阅读说明：本技术 一种输入串联输出并联的电源系统 (Input-series output-parallel power supply system ) 是由 不公告发明人 于 2021-08-19 设计创作，主要内容包括：本发明涉及一种开关电源控制方法,公开了一种输入串联输出并联的电源系统,包括N(N≥2)个变换器模块,包括N个变换器模块,各变换器模块的输入端串联连接,且各变换器模块的输出端并联连接；每一变换器模块包括输入电容以及变换器,其中每一变换器设有输入电压检测电路、占空比控制电路以及主功率电路。电源系统中的每个变换器模块的输出电压跟随输入电压变化而变化,并且呈正相关特性,且能自动形成负反馈,最终能达到输入电压和输出功率为预设值的平衡状态。(The invention relates to a switching power supply control method, and discloses a power supply system with input in series and output in parallel, which comprises N (N is more than or equal to 2) converter modules, wherein the converter modules comprise N converter modules, the input ends of the converter modules are connected in series, and the output ends of the converter modules are connected in parallel; each converter module comprises an input capacitor and a converter, wherein each converter is provided with an input voltage detection circuit, a duty ratio control circuit and a main power circuit. The output voltage of each converter module in the power supply system changes along with the change of the input voltage, has positive correlation characteristic, can automatically form negative feedback, and finally can reach the balance state that the input voltage and the output power are preset values.)

1. A kind of input series output connects the electrical power generating system in parallel, characterized by that: the converter comprises N converter modules, wherein N is an integer greater than or equal to 2, the input ends of the converter modules are connected in series, and the output ends of the converter modules are connected in parallel; each converter module comprises an input capacitance and a converter,

the positive electrode of the input capacitor in each converter module is connected with the positive input end of the converter corresponding to the input capacitor, and the negative electrode of the input capacitor is connected with the negative input end of the converter corresponding to the input capacitor;

each converter is provided with an input voltage detection circuit, a duty ratio control circuit and a main power circuit;

the input voltage detection circuit is used for obtaining the input voltage of the converter by detecting the voltage between the anode and the cathode of the input capacitor;

the duty ratio control circuit is used for controlling the duty ratio of the driving signal output to the main power circuit according to the input voltage, so that the output voltage of the main power circuit changes along with the change of the input voltage of the converter, and the output voltage and the input voltage have positive correlation.

2. The power supply system with parallel input and output according to claim 1, wherein: the duty ratios of the driving signals of the main power circuits in the converters are the same; the corresponding relation between the duty ratio of the driving signal of each main power circuit and the input voltage is as follows: duty cycleWhere k is a constant greater than zero or a function related to the input voltage, A is the output voltage of the main power circuit, V_inIs the input voltage.

3. The power supply system with parallel input and output according to claim 1, wherein: the duty ratios of the driving signals of the main power circuits in the converters are the same; the corresponding relation between the duty ratio of the driving signal of each main power circuit and the input voltage is as follows: when the input voltage is in a low-voltage section, the duty ratio of a driving signal of the main power circuit is a certain first set value; when the input voltage is in a high-voltage section, the duty ratio of a driving signal of the main power circuit is a certain second set value, wherein the second set value is lower than the first set value.

4. The power supply system with parallel input and output according to claim 1, wherein: the N converter modules are respectively a first converter module to an Nth converter module in sequence; the input end of each converter module is connected in series, and the output end of each converter module is connected in parallel specifically as:

the positive input end of the first converter module is used as the positive input end of the power supply system, the negative input end of the first converter module is connected with the positive input end of the second converter module, and so on, the negative input end of the (N-1) th converter module is connected with the positive input end of the Nth converter module, the positive output ends of the first converter module to the Nth converter module are connected and then used as the positive output end of the voltage system, and the negative output ends of the first converter module to the Nth converter module are connected and then used as the negative output end of the system.

5. The power supply system with parallel input and output according to claim 1, wherein: the input capacitor is composed of high-voltage capacitors or low-voltage capacitors connected in series.

6. The power supply system with parallel input and output according to claim 1, wherein: the duty ratio control circuit is a single hardware circuit or a programmable logic circuit.

7. The power supply system with parallel input and output according to claim 1, wherein: the main power circuit is an isolated or non-isolated circuit; each of the main power circuits is of the same circuit topology or of a different circuit topology.

Technical Field

The invention relates to a control method of a switching power supply, in particular to a control method of a power supply system with a plurality of converter modules connected in series and output in parallel in the switching power supply.

Background

With the new revolution of power system innovation, the number of ultrahigh voltage and extra-high voltage power transmission systems is further increased, and the energy-taking power supplies of the corresponding control systems also need to be further upgraded and updated. The input voltage of the energy-taking power supply of the control system in the occasions of SVG, flexible direct current transmission and the like reaches 3000V, and the current circuit scheme can only select a semiconductor device with the withstand voltage of 4500V or even higher. In order to obtain a semiconductor device with higher withstand voltage, a scheme of increasing the Input voltage level by using a plurality of converter module inputs in series is proposed in the industry, for example, in patent publications CN106787627A and CN207283409U, a control method of module power supply Input series Output Parallel (Input series Output Parallel: ISOP) is proposed. However, the presently disclosed methods of controlling the ISOP require a single converter module to have a closed-loop feedback loop, and each converter module in the ISOP system adopts the same circuit topology and device parameters, which greatly limits the development and application of the ISOP system, and increases the design cost and design difficulty of the ISOP system.

Disclosure of Invention

In view of this, the technical problem to be solved by the present invention is to overcome the defects of the existing input series output parallel control method, and provide a power supply system with input series output parallel, which breaks through the limitation that a single converter module in the ISOP system must have closed-loop feedback, and each converter module adopts the same circuit topology and device parameters, so that the input series output parallel system is simpler in design and wider in application condition.

In order to solve the technical problems, the invention is realized by the following technical measures:

a power supply system with input connected in series and output connected in parallel comprises N converter modules, wherein N is an integer greater than or equal to 2, the input ends of the converter modules are connected in series, and the output ends of the converter modules are connected in parallel; each converter module comprises an input capacitance and a converter,

the positive electrode of the input capacitor in each converter module is connected with the positive input end of the converter corresponding to the input capacitor, and the negative electrode of the input capacitor is connected with the negative input end of the converter corresponding to the input capacitor;

each converter is provided with an input voltage detection circuit, a duty ratio control circuit and a main power circuit;

the input voltage detection circuit is used for obtaining the input voltage of the converter by detecting the voltage between the anode and the cathode of the input capacitor;

the duty ratio control circuit is used for controlling the duty ratio of the driving signal output to the main power circuit according to the input voltage, so that the output voltage of the main power circuit changes along with the change of the input voltage of the converter, and the output voltage and the input voltage have positive correlation.

Optionally, the duty ratios of the driving signals of the main power circuits in each converter are the same; drive for each of the main power circuitsThe corresponding relation between the duty ratio of the dynamic signal and the input voltage is as follows: duty cycleWhere k is a constant greater than zero or a function related to the input voltage, a is the output voltage of the main power circuit, and Vin is the input voltage.

Optionally, the duty ratios of the driving signals of the main power circuits in each converter are the same; the corresponding relation between the duty ratio of the driving signal of each main power circuit and the input voltage is as follows: when the input voltage is in a low-voltage section, the duty ratio of a driving signal of the main power circuit is a certain first set value; when the input voltage is in a high-voltage section, the duty ratio of a driving signal of the main power circuit is a certain second set value, wherein the second set value is lower than the first set value.

Optionally, the N converter modules are sequentially a first converter module to an nth converter module, respectively; the input end of each converter module is connected in series, and the output end of each converter module is connected in parallel specifically as:

the positive input end of the first converter module is used as the positive input end of the power supply system, the negative input end of the first converter module is connected with the positive input end of the second converter module, and so on, the negative input end of the (N-1) th converter module is connected with the positive input end of the Nth converter module, the positive output ends of the first converter module to the Nth converter module are connected and then used as the positive output end of the voltage system, and the negative output ends of the first converter module to the Nth converter module are connected and then used as the negative output end of the system.

Optionally, the input capacitor is composed of a high-voltage capacitor or a low-voltage capacitor connected in series.

Optionally, the duty cycle control circuit is a single hardware circuit or a programmable logic circuit.

Optionally, the main power circuit is an isolated or non-isolated circuit; each of the main power circuits is of the same circuit topology or of a different circuit topology.

Compared with the prior art, the power supply system with the input connected in series and the output connected in parallel has the following beneficial effects:

1. a single converter module in the power supply system does not need to be provided with a feedback circuit, so that the circuit structure of the voltage system is simplified, and the manufacturing cost of the power supply system is reduced;

2. each converter module in the power supply system does not need to adopt the same circuit topology and the same device model, so that the development and application occasions of the power supply system are favorably widened, and the design cost and the design difficulty of the power supply system are reduced;

3. the output voltage ratio (output voltage ratio: output voltage maximum divided by output voltage minimum) of the power supply system is smaller than the input voltage ratio (input voltage ratio: input voltage maximum divided by input voltage minimum), so that the main power topology selection of the post-stage converter module is facilitated;

4. the control principle is simple, and the design range and the application occasions of the power supply system are widened.

Drawings

The invention is described in further detail below with reference to the figures and the specific embodiments.

FIG. 1 is a connection diagram of N converter modules of a power system with input connected in series and output connected in parallel according to the present invention;

FIG. 2 is a connection diagram of 2 converter modules of a power system with input connected in series and output connected in parallel according to the present invention;

FIG. 3 is a duty cycle control diagram of a first embodiment of the present invention in an input-series-output-parallel power system;

fig. 4 is a duty ratio control diagram of a power system with input connected in series and output connected in parallel according to a second embodiment of the present invention.

Detailed Description

In order to make the invention more clearly understood, the invention is further described in detail below with reference to the attached drawings and examples. In all the embodiments described later, the main power circuit is used as a buck-boost topology, the circuit parameters with the transformer turn ratio of 1 are analyzed, and other topology analysis and control methods are similar; for the sake of brevity, the following ISOP system is composed of 2 converter modules as shown in FIG. 2, and the system analysis and control method composed of multiple modules is similar. The above similar analysis processes are not described in detail in this application. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

First embodiment

Referring to fig. 1, the present invention provides a power system (hereinafter referred to as an ISOP system) with serial input and serial output, wherein N converter modules are respectively a first converter module to an nth converter module in sequence; the input of each converter module is connected in series, and the output of each converter module is connected in parallel, promptly: the positive input terminal Vin1+ of the first converter module is used as the positive input terminal Vin + of the ISOP system, the negative input terminal Vin 1-of the first converter module is connected with the positive input terminal Vin2+ of the second converter module, and so on, the negative input terminal of the (N-1) th converter module is connected with the positive input terminal of the (N) th converter module, the positive output terminals of the first to N-th converter modules are connected to be used as the positive output terminal Vo + of the ISOP system, and the negative output terminals of the first to N-th converter modules are connected to be used as the negative output terminal Vo-of the ISOP system.

Each converter module in the ISOP system adopts the output voltage to change along with the change of the input voltage, and the output voltage and the input voltage have positive correlation relation, namely: when the input voltage of one converter module rises, the output voltage of the converter module rises; when the input voltage decreases, its output voltage decreases. And when the input voltage of one of the converter modules increases, the input voltage and the output voltage of the other converter modules in the ISOP system are both reduced.

In the ISOP system, because the output ends of the converter modules are in parallel connection, the output power of the converter modules with increased output voltage is increased, the output power of the converter modules with decreased output voltage is decreased, the converter modules with increased output power pull down the input voltage of the corresponding converter modules, the converter modules with decreased output power lift up the input voltage of the corresponding converter modules, and the ISOP system automatically forms a negative feedback system through the control process, so that the balance state that the input voltage and the output power are preset values is finally achieved.

To illustrate the ISOP system of the present invention more clearly, the following description will use an ISOP system composed of 2 converter modules, as shown in FIG. 2, which is composed of a module A (i.e., the first converter module) and a module B (i.e., the second converter module).

Module a includes an input capacitor Cin1 and a converter, wherein the converter is provided with an input voltage detection circuit, a duty cycle control circuit and a main power circuit.

The anode of the input capacitor Cin1 is connected with the positive input end Vin1+ of the module A, and the cathode of the input capacitor Cin1 is connected with the negative input end Vin 1-of the module A; the positive input end of the input voltage detection circuit is connected with the positive input end Vin1+ of the module A, the negative input end of the input voltage detection circuit is connected with the negative input end Vin 1-of the module A, and the input voltage detection circuit is used for obtaining the input voltage of the converter by detecting the voltage between the positive pole and the negative pole of the input capacitor, converting the input voltage into a voltage signal with relatively reduced voltage and transmitting the voltage signal to the duty ratio control circuit; the input end of the duty ratio control circuit is connected with the output end of the input voltage detection circuit, the duty ratio control circuit is used for controlling the duty ratio of the driving signal output to the main power circuit according to the converted input voltage, so that the output voltage of the main power circuit changes along with the change of the input voltage of the converter, and the output voltage and the input voltage are in positive correlation.

The module B comprises an input capacitor Cin2 and an inverter, wherein the anode of the input capacitor Cin2 is connected with the positive input end Vin2+ of the inverter, and the cathode of the input capacitor Cin2 is connected with the negative input end Vin 2-of the inverter; the converter structure in module B is the same as the converter structure in module a, and similarly includes an input voltage detection circuit, a duty ratio control circuit, and a main power circuit.

If the input voltage Va of the module a increases due to some disturbance in the ISOP system, the input voltage Vb of the module B decreases. In the module a, since the input voltage Va increases, the input voltage detection circuit in the module a will detect the voltage signal representing the increase of the input voltage Va, and after the voltage signal representing the increase of the input voltage Va is transmitted to the duty ratio control circuit, the duty ratio control circuit will increase the output voltage of the module a by adjusting the duty ratio of the driving signal transmitted to the main power circuit, so that the output power Pa of the module a increases.

At this time, because the output terminals of the module a and the module B are connected in parallel, when the output voltage of the module a increases, the output current Ioa of the module a increases, which in turn causes the input current Iin1 of the module a to increase; and in the module B, when the output voltage of the module a increases, the input voltage of the converter in the module B decreases, at this time, the input voltage detection circuit in the module B detects a voltage signal of the decreased input voltage Vb, and after the voltage signal of the decreased input voltage Vb is transmitted to the duty control circuit, the duty control circuit adjusts the duty ratio of the driving signal transmitted to the main power circuit, so that the output voltage of the module B decreases, and the output power Pb of the module B also decreases, that is: the output current Iob of the module B decreases, which causes the input current Iin2 of the converter in the module B to decrease when the output current Iob of the module B decreases.

In the ISOP system, since the input terminals of the converter modules are connected in series, the input current Iin1 of the converter in module a and the current Ic1 of the input capacitor Cin1 have the following relationship with the input current Iin2 of the converter in module B and the current Ic2 of the input capacitor Cin 2: when the current Ic1 of the input capacitor Cin1 decreases, the current Ic2 of the input capacitor Cin2 increases, and the input voltage Va of the module a decreases and the input Vb of the module B increases according to the principle of charging and discharging capacitors. Through the process, the ISOP system formed by the module A and the module B automatically forms a feedback state, and the input voltage is finally stabilized at a set value.

The correspondence between the duty ratio of the drive signal of the main power circuit and the input voltage will be described below by taking the module a as an example. In this embodiment, the duty ratio of the driving signal of the main power circuit in the module B is the same as the duty ratio of the driving signal of the main power circuit in the module a.

Known as turnsThe converter voltage gain expression of the buck-boost topology with the ratio of 1 isWhen the input voltage Vin is in the range of 300Vdc-1500Vdc, the single converter module a operates according to the duty cycle control diagram shown in fig. 3. When the input voltage Vin is in the range of 300Vdc-700Vdc (namely in a low-voltage section), the duty ratio of the driving signal of the main power circuit in each converter is 0.6, and the output voltage range is 450Vdc-1050Vdc through the step-up and step-down conversion of the main power circuit; when the input voltage Vin is in the range of 700Vdc-1500Vdc (i.e. in a relatively high-voltage section), the duty ratio D of the driving signal of the main power circuit in each converter is 0.4, and the output voltage ranges from 467Vdc to 1000Vdc through the buck-boost conversion of the main power circuit. The input voltage ratio is known to be 5: 1 (1500: 300), the output voltage ratio after the mode conversion is controlled according to the control mode of FIG. 3 is 2.3:1 (1050: 450), so that the voltage ratio is obviously reduced, and the main power topology selection of the post-stage converter module is facilitated.

Second embodiment

Referring to fig. 4, fig. 4 is a duty ratio control diagram in a second embodiment of the present invention. The connection manner of each converter module in the power supply system with input connected in series and output connected in parallel in this embodiment is the same as that of the first embodiment, except that: in this embodiment, the duty cycle control scheme is not a single segmented control, but a programmable logic device is used to control the duty cycle in real time.

If a closed-loop buck-boost topology with an output of 700V is designed under the conditions of input voltages 300Vdc-1500Vdc and a turn ratio of 1, the relationship between the duty ratio and the input voltage is shown as a dotted line in FIG. 4, and the relationship between the corresponding duty ratio and the input voltage Vin isWhere a is Vo 700 and a is the output voltage. As can be seen from the functional relationship, when the input voltage Vin is 400, the duty ratio D1 is 0.636, so that the output voltage can be maintained at 700V. But after the addition of the control scheme of the present embodiment,at Vin of 400, the duty cycle takes a value greater than 0.636, so that the output voltage is slightly greater than 700V, for example according to the function corresponding to the dashed line in fig. 4D2 is calculated to be equal to 0.65, at this time Vo is 743V, so that the output voltage is slightly larger than the output voltage value of the closed loop stable system, so that the power of the corresponding module is increased, and then the input voltage Vin is pulled down to a preset value, so as to ensure that the operation of the ISOP system is normal.

Therefore, the core of this embodiment is that under the condition that the input voltage Vin is increased, the duty ratio is adjusted to be slightly larger than the closed-loop duty ratio through the programmable logic device, so that the output voltage is slightly higher than the output voltage when the loop is closed, and the single inverter module shows that the output voltage is positively changed along with the input voltage Vin. Duty cycleWhere k > 0, k may be constant or a function of the input voltage Vin, and the duty cycle D2 is satisfied at V_in2-V_in1When the pressure is higher than 0, the pressure is higher,and D₂E (0,1), wherein V_in2-V_in1> 0 represents an increase in the input voltage,representing a rise in output voltage, i.e., as the input rises, the output voltage also rises. The principle of the ISOP system for balancing the input voltage in the present embodiment is the same as that in the first embodiment, and is not described herein again.

According to the present invention, it is understood that the circuit implementation of the present invention may be modified, replaced or changed in various forms without departing from the basic technical idea of the present invention.