Cascading device and control method thereof

Abstract

The application discloses a kind of cascade equipment and its control method.Cascading equipment includes at least two cascading power modules;Power module includes bus capacitor, switching power supply, linear power supply, auxiliary module and power module;Wherein, the input end of power module, switching power supply and the input end of linear power supply are coupled with the two ends of bus capacitor;Switching power supply is used to convert the DC bus voltage on bus capacitor into first power supply voltage, and linear power supply is used to convert DC bus voltage into second power supply voltage;The power supply end of auxiliary module is coupled with the output end of switching power supply, and the power supply end of auxiliary module is coupled with the output end of linear power supply;Auxiliary module controls power supply to auxiliary module by switching power supply or linear power supply according to DC bus voltage and voltage-sharing target value, to carry out voltage-sharing control to power module;Wherein, voltage-sharing target value is the average of the bus voltage of all power modules.The application realizes the voltage-sharing of power module with lower power consumption.

Description

Technical Field

[0001] This invention relates to the field of pressure equalization technology for cascaded equipment, and more particularly to a cascaded equipment and its control method. Background Technology

[0002] A cascaded static var generator (SVR) consists of several cascaded power modules. Therefore, the total current flowing through each power module is the same. However, under some operating conditions, the bus voltage of each power module is different, so it is necessary to equalize the voltage of the power modules. Summary of the Invention

[0003] This invention provides a cascaded device and its control method to solve the voltage equalization problem of power modules in a cascaded device.

[0004] According to one aspect of the present invention, a power module for a cascaded device is provided, comprising at least two cascaded power modules;

[0005] The power module includes a bus capacitor, a switching power supply, a linear power supply, an auxiliary module, and a power module.

[0006] The power module, the input terminal of the switching power supply, and the input terminal of the linear power supply are all coupled to the two ends of the bus capacitor; the switching power supply is used to convert the DC bus voltage on the bus capacitor into a first supply voltage, and the linear power supply is used to convert the DC bus voltage into a second supply voltage.

[0007] The power supply terminal of the auxiliary module is coupled to the output terminal of the switching power supply, and the power supply terminal of the auxiliary module is coupled to the output terminal of the linear power supply; the auxiliary module controls the power supply from the switching power supply or the linear power supply to the auxiliary module according to the DC bus voltage and the voltage equalization target value, so as to perform voltage equalization control on the power module; wherein, the voltage equalization target value is the average value of the bus voltage of all the power modules.

[0008] Optionally, the switching power supply includes a first main circuit and a first control unit. The first main circuit includes a first feedback terminal. The control terminal of the first control unit serves as the control terminal of the switching power supply. The output terminal of the first control unit is coupled to the first feedback terminal. The first control unit controls whether the switching power supply works by controlling the voltage of the first feedback terminal.

[0009] The linear power supply includes a second main circuit and a second control unit. The second main circuit includes a second feedback terminal. The control terminal of the second control unit serves as the control terminal of the linear power supply. The output terminal of the second control unit is coupled to the second feedback terminal. The second control unit controls whether the linear power supply works by controlling the voltage of the second feedback terminal.

[0010] Optionally, the first control unit includes a first transistor, the base of the first transistor serves as the control terminal of the first control unit, the first terminal of the first transistor is grounded, and the second terminal of the first transistor serves as the output terminal of the first control unit;

[0011] Optionally, the second control unit includes a second transistor, the base of which serves as the control terminal of the second control unit, the first terminal of which is grounded, and the second terminal of which serves as the output terminal of the second control unit.

[0012] Optionally, the first main circuit includes a switching transistor, an energy storage element, a power control subunit, and a feedback regulation circuit; wherein, the input terminal of the feedback regulation circuit is coupled to the output terminal of the switching power supply, the output terminal of the feedback regulation circuit is coupled to the feedback terminal of the power control subunit, the control terminal of the power control subunit is electrically connected to the gate of the switching transistor, the first terminal of the switching transistor is coupled to the bus capacitor, and the second terminal of the switching transistor is coupled to the energy storage element; the feedback terminal of the power control subunit serves as the first feedback terminal of the first main circuit.

[0013] Optionally, the second main circuit includes a third transistor and a Zener diode; wherein, the first terminal of the Zener diode is coupled to the output terminal of the linear power supply, the second terminal of the Zener diode is coupled to the base of the third transistor, the first terminal of the third transistor is coupled to the bus capacitor, and the second terminal of the third transistor is coupled to the power supply terminal of the auxiliary module; the second terminal of the Zener diode serves as the second feedback terminal of the second main circuit.

[0014] Optionally, the power module also includes:

[0015] A status detection module is provided, wherein the detection input terminal of the status detection module is coupled to the output terminal of the switching power supply or the output terminal of the linear power supply, and the signal output terminal of the status detection module is coupled to the auxiliary module; the status detection module is used to detect the operating status of the switching power supply or the linear power supply.

[0016] Optionally, the state detection module includes:

[0017] A voltage divider unit, coupled to the detection input terminal, is used to divide the voltage at the detection input terminal.

[0018] A first comparator has its first input terminal coupled to the output terminal of the voltage divider unit, its second input terminal connected to a voltage reference value, and its output terminal serving as the output terminal of the state detection module.

[0019] The first resistor has its first end connected to a low-voltage power supply, and its second end coupled to the output of the first comparator.

[0020] Optionally, the auxiliary module includes a power control unit, wherein the first output terminal of the power control unit is coupled to the control terminal of the switching power supply as the first control output terminal of the auxiliary module, and the second output terminal of the power control unit is coupled to the control terminal of the linear power supply as the second control output terminal of the auxiliary module.

[0021] The power control unit is implemented using at least one of hardware circuits and software methods.

[0022] Optionally, the power control unit includes:

[0023] A hysteresis comparator, wherein the first input terminal of the hysteresis comparator is connected to a first equalization reference voltage, the second input terminal of the hysteresis comparator is connected to a sampled value of the DC bus voltage, and the output terminal of the hysteresis comparator outputs a first control signal;

[0024] An inverter, the input of which is coupled to the output of the hysteresis comparator, and the output of which outputs a second control signal;

[0025] Wherein, the first control signal is connected to the control terminal of the switching power supply and the second control signal is connected to the control terminal of the linear power supply; or, the first control signal is connected to the control terminal of the linear power supply and the second control signal is connected to the control terminal of the switching power supply.

[0026] Optionally, the power control unit includes:

[0027] A compensation amplifier, wherein the first input terminal of the compensation amplifier is connected to a second equalization reference voltage, and the second input terminal of the compensation amplifier is connected to a sampled value of the DC bus voltage;

[0028] The second comparator has its first input terminal coupled to the output terminal of the compensation amplifier, its second input terminal connected to a carrier signal, and its output terminal outputting a first control signal.

[0029] An inverter, wherein the input terminal of the inverter is coupled to the output terminal of the second comparator, and the output terminal of the inverter outputs a second control signal;

[0030] Wherein, the first control signal is connected to the control terminal of the switching power supply and the second control signal is connected to the control terminal of the linear power supply; or, the first control signal is connected to the control terminal of the linear power supply and the second control signal is connected to the control terminal of the switching power supply.

[0031] According to another aspect of the present invention, a control method for a power module of a cascaded device is provided, which is applied to a power module of a cascaded device as described in any embodiment of the present invention, wherein the control method is executed by the auxiliary module;

[0032] During the voltage equalization process of the power module, the auxiliary module controls the power supply to be supplied by the switching power supply or the linear power supply based on the collected DC bus voltage.

[0033] Optionally, the step of controlling the supply of power to the auxiliary module by the switching power supply or the linear power supply based on the acquired DC bus voltage includes:

[0034] The upper and lower adjustment limits are determined based on the target pressure equalization value.

[0035] If the sampled value of the DC bus voltage is greater than the adjustment upper limit, then control the linear power supply to supply power to the auxiliary module separately;

[0036] If the sampled value of the DC bus voltage is less than the adjustment lower limit, then the auxiliary module is powered separately by the switching power supply.

[0037] If the sampled value of the DC bus voltage is between the lower adjustment limit and the upper adjustment limit, the power supply of the auxiliary module remains unchanged.

[0038] Optionally, the step of controlling the supply of power to the auxiliary module by the switching power supply or the linear power supply based on the acquired DC bus voltage includes:

[0039] The adjustment baseline value is determined based on the target value of the equalizing pressure.

[0040] The carrier comparison value is determined based on the sampled value of the DC bus voltage and the adjustment reference value;

[0041] If the carrier comparison value is greater than the instantaneous value of the carrier signal, then the auxiliary module is powered separately by the switching power supply.

[0042] If the carrier comparison value is less than the instantaneous value of the carrier signal, then the linear power supply is used to supply power to the auxiliary module separately.

[0043] The carrier comparison value is between the maximum and minimum values ​​of the carrier signal. Within one period of the carrier signal, the sum of the time during which the switching power supply alone powers the auxiliary module and the time during which the linear power supply alone powers the auxiliary module is equal to the period of the carrier signal.

[0044] Optionally, the operating conditions for equalizing the voltage of the power module include at least one of the following: equipment standby, equipment no-load, and equipment light-load.

[0045] Optionally, the control method further includes:

[0046] During the device startup process, the auxiliary module is powered by the switching power supply and the linear power supply;

[0047] And / or, during normal operation of the equipment, the switching power supply serves as the main power supply for the power module, and the linear power supply serves as the backup power supply for the power module.

[0048] In summary, this embodiment of the invention sets the redundant power supply as a linear power supply in the power module. This linear power supply and the switching power supply jointly supply power to the auxiliary module. The constant current characteristic of the linear power supply under a given load is utilized in conjunction with the constant power characteristic of the switching power supply under a given load. Specifically, during voltage equalization, when using the linear power supply, the bus capacitor of the power module is charged; when using the switching power supply, the bus capacitor of the power module is discharged, thus achieving the voltage equalization function of the power module.

[0049] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 A circuit diagram of a cascaded device provided in an embodiment of the present invention;

[0052] Figure 2 A schematic diagram illustrating the principle of pressure equalization problem analysis provided in an embodiment of the present invention;

[0053] Figure 3 A circuit diagram of a power module for a cascaded device provided in an embodiment of the present invention;

[0054] Figure 4 A schematic diagram illustrating the voltage equalization principle of the power modules in the cascaded equipment provided in this embodiment of the invention;

[0055] Figure 5 A circuit diagram of a switching power supply provided for an embodiment of the present invention;

[0056] Figure 6 A circuit diagram of another switching power supply provided in an embodiment of the present invention;

[0057] Figure 7 A circuit diagram of a linear power supply provided for an embodiment of the present invention;

[0058] Figure 8 A circuit diagram of the power module of another cascaded device provided in an embodiment of the present invention;

[0059] Figure 9 A circuit diagram of a state detection module provided in an embodiment of the present invention;

[0060] Figure 10 A circuit diagram of a power control unit provided in an embodiment of the present invention;

[0061] Figure 11 A characteristic curve diagram of a hysteresis comparator provided in an embodiment of the present invention;

[0062] Figure 12 A circuit diagram of another power control unit provided in an embodiment of the present invention;

[0063] Figure 13 This is a waveform diagram of a closed-loop control voltage equalization provided in an embodiment of the present invention;

[0064] Figure 14 A flowchart illustrating a control method for switching between a switching power supply and a linear power supply using a hysteresis comparator, provided as an embodiment of the present invention;

[0065] Figure 15 A flowchart illustrating a control method for switching between a switching power supply and a linear power supply using a closed-loop control scheme, provided in an embodiment of the present invention.

[0066] Figure 16 This is a circuit diagram of a cascaded device provided in an embodiment of the present invention. Detailed Implementation

[0067] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0068] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0069] As described in the background section, existing cascaded devices suffer from voltage equalization issues in their power modules. A detailed analysis follows:

[0070] Figure 1 This is a circuit diagram of a cascaded device provided in an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating the principle of pressure equalization problem analysis provided in an embodiment of the present invention. See also... Figure 1 and Figure 2 The cascaded device includes multiple power modules 100 connected in cascade. Each power module 100 uses a switching power supply 110 as its power supply. The switching power supply 110 draws power from the DC bus of its respective power module 100 to supply power to the auxiliary module 120. The auxiliary module 120 can perform functions such as driving, controlling and protecting the inverter circuit 130 in the power module 100.

[0071] Under normal operating conditions of the cascaded equipment, the auxiliary module 120 can control the voltage equalization of each power module 100 by controlling the switching state of the inverter circuit 130.

[0072] i represents the total current flowing through the cascaded devices. Since the power modules 100 are connected in series, the total current flowing through the cascaded devices is the same as the total current flowing through each power module 100, and the total current i of each power module 100 is equal. C Let i be the current of the bus capacitor in each power module 100. Specifically, the current of the bus capacitor in power module 1 is i. c1 The current of the bus capacitor of power module 2 is i c2 The current in the bus capacitor of power module n is i. cn U represents the voltage of the bus capacitor in each power module 100. Specifically, the voltage of the bus capacitor in power module 1 is U1, the voltage of the bus capacitor in power module 2 is U2, ..., and the voltage of the bus capacitor in power module n is U... n .

[0073] i spsThe current flowing through the switching power supply 110 is, specifically, the current flowing through the switching power supply of the power module 1 is i. sps1 The current flowing through the switching power supply of power module 2 is i sps2 The current flowing through the switching power supply of power module n is i... spsn i leak This refers to the leakage current in power module 100 excluding the switching power supply 110. Specifically, the leakage current of power module 1 is i. leak1 The leakage current of power module 2 is i leak2 The leakage current of power module n is i leakn Among them, i leak Much smaller than i sps Its impact is negligible.

[0074] Since the switching power supply 110 has a constant power characteristic, i.e., input power = output power, then i sps =P / U, where P is the input or output power of the switching power supply 110, and U is the voltage of the bus capacitor corresponding to the switching power supply 110. Therefore, the power module 100 with a higher bus capacitor voltage will have a higher current i flowing through its switching power supply 110. sps Smaller; conversely, for power modules 100 with lower bus capacitor voltage, the current i flowing through their switching power supply 110 is smaller. sps The total current flowing through power modules 100 is equal, so the power module 100 with the higher bus capacitor voltage will have a higher current i flowing through its bus capacitor. c Larger; conversely, for power modules 100 with lower bus capacitor voltage, the current i flowing through their bus capacitor is larger. c Therefore, the charging current of the power module 100 with a higher bus capacitor voltage will be greater than that of the power module 100 with a lower voltage, causing the voltage of the power module 100 with a higher voltage to increase and the voltage of the power module 100 with a lower voltage to decrease, until the power module 100 with a higher voltage triggers overvoltage protection or the power module 100 with a lower voltage triggers undervoltage protection.

[0075] In some cases, existing technologies incorporate two switching power supplies 110 in the power module 100, with one power supply 110 serving as a redundant power supply for the other to improve the stability of the power module 100's operation. However, this redundant configuration of two switching power supplies 110 cannot achieve voltage equalization.

[0076] In view of this, embodiments of the present invention provide a cascaded device. The cascaded device includes at least two cascaded power modules. Figure 3 This is a circuit diagram of a power module for a cascaded device provided in an embodiment of the present invention. See also... Figure 3The power module 200 includes a bus capacitor C, a switching power supply 210, a linear power supply 220, an auxiliary module 230, and a power module.

[0077] The power module, the input terminals of the switching power supply 210, and the input terminals of the linear power supply 220 are all coupled to both ends of the bus capacitor, with the linear power supply 220 serving as a redundant power supply. The switching power supply 210 is used to convert the DC bus voltage on the bus capacitor C into the first supply voltage U. s The linear power supply 220 is used to convert the DC bus voltage to a second supply voltage U. L Specifically, the input terminals of the switching power supply 210 include a positive input terminal Vinsps+ and a negative input terminal Vinsps-, which are respectively coupled to the two ends of the bus capacitor C; the output terminals of the switching power supply 210 include a positive output terminal Vosps+ and a negative output terminal Vosps-, and the voltage difference between the positive output terminal Vosps+ and the negative output terminal Vosps- is the first supply voltage U. s The linear power supply 220 has two input terminals: a positive input terminal Vinlps+ and a negative input terminal Vinlps-. These terminals are coupled to the two ends of the bus capacitor C, respectively. The linear power supply 220 also has two output terminals: a positive output terminal Volps+ and a negative output terminal Volps-. The voltage difference between these two terminals is the second supply voltage U. L .

[0078] The power supply terminal of the auxiliary module 230 is coupled to the output terminal of the switching power supply 210, and the power supply terminal of the auxiliary module 230 is coupled to the output terminal of the linear power supply 220; the auxiliary module 230 is powered by the switching power supply 210 and / or the linear power supply 220.

[0079] The acquisition end of auxiliary module 230 ( Figure 3 (Not shown in the diagram) is coupled to the bus capacitor C. The first control output terminal of the auxiliary module 230 is coupled to the control terminal ENsps of the switching power supply 210, and the second control output terminal of the auxiliary module 230 is coupled to the control terminal ENlps of the linear power supply 220.

[0080] The auxiliary module 230 controls the supply of power from the switching power supply 210 or the linear power supply 220 to the power module based on the DC bus voltage U and the voltage equalization target value, in order to perform voltage equalization control on the power module; wherein, the voltage equalization target value is the average value of the bus voltage of all power modules. In addition, the auxiliary module can also control the conduction state of each transistor included in the power module to supply power to the bus capacitor C.

[0081] The switching power supply 210 and the linear power supply 220 have different characteristics. The switching power supply 210 has constant power characteristics, while the linear power supply 220 has constant current characteristics. This embodiment of the invention utilizes the different characteristics of the two power supplies to equalize the voltage of the power module 200.

[0082] Figure 4 This is a schematic diagram illustrating the voltage equalization principle of the power modules in the cascaded device provided in this embodiment of the invention. (See also...) Figure 4 The auxiliary module 230 can control the switching power supply 210 by sending control signals to the control terminal ENsps, and can control the operating state of the linear power supply 220 by sending control signals to the control terminal ENlps. Similar to the aforementioned analysis, i leak For the leakage current in the power module 200 other than the power supplies (including the switching power supply 210 and the linear power supply 220), i leak Much smaller than i sps and i lps Its impact is negligible.

[0083] Assume the power of the drive and control protection circuit is P1, the bus voltage is U (i.e., the voltage across the bus capacitor C is U), the total current of the power module 200 is i, and the current of the bus capacitor is i. c Specifically, when i c When i > 0, the bus capacitor C charges, and the voltage U increases; when i c When i < 0, the bus capacitor C discharges, and the voltage U decreases; when i c =0 The voltage U across the bus capacitor C remains constant. Both the switching power supply 210 and the linear power supply 220 draw power from the bus. The current consumed by the switching power supply 210 from the bus is i. sps The current consumed by the linear power supply 220 from the bus is i lps i c =ii sps -i lps -i leak .

[0084] When the auxiliary module 230 is powered by the switching power supply 210, according to the constant power characteristic of the switching power supply 210, the output power = input power, and the current i consumed by the switching power supply 210 from the bus... sps ≈P1 / U; When the auxiliary module 230 is powered by the linear power supply 220, according to the constant current characteristic of the linear power supply 220, the current i consumed by the linear power supply 220 from the bus is approximately equal to the current i. lps ≈i olps =P1 / U L Generally, U > U L (For example, U>10U) L Therefore, i sps lps , and i​lps It hardly changes with the bus voltage U.

[0085] In practical applications, the power modules 200 are connected in series, and the total current i flowing through each power module 200 is the same. When the power module 200 with a high bus voltage is powered independently by the linear power supply 220, the capacitive current i of that power module 200 is... c = (i - i lps -i leak ), and i lps When the power module 200 with low bus voltage is powered solely by the switching power supply 210, the capacitor current i of the power module 200... c = (i - i sps -i leak As can be seen from the foregoing analysis, further derivation can yield i sps +i leak <i<i lps +i leak Therefore, it can be seen that when the power module 200 with a high bus voltage is powered solely by the linear power supply 220, the capacitor current i of the power module 200 is... c When the voltage of the bus capacitor C is less than 0, the voltage of the bus capacitor C is discharged, thus reducing its voltage. When the power module 200 with low bus voltage is powered solely by the switching power supply 210, the capacitor current i of the power module 200 is... c When the voltage is greater than 0, the bus capacitor C is charged, which increases its voltage and thus achieves voltage equalization.

[0086] In summary, this embodiment of the invention sets the redundant power supply as a linear power supply 220 in the power module 200. This linear power supply 220 and the switching power supply 210 jointly supply power to the auxiliary module 230. Furthermore, the constant current characteristic of the linear power supply 220 under a given load is used in conjunction with the constant power characteristic of the switching power supply 210 under a given load to achieve voltage equalization for the power module 200.

[0087] In the above embodiments, there are various ways to configure the switching power supply 210. The following are exemplary descriptions, but they are not intended to limit the present invention.

[0088] Figure 5 This is a circuit diagram of a switching power supply provided in an embodiment of the present invention. (In conjunction with...) Figure 3 and Figure 5 ​In one embodiment, the switching power supply 210 includes a first main circuit 211 and a first control unit 212. The first main circuit 211 includes a first feedback terminal 211F. The control terminal of the first control unit 212 serves as the control terminal ENsps of the switching power supply 210. The output terminal of the first control unit 212 is coupled to the first feedback terminal 211F. The first control unit 212 controls whether the switching power supply 210 works by controlling the voltage of the first feedback terminal 211F.

[0089] The first feedback terminal 211F can receive feedback signals from the first main circuit 211 and control the operating state of the first main circuit 211 based on these feedback signals. In this embodiment of the invention, by connecting the first control unit 212 to the first feedback terminal 211F, the potential of the first feedback terminal 211F can be controlled, thereby changing the potential of the first feedback terminal 211F as needed, and thus controlling the operating state of the first main circuit 211. This configuration results in a stable control method, a simple circuit structure, and ease of implementation.

[0090] In this embodiment of the invention, the topology of the first main circuit 211 is not limited. The first main circuit 211 can be any type of switching power supply topology, such as flyback power supply topology, forward power supply topology, push-pull power supply topology, half-bridge power supply topology, buck power supply topology, boost power supply topology, and buck-boost power supply topology.

[0091] See also Figure 5 In one embodiment, the first main circuit 211 includes a switching transistor Q1, an energy storage element T1, a power control subunit 211A, and a feedback regulation circuit 211B, etc.; wherein, the input terminal of the feedback regulation circuit 211B is coupled to the output terminal (including the positive output terminal Vosps+ and the negative output terminal Vosps-) of the switching power supply 210, the output terminal of the feedback regulation circuit 211B is coupled to the feedback terminal FB of the power control subunit 211F, the control terminal of the power control subunit 211A is electrically connected to the gate of the switching transistor Q1, and the first terminal of the switching transistor Q1 is connected to the bus capacitor ( Figure 5 (Not shown in the diagram) is coupled, and the second terminal of the switching transistor Q1 is coupled to the energy storage element T1; the feedback terminal FB of the power control subunit 211A serves as the first feedback terminal 211F of the first main circuit 211.

[0092] The power control subunit 211A can be, for example, a power control chip. The power control subunit 211A can control the switching state of the switching transistor Q1 based on the voltage output from the feedback adjustment circuit 211B and the first control unit 212, thereby controlling the storage and release of energy in the energy storage element T1, and consequently controlling the control state of the first main circuit 211. This configuration results in stable control, a simple circuit structure, and ease of implementation.

[0093] Figure 6 A circuit diagram of another switching power supply provided in an embodiment of the present invention. See also Figure 6 In one embodiment, the first main circuit 211 of the switching power supply is a flyback power supply, the energy storage element T1 is an isolation transformer, and the switching transistor Q1 is a MOSFET. The first main circuit 211 also includes an input capacitor Csps1, an output capacitor Csps2, and a diode Dsps, etc. Specifically, the input capacitor Csps1 is connected in parallel to the input terminals of the switching power supply 210 (including the positive input terminal Vinsps+ and the negative input terminal Vinsps-), and the input current of the switching power supply is isps. The primary side of the isolation transformer and the switching transistor Q1 are connected in series and then in parallel with the input capacitor Csps1. An anti-parallel diode for freewheeling is provided on the switching transistor Q1, and the same-name terminal of the primary side of the isolation transformer is coupled to the positive input terminal Vinsps+. The secondary side of the isolation transformer is connected in parallel with the output capacitor Csps2 via diode Dsps. The output capacitor Csps2 is coupled to the output terminals (positive output terminal Vosps+ and negative output terminal Vosps-) of the switching power supply 210. The corresponding terminal of the secondary side of the isolation transformer is coupled to the negative output terminal Vosps-. The output current of the switching power supply is iosps. The first main circuit 211 is set up in this way, and the circuit structure is simple and easy to implement.

[0094] See also Figure 6 In one embodiment, the first control unit 212 includes a first transistor Q2. The base of the first transistor Q2 serves as the control terminal of the first control unit 212, the first terminal of the first transistor Q2 is grounded, and the second terminal of the first transistor Q2 serves as the output terminal of the first control unit 212. For example, when the first transistor Q2 is an NPN transistor, if the base of the first transistor Q2 is low, the first transistor Q2 is off, and the first feedback terminal 211F can normally receive the feedback signal from the feedback adjustment circuit 211B. The power control subunit 211A controls the switching transistor Q1 to work normally. If the base of the first transistor Q2 is high, the first transistor Q2 is grounded, pulling the feedback signal from the feedback adjustment circuit 211B low, the first feedback terminal 211F becomes low, and the power control subunit 211A controls the switching transistor Q1 to stop working. In other embodiments, the first transistor Q2 can also be a PNP transistor, etc., as needed. In this embodiment of the invention, the first control unit 212 includes a first transistor Q2, which has a simple structure and is easy to implement.

[0095] In the above embodiments, there are various ways to configure the linear power supply 220. The following are exemplary descriptions, but they are not intended to limit the present invention.

[0096] Figure 7This is a circuit diagram of a linear power supply provided in an embodiment of the present invention. (In conjunction with...) Figure 3 and Figure 7 In one embodiment, the linear power supply 220 includes a second main circuit 221 and a second control unit 222. The second main circuit 221 includes a second feedback terminal 221F. The control terminal of the second control unit 222 serves as the control terminal ENlps of the linear power supply 220. The output terminal of the second control unit 222 is coupled to the second feedback terminal 221F. The second control unit 222 controls whether the linear power supply 220 works by controlling the voltage of the second feedback terminal 221F.

[0097] The second feedback terminal 221F can receive feedback signals from the second main circuit 221 and control the operating state of the second main circuit 221 according to these feedback signals. In this embodiment of the invention, by connecting the second control unit 222 to the second feedback terminal 221F, the potential of the second feedback terminal 221F can be controlled, thereby changing the potential of the second feedback terminal 221F as needed, and thus controlling the operating state of the second main circuit 221. This configuration results in a stable control method, a simple circuit structure, and ease of implementation.

[0098] In this embodiment of the invention, the topology of the second main circuit 221 is not limited, and the second main circuit 221 can be any type of linear power supply topology.

[0099] See also Figure 7 In one embodiment, the second main circuit 221 includes a third transistor Q3 and a Zener diode Z1; wherein, the first terminal of the Zener diode Z1 is coupled to the output terminal of the linear power supply 220, the second terminal of the Zener diode Z1 is coupled to the base of the third transistor Q3, and the first terminal of the third transistor Q3 is coupled to the bus capacitor ( Figure 7 (Not shown in the diagram) The second terminal of the third transistor Q3 is coupled to the power supply terminal of the auxiliary module 230; the second terminal of the Zener diode Z1 serves as the second feedback terminal 221F of the second main circuit 221.

[0100] The third transistor Q3 can control the output current based on the voltage output by the Zener diode Z1 and the second control unit 222, thereby controlling the control state of the first main circuit 211. This configuration results in a stable control method, a simple circuit structure, and ease of implementation.

[0101] See also Figure 7The second main circuit 211 also includes: an input capacitor Clps 1, an output capacitor Clps 2, a resistor R1, and a diode Dlps. Specifically, the input capacitor Clps 1 is connected in parallel to the input terminals of the linear power supply 220 (including the positive input terminal Vinlps+ and the negative input terminal Vinlps-), and the input current of the linear power supply is ilps. The first terminal (e.g., the collector) of the third transistor Q3 is coupled to the positive input terminal Vinlps+, the resistor R1 is connected between the base and collector of the third transistor Q3, and the second terminal (e.g., the emitter) of the third transistor Q3 is coupled to the positive output terminal Volps+. Diode Dlps is connected in anti-parallel to the third transistor Q3. Output capacitor Clps2 is coupled to the output terminals (positive output terminal Volps+ and negative output terminal Volps-) of linear power supply 220. The positive terminal of Zener diode Z1 is coupled to the negative output terminal Volps-, and the negative terminal of Zener diode Z1 is coupled to the base of the third transistor Q3. The output current of the switching power supply is iolps. The second main circuit 221 is set up in this way, and the circuit structure is simple and easy to implement.

[0102] See also Figure 7 In one embodiment, the second control unit 222 includes a second transistor Q4. The base of the second transistor Q4 serves as the control terminal ENLPS of the second control unit 222, the first terminal of the second transistor Q4 is grounded, and the second terminal of the second transistor Q4 serves as the output terminal of the second control unit 222. For example, when the second transistor Q4 is an NPN transistor, if the base of the second transistor Q4 is at a low level, the second transistor Q4 is disconnected, and the second feedback terminal 221F can normally control the third transistor Q3 to work normally according to the negative potential of the Zener diode Z1; if the base of the second transistor Q4 is at a high level, the second transistor Q4 is grounded, pulling the second feedback terminal 221F low, controlling the second transistor Q3 to stop working. In other embodiments, the second transistor Q4 can also be a PNP transistor, etc., as needed. The embodiment of the present invention provides a second control unit 222 including a second transistor Q4, which has a simple structure and is easy to implement.

[0103] Figure 8 A circuit diagram of a power module for another cascaded device provided in an embodiment of the present invention. See also... Figure 8Based on the above embodiments, the power module 200 of the cascaded device further includes a status detection module 240. The detection input terminal of the status detection module 240 is coupled to the output terminal of the switching power supply 210 or the linear power supply 220, and the signal output terminal of the status detection module 240 is coupled to the auxiliary module 230. The status detection module 240 is used to detect the operating status of the switching power supply 210 or the linear power supply 220. For example, the power module 220 is provided with two status detection modules 240, which are used to detect the operating status of the switching power supply 210 and the linear power supply 220, respectively. By setting the status detection module 240, this embodiment of the invention can detect the operating status of the switching power supply 210 and the linear power supply 220, thereby controlling the switching between the switching power supply 210 and the linear power supply 220. For example, when a fault is detected in the switching power supply 210, it can switch to the linear power supply 220. This configuration helps to improve the stability and intelligence of the power module 200.

[0104] Figure 9 This is a circuit diagram of a state detection module provided in an embodiment of the present invention. See also... Figure 9 Based on the above embodiments, the state detection module 240 includes:

[0105] Voltage divider unit 241 is coupled to the detection input terminal and is used to divide the voltage at the detection input terminal. For example, voltage divider unit 241 includes resistors R3 and R4 connected in series, and the connection point of resistors R3 and R4 serves as the output terminal of voltage divider unit 241.

[0106] The first comparator U2 has its first input terminal (e.g., the non-inverting input terminal) coupled to the output terminal of the voltage divider unit 241, and its second input terminal (e.g., the inverting input terminal) connected to the voltage reference value Vporef. The output terminal of the first comparator U2 serves as the output terminal of the state detection module 240.

[0107] The first resistor R5 has its first end connected to the low-voltage power supply Vcc, and its second end is coupled to the output of the first comparator U2.

[0108] For example, the voltage state detection module 240 achieves voltage state detection by comparing the power supply voltage divider value with the voltage reference value Vporef using the first comparator U2. Specifically, the voltage divider unit 241 divides the input voltage of the switching power supply or linear power supply to match the input voltage of the first comparator U2. If the divided voltage value is higher than the voltage reference value Vporef, the output of the first comparator U2 outputs a high level, indicating that the switching power supply or linear power supply is in normal condition. If the divided voltage value is lower than the voltage reference value Vporef, the output of the first comparator U2 outputs a low level, indicating that the switching power supply or linear power supply is in abnormal condition. For example, the voltage reference value Vporef can be set to 90% of the normal operating voltage divider value of the power supply.

[0109] In this embodiment of the invention, the state detection module 240 includes a voltage divider unit 241, a first comparator U2, and a first resistor R5. Its circuit structure is simple and easy to implement. In other embodiments, a sampling circuit can be configured to send the collected voltage of the switching power supply or linear power supply to an auxiliary module 230. The auxiliary module 230 has a built-in state detection module 240, which is implemented by software code.

[0110] See also Figure 8 Based on the above embodiments, the auxiliary module 230 includes a power control unit 231. The first output terminal of the power control unit 231 serves as the first control output terminal of the auxiliary module 230 and is coupled to the control terminal of the switching power supply. This first output terminal is also coupled to the control terminal ENsps of the switching power supply 210. The second output terminal of the power control unit 231 serves as the second control output terminal of the auxiliary module 230 and is coupled to the control terminal of the linear power supply. This second output terminal is also coupled to the control terminal ENlps of the linear power supply 220. The power control unit 231 is implemented using at least one of hardware circuitry and software methods. For example, the power control unit 231 can control the switching between the switching power supply 210 and the linear power supply 220 based on the bus voltage sampling value during power module voltage equalization.

[0111] Figure 10 This is a circuit diagram of a power control unit provided in an embodiment of the present invention. In one embodiment, a hysteresis comparator is used to switch between a switching power supply and a linear power supply. Specifically, the power control unit 231 includes:

[0112] Hysteresis comparator 2311, the first input terminal of hysteresis comparator 2311 is connected to the first equalization reference voltage Vref1, the second input terminal of hysteresis comparator 2311 is connected to the sampled value of DC bus voltage, and the output terminal of hysteresis comparator 2311 outputs the first control signal;

[0113] Inverter U4 has its input terminal coupled to the output terminal of hysteresis comparator 2311, and its output terminal outputs a second control signal; inverter U4 can be, for example, a NOT gate.

[0114] in, Figure 10 In one embodiment, the first control signal is a linear power supply control signal, which is connected to the control terminal of the linear power supply; the second control signal is a switching power supply control signal, which is connected to the control terminal of the switching power supply 210. In other embodiments, the first control signal may also be a switching power supply control signal, which is connected to the control terminal of the switching power supply; and the second control signal may be a linear power supply control signal, which is connected to the control terminal of the linear power supply. The first and second control signals have opposite voltage levels to prevent the switching power supply and the linear power supply from operating simultaneously during voltage equalization by the power module.

[0115] Figure 11 The diagram shows the characteristic curves of a hysteresis comparator provided in an embodiment of the present invention. See also... Figure 11 For example, two threshold values ​​are set, namely the high-voltage threshold value V. H and low-voltage threshold value V L Set the output level of the hysteresis comparator 2311 to a high level U. OH and low level U OL When the sampled value of the bus voltage > the high voltage threshold V H When the sampled value of the bus voltage is less than the low-voltage threshold value V, the hysteresis comparator 2311 outputs a low level; L When the hysteresis comparator 2311 outputs a high level, the sampled value of the bus voltage is within V. L ~V H During this period, the output level of the hysteresis comparator 2311 remains unchanged.

[0116] The state table for voltage equalization using a hysteresis comparator is shown in Table 1.

[0117] Table 1

[0118] Sampled value of bus voltage <![CDATA[>In H ]]> <![CDATA[<V L ]]> <![CDATA[V L ~V H ]]> Hysteresis comparator output <![CDATA[Low level U OL > <![CDATA[High level U OL > remain unchanged Power supply status Linear power supply with separate power supply Switching power supply with separate power supply remain unchanged Bus capacitor charging and discharging status Discharge Charge remain unchanged

[0119] Referring to Table 1, further, when the hysteresis comparator 2311 outputs a low level U... OL At that time, the linear power supply control signal is low level U. OL The switching power supply control signal is high level U. OH When the linear power supply is working, the switching power supply is not working. As analyzed above, when the linear power supply is working, the bus capacitor discharges, and the bus voltage decreases to achieve voltage equalization. When the hysteresis comparator 2311 outputs a high level U... OH At that time, the linear power supply control signal is high level U. OH The switching power supply control signal is low level U.OL The linear power supply is not working, while the switching power supply is working. As can be seen from the above analysis, when the switching power supply is working, the bus capacitor is charged, and the bus voltage increases to achieve voltage equalization.

[0120] Therefore, it can be seen that using a hysteresis comparator helps to avoid frequent switching between switching power supplies and linear power supplies, thereby improving the stability of power module operation.

[0121] See also Figure 10 In one embodiment, the hysteresis comparator 2311 includes a comparator U3, resistors R6, R7, and R11. The non-inverting input of comparator U3 is connected to a first equalization reference voltage Vref1 via resistor R11, the inverting input of comparator U3 is connected to a sampled value of the bus voltage, and the output of the comparator is the output of the hysteresis comparator 2311. Resistor R6 is connected between the non-inverting input and output of comparator U3. The first end of resistor R7 is coupled to the low-voltage power supply Vcc, and the second end of resistor R7 is coupled to the output of comparator U3. The high-voltage threshold Vref1 of the hysteresis comparator 2311 can be adjusted by adjusting the values ​​of the first equalization reference voltage Vref1, resistors R11, R6, and R7. H and low-voltage threshold value V L The adjustment is as follows. The hysteresis comparator 2311 is configured in this way, resulting in a simple circuit structure that is easy to implement.

[0122] For example, the high-voltage threshold value V L and low-voltage threshold value V H The average bus voltage U of all power modules can be used as a reference. ave To set this, specifically, the high voltage threshold value V is adjusted by modifying the first equalization reference voltage Vref1, resistor R6, and resistor R7. H Set to 1.2×k u ×U ave The low-voltage threshold value V L Set to 0.8×k u ×U ave Among them, k u The sampling coefficient for bus voltage.

[0123] Figure 12 This is a circuit diagram of another power control unit provided in an embodiment of the present invention. In one embodiment, a closed-loop control scheme is used to switch between the switching power supply and the linear power supply, resulting in more precise control. Specifically, the power control unit 231 includes:

[0124] The compensation amplifier 2312 has a first input terminal connected to a second equalization reference voltage Vref2, and a second input terminal connected to a sampled value of the DC bus voltage. The output terminal of the compensation amplifier 2312 outputs a carrier comparison signal VEA, which is an analog signal.

[0125] The second comparator 2313 has its first input terminal coupled to the output terminal of the compensation amplifier 2312. The second input terminal of the second comparator 2313 is connected to the carrier signal Vf, and the output terminal of the second comparator 2313 outputs the first control signal.

[0126] Inverter U7 has its input terminal coupled to the output terminal of the second comparator 2313, and its output terminal outputs the second control signal; inverter U7 can be, for example, a NOT gate.

[0127] in, Figure 12 In one embodiment, the first control signal is a linear power supply control signal, which is connected to the control terminal of the linear power supply; the second control signal is a switching power supply control signal, which is connected to the control terminal of the switching power supply 210. In other embodiments, the first control signal may also be a switching power supply control signal, which is connected to the control terminal of the switching power supply; and the second control signal may be a linear power supply control signal, which is connected to the control terminal of the linear power supply. The first and second control signals are digital signals with opposite voltage levels, so as to prevent the switching power supply and the linear power supply from operating simultaneously during the voltage equalization process of the power module.

[0128] Figure 13 This is a waveform diagram illustrating closed-loop control voltage equalization provided in an embodiment of the present invention. See also... Figure 13 For example, the carrier signal Vf is a triangular wave with a period of T; the second equalization reference voltage Vref2 can be based on the average value U of the bus voltages of all power modules. ave To set, for example, set the second equalization reference voltage Vref2 = k u ×U ave , where k u The sampling coefficient for bus voltage.

[0129] Combination Figure 12 and Figure 13 When the sampled value of the bus voltage decreases, the carrier comparison signal VEA output by the compensation amplifier 2312 increases; when the sampled value of the bus voltage increases, the carrier comparison signal VEA output by the compensation amplifier 2312 decreases. When the carrier comparison signal VEA is higher than the instantaneous value of the carrier signal Vf, the second comparator 2313 outputs a high level; when the carrier comparison signal VEA is lower than the instantaneous value of the carrier signal Vf, the second comparator 2313 outputs a low level.

[0130] The state table for pressure equalization using a closed-loop control scheme is shown in Table 2.

[0131] Sampled value of bus voltage rise reduce Carrier Comparison Signal VEA Decrease Increase High level duration TH Decrease Increase Low level duration TL Increase Decrease Current consumed by the power supply Increase Decrease

[0132] Assume that within one period T, the duration of the high level of the second comparator 2313 is TH, and the duration of the low level is TL, where TH + TL = T. When the second comparator 2313 outputs a high level, the linear power supply control signal is high, the switching power supply control signal is low, the linear power supply is not working, and the switching power supply is working; that is, the duration of the switching power supply's operation is TH. When the second comparator 2313 outputs a low level, the linear power supply control signal is low, the switching power supply control signal is high, the linear power supply is working, and the switching power supply is not working; that is, the duration of the linear power supply's operation is TL. Within one period T, the average current consumed by the switching power supply and the linear power supply is:

[0133]

[0134] Wherein, the average current i ave It can be controlled in i sps ~i lps Between. As can be seen from the above analysis, i sps lps When the bus voltage increases, the carrier comparison signal VEA decreases, the operating duration TH of the switching power supply decreases, and the operating duration TL of the linear power supply increases. This increases the current consumed by the power supply (including both linear and switching power supplies), thus reducing the voltage of the bus capacitor. Conversely, when the bus voltage decreases, the carrier comparison signal VEA increases, TH increases, the operating duration TL of the linear power supply decreases, and the current consumed by the power supply (including both linear and switching power supplies) decreases, thus increasing the voltage of the bus capacitor. This embodiment of the invention achieves closed-loop control of the power supply by adding a compensation amplifier 2312, thereby achieving precise control of the charging and discharging current of the bus capacitor and ultimately precise control of the bus voltage.

[0135] See also Figure 12 In one embodiment, the compensation amplifier 2312 is a Type II compensation amplifier, specifically including an operational amplifier U5, resistors R8 and R9, and capacitors C1 and C2. The inverting input of operational amplifier U5 is connected to the sampled value of the bus voltage through resistor R8, and the non-inverting input is connected to the second equalization reference voltage Vref2. The output of operational amplifier U5 outputs a carrier comparison signal VEA. The two ends of capacitor C2 are connected to the inverting input and output of operational amplifier U5, respectively. Capacitor C1 and resistor R9 are connected in series and to the inverting input and output of operational amplifier U5. This configuration of the compensation amplifier 2312 results in a simple circuit structure that is easy to implement. ​

[0136] The second comparator 2313 includes comparator U6 and resistor R10. The non-inverting input of comparator U6 is coupled to the output of compensation amplifier 2312, and the inverting input of comparator U6 is connected to a carrier signal Vf. The output of comparator U6 outputs a first control signal. The first end of resistor R10 is connected to a low-voltage power supply Vcc, and the second end of resistor R10 is coupled to the output of comparator U6. This configuration of the second comparator 2313 results in a simple circuit structure that is easy to implement.

[0137] It should be noted that the compensation amplifier 2312 can also be configured as other types of compensation amplifiers, such as Type I compensation amplifiers or Type III compensation amplifiers, which can be set according to the needs in practical applications.

[0138] This invention also provides a control method for the power module of a cascaded device. This control method can be applied to the power module of the cascaded device as provided in any embodiment of this invention and has corresponding beneficial effects. The control method is executed by an auxiliary module, which can be implemented by software and / or hardware. Specifically, when the power module is performing voltage equalization, the auxiliary module controls the supply of power to the auxiliary module from a switching power supply or a linear power supply based on the acquired DC bus voltage.

[0139] In this embodiment of the invention, the linear power supply and the switching power supply are controlled to supply power to the auxiliary module in a switching manner during voltage equalization. The constant current characteristic of the linear power supply is used in conjunction with the constant power characteristic of the switching power supply to achieve voltage equalization of the power module. The principle of voltage equalization has been described in detail in the foregoing embodiments and will not be repeated here.

[0140] The control methods for the power modules of cascaded devices are illustrated in the various embodiments described, and these control methods are also within the scope of protection of this invention.

[0141] Figure 14 This is a flowchart illustrating a control method for switching between a switching power supply and a linear power supply using a hysteresis comparator, provided as an embodiment of the present invention. See also... Figure 14 The auxiliary module is powered by a switching power supply or a linear power supply based on the collected DC bus voltage, including the following steps:

[0142] S310. Determine the upper and lower limits of adjustment based on the target value of equal pressure.

[0143] The voltage equalization target value could be, for example, the average bus voltage U of all power modules. ave The upper limit value is adjusted to the high-voltage threshold value V. H The lower limit value is adjusted to the low-voltage threshold value V. L ;

[0144] S320. Determine the relationship between the sampled value of the DC bus voltage and the upper and lower adjustment limits;

[0145] S330. If the sampled value of the DC bus voltage is greater than the adjustment upper limit, control the power supply to the auxiliary module separately from the linear power supply.

[0146] S340. If the sampled value of the DC bus voltage is less than the adjustment lower limit, the control will supply power to the auxiliary module separately from the switching power supply.

[0147] S350. If the sampled value of the DC bus voltage is between the lower and upper adjustment limits, the power supply of the auxiliary module remains unchanged.

[0148] The method of switching between switching power supplies and linear power supplies using a hysteresis comparator is simple to implement and has a fast response.

[0149] Figure 15 This is a flowchart illustrating a control method for switching between a switching power supply and a linear power supply using a closed-loop control scheme, provided as an embodiment of the present invention. See also... Figure 15 The auxiliary module is powered by a switching power supply or a linear power supply based on the collected DC bus voltage, including the following steps:

[0150] S410. Determine the adjustment reference value based on the target pressure equalization value;

[0151] The voltage equalization target value could be, for example, the average bus voltage U of all power modules. ave The reference value is adjusted to the second equalization reference voltage Vref2.

[0152] S420. Determine the carrier comparison value based on the sampled value of the DC bus voltage and the adjustment reference value;

[0153] The carrier comparison value is the value of the carrier comparison signal VEA.

[0154] S430. Determine the relationship between the sampled value of the DC bus voltage and the carrier comparison value;

[0155] S440. If the carrier comparison value is greater than the instantaneous value of the carrier signal, control the power supply to the auxiliary module separately from the switching power supply.

[0156] S450. If the carrier comparison value is less than the instantaneous value of the carrier signal, control the linear power supply to supply power to the auxiliary module separately.

[0157] The carrier comparison value lies between the maximum and minimum values ​​of the carrier signal. Within one cycle of the carrier signal, the sum of the time the switching power supply provides power to the auxiliary module alone and the time the linear power supply provides power to the auxiliary module alone equals the cycle of the carrier signal. The carrier comparison value determines the ratio of the time the switching power supply provides power to the auxiliary module alone to the time the linear power supply provides power to the auxiliary module alone within one cycle. When the duration of operation of the linear power supply increases, the current consumed by the power supply (including both linear and switching power supplies) increases, achieving discharge and reducing the voltage of the bus capacitor. Conversely, when the duration of operation of the switching power supply increases, the current consumed by the power supply (including both linear and switching power supplies) decreases, achieving charging and increasing the voltage of the bus capacitor, thus achieving voltage equalization.

[0158] The method of switching between switching power supplies and linear power supplies by adopting a closed-loop control scheme results in more precise control.

[0159] Based on the above embodiments, the operating conditions for voltage equalization of the power module 200 include at least one of the following: equipment standby, equipment no-load, and equipment light load. During normal equipment operation, the auxiliary module can control the voltage equalization of each power module by controlling the switching state of the inverter circuit. Therefore, under normal operating conditions, there is generally no bus voltage imbalance. However, under conditions such as equipment standby, equipment no-load, and equipment light load, voltage equalization cannot be performed using the inverter circuit; therefore, an additional voltage equalization circuit is required. This embodiment of the invention cleverly utilizes the different characteristics of linear power supplies and switching power supplies by setting up line power supplies for voltage equalization, and it suffers lower losses compared to voltage equalization circuits such as voltage equalization resistors.

[0160] Based on the above embodiments, the control method further includes: during device startup, power is supplied to the auxiliary module by both a switching power supply and a linear power supply. Simultaneously activating both the switching power supply and the linear power supply during device startup facilitates the monitoring of both power supplies, thereby promoting safer device operation.

[0161] Based on the above embodiments, the control method further includes: during normal operation of the equipment, the switching power supply serves as the main power supply for the power module, and the linear power supply serves as the backup power supply for the power module. Specifically, when a switching power supply failure is detected, the system can switch to linear power supply. This configuration helps improve the stability of the power module's operation.

[0162] The cascaded device provided in this embodiment of the invention can be applied to scenarios such as static var generators. Figure 16 This is a circuit diagram of a cascaded device provided in an embodiment of the present invention. See also... Figure 16The cascaded device includes n cascaded power modules 200 as provided in any embodiment of the present invention, where n ≥ 2. The technical principle and effect of voltage equalization of this cascaded device are similar to those of the aforementioned embodiments and will not be repeated here.

[0163] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0164] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A cascaded device, characterized in that, Includes at least two cascaded power modules; The power module includes a bus capacitor, a switching power supply, a linear power supply, an auxiliary module, and a power module. The power module, the input terminal of the switching power supply, and the input terminal of the linear power supply are all coupled to the two ends of the bus capacitor; the switching power supply is used to convert the DC bus voltage on the bus capacitor into a first supply voltage, and the linear power supply is used to convert the DC bus voltage into a second supply voltage. The power supply terminal of the auxiliary module is coupled to the output terminal of the switching power supply, and the power supply terminal of the auxiliary module is coupled to the output terminal of the linear power supply; the auxiliary module controls the power supply from the switching power supply or the linear power supply to the auxiliary module according to the DC bus voltage and the voltage equalization target value, so as to perform voltage equalization control on the power module; wherein, the voltage equalization target value is the average value of the bus voltage of all the power modules.

2. The cascaded device according to claim 1, characterized in that, The switching power supply includes a first main circuit and a first control unit. The first main circuit includes a first feedback terminal. The control terminal of the first control unit serves as the control terminal of the switching power supply. The output terminal of the first control unit is coupled to the first feedback terminal. The first control unit controls whether the switching power supply works by controlling the voltage of the first feedback terminal. The linear power supply includes a second main circuit and a second control unit. The second main circuit includes a second feedback terminal. The control terminal of the second control unit serves as the control terminal of the linear power supply. The output terminal of the second control unit is coupled to the second feedback terminal. The second control unit controls whether the linear power supply works by controlling the voltage of the second feedback terminal.

3. The cascaded device according to claim 2, characterized in that, The first control unit includes a first transistor, the base of the first transistor serves as the control terminal of the first control unit, the first terminal of the first transistor is grounded, and the second terminal of the first transistor serves as the output terminal of the first control unit; And / or, the second control unit includes a second transistor, the base of the second transistor serving as the control terminal of the second control unit, the first terminal of the second transistor being grounded, and the second terminal of the second transistor serving as the output terminal of the second control unit.

4. The cascaded device according to claim 2, characterized in that, The first main circuit includes a switching transistor, an energy storage element, a power control subunit, and a feedback regulation circuit; wherein, the input terminal of the feedback regulation circuit is coupled to the output terminal of the switching power supply, the output terminal of the feedback regulation circuit is coupled to the feedback terminal of the power control subunit, the control terminal of the power control subunit is electrically connected to the gate of the switching transistor, the first terminal of the switching transistor is coupled to the bus capacitor, and the second terminal of the switching transistor is coupled to the energy storage element; the feedback terminal of the power control subunit serves as the first feedback terminal of the first main circuit. And / or, the second main circuit includes a third transistor and a Zener diode; wherein, the first terminal of the Zener diode is coupled to the output terminal of the linear power supply, the second terminal of the Zener diode is coupled to the base of the third transistor, the first terminal of the third transistor is coupled to the bus capacitor, and the second terminal of the third transistor is coupled to the power supply terminal of the auxiliary module; the second terminal of the Zener diode serves as the second feedback terminal of the second main circuit.

5. The cascaded device according to claim 1, characterized in that, Also includes: A status detection module is provided, wherein the detection input terminal of the status detection module is coupled to the output terminal of the switching power supply or the output terminal of the linear power supply, and the signal output terminal of the status detection module is coupled to the auxiliary module; the status detection module is used to detect the operating status of the switching power supply or the linear power supply.

6. The cascaded device according to claim 5, characterized in that, The status detection module includes: A voltage divider unit, coupled to the detection input terminal, is used to divide the voltage at the detection input terminal. A first comparator has its first input terminal coupled to the output terminal of the voltage divider unit, its second input terminal connected to a voltage reference value, and its output terminal serving as the output terminal of the state detection module. The first resistor has its first end connected to a low-voltage power supply, and its second end coupled to the output of the first comparator.

7. The cascaded device according to claim 1, characterized in that, The auxiliary module includes a power control unit. The first output terminal of the power control unit is coupled to the control terminal of the switching power supply as the first control output terminal of the auxiliary module. The second output terminal of the power control unit is coupled to the control terminal of the linear power supply as the second control output terminal of the auxiliary module. The power control unit is implemented using at least one of hardware circuits and software methods.

8. The cascaded device according to claim 7, characterized in that, The power control unit includes: A hysteresis comparator, wherein the first input terminal of the hysteresis comparator is connected to a first equalization reference voltage, the second input terminal of the hysteresis comparator is connected to a sampled value of the DC bus voltage, and the output terminal of the hysteresis comparator outputs a first control signal; An inverter, the input of which is coupled to the output of the hysteresis comparator, and the output of which outputs a second control signal; Wherein, the first control signal is connected to the control terminal of the switching power supply and the second control signal is connected to the control terminal of the linear power supply; or, the first control signal is connected to the control terminal of the linear power supply and the second control signal is connected to the control terminal of the switching power supply.

9. The cascaded device according to claim 7, characterized in that, The power control unit includes: A compensation amplifier, wherein the first input terminal of the compensation amplifier is connected to a second equalization reference voltage, and the second input terminal of the compensation amplifier is connected to a sampled value of the DC bus voltage; The second comparator has its first input terminal coupled to the output terminal of the compensation amplifier, its second input terminal connected to a carrier signal, and its output terminal outputting a first control signal. An inverter, wherein the input terminal of the inverter is coupled to the output terminal of the second comparator, and the output terminal of the inverter outputs a second control signal; Wherein, the first control signal is connected to the control terminal of the switching power supply and the second control signal is connected to the control terminal of the linear power supply; or, the first control signal is connected to the control terminal of the linear power supply and the second control signal is connected to the control terminal of the switching power supply.

10. A control method for cascaded devices, characterized in that, Applied to the cascaded device as described in any one of claims 1-9, the control method is executed by the auxiliary module; During the voltage equalization process of the power module, the auxiliary module controls the power supply to be supplied by the switching power supply or the linear power supply based on the collected DC bus voltage.

11. The control method for cascaded equipment according to claim 10, characterized in that, The step of controlling the supply of power to the auxiliary module by the switching power supply or the linear power supply based on the collected DC bus voltage includes: The upper and lower adjustment limits are determined based on the target pressure equalization value. If the sampled value of the DC bus voltage is greater than the adjustment upper limit, then control the linear power supply to supply power to the auxiliary module separately; If the sampled value of the DC bus voltage is less than the adjustment lower limit, then the auxiliary module is powered separately by the switching power supply. If the sampled value of the DC bus voltage is between the lower adjustment limit and the upper adjustment limit, the power supply of the auxiliary module remains unchanged.

12. The control method for cascaded equipment according to claim 10, characterized in that, The step of controlling the supply of power to the auxiliary module by the switching power supply or the linear power supply based on the collected DC bus voltage includes: The adjustment baseline value is determined based on the target value of the equalizing pressure. The carrier comparison value is determined based on the sampled value of the DC bus voltage and the adjustment reference value; If the carrier comparison value is greater than the instantaneous value of the carrier signal, then the auxiliary module is powered separately by the switching power supply. If the carrier comparison value is less than the instantaneous value of the carrier signal, then the linear power supply is used to supply power to the auxiliary module separately. The carrier comparison value is between the maximum and minimum values ​​of the carrier signal. Within one period of the carrier signal, the sum of the time during which the switching power supply alone powers the auxiliary module and the time during which the linear power supply alone powers the auxiliary module is equal to the period of the carrier signal.

13. The control method for cascaded equipment according to claim 10, characterized in that, The operating conditions for equalizing the voltage of the power module include at least one of the following: equipment standby, equipment no-load, and equipment light-load.

14. The control method for cascaded equipment according to claim 10, characterized in that, Also includes: During the device startup process, the auxiliary module is powered by the switching power supply and the linear power supply; And / or, during normal operation of the equipment, the switching power supply serves as the main power supply for the power module, and the linear power supply serves as the backup power supply for the power module.

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