Power module control method of constant-high-voltage high-power direct-current power supply based on IPOS combination

Abstract

The invention discloses a power module control method of a constant-high-voltage high-power direct-current power supply based on IPOS combination. The constant-high-voltage high-power direct-current power supply based on the IPOS combination comprises n sub-power modules and one system control module, the n sub-power modules are connected in an input-parallel output-series mode, and the constant-high-voltage high-power direct-current power supply based on the IPOS combination is provided with a double-layer three-ring control loop, the double-layer three-loop control loop comprises a system layer total voltage output closed loop and a module layer voltage-sharing output closed loop, and the module layer voltage-sharing output closed loop comprises an output voltage-sharing control loop and an input current-sharing control loop. The invention provides a power module control method of a constant-high-voltage high-power direct-current power supply based on IPOS combination, which can effectively guarantee the stability of output voltage of a power module, the output voltage sharing of the power module and the accuracy of total output voltage of a system.

Description

Technical Field

[0001] The present invention relates to the technical field of power control, and particularly to a power module control method for a constant high-voltage high-power DC power supply based on IPOS combination. Background Art

[0002] In high-power high-voltage power supplies, limited by the performance of power components in terms of withstand working voltage and current, it is difficult to achieve an output of nearly ten thousand volts and dozens of amperes through a single power circuit device. Therefore, multiple power modules often work in combination in series or parallel forms. According to different connection forms, multi-power-module series-parallel combination systems mainly have the following four categories: ISOP (input series, output parallel), ISOS (input series, output series), IPOP (input parallel, output parallel), and IPOS (input parallel, output series). For a power supply composed of multiple power modules working in combination, the key is to ensure the voltage equalization or current sharing of the input / output of each power module. Therefore, the control method of power modules is very important and has an important impact on the power loss, expansion performance, heat dissipation characteristics, etc. of the system. Existing power module control methods mainly include: 1. Master-slave control method: Select one of all the power modules as the master power module (usually the first one), and the remaining power modules are all slave power modules for output voltage equalization. The output voltages of all slave power modules change according to the change of the output voltage of the master power module.

[0003] It has the following disadvantages: ① This control method has high requirements for the loop control accuracy and stability of the master power module, which is difficult to achieve; ② When the master power module outputs a bias voltage, other slave powers will follow the master power module to have a bias voltage together; ③ The master power module is a single-point failure point. Once the control signal of its working loop is unstable or interfered, it will affect the control of other slave power modules and the failure of the entire system to work.

[0004] Generally speaking, using this control method will result in low working reliability of the power supply.

[0005] 2. Common duty cycle control method: All power modules share a control loop, and all power modules are simultaneously controlled and adjusted by the same control loop, reducing the complexity of system control and having a rapid response.

[0006] It has the following disadvantages: ① This control method has very high requirements for the consistency of each power module. Only when the operating parameter performance of each power module is highly consistent can the overall system achieve better results. It highly tests the stability of component parameters and the production process. Currently, it is difficult to achieve in actual mass production, and the application effect is not ideal.

[0007] ② Due to the parameter differences between each power module, the voltage sharing performance between modules is poor.

[0008] 3. Single-module independent control method: Each power module adopts independent control. A control loop is formed through voltage closed-loop or current closed-loop inside the module, and there is no control connection between modules.

[0009] It has the following disadvantages: Since the modules are all independent individuals, the voltage drop losses on the external cables, switches and other electrical components of the module output will cause a large deviation between the accuracy of the system total voltage output and the required set value, and the output accuracy is insufficient. It is difficult to be used in occasions that require precise output voltage. Summary of the Invention

[0010] In order to solve the deficiencies of the existing control methods and achieve the reliable operation and mass production of a constant high-voltage high-power DC power supply based on the IPOS combination, the present invention provides a power module control method for a constant high-voltage high-power DC power supply based on the IPOS combination. This power module control method for a constant high-voltage high-power DC power supply based on the IPOS combination can effectively ensure the output voltage stability of the power module, the voltage sharing of the power module output, and the accuracy of the system total output voltage.

[0011] The present invention provides a power module control method for a constant high-voltage high-power DC power supply based on the IPOS combination. The constant high-voltage high-power DC power supply based on the IPOS combination includes n sub-power modules and 1 system control module. The n sub-power modules are connected in a way of input parallel and output series. The constant high-voltage high-power DC power supply based on the IPOS combination has a double-layer three-loop control loop. The double-layer three-loop control loop includes a system-layer total voltage output closed-loop and a module-layer voltage sharing output closed-loop. The module-layer voltage sharing output closed-loop includes an output voltage sharing control loop and an input current sharing control loop. The power module control method includes the following steps: Step 1. The system control module receives a user instruction to obtain the total output voltage target value U tgt ; Step 2. The system control module sets the total output power reference value according to the total output voltage target value U tgt U ref, and decomposed into the output voltage reference values of the sub - power modules according to the number n of the sub - power modules U nref ; Step 3: The system control module transmits the total output voltage reference value U ref to each sub - power module. After receiving the instruction, the sub - power module turns on its respective output switch, and calculates the theoretically required duty cycle based on the total output voltage reference value U ref and the switching frequency value f, and controls the output; Step 4: The system control module collects the total input current I in , and decomposed into the input current reference values of the sub - power modules according to the number n of the sub - power modules I nref , then transmits the current reference value I nref to each sub - power module to form an input current sharing control loop, and assist the output voltage equalization control loop to work; Step 5: Each sub - power module collects its output voltage U nout and input current I nin and uploads them. All sub - power modules obtain the output voltages U nout and input currents I nin of other sub - power modules, calculates the output voltage equalization values U avg and input current sharing values I avg of all sub - power modules, and uses them as new output voltage reference values; Step 6: Judge whether the output voltage equalization degree of all sub - power modules meets the requirements. If it meets, the system control module collects the total output voltage U out . If it does not meet, adjust the duty cycle through PWM according to their difference and return to the above Step 5; Step 7: Compare the total output voltage U out with the total output voltage reference value formed by the user instruction U ref , judge whether the accuracy of the total output voltage meets the requirements. If it meets, maintain a precise and stable output until the end. If it does not meet, adjust the duty cycle through PWM according to their difference and return to the above Step 2.

[0012] In a preferred embodiment of the power module control method of the constant high-voltage high-power DC power supply based on the IPOS combination provided by the present invention, the closed-loop of the total voltage output at the system layer is used to ensure the accuracy of the total output to meet the output requirements of the user operation instructions; the closed-loop of the equal-voltage output at the module layer is used to ensure the balanced operation output of each sub-power module, reduce the output DC ripple, and improve the power quality.

[0013] In a preferred embodiment of the power module control method of the constant high-voltage high-power DC power supply based on the IPOS combination provided by the present invention, the output equal-voltage control loop is used for the output equal-voltage control under static conditions. The input equal-current control loop serves as a supplement to the output equal-voltage control loop to improve the dynamic response rate of the output under dynamic change conditions. In addition, it can also serve as the redundant control loop of the sub-power module. When the output equal-voltage control loop cannot perform normal cyclic control, it can work as a backup to improve the working life and reliability of the system.

[0014] In a preferred embodiment of the power module control method of the constant high-voltage high-power DC power supply based on the IPOS combination provided by the present invention, step seven specifically includes: the system control module collects the total voltage output after the series connection of each sub-power module U out which is transformed and conditioned to become V Uout , and is compared with the output reference value V Uref required by the output instruction issued by the user. The difference is used to update and form the reference value U nref of the output voltage of each sub-power module, and is transmitted to each sub-power module through the communication control bus; meanwhile, the system control module forms and decomposes the input total current I in collected into the input current reference value I nref of each sub-power module, and issues it to each sub-power module through the communication control bus.

[0015] In a preferred embodiment of the power module control method of the constant high-voltage high-power DC power supply based on the IPOS combination provided by the present invention, after each sub-power module receives the updated output voltage reference value, a new output voltage reference V Unref and V Inref are formed. The sub-power module transforms and conditions the output voltage U nout and input current I nin collected by itself to become VUnout and V Inin After comparison, the difference is used to adjust the duty cycle through PWM to achieve the adjustment of the output voltage, so as to meet the requirement of the total output voltage accuracy; meanwhile, the output voltage equalization of the sub-power modules is achieved through the communication control bus. Each sub-power module can obtain the output voltages of other sub-power modules, and after calculating the average output voltage value and the average input current value, they are used as the new output voltage reference again V Unref and V Inref and then compared with the currently collected output voltage U nout and input current I nin After transformation and conditioning, they become V Unout and V Inin After comparison, the difference is used to adjust the duty cycle through PWM to ultimately achieve the purpose of not only meeting the requirement of the total output voltage accuracy but also ensuring the output voltage equalization of each sub-power module.

[0016] Compared with the prior art, the power module control method of the constant high-voltage high-power DC power supply based on the IPOS combination provided by the present invention has the following beneficial effects: 1. The total output voltage accuracy of the system is high. Through the output voltage feedback control loop at the system level, an isolated high-voltage Hall voltage sensor is used to sample the DC high-voltage output, and its sampling accuracy is as high as ±0.1%, which can ensure that the high-voltage output accuracy of the whole machine reaches more than ±0.2%. It can be widely applied to occasions with higher requirements for the performance of high-voltage DC power supplies.

[0017] 2. The output voltage equalization between sub-power modules is high, and the input current sharing is good. It can balance the output voltage stress and input current stress differences between sub-power modules, and can effectively improve the working service life of sub-power modules in the long run.

[0018] 3. The sub-power modules adopt the output voltage equalization control loop and the input current sharing control loop. By taking advantage of the high precision of voltage control and the fast response of current control, it can effectively make up for the shortcomings of slow response of single voltage control and inaccurate single current control, so that the output of the sub-power module has the advantages of fast response and precise output. Brief Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings, where: Figure 1 is a flowchart of a power module control method for a constant high-voltage high-power DC power supply based on an IPOS combination provided by the present invention; Figure 2 is Figure 1 a control block diagram of the power module control method for the constant high-voltage high-power DC power supply shown based on an IPOS combination. Detailed implementation manners

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0021] Please refer to Figure 1 and Figure 2 together, where Figure 1 is a flowchart of a power module control method for a constant high-voltage high-power DC power supply based on an IPOS combination provided by the present invention; Figure 2 is Figure 1 a control block diagram of the power module control method for the constant high-voltage high-power DC power supply shown based on an IPOS combination.

[0022] The constant high-voltage high-power DC power supply based on an IPOS combination includes n sub-power modules and 1 system control module, where n≥2, and the output voltage of the high-voltage DC power supply U out ≥1 kV dc. The system control module is responsible for the feedback regulation control of the total output voltage of the DC power supply, and uses an isolated high-voltage Hall voltage sensor to sample the DC high-voltage output. Its sampling accuracy is as high as ±0.1%, which can ensure that the high-voltage output accuracy of the whole machine reaches ±0.2% or more, and can be widely used in occasions with higher requirements for the performance of high-voltage DC power supplies. Each of the sub-power modules has an independent input interface, output interface, and communication control interface. The input interfaces of each sub-power module are connected in parallel to an external input power supply (either an AC source or a DC source), the output interfaces are connected in series, and the total output is connected to an external load after passing through a high-voltage output switch.

[0023] The constant high-voltage high-power DC power supply based on the IPOS combination has a double-layer triple-loop control loop. The double-layer triple-loop control loop includes a system-layer total voltage output closed loop and a module-layer voltage equalization output closed loop. Among them, the system-layer total voltage output closed loop is used to ensure the accuracy of the total output to meet the output requirements of the user operation instructions. The module-layer voltage equalization output closed loop is used to ensure the balanced operation output of each power module, reduce the output DC ripple, and improve the power quality. The module-layer voltage equalization output closed loop includes an output voltage equalization control loop and an input current sharing control loop. The output voltage equalization control loop is used for output voltage equalization control under static conditions. The input current sharing control loop, as a supplement to the output voltage equalization control loop, improves the dynamic response rate of the output under dynamic change conditions. In addition, it can also be used as a redundant control loop for sub-power modules. When the output voltage equalization control loop is interfered with or cannot perform normal cyclic control for other reasons, it can work as a backup to improve the working life and reliability of the system.

[0024] The power module control method of the constant high-voltage high-power DC power supply based on the IPOS combination includes the following steps: Step 1: The system control module receives the user instruction to obtain the total output voltage target value U tgt ; Step 2: The system control module sets the total output power reference value according to the total output voltage target value U tgt and decomposes it into the output voltage reference values of sub-power modules according to the number n of sub-power modules U ref = 1 / n • U nref = 1 / n • U ref ; Specifically, the total output voltage target value of the user U tgt should be the same as the total output voltage reference value set by the system control module in an ideal situation. However, in actual situations, due to voltage drop losses inside the power supply, including the voltage drop introduced by the DC reverse voltage protection device at the total output end of the system layer and the voltage drop on the cable, the actual total output voltage of the power supply will be lower than the set total output power reference value U ref . Therefore, in order to make the actual total output voltage of the power supply as close as possible to U ref and ensure the accuracy of the output, U tgt will be set to be slightly greater than U ref For example, the total output voltage target value of the user U tgt U ​tgt is 5 kV , after actually receiving the instruction, it will set the output voltage reference value U ref to 5.05 kV .

[0025] Step 3: The system control module transmits the total output voltage reference value U ref to each sub - power module. After receiving the instruction, the sub - power module turns on its respective output switch and calculates the theoretically required duty cycle based on the total output voltage reference value U ref and the switching frequency value f, and controls the output; Specifically, the switching frequency value f refers to the operating frequency of the switching devices such as MOS transistors and IGBTs in the sub - power module. In the present invention, each sub - power module adopts a PWM control method. Its approximate calculation formula is output voltage = input voltage × duty cycle × conversion coefficient, where the duty cycle is the ratio of the switch - on time to the cycle time in the switching cycle, and its value is selected with reference to the switching frequency of the power switch device, usually considered according to empirical values; the conversion coefficient is mainly related to the turns ratio of the transformer in the circuit. In addition, the filter inductor also affects the output voltage. In fact, there are many factors affecting the output voltage and it is relatively complex. The calculation formula is usually only used as a directional reference; finally, the output voltage value of each sub - power module is controlled by PI regulation; Step 4: The system control module collects the total input current I in , and according to the number n of sub - power modules, decomposes it into the input current reference value of the sub - power module I nref = 1 / n • I in , and then transmits the current reference value I nref to each sub - power module, forming an input current sharing control loop and assisting the output voltage sharing control loop to work; Step 5: Each sub - power module collects its output voltage U nout and input current I nin and uploads them. All sub - power modules obtain the output voltage U nout and input current I nin of other sub - power modules, calculates the output voltage sharing value U avg and input current sharing value I avg , and uses them as the new output voltage reference value; Step 6: Determine whether the output voltage equalization degree of all sub - power modules meets the requirements. If it meets, the system control module collects the total output voltage U out , if it does not meet, adjust the duty cycle through PWM according to the difference and return to the above - mentioned Step 5; Step 7: Compare the total output voltage U out with the total output voltage reference value formed by the user instruction U ref to determine whether the accuracy of the total output voltage meets the requirements. If it meets, maintain the precise and stable output until the end. If it does not meet, adjust the duty cycle through PWM according to the difference and return to the above - mentioned Step 2.

[0026] Specifically, the above - mentioned Step 7 includes: the system control module changes the total voltage output after connecting in series each of the collected sub - power modules U out after arithmetic conditioning to V Uout , and compares it with the output reference value required by the user's output instruction V Uref . The difference is used to update and form the reference values of the output voltages of each of the sub - power modules U nref , and transmits them to each sub - power module through the communication control bus; meanwhile, the system control module forms and decomposes the input current reference values of each sub - power module by collecting the input total current I in and I nref , and issues them to each sub - power module through the communication control bus; with such settings, even if a certain sub - power module fails or is damaged during the working process, after the abnormal power module bypasses and exits, the system control module can re - confirm the number n of available power modules, recalculate the target value of the output voltage of the sub - power modules and issue it again, and continue to carry out the power supply task.

[0027] After each sub - power module receives the updated output voltage reference value, it forms a new output voltage reference V Unref and V Inref . The sub - power module changes the output voltage U nout and the input current I nin collected by itself after transformation and conditioning to V Unout and V Inin, after comparison, the difference is used to adjust the duty cycle through PWM to achieve the adjustment of the output voltage, so that the total output voltage accuracy meets the requirements; At the same time, the output voltage sharing of the sub-power modules is achieved through the communication control bus. Each sub-power module can obtain the output voltages of other sub-power modules, calculate the average output voltage value and the average input current value, and then use them as the new output voltage reference again. V Unref and V Inref , and then compared with the currently collected output voltage U nout and input current I nin . After transformation and conditioning, they become V Unout and V Inin . After comparison, the difference is used to adjust the duty cycle through PWM to finally achieve the purpose of meeting both the total output voltage accuracy requirement and ensuring the output voltage sharing of each sub-power module.

[0028] In the sub-power module, the output voltage sharing control loop and the input current sharing control loop use the output voltage sharing control loop as the main control and the input current sharing control loop as the auxiliary control. The output voltage sharing control loop has the characteristic of high control accuracy, but its response rate is slower compared with the input current sharing control loop. Therefore, when there is an instantaneous dynamic change in the external load, first, the input current sharing control loop with a faster current response rate will perform adjustment control, which can ensure that the power supply will not have a large transient response change and can quickly recover after the transient response occurs.

[0029] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A power module control method of a constant high-voltage high-power DC power supply based on an IPOS combination, wherein the constant high-voltage high-power DC power supply based on an IPOS combination comprises n sub-power modules and a system control module, wherein the n sub-power modules are connected in a parallel input and a series output manner, characterized in that: The constant high-voltage and high-power DC power supply based on the IPOS combination has a double-layer three-loop control loop, which includes a system-layer total voltage output closed loop and a module-layer voltage-balanced output closed loop. The module-layer voltage-balanced output closed loop includes an output voltage-balanced control loop and an input current-balanced control loop. The power module control method includes the following steps: Step 1: The system control module receives the user's instruction and obtains the total output voltage target value U tgt ; Step 2: The system control module determines the total output voltage target value. U tgt Set the total output voltage reference value U ref , and according to the number of sub-power modules n, it is decomposed into the sub-power module output voltage reference value U nref ; Step 3: The system control module sets the total output voltage reference value U ref The instructions are transmitted to each sub-power module. After receiving the instructions, the sub-power modules open their respective output switches and adjust the output voltage according to the total output voltage reference value. U ref , switching frequency value f, calculate the theoretical required duty cycle and control the output; Step 4: The system control module collects the total input current I in , and according to the number of sub-power modules n, it is decomposed into the sub-power module input current reference value I nref , then the current reference value I nref Transmitted to each sub-power module to form an input current sharing control loop and assist the output voltage sharing control loop; Step 5: Each sub-power module collects its output voltage U nout , Input current I nin And upload, all sub-power modules obtain the output voltage of other sub-power modules U nout and input current I nin , calculate the output voltage of all sub-power modules U avg and input current sharing value I avg , and used as the new output voltage reference value; Step 6: Determine whether the output voltage of all sub-power modules meets the requirements. If so, the system control module collects the total output voltage. U out If not, the duty cycle is adjusted by PWM according to the difference and the process returns to step 5; Step 7: Set the total output voltage U out The total output voltage reference value formed by the user command U ref A comparison is made to determine whether the total output voltage accuracy meets the requirements. If so, the precise and stable output is maintained until the end. If not, the duty cycle is adjusted through PWM according to the difference and the process returns to step 2.

2. The power module control method of the constant high-voltage and high-power DC power supply based on IPOS combination according to claim 1 is characterized in that: The system-level total voltage output closed loop is used to ensure the accuracy of the total output to meet the output requirements of user operation instructions; the module-level voltage-balanced output closed loop is used to ensure the balanced working output of each sub-power module, reduce the output DC ripple, and improve the power quality.

3. The power module control method of the constant high-voltage and high-power DC power supply based on IPOS combination according to claim 1 is characterized in that: The output voltage equalizing control loop is used for output voltage equalizing control under static conditions. The input current equalizing control loop serves as a supplement to the output voltage equalizing control loop to improve the dynamic response rate of the output under dynamic change conditions. In addition, it can also serve as a redundant control loop of the sub-power module. When the output voltage equalizing control loop cannot perform normal cycle control, it can work as a standby to improve the service life and reliability of the system.

4. The power module control method of the constant high-voltage and high-power DC power supply based on IPOS combination according to claim 1 is characterized in that: The step 7 specifically includes: the system control module collects the total voltage output by connecting the sub-power modules in series U out After calculation and conditioning, it becomes V Uout , and the output reference value required by the user to issue an output instruction V Uref The difference is used to update the output voltage reference value of each sub-power module. U nref and transmits it to each sub-power module through the communication control bus; at the same time, the system control module collects the total input current I in , formed and decomposed into the input current reference value of each sub-power module I nref and sent to each sub-power module through the communication control bus.

5. The power module control method of the constant high-voltage and high-power DC power supply based on IPOS combination according to claim 4 is characterized in that: After receiving the updated output voltage reference value, each sub-power module forms a new output voltage reference value. V Unref and V Inref The sub-power modules collect their own output voltages U nout and input current I nin , after transformation and conditioning, becomes V Unout and V Inin After comparison, the difference is adjusted through PWM duty cycle to adjust the output voltage and achieve the total output voltage accuracy that meets the requirements; at the same time, the output voltage of the sub-power module is controlled through the communication bus, and each sub-power module can obtain the output voltage of other sub-power modules, and the average output voltage value and the average input current value are calculated and used as the new output voltage reference again. V Unref and V Inref , again with the current acquisition output voltage U nout and input current I nin , after transformation and conditioning, becomes V Unout and V Inin After comparison, the difference is adjusted through PWM duty cycle to achieve the goal of satisfying the total output voltage accuracy requirements and ensuring the output voltage balance of each sub-power module.

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