainly used in an environment where a power line 200 is coupled to a load 300 and the power supply system 100 and the load 300 are at a relatively long distance. Figure 1 Taking the electric tower A as an example, the power supply system 100 is arranged under the electric tower A, and the load 300 is arranged on the electric tower A. The load 300 is a device with a large power consumption, such as but not limited to 5G communication equipment. Since the power line 200 connected to the load 300 needs to be pulled down from the electric tower A to the electric tower A, the line loss of the power line 200 is very significant. Therefore, there will be a large difference between the voltage output by the power supply system 100 under the electric tower A and the voltage received by the load 300 on the electric tower A. In the case where the current drawn by the load 300 is large, the voltage difference may even exceed ten volts, and the greater the current flowing through the power line 200, the greater the line loss caused. Therefore, in the case where the load 300 is a device with a large power consumption, it is very important to reduce the loss of the power line 200.

[0041] See also Figure 2 The circuit block diagram of the power supply system with reduced line loss of the present invention is shown in FIG. Figure 1 . The power supply system 100 under the power tower A supplies power to the load 300 on the power tower A through the power line 200, and the power supply system 100 includes a rectifier unit 10, a boost converter 20, a detection circuit 30 and a control unit 40. The input end 22 of the boost converter 20 is coupled to the rectifier unit 10, and the output end 24 is coupled to the load 300 through the power line 200. The rectifier unit 10 receives the AC voltage Vac and rectifies the AC voltage Vac into an input voltage Vin. The boost converter 20 receives the input voltage Vin and converts the input voltage Vin into an output voltage Vo under the control of the control unit 40. The power line 200 receives the output voltage Vo, and after the power line voltage drop Vr of the power line, provides a load voltage Vl to the load 300 at the terminal of the power line. Due to the influence of the power line voltage drop Vr, the voltage value of the load voltage Vl will be smaller than the voltage value of the output voltage Vo.

[0042] The detection circuit 30 is coupled to the output terminal 24 of the boost converter 20 and is used to detect the output voltage Vo and the output current Io of the output terminal 24. The detection circuit 30 provides an output signal So to the control unit 40 according to the magnitude of the output voltage Vo and the output current Io, so that the control unit 40 knows the magnitude of the output voltage Vo and the output current Io. The control unit 40 receives the output signal So and provides a first control signal Sc1 to the boost converter 20 according to the output signal So to adjust and stabilize the voltage value of the output voltage Vo to a set voltage value. The boost converter 20, the detection circuit 30 and the control unit 40 can be integrated into a power supply, and the control unit 40 is a power control processor of the power supply.

[0043] See also Figure 2 The power supply system 100 under the power tower also includes a bypass switch 50, a DC converter 60, a renewable energy source 60-1 and a battery 70. The bypass switch 50 is connected in parallel with the boost converter 20 (i.e., one end is coupled to the input end 22 and the other end is coupled to the output end 24), and is coupled to the control unit 40. The bypass switch 50 is turned on by the second control signal Sc2 provided by the control unit 40 to bypass the boost converter 20 so that the power supply system 100 does not provide a boost function. The DC converter 60 can be connected to another backup power source (for example, but not limited to, the renewable energy source 60-1) to output a DC voltage, such as connecting to renewable energy sources such as solar energy and wind power generation. The DC converter 60 can be selectively set according to system requirements, or connected to other backup energy sources in different configurations. The battery 70 is coupled to the input end 22 of the boost converter 20, and provides an input power source Vin to power the boost converter 20 when there is no AC voltage Vac or the DC converter 60 has no output. The input power Vin is mainly used to provide the voltage required by the base station equipment under the tower, including baseband units and other base station equipment (not shown).

[0044] See also Figure 3A This is a flowchart of the method for reducing line loss in the power supply system of the present invention, and is also referred to in conjunction with Figure 1 to Figure 2. Since the reduction of line loss must be considered from the overall efficiency of the entire power supply system 100, the addition of a boost converter 20 or even a buck converter must be added to the power tower A. The efficiency of these converters will have a decreasing effect on the efficiency of the entire power supply system 100. Therefore, we cannot only look at the improvement of the power loss of the power line 200 transmission, but must consider the impact of these parameters on the overall efficiency. Furthermore, under different load conditions, there will be different adjustment mechanisms. In addition, in addition to considering the impact of these parameters on the overall efficiency when there is an AC voltage Vac, when there is no AC voltage Vac, the adjustment of the output voltage Vo must also consider the impact of the above parameters on the overall efficiency because the power source is supplied by the battery 70. Therefore, the battery capacity of the battery 70 must also be added to the impact of the above parameters on the overall efficiency. Therefore, there are too many factors to consider in the adjustment of the output voltage Vo, which must be determined based on the efficiency and needs of the overall power supply system 100.

[0045] Therefore, the present invention proposes a special method for reducing line loss. The method first includes setting the terminal voltage required by the load, controlling the output voltage of the boost converter to be the terminal voltage, and detecting the corresponding output current as the current current; obtaining the first output power by multiplying the terminal voltage and the current current (S100). The detection circuit 30 detects the output terminal 24 of the boost converter 20 to obtain the output signal So. The control unit 40 can control the output voltage of the boost converter to be the terminal voltage by receiving the output signal So, which is the general feedback control principle, and at the same time can detect the corresponding output current as the current current. Then, the control unit 40 obtains the first output power provided by the boost converter 20 at this time by multiplying the terminal voltage and the current current. Since the first output power provided by the boost converter 20 at this time is equal to the power consumed by the power line 200 at this time plus the power consumed by the load 300, it can be expressed as: Vo1×Io1=Vr1×Io1+Vl1×Io1. Among them, Vo1 represents the current output voltage of the boost converter, and the output voltage at this time is the terminal voltage set by the control unit, Io1 represents the current current, Vr1 represents the current power line voltage drop (ie, the first voltage drop), and Vl1 represents the current load voltage.

[0046] Then, the output voltage of the boost converter is controlled to be a modulation voltage, and the corresponding output current is detected to be a modulation current, so as to obtain the second output power by multiplying the modulation voltage and the modulation current (S200). The control unit 40 modulates the output voltage Vo by controlling the boost converter 20 to modulate the output voltage to the modulation voltage (i.e., change the voltage value of the output voltage Vo). The control unit 40 can control the output voltage of the boost converter to be a modulation voltage by receiving the output signal So, and at the same time detect the corresponding output current as the modulation current. Then, the control unit 40 calculates the second output power provided by the boost converter 20 at this time by multiplying the modulation voltage and the modulation current. Since the second output power provided by the boost converter 20 at this time will also be equal to the power consumed by the power line 200 at this time plus the power consumed by the load 300, it can be expressed as: Vo2×Io2=Vr2×Io2+Vl2×Io2. Among them, Vo2 represents the modulation voltage, Io2 represents the modulation current, Vr2 represents the modulated power line voltage drop, and Vl2 represents the load voltage at this time.

[0047] Then, the power difference is obtained by subtracting the first output power from the second output power, and the power line voltage drop of the power line is obtained as the first voltage drop according to the power difference, the current current and the modulation current (S300). In theory, when the power of the load 300 remains unchanged, the power of the load 300 before modulation will be equal to the power of the load 300 after modulation, that is, Vl1×Io1=Vl2×Io2. Therefore, the current power line voltage drop can be obtained as Vr1=ΔP×Io1 / (Io12-Io22). Among them, ΔP is the power difference between the first output power and the second output power, which can be obtained by subtracting the first output power from the second output power. Therefore, when the power difference, the current current and the modulation current are known, the current power line voltage drop (i.e., the first voltage drop) can be obtained. Through the above steps and processes, the present invention can obtain the voltage drop of the power line without measuring the impedance of the power line 200. In order to avoid the power of the load 300 before modulation not being equal to the power of the load 300 after modulation due to the change of the power of the load 300 during the modulation of the output voltage Vo (this situation will cause the calculated value of the first voltage drop to be an incorrect value), the control unit 40 can set a confirmation mechanism to avoid the above situation. That is, after the output voltage Vo of the boost converter 20 is modulated from the terminal voltage to the modulation voltage, the control unit 40 adjusts the output voltage Vo back to the terminal voltage, and then uses the product of the terminal voltage and the output current Io at this time to obtain the output power at this time, so as to confirm whether the output power at this time is within the error range of the first output power, or detect the output current Io at this time as the confirmation current, and determine whether the confirmation current is within the error range of the current current Io1 previously detected. The error range can be selected according to design requirements, for example but not limited to 3%. When the output power or output current at this time is within the error range, it means that the power of the load 300 is approximately or equal to the original value, and the calculated first voltage drop is an accurate value. Otherwise, it means that the power of the load 300 has changed, and the calculated first voltage drop is not an accurate value.

[0048] Finally, the output voltage of the boost converter is adjusted to the first predetermined voltage by the first voltage drop and the terminal voltage (S400). The current power line voltage drop (i.e., the first voltage drop) has been obtained in step (S300). Since the load power is substantially unchanged, it is possible to obtain the voltage value of the output voltage Vo under this condition to which the input end (load voltage) of the load 300 will be exactly equal to the set terminal voltage. Since the output voltage of the boost converter is adjusted, the corresponding output current will change, and the voltage drop of the power line will also change at the same time, so it is not enough to directly add the obtained first voltage drop Vr1 to Vo1. The control unit 40 uses the terminal voltage Vo1 plus the compensation amount of the power line voltage drop Vr1 in response to the current change to obtain the adjusted output voltage Vo(set) (i.e., the first predetermined voltage). The above description is expressed by the formula Vo(set)=Vo1+Vr1×(Vo1-Vr1) / Vo1, where Vo(set) is the first predetermined voltage. After the control unit 40 obtains the first predetermined voltage according to the above steps, it adjusts the output voltage Vo of the boost converter 20 to the first predetermined voltage through the first control signal Sc1, so that when the first predetermined voltage is transmitted to the input end of the load 300 by deducting the loss of the power line 200, the voltage at the input end of the load 300 will be exactly equal to the terminal voltage Vo1 preset by the control unit 40. Therefore, the main purpose of the present invention is that, through the above steps and processes, the voltage drop of the power line 200 can be obtained according to the voltage and current output by the boost converter 20 measured by the measuring circuit 30 without adding a conversion device or an impedance measuring device, and it is not necessary to obtain and confirm the impedance of the power line 200 and the voltage at the input end of the load 300 in addition, so that the technical effect of accurately and quickly calculating the voltage size to be adjusted can be achieved without additionally increasing the circuit cost.

[0049] In short, the main purpose of the above steps is that due to the voltage drop of the power line 200, it is hoped that the output voltage is as high as possible to reduce the transmission current and thus reduce the loss, but it cannot exceed the maximum allowable voltage of the equipment on the tower. The control unit 40 pre-sets the terminal voltage required by the load, and controls the output voltage of the boost converter to be the terminal voltage and the modulation voltage, and detects the corresponding currents respectively, thereby obtaining the power line voltage drop (i.e., the first voltage drop) when the output voltage is the terminal voltage. In this way, it is possible to quickly determine how the output voltage of the boost converter should be adjusted, and it is possible to ensure that the voltage at the load input terminal is maintained at the set terminal voltage value, which has the advantages of being fast and accurate.

[0050] See also Figure 3B This is a flow chart of the steps of subsequent circuit adjustment of the method for reducing line loss of the power supply system of the present invention, and is also referred to in conjunction with Figures 1 to 3A. After the control unit 40 adjusts the output voltage Vo of the boost converter 20 to the first predetermined voltage, the output current Io at this time is the first predetermined current. When the load power of the load 300 changes, due to the influence of the power line voltage drop Vr on the power line 200, the voltage value of the load voltage Vl will also change accordingly and will no longer be equal to the set terminal voltage. Therefore, when the load power of the load 300 changes, the control unit 40 must adjust the voltage value of the output voltage Vo to cope with the change in load power. The final adjustment value of the output voltage Vo can be obtained through the following steps: when the load power of the load changes and the first predetermined current changes to the first change current Io3, the second voltage drop Vr3 is obtained according to the first voltage drop, the first change current Io3 and the current current Io1, and the output voltage is adjusted to the second predetermined voltage according to the second voltage drop Vr3, the terminal voltage Vo1 and the first predetermined voltage Vo(set) (S500).

[0051] Specifically, when the load power changes, the current value of the output current Io will change (i.e., it changes from the first predetermined current to the first variable current Io3), and since the change of the output current Io is proportional to the change of the power line voltage drop Vr, the change of the power line voltage drop Vr (i.e., the second voltage drop Vr3 is obtained from the first voltage drop Vr1) when the output current Io is the first variable current Io3 (the control unit 40 knows it through the detection circuit 30) can be obtained by the formula Vr3=Vr1×Io3 / Io1. Among them, Vr3 in the above formula is the second voltage drop, Io3 is the first variable current, and Io1 is the current current corresponding to the first voltage drop. Since the output voltage Vo of the boost converter 20 is the first predetermined voltage Vo(set) at this time, the power line voltage drop becomes the second voltage drop Vr3. Therefore, the new predetermined value of the output voltage Vo (i.e., the second predetermined voltage Vo(set2)) can be determined by substitution using the aforementioned formula Vo(set)=Vo1+Vr1×(Vo1-Vr1) / Vo1. The formula of the second predetermined voltage Vo(set2) is Vo(set2)=Vo1+Vr3×(Vo(set)-Vr3) / Vo1. The second predetermined voltage is obtained by the above method, so that when the load power changes, the voltage value at the load end can still be maintained at the preset terminal voltage Vo1. When the subsequent load power continues to change, the same control method is adopted. For example, if the output current Io continues to change from the first change current Io3 to the second change current Io4, the third voltage drop Vr4 can also be known as Vr4=Vr1×Io4 / Io1. According to the above principle, the output voltage Vo can be adjusted to the third predetermined voltage Vo(set3) at this time, and the formula of the third predetermined voltage Vo(set3) is Vo(set3)=Vo1+Vre4×(Vo(set2)-Vr4) / Vo1. In this way, the load end voltage is ensured to be the preset terminal voltage Vo1. The subsequent load changes all use the same substitution and iteration principle, which will not be repeated.

[0052] See also Figure 2In some special cases, the control unit 40 provides a second control signal Sc2 to control the bypass switch 50 to be turned on to bypass the boost converter 20. Specifically, the boost converter 20 has different conversion efficiencies at different loads. Each 10% load is a point, and there are 10 points from 10% to 100%. The load may be the lowest at 10%, and the efficiency shows an upward trend from 10% to 40%. There is usually an optimal efficiency point at 50%, and then the efficiency shows a downward trend from 60% to 100%. Therefore, when the load is not high, the boost converter 20 has a poor conversion efficiency and causes a large power loss. Because the load is not high, the current is relatively small, and the loss on the power line is not large. It can be considered to turn on the bypass switch 50 to save the loss of the boost converter. Therefore, the control unit 40 calculates how much the output voltage Vo needs to be adjusted, and how much the power line power loss can be reduced, as well as the power loss of the boost converter 20 under this condition. Therefore, the control unit 40 can determine whether to execute the boost mode or the bypass mode so that the entire system can obtain the highest efficiency.

[0053] The highest efficiency of the whole system can be confirmed by: confirming the conversion efficiency of the boost converter to obtain the increased loss; evaluating the power line loss when the boost converter is bypassed, that is, the power line loss caused by directly providing the input voltage Vin to the power line 200; determining the boost converter and power line loss when the boost converter boosts the voltage. Based on these losses, the control unit 40 can determine whether to execute the boost mode or the bypass mode to achieve the highest efficiency of the whole system.

[0054] The following examples are given of possible implementation methods of each loss, but are not limited to this. The conversion efficiency of the boost converter can be known by pre-measuring the conversion efficiency of each load, or by detecting the input and output power of the boost converter in real time to know the loss of the boost converter under a specific load. The power line loss when the boost converter is bypassed, because the input voltage Vin, the terminal voltage Vo1, the power line voltage drop at this time and the first predetermined current at this time are all known, which is equivalent to the load power consumption at this time is also known, the control unit can calculate the power line loss when the boost converter is bypassed, for example, the control unit can solve the current when bypassed by Newton iteration method, and then know the power line loss. If the boost converter is boosting, the loss of the boost converter and the power line can also be easily known. Taking the aforementioned first predetermined voltage as an example, according to Vo(set)=Vo1+Vr1×(Vo1-Vr1) / Vo1, it can be known that the power line loss at this time is equal to the product of the first predetermined current at this time and the power line voltage drop at this time (Vr1×(Vo1-Vr1) / Vo1).

[0055] In addition, another implementation method can also use a simpler method to make a judgment. When the load-end voltage is maintained at the set terminal voltage, if the voltage difference between the input voltage and the output voltage of the boost converter is lower than the threshold, in other words, the output voltage does not need to be too high to maintain the voltage at the load end equal to the set terminal voltage, indicating that the load may be lower at this time, and the control unit 40 can also enter the bypass mode to avoid the self-loss of the boost converter being greater than the loss reduced after the boost, wherein the threshold can be appropriately selected according to the efficiency curve of the boost converter.

[0056] However, the above description is only a detailed description and drawings of the preferred specific embodiments of the present invention, and the features of the present invention are not limited thereto and are not intended to limit the present invention. The entire scope of the present invention shall be based on the following claims. All embodiments that are consistent with the concepts of the claims of the present invention and similar variations thereof shall be included in the scope of the present invention. Any changes or modifications that can be easily conceived by any person skilled in the art within the field of the present invention shall be covered by the following claims of the present disclosure.

Claims

1. A method for reducing line loss of a power supply system, the power supply system comprising a boost converter, and the boost converter provides a load voltage to a load through a power line, the method for reducing line loss comprising the following steps: Setting a terminal voltage required by the load, and controlling an output voltage of the boost converter to be the terminal voltage; Detecting an output current corresponding to the terminal voltage as a current current; Controlling the output voltage to be a modulation voltage, and detecting that the output current corresponding to the modulation voltage is a modulation current; and adjusting the output voltage of the boost converter to a first predetermined voltage according to the terminal voltage, the current current, the modulation voltage and the modulation current; in, The load voltage after deducting a power line voltage drop of the power line from the first predetermined voltage satisfies the preset terminal voltage, and Wherein, when the output voltage is adjusted to the first predetermined voltage and can satisfy the load voltage being the pre-set terminal voltage, a first loss of the boost converter and the power line is calculated when the output voltage is the first predetermined voltage, and a second loss of the power line when the boost converter is bypassed is calculated; when the first loss is greater than or equal to the second loss, the boost converter is bypassed.

2. The line loss reduction method according to claim 1, further comprising the following steps: Obtaining a first output power by multiplying the terminal voltage by the current current; Obtaining a second output power by multiplying the modulation voltage by the modulation current; Subtracting the first output power from the second output power to obtain a power difference; The output voltage is adjusted to the first predetermined voltage according to the power difference, the terminal voltage, the current current, the modulation voltage and the modulation current.

3. The line loss reduction method according to claim 2, further comprising the following steps: The power line voltage drop is obtained as a first voltage drop according to the power difference, the current current, the modulation voltage and the modulation current; The output voltage is adjusted to the first predetermined voltage through the first voltage drop and the terminal voltage.

4. The line loss reduction method as described in claim 2, wherein after the output voltage is adjusted from the terminal voltage to the modulation voltage, the output voltage is adjusted back to the terminal voltage to confirm that the product of the terminal voltage and the output current corresponding to the terminal voltage is within an error range of the first output power.

5. The line loss reduction method as claimed in claim 3, wherein the first predetermined voltage satisfies: Vo(set)=Vo1+Vr1×(Vo1-Vr1) / Vo1, wherein Vo(set) is the first predetermined voltage, Vo1 is the terminal voltage, and Vr1 is the first voltage drop.

6. The line loss reduction method as described in claim 3, wherein when the output voltage is adjusted to the first predetermined voltage, the output current is a first predetermined current; when a load power of the load changes so that the first predetermined current changes to a first variable current, a second voltage drop is obtained according to the first voltage drop, the first variable current, and the current current, and the output voltage is adjusted to a second predetermined voltage according to the terminal voltage, the first predetermined voltage, and the second voltage drop.

7. The line loss reduction method according to claim 6, wherein the second voltage drop satisfies: Vr3 = Vr1 × Io3 / Io1, wherein Vr3 is the second voltage drop, Vr1 is the first voltage drop, Io3 is the first changing current, and Io1 is the current current.

8. The line loss reduction method as claimed in claim 1, wherein when the output voltage is adjusted to the first predetermined voltage and can satisfy the load voltage to be the preset terminal voltage, when a voltage difference between an input voltage and the output voltage of the boost converter is lower than a threshold value, the boost converter is bypassed.

9. A power supply system with reduced line loss, providing a load voltage to a load through a power line, the power supply system comprising: a boost converter receiving an input voltage from an input terminal and providing an output voltage from an output terminal to power the load; a detection circuit coupled to the output terminal; a control unit, coupled to the boost converter and the detection circuit, and controlling the boost converter to convert the input voltage into the output voltage; and a bypass switch connected in parallel with the boost converter and coupled to the control unit, Wherein, the control unit sets a terminal voltage required by the load, and controls the voltage of the output end to be the terminal voltage; the control unit detects the output end through the detection circuit to obtain an output current corresponding to the terminal voltage as a current current; the control unit controls the output voltage to be a modulation voltage, and detects the output end through the detection circuit to obtain a modulation current corresponding to the modulation voltage; the control unit adjusts the output voltage to a first predetermined voltage according to the terminal voltage, the current current, the modulation voltage and the modulation current, so that the load voltage after deducting a power line voltage drop of the power line from the first predetermined voltage meets the terminal voltage preset by the control unit, and In which, the control unit calculates a first loss of the boost converter and the power line when the output voltage is the first predetermined voltage, and calculates a second loss of the power line when the boost converter is bypassed; when the control unit determines that the first loss is greater than or equal to the second loss, the control unit turns on the bypass switch to bypass the boost converter.

10. A power supply system as described in claim 9, wherein after the output voltage is adjusted from the terminal voltage to the modulation voltage, the control unit adjusts the output voltage back to the terminal voltage, and detects the output current as a confirmation current through the detection circuit; the control unit determines whether the confirmation current is within an error range of the current current.

11. The power supply system as claimed in claim 9, wherein when the output voltage is adjusted to the first predetermined voltage, the output current is a first predetermined current; when the detection circuit detects that the first predetermined current changes to a first variable current, the control unit adjusts the output voltage to a second predetermined voltage.

12. The power supply system according to claim 9, in, The detection circuit is further coupled to the input end, and the control unit detects the input end through the detection circuit to obtain the input voltage; when the control unit learns through the detection circuit that a voltage difference between the input voltage and the output voltage is lower than a threshold, the control unit turns on the bypass switch to bypass the boost converter.

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