A circuit and method for switching power supply line loss compensation

Abstract

The application discloses a kind of switching power supply line loss compensation circuit and method.The switching power supply line loss compensation circuit includes switching power supply output module, MCU module, current acquisition module, voltage acquisition module, compensation conversion switch module and sampling resistance, internal power resistance and line equivalent resistance.The application uses conversion switch to use internal power resistance as load, uses sampling circuit to collect and convert the method of lead-out line impedance after external lead-out line two ends short circuit, compensates lead-out line loss into set output parameter, can meet the effect that set parameter is consistent with lead-out line two ends parameter, only adds two main components in original switching power supply circuit to improve the output accuracy of switching power supply, with extremely high cost performance.The application can still quickly carry out line loss compensation in the case of external replacement other lead-out line, so that switching power supply works stably, and operation is simple, applicable to various switching power supply application occasions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of switching power supply converter, and particularly relates to a line loss compensation circuit based on switching power supply output. BACKGROUND

[0002] For the existing switching power supply, to ensure the stability of the output end, the output voltage and current of the switching power supply need to be collected, and a loop design is performed on the same, so that the required output power can be stably reached; however, for most applications of the switching power supply, the collected voltage cannot be accurate to the voltage received by the power utilization equipment, and most power supplies need to add an outgoing line to the power utilization equipment. This causes a certain line loss, that is, there is a certain difference between the voltage received by the power utilization equipment and the actual set output voltage; in a power utilization strict occasion, such a voltage difference will cause different degrees of harm.

[0003] Generally, the switching power supply collects current and voltage parameters by connecting a current sampling resistor in series and a voltage sampling resistor in parallel on the output main circuit; then the sampled current and voltage are processed through an amplifier and a filter circuit, and finally the collected signals are corrected by an MCU and then used to control the output of the switching power supply.

[0004] The existing scheme is to add a voltage measurement module at the power supply end of the power utilization equipment, to transmit the collected data to an MCU through a wireless device for output line loss compensation of the switching power supply; there is also a scheme of adding a compensation resistor at the output voltage end of the line outlet of the switching power supply power supply equipment, to adjust the size of the compensation resistor for line loss compensation; there is also a scheme of line loss compensation through an active IC chip. These schemes need to increase more devices in the original switching power supply output equipment, and also increase the difficulty of use to a certain extent. SUMMARY

[0005] The present application aims to design a circuit which can simply and quickly solve the output line loss of the switching power supply and has high cost performance.

[0006] A switching power supply line loss compensation circuit and method comprises a switching power supply output circuit, an MCU circuit, a voltage collection circuit, a current collection circuit, and a conversion switch and an internal power resistor.

[0007] The application uses a method of short-circuiting the lead-out line of a switching power supply device to compensate for line loss of power supply output. Stable output of the switching power supply output circuit needs to rely on the collection circuit to collect output parameters to ensure. The output voltage and current of the switching power supply output circuit are collected by the voltage and current collection circuit to design a loop, and the output voltage and current of the switching power supply are regulated. At the same time, the voltage and current collection circuit for controlling the stable output of the switching power supply circuit is also applied to line loss compensation, without the need to additionally increase the voltage and current collection circuit, and the line loss compensation can be completed with reduced additional design cost.

[0008] When a stable switching power supply output circuit is obtained, a changeover switch is added to the low end of the output lead-out line of the switching power supply device, and the MCU can control the changeover of the changeover switch. In the normal state, the normal output state is normal. When line loss compensation is selected, the MCU adjusts the changeover switch, and the changeover switch will connect the switching power supply to the internal load resistor. The load resistor is located at the low end of the switching power supply output and the other end of the changeover switch which is fixed. At this time, the line loss compensation is started, the power supply lead-out line is short-circuited, and the line loss compensation is completed.

[0009] Only one changeover switch and one internal load need to be added to the original switching power supply device to complete the line loss compensation. To a certain extent, the use of components is reduced while achieving the same function, without the need to add additional complex circuits, and the cost performance is high. By short-circuiting the power supply lead-out line, whether a professional or a non-professional uses the switching power supply device, after replacing the power supply lead-out line, only one line loss compensation needs to be performed when starting the device for the first time to collect the parameters of the lead-out line. As long as the power supply output lead-out line is not replaced, the collected lead-out line parameters will not be changed due to the restart of the device, and repeated line compensation operations are not required. BRIEF DESCRIPTION OF DRAWINGS

[0010] As shown in Figure 1 , the MCU can control the output state of the switching power supply. The output current of the switching power supply is detected by the voltage on R5, and the collected current value is converted to I o =U1 / R5. Since R3 and R4 used are much larger than the load connected to the switching power supply device, the current flowing through R2, R3 and R4 can be ignored, so the collected I o can be used as the output current of the switching power supply device. The output voltage of the switching power supply is detected by collecting the voltage on R2, and the converted value of the collected voltage is U=(R2+R3+R4)U2 / R2. r is the equivalent resistance of the power supply lead-out line, and the actual output voltage U out =U-ΔU, so the loss of the power supply lead-out line is ΔU=I o r. To make the end voltage of the power supply lead-out line be the set voltage output, the set voltage needs to be compensated in the MCU, that is, Uset =U+ΔU, U set The output voltage of the switching power supply is set for the MCU. That is, after the line loss compensation operation, the MCU calculates ΔU from the collected voltage and current parameters, records and stores ΔU in the internal memory of the MCU, and increases ΔU to the set voltage when the output voltage is set, so that the voltage at the output end of the power supply line is consistent with the set voltage. DETAILED DESCRIPTION

[0011] To make the above-mentioned implementation purposes of the present application clearer, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0012] As shown in Figure 1 The present application is composed of a switching power supply output circuit, an MCU circuit, a current collection circuit, a voltage collection circuit, a conversion switch circuit, and an internal power resistor.

[0013] The output + end of the switching power supply output circuit is connected to the sampling resistor R5 of the current collection circuit. The current collection circuit uses an operational amplifier to collect the current flowing through the sampling resistor R5, which is an important parameter for regulating the switching power supply output circuit, and also plays a key role in the line loss compensation mentioned in the present application. The current sampling resistor is connected to the external lead-out line interface and also connected to the sampling resistor R4 in the voltage sampling circuit. The sampling resistor in the voltage sampling circuit is composed of R2, R3, and R4 in series, in which R2 is much smaller than R3 and R4. The output voltage value at the lead-out end is calculated by collecting the voltage value at R2 through an operational amplifier. The three voltage sampling resistors used in the present application are mainly to prevent the sampling voltage from exceeding the threshold of the ADC sampling in the MCU when the output voltage at the lead-out end is too large, thereby protecting the main devices. The voltage values collected above can be used to regulate the output of the switching power supply circuit and also for line loss compensation.

[0014] Through the above description, the current and voltage parameters collected by the collection circuit are used for both controlling the switching power supply circuit and performing line loss compensation. The collection circuit plays a key role in achieving stable output of the switching power supply circuit and can also achieve the purpose of line loss compensation. Therefore, the present application uses the original collection circuit in the switching power supply circuit, without the need for additional collection circuits, thereby saving design and device costs and achieving the required voltage and current parameters for line loss compensation, with high cost performance.

[0015] The additional capacitive coupling measurement electrode is used to attach to the outside of clothes on the human heart and chest with the capacitive coupling reference electrode to perform impedance volume characteristic detection. The voltage sampling resistor R3 is connected with the other end of the switching power supply lead wire end, and is also connected with the moving end of the conversion switch S1. The fixed end ① of the conversion switch S1 is connected with the - end of the switching power supply output circuit, and the ② end of the conversion switch S1 is connected with one end of the internal power resistor R1. The other end of the internal power resistor R1 is connected with the - end of the switching power supply output circuit. The conversion switch S1 and the internal power resistor are the main devices of the application, and the purpose of line loss compensation can be achieved by shorting the external lead wire.

[0016] As shown in Figure 1 , the equivalent resistance of the lead wire is r. When the line loss compensation mode is selected, the MCU controls the moving end of the conversion switch to be connected to the ② end of the conversion switch S1, so that the switching power supply circuit outputs through the internal power resistor R1, and the internal power resistor R1 is used as a load. At this time, the current collected by the current collection circuit can be considered as the current I o flowing through the lead wire, and the collected voltage U is the voltage on the lead wire. Therefore, the equivalent resistance r of the external lead wire (r=U / I o ) can be obtained at this time, and the voltage value ΔU to be compensated (ΔU=I o r) can be obtained, and the line loss compensation is completed.

[0017] In summary, the application adds an internal resistor R1 and a conversion switch S1 in the switching power supply circuit, uses the original current collection circuit and voltage collection circuit, collects the corresponding current and voltage parameters after shorting the external lead wire, and the purpose of line loss compensation is achieved. Resources are greatly saved, and the application value of the switching power supply in high requirement occasions is improved.

Claims

1. A circuit and method for line loss compensation in a switching power supply, characterized in that: It is composed of switching power output circuit, MCU circuit, current collection circuit, voltage collection circuit, conversion switch circuit and internal power resistor; the collection circuit is composed of operational amplifier and sampling resistor, and the conversion switch is used for converting normal output mode and line loss compensation mode; Among them, the sampling resistor in the current sampling circuit is connected in series at the high end of the switching power output, and the switching power output current is collected by using high-end sampling mode; the voltage sampling resistor is composed of three resistors R2, R3 and R4, wherein R2 is far smaller than R3 and R4; the collected voltage is prevented from being too high to damage the device; the internal power resistor is used as a load when line loss compensation is performed; when the conversion switch is hit to ①, it indicates that the switching power is normally output, and when the conversion switch is hit to ②, it indicates that line loss compensation is performed; The conversion switch is located at the low end of the switching power output end, and the common end is connected to the lead-out line end, so that the switching power can be quickly converted to the normal output mode after line loss compensation operation; The internal power resistor is connected with the low end of the switching power output and one end of the conversion switch, and provides a stable load for the switching power in the line loss compensation mode, so that the switching power output module can work in the stable output mode; The conversion switch S1 is short-circuited with the internal power resistor and the external lead-out line; The equivalent resistance r of the lead-out line is an undetermined value, which is determined by the material, size and length of the lead-out line.

2. The circuit and method of claim 1, wherein: The voltage and current parameters collected by the collection circuit are transmitted to the MCU, and the MCU uses the voltage and current parameters for digital loop control, so that the switching power output circuit can stably output voltage and current.

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