A self-powered circuit, method, bridge circuit, and power converter

Abstract

This invention discloses a self-powered circuit, method, bridge circuit, and power converter, relating to the field of power electronics technology. When a DC power supply charges each series-connected clamping capacitor, the balancing circuit and the auxiliary power supply simultaneously consume the current provided by the DC power supply. Since the auxiliary power supply operates in constant power mode, the current consumed by the auxiliary power supply decreases as the voltage of the clamping capacitor increases, exhibiting negative resistance. Meanwhile, the current consumed by the balancing circuit increases as the voltage across its terminals increases, and its positive resistance can offset the negative resistance of the auxiliary power supply, preventing the clamping capacitor voltage from becoming unstable due to positive voltage feedback. For each clamping capacitor, a corresponding balancing circuit is set up. The balancing circuit passively controls the equivalent resistance across each clamping capacitor to exhibit positive resistance, keeping the voltage of each clamping capacitor consistent, thereby suppressing voltage oscillations of the clamping capacitor and ensuring the normal startup and operation of the auxiliary power supply.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a self-powered circuit, method, bridge circuit, and power converter. Background Technology

[0002] In the medium- and high-voltage (10kV and above) field, to ensure that power electronic devices meet the withstand voltage requirements when connected to the medium- and high-voltage power grid, besides using high-voltage power semiconductor devices, a feasible alternative is to use a series system of devices. This involves connecting multiple low-voltage power semiconductor devices in series to meet the withstand voltage requirements of medium- and high-voltage applications. To save design costs, current medium- and high-voltage power electronic converters use self-powered auxiliary power supplies for the series-connected power semiconductor devices. Compared to traditional external centralized power supply schemes, self-powered auxiliary power supplies have significant advantages in reducing the insulation requirements of the auxiliary power supply itself, suppressing common-mode interference, and reducing the cost of the auxiliary power supply system. The auxiliary power supply provides the power required to drive the power semiconductor devices, thereby ensuring the effective operation of the series-connected system. Therefore, ensuring a stable supply of auxiliary power in this architecture is a pressing issue that needs to be addressed.

[0003] In existing technologies, clamping capacitors are connected in parallel across each series-connected power semiconductor device to ensure voltage equalization. During the initial power-on phase of the series-connected system, due to the constant power characteristics of the auxiliary power supply, the voltage distribution during pre-charging of the clamping capacitors often exhibits imbalance and voltage oscillations. Once these voltage oscillations occur, the auxiliary power supply is highly susceptible to repeated start-stop cycles due to input voltage fluctuations exceeding its normal operating range, making it impossible to establish a stable normal operating state. Summary of the Invention

[0004] The purpose of this invention is to provide a self-powered circuit, method, bridge circuit, and power converter to solve the problem that the auxiliary power supply cannot be turned on normally due to repeated start-stop cycles caused by voltage oscillations during the initial power-on stage of the series power device circuit and the pre-charging stage of the clamping capacitor.

[0005] In a first aspect, the present invention provides a self-powered circuit applied to a series power device circuit. The series power device circuit includes a plurality of series-connected device series units. Each device series unit includes a main power device, an auxiliary power device, and a clamping capacitor. The main power devices in the plurality of series-connected device series units are connected in series. The first terminal of the auxiliary power device is connected to the first terminal of the main power device. The first terminal of the clamping capacitor is connected to the second terminal of the auxiliary power device. The second terminal of the clamping capacitor is connected to the second terminal of the main power device. A plurality of self-powered circuits are connected one-to-one with a plurality of device series units in the series power device circuit.

[0006] For any self-powered circuit, the self-powered circuit includes:

[0007] An auxiliary power supply is used to obtain energy from the corresponding clamping capacitor. When the voltage of the corresponding clamping capacitor reaches a first preset voltage, it starts after a preset delay time. After it is fully started, it outputs voltage to the control terminal of the corresponding main power device so that the controller can drive each main power device to operate normally after all the auxiliary power supplies are fully started. The output power of the auxiliary power supply is constant, and the input terminal of the auxiliary power supply has a negative resistance characteristic.

[0008] A balancing circuit, wherein a first terminal of the balancing circuit is connected to the first input terminal of the auxiliary power supply and the first terminal of the clamping capacitor in the corresponding series unit of the device, and a second terminal is connected to the second input terminal of the auxiliary power supply and the second terminal of the clamping capacitor in the corresponding series unit of the device; the two ends of the balancing circuit have positive resistance characteristics; the balancing circuit is used to control the conduction or cutoff based on a preset control signal;

[0009] When the balancing circuit is turned on, the positive dynamic resistance of the balancing circuit is less than the absolute value of the negative dynamic resistance of the auxiliary power supply, so that the corresponding self-powered circuit exhibits positive resistance characteristics.

[0010] Optionally, the balancing circuit includes:

[0011] The first resistive element, with its first end serving as the first end of the balancing circuit, is connected to the first input end of the corresponding auxiliary power supply and the first end of the corresponding clamping capacitor, respectively.

[0012] The first voltage regulator has its positive terminal connected to the second terminal of the first resistor element. The voltage regulation threshold of the first voltage regulator is a second preset voltage. The first voltage regulator is used to cut off when the voltage of the corresponding clamping capacitor is less than the second preset voltage; and to maintain the voltage across the first resistor element at the difference between the voltage of the corresponding clamping capacitor and the second preset voltage when the voltage of the corresponding clamping capacitor is not less than the second preset voltage. The second preset voltage is less than the first preset voltage.

[0013] The normally open switch has its first terminal connected to the negative terminal of the first voltage regulator, its second terminal serving as the second terminal of the balancing circuit, and is connected to the second input terminal of the corresponding auxiliary power supply and the second terminal of the corresponding clamping capacitor, respectively. The control terminal is connected to the output terminal of the controller; the normally open switch is turned on by default.

[0014] The controller is used to output a preset control signal to control the normally open switch to turn off when the voltage of the corresponding clamping capacitor reaches a third preset voltage; the third preset voltage is greater than a fourth preset voltage and less than a fifth preset voltage; wherein, the fourth preset voltage is the maximum voltage that the clamping capacitor can reach before the auxiliary power supply is fully started, and the fourth preset voltage is greater than a first preset voltage, and the fifth preset voltage is the rated voltage reached by the clamping capacitor after the main power device operates normally.

[0015] Optionally, the auxiliary power supply is a DC / DC converter.

[0016] Optionally, the controller is also used for:

[0017] When all auxiliary power supplies in the series power device circuit are fully started, a drive signal is output to the control terminal of the main power device and / or the control terminal of the auxiliary power device to control the main power device and / or the auxiliary power device to operate normally and realize power conversion.

[0018] Optionally, the self-powered circuit further includes:

[0019] The first end of the second resistor element is connected to the first end of the first resistor element, the first input end of the corresponding auxiliary power supply, and the first end of the corresponding clamping capacitor.

[0020] The positive terminal of the second voltage regulator is connected to the second end of the second resistor element. The voltage regulation threshold of the second voltage regulator is a seventh preset voltage, which is greater than the first preset voltage and less than the third preset voltage.

[0021] The controllable switch has its first terminal connected to the negative terminal of the second voltage regulator, its second terminal connected to the second terminal of the normally open switch, the second input terminal of the corresponding auxiliary power supply, and the second terminal of the corresponding clamping capacitor, and its control terminal connected to the output terminal of the controller.

[0022] The controller is also used to output a preset control signal to control the normally open switch to turn off when the voltage of the corresponding clamping capacitor reaches a third preset voltage, and to control the controllable switch to turn on, so that the second resistive element, the second voltage regulator and the controllable switch take over the voltage equalization control of the clamping capacitor.

[0023] Secondly, the present invention provides a bridge circuit, including N bridge arm structures and a self-powered circuit as described above, where N is a positive integer.

[0024] The bridge arm structure includes a first bridge arm composed of a series power device circuit and a second bridge arm composed of a series power device circuit, and the self-powered circuit is connected to the series unit of the device in the series power device circuit.

[0025] Optionally, the bridge circuit further includes a first bus capacitor and a second bus capacitor;

[0026] The first end of the first bus capacitor is connected to the first output terminal of the power supply and the first end of the first bridge arm, respectively. The second end is connected to the first end of the second bus capacitor and the first end of the load, respectively. The second end of the first bridge arm is connected to the second end of the load and the first end of the second bridge arm, respectively. The second end of the second bus capacitor is connected to the second output terminal of the power supply and the second end of the second bridge arm, respectively.

[0027] Thirdly, the present invention provides a power converter including the bridge circuit as described above.

[0028] Fourthly, the present invention provides a self-powered method applied to a series power device circuit. The series power device circuit includes a plurality of series-connected device series units. Each device series unit includes a main power device, an auxiliary power device, and a clamping capacitor. The main power devices in the plurality of series-connected device series units are connected in series. The first terminal of the auxiliary power device is connected to the first terminal of the main power device. The first terminal of the clamping capacitor is connected to the second terminal of the auxiliary power device, and the second terminal of the clamping capacitor is connected to the second terminal of the main power device. A plurality of self-powered circuits as described above are connected one-to-one with the plurality of device series units in the series power device circuit. The self-powered method includes:

[0029] When the clamping capacitor in the series-connected device unit is charged, energy is obtained from the corresponding clamping capacitor through the auxiliary power supply in the self-powered circuit, so that the auxiliary power supply starts after a preset delay time when the voltage of the corresponding clamping capacitor reaches the first preset voltage, and outputs voltage to the control terminal of the corresponding main power device after full startup; wherein, the input terminal of the auxiliary power supply has a negative resistance characteristic.

[0030] The energy of the corresponding clamping capacitor is consumed by the balancing circuit that is turned on in the self-powered circuit; wherein, the two ends of the balancing circuit have positive resistance characteristics, and when the balancing circuit is turned on, the positive dynamic resistance of the balancing circuit is less than the absolute value of the negative dynamic resistance of the auxiliary power supply.

[0031] After all the auxiliary power supplies are fully started, they drive each main power device to operate normally.

[0032] This invention provides a self-powered circuit applied to series power device circuits. The self-powered circuit includes a balancing circuit and an auxiliary power supply. Both the balancing circuit and the auxiliary power supply are connected in parallel across the clamping capacitors of the series-connected units in the series power device circuit. When a DC power supply is present to charge each of the series-connected clamping capacitors, the balancing circuit and the auxiliary power supply simultaneously consume the current provided by the DC power supply. Since the auxiliary power supply operates in constant power mode, the current consumed by the auxiliary power supply decreases as the voltage of the clamping capacitor increases, exhibiting negative resistance. Meanwhile, the current consumed by the balancing circuit increases as its own voltage increases, and its positive resistance can offset the negative resistance of the auxiliary power supply, thereby limiting the voltage change of the clamping capacitor and preventing the clamping capacitor voltage from becoming unstable due to positive voltage feedback. For each clamping capacitor, a corresponding balancing circuit is provided. The balancing circuit passively controls the equivalent resistance across each clamping capacitor to exhibit positive resistance, ensuring that the voltage of each clamping capacitor remains consistent, thereby suppressing voltage oscillations and ensuring the normal startup of the auxiliary power supply.

[0033] The present invention also provides a bridge circuit and a power converter, which have the same beneficial effects as the self-powered circuit described above. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the 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.

[0035] Figure 1 A schematic diagram of a self-powered circuit provided by the present invention;

[0036] Figure 2 A schematic diagram comparing the current consumption before and after setting up a balancing circuit, provided for the present invention;

[0037] Figure 3 A schematic diagram of a half-bridge topology circuit based on series power device circuit provided by the present invention;

[0038] Figure 4 A schematic diagram of a balanced circuit structure corresponding to a single device series unit provided by the present invention;

[0039] Figure 5 A circuit equivalent diagram of a series power device circuit and its corresponding self-powered circuit provided by the present invention in the stage when the auxiliary power supply is not started;

[0040] Figure 6A circuit equivalent diagram of a series power device circuit and its corresponding self-powered circuit during the startup phase of the auxiliary power supply section, provided by the present invention.

[0041] Figure 7 A circuit equivalent diagram of a series power device circuit and its corresponding self-powered circuit provided by the present invention at the moment when the auxiliary power supply is fully started.

[0042] Figure 8 A circuit equivalent diagram of a series power device circuit and its corresponding self-powered circuit during the normal operation phase of the series power device circuit, provided by the present invention.

[0043] Figure 9 A schematic diagram of the startup process of a power converter provided by the present invention;

[0044] Figure 10 A schematic diagram of a balanced circuit structure corresponding to another device series unit provided by the present invention;

[0045] Figure 11 A schematic diagram comparing the clamping capacitor voltages of the three series-connected devices provided by this invention before and after setting the balancing circuit;

[0046] Figure 12 A schematic diagram comparing the losses of the first resistive element with and without the first voltage regulator device in the balancing circuit provided by the present invention. Detailed Implementation

[0047] The core of this invention is to provide a self-powered circuit, method, bridge circuit, and power converter. By utilizing the positive resistance of the balancing circuit to cancel the negative resistance of the auxiliary power supply, the auxiliary power supply and the balancing circuit as a whole present positive resistance. This causes the voltage of each clamping capacitor to automatically tend to be consistent, thereby suppressing the voltage oscillation of the clamping capacitor and ensuring the normal start-up of the auxiliary power supply.

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] See Figure 1 As shown, Figure 1This invention provides a schematic diagram of a self-powered circuit. In a first aspect, the invention provides a self-powered circuit applied to a series power device circuit. The series power device circuit includes several series-connected device series units 1, each device series unit 1 including a main power device S and an auxiliary power device S2. a and clamping capacitor C a The main power device S in the series-connected unit 1 is connected in series; the auxiliary power device S a The first terminal is connected to the first terminal of the main power device S, and the clamping capacitor C a The first terminal and the auxiliary power device S a The second terminal is connected to the clamping capacitor C. a The second end is connected to the second end of the main power device S; several self-powered circuits are connected one-to-one with several device series units 1 in the series power device circuit;

[0050] For any self-powered circuit 2, the self-powered circuit 2 includes:

[0051] Auxiliary power supply 22 is used to supply power from the corresponding clamping capacitor C. a Energy is obtained from the upper part of the clamping capacitor C. a When the voltage reaches the first preset voltage, it starts after a preset delay time, and after it is fully started, it outputs voltage to the control terminal of the corresponding main power device S so that the controller can drive each main power device S to operate normally after all auxiliary power supplies 22 are fully started; the output power of auxiliary power supply 22 is constant, and the input terminal of auxiliary power supply 22 has a negative resistance characteristic.

[0052] The first terminal of the balancing circuit 21 is connected in series with the first input terminal of the auxiliary power supply 22 and the clamping capacitor C in the corresponding device unit. a The first terminal is connected, and the second terminal is connected to the second input terminal of the auxiliary power supply 22 and the clamping capacitor C in the corresponding device series unit. a The second end is connected; the two ends of the balancing circuit 21 have positive resistance characteristics; the balancing circuit 21 is used to control the conduction or cutoff based on a preset control signal;

[0053] When the balancing circuit 21 is turned on, the positive dynamic resistance of the balancing circuit 21 is less than the absolute value of the negative dynamic resistance of the auxiliary power supply 22, so that the corresponding self-powered circuit 2 exhibits positive resistance characteristics.

[0054] It is not difficult to understand that the main power device S and the auxiliary power device S in the device series unit 1 aAll devices require a controller to control the switching action. The controller needs power to function properly. If a power supply module is installed externally to the power distribution system corresponding to device series unit 1, this module needs strong insulation and good common-mode noise immunity, increasing design complexity and cost. To reduce the impact of common-mode interference and alleviate insulation design pressure, device series unit 1 uses a self-powered circuit 2. This circuit includes an auxiliary power supply 22, which draws power from the local device series unit 1 and supplies it to the controller, thus achieving self-powering for device series unit 1. Furthermore, for modular design convenience, each device series unit 1 has a corresponding self-powered circuit 2.

[0055] In practical applications, auxiliary power supply 22 is used to power the controller corresponding to the series unit 1 of the devices. Each series unit 1 in the series power device circuit can share the same controller. Generally, the static power consumption and drive power consumption of the controller are relatively constant, so auxiliary power supply 22 will operate in constant power mode and can be considered a constant power load. When the power P is constant, the relationship between the input voltage v of auxiliary power supply 22 and the consumed current i is v(i) = P / i. Taking a small variable near any point (i0, v0) on the v(i) curve gives... Thus, the dynamic resistance of the input terminal of the auxiliary power supply 22 corresponding to any point on the v(i) curve. The condition is always met, meaning that the input terminal of the auxiliary power supply 22, as mentioned above, exhibits negative resistance. The auxiliary power supply 22 is based on the clamping capacitor C. a The voltage is turned on and it operates. Several main power devices S in unit 1 are connected in series sequentially, and auxiliary power devices S... a and clamping capacitor C a The series circuit is connected in parallel across the corresponding main power device S, and the two input terminals of the auxiliary power supply 22 are connected in parallel across the corresponding clamping capacitor C. a At both ends, when the series power device circuit begins to prepare for power-on, the power supply will first power each clamping capacitor C. a Charging continues, and because the series power device circuit is not yet fully powered on and has not entered the working state, the output voltage of the power supply remains fixed, while the clamping capacitor C... a The voltage across the terminals will gradually increase. Due to the constant power load characteristics of auxiliary power supply 22, the output current to auxiliary power supply 22 will increase with the clamping capacitor C. a The resistance gradually decreases as the voltage increases, exhibiting negative resistance characteristics; this leads to a higher voltage clamping capacitance C. a The circuit receives more current, and the clamping capacitor C has a higher voltage. aAs the charging current increases, the voltage continues to increase, resulting in a clamping capacitance C with a larger voltage across its terminals. a An abnormal state where faster charging leads to a faster voltage increase can cause problems for the clamping capacitors C. a The continuous divergence of the voltage eventually causes voltage oscillations. This is especially true at the clamping capacitor C. a When the capacitance value is relatively small, the small capacitance value capacitor is more sensitive to current disturbances, and its voltage is more likely to generate rapid and large amplitude oscillations.

[0056] In view of this situation, this application further adds a balancing circuit 21 to the self-powered circuit 2. The balancing circuit 21 is set in a similar manner to the auxiliary power supply 22, and both are connected in parallel to the corresponding clamping capacitor C. a At both ends, when the series power device circuit is powered on, the balancing circuit 21, the auxiliary power supply 22, and the clamping capacitor C a Both will consume the output current of the power-on current, and at the same time, the current flowing through the balancing circuit 21 will change with the corresponding clamping capacitor C. a The voltage increases, meaning the current flowing through the balancing circuit 21 and the clamping capacitor C increase. a The voltage is positively correlated with the dynamic resistance across the balancing circuit 21. That is, the dynamic resistance of the balancing circuit 21 is the resistance value of the first resistive element, and is always greater than zero; the two ends of the balancing circuit 21 exhibit positive resistance characteristics; where, To balance the voltage change across the circuit. To balance the change in current across the circuit. This is the resistance value of the first resistive element in the balancing circuit. When the clamping capacitor C... a When the voltage increases with charging, and the absolute value of the positive dynamic resistance of the balancing circuit 21 is less than the negative dynamic resistance of the auxiliary power supply 22, the increase in current consumed by the balancing circuit 21 can compensate for the decrease in current consumed by the auxiliary power supply 22, thereby preventing clamping capacitor C from being damaged. a The increase in charging current suppresses the clamping capacitor C a The charging speed is increased to avoid voltage divergence in the clamping capacitor and prevent voltage oscillations from affecting the startup of the auxiliary power supply 22.

[0057] It should be noted that the normal operation of the main power device S refers to the main power device S being turned on or off as needed under the control of the controller when the series power device circuit is working normally. The normal operation of the series power device circuit refers to all clamping capacitors C... a Once charging is complete, the power converter, composed of series power device circuits, alternately turns on its bridge arms according to application requirements. After the series power device circuit is powered on, the clamping capacitor C... a The voltage across the terminals will gradually increase, when the clamping capacitor C aWhen the voltage reaches the first preset voltage, the corresponding auxiliary power supply 22 is turned on, and at this time the clamping capacitor C a The voltage at both ends will continue to rise until it reaches the fourth preset voltage and then remains constant, supporting the gradual opening of the auxiliary power supply 22. As the auxiliary power supply 22 is turned on, the controller can be powered. When all auxiliary power supplies 22 are fully turned on, the controller can control the normal operation of the main power device S according to the application requirements.

[0058] Understandably, see Figure 2 As shown, Figure 2 This invention provides a schematic diagram comparing the current consumption before and after setting up a balancing circuit; wherein, the vertical axis represents the current consumption i. c The horizontal axis represents the voltage V of the clamping capacitor. ca The solid blue line represents the relationship between the current consumed by the auxiliary power supply 22 and the voltage of the corresponding clamping capacitor when the balancing circuit 21 is not installed. The current consumed by the auxiliary power supply 22 is i c With the corresponding clamping capacitor voltage V ca The voltage decreases continuously as the voltage increases. Taking a unit 1 with two devices connected in series and connected to the DC bus as an example, corresponding to two clamping capacitors, the voltage of the first clamping capacitor is V. c1 The voltage across the second clamping capacitor is V. c2 When V c1 >V c2 At that time, the current i consumed by the two auxiliary power supplies 22 is... c1 c2 However, if the output current i of the DC bus is equal, then ii c1 >ii c2 The corresponding voltage change Δv of the clamping capacitor c1 >Δv c2 Therefore, the voltage of the clamping capacitor with a higher voltage will increase more as its own voltage increases, resulting in voltage divergence. After adding a balancing circuit 21 to the self-powered circuit 2, the relationship between the current consumed by the balancing circuit 21 and the corresponding clamping capacitor voltage is shown by the red solid line. The current consumed by the balancing circuit 21 will increase with the corresponding clamping capacitor voltage V. ca The current increases continuously with the increase of V, and the current consumed by the balancing circuit also increases with the increase of V. ca The increase in current consumption exceeds the corresponding decrease in current consumption by the auxiliary power supply. The relationship between the total current consumption of the balancing circuit 21 and the auxiliary circuit and the corresponding clamping capacitor voltage is shown by the purple dashed line. At the corresponding clamping capacitor voltage V... ca The second preset voltage V is greater than that of the balancing circuit 21 Z Subsequently, the total current consumed by the balancing circuit 21 and the auxiliary circuit increases with the corresponding clamping capacitor voltage V. ca The clamping capacitor C increases continuously as the voltage increases, thereby avoiding high voltage clamping capacitance C.​a To prevent voltage divergence in cases of continuously rising voltage, the clamping capacitor C is kept in place. a The voltage is stable.

[0059] It should be noted that this application does not impose any special limitations on the specific types and implementation methods of the main power device, auxiliary power device, and clamping capacitor in the device series unit 1. The main power device S and the auxiliary power device S... a Power devices such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) can be selected according to application requirements. This application does not impose specific limitations on the type and implementation of the balancing circuit 21 and auxiliary power supply 22 in the self-powered circuit 2. The balancing circuit 21 can be implemented using discrete components such as Zener diodes, and the auxiliary power supply 22 can be implemented using a flyback power supply structure. There are also various application scenarios for the device series unit 1 and the corresponding self-powered circuit 2. It is applicable to input-series-output-parallel converters with small-capacity energy storage capacitors, multi-level inverters (such as midpoint clamp converters and modular multi-level converters), solid-state circuit breakers, and SST (Solid-State Transformers). Examples include quasi-two-level modular multi-level converters, device series converters based on active clamp circuits, and flying capacitor multi-level converters with additional local energy storage capacitors. Any circuit or system with a series architecture of the device series unit 1 is applicable.

[0060] As one specific embodiment, see Figure 3 As shown, Figure 3 This invention provides a schematic diagram of a half-bridge topology circuit based on series power device circuitry; Figure 3 Taking the half-bridge circuit topology as an example, the half-bridge circuit includes two bridge arms, and both bridge arms use N devices connected in series (unit 1) to share the medium-voltage bus voltage. Each device series unit 1 includes a main power device S and an auxiliary power device S2. a Clamping capacitor C a The first resistive element R b The first voltage regulator Z b and normally open type switch S de The balancing circuit 21 and the auxiliary power supply 22, which can be considered as a constant power load, are shown in the attached diagram. Figure 4 As shown, Figure 4 This invention provides a schematic diagram of a balanced circuit structure corresponding to a single device series unit; in order to satisfy the main power device S and / or auxiliary power device S aTo meet the driving requirements, a DC / DC (Direct Current to Direct Current) module can be further added to the circuit to convert the power supply voltage output by the auxiliary power supply 22 to the main power device S and / or the auxiliary power device S. a Available drive voltage. Several auxiliary power supplies 22 corresponding to several devices connected in series 1 constitute the auxiliary power supply system of the entire half-bridge circuit, clamping capacitor C. a It is implemented using a relatively small capacitance (hundreds of nanofarads to tens of microfarads). The balancing circuit 21 consists of a first resistive element R connected in series. b The first voltage regulator Z b and normally open type switch S de Composed in series. The auxiliary power supply 22 outputs power supply V. aps Power is provided to the controller and other components of the corresponding serial unit 1.

[0061] This invention provides a self-powered circuit 2, designed to passively stabilize the voltage of a small-capacitance module capacitor during startup, and to clamp capacitor C in the auxiliary power supply 22 startup and the device series unit 1. a During the pre-charging phase, the current flowing through the balancing circuit 21 passively responds to changes in the clamping capacitor voltage. This passive approach ensures system stability during the asynchronous and partial startup of the auxiliary power supply 22, without requiring active control intervention. It passively stabilizes the clamping capacitor voltage in the device series unit 1, ensuring a stable and reliable startup of the entire auxiliary power supply system. Even during asynchronous and / or partial startup of the auxiliary power supply 22, it effectively intervenes to maintain the stability of the clamping capacitor voltage. Therefore, there are no strict requirements regarding parameter differences and startup asynchronous times between the various auxiliary power supplies 22 in the auxiliary power supply system. General commercial power modules or power chips can be used in the design, saving design and debugging time and economic costs, while ensuring reliable startup and efficient operation of the auxiliary power supply system.

[0062] Based on the above embodiments:

[0063] As an optional embodiment, the balancing circuit 21 includes:

[0064] First resistive element R b The first terminal serves as the first terminal of the balancing circuit 21, and is connected to the first input terminal of the corresponding auxiliary power supply 22 and the corresponding clamping capacitor C, respectively. a The first end is connected;

[0065] First voltage regulator Z b The positive electrode is connected to the first resistive element R. bThe second terminal is connected, and the voltage regulation threshold of the first voltage regulator is a second preset voltage. The first voltage regulator is used to cut off when the voltage of the corresponding clamping capacitor is less than the second preset voltage; when the voltage of the corresponding clamping capacitor is not less than the second preset voltage, it maintains the voltage across the first resistor element at the difference between the voltage of the corresponding clamping capacitor and the second preset voltage; the second preset voltage is less than the first preset voltage V. th ;

[0066] Normally open switch S de The first terminal is connected to the first voltage regulator Z. b The negative terminal is connected, and the second terminal serves as the second terminal of the balancing circuit 21, and is also connected to the second input terminal of the corresponding auxiliary power supply 22 and the corresponding clamping capacitor C. a The second terminal is connected, and the control terminal is connected to the output terminal of the controller; the normally open type switch is open by default.

[0067] The controller outputs a preset control signal to control the normally open switch to turn off when the voltage of the corresponding clamping capacitor reaches the third preset voltage. The third preset voltage is greater than the fourth preset voltage and less than the fifth preset voltage. The fourth preset voltage is the maximum voltage that the clamping capacitor can reach before the auxiliary power supply is fully started, and the fourth preset voltage is greater than the first preset voltage. The fifth preset voltage is the rated voltage that the clamping capacitor reaches after the main power device has been operating normally.

[0068] It is not difficult to understand that the first voltage regulator Z can be set in the balancing circuit 21. b and the first resistive element R b This is used in conjunction to achieve passive control of the clamping capacitor voltage. When the corresponding clamping capacitor C... a When the voltage is less than the second preset voltage, the voltage drop across the balancing circuit 21 is entirely regulated by the first voltage regulator Z. b During this period, there is no current in the balancing circuit 21, it is almost cut off, and it does not participate in the adjustment of the clamping capacitor voltage; when the corresponding clamping capacitor C... a When the voltage is not less than the second preset voltage, the first voltage regulator Z b The voltage across the terminals remains at the second preset voltage; the portion exceeding the second preset voltage is controlled by the first resistive element R. b Bearing the responsibility, when the clamping capacitor C a When the voltage increases, the first resistive element R b The voltage across the two ends also increases, flowing through the first resistive element R b That is, the current flowing through the balancing circuit 21 will also increase, thereby compensating for the decrease in current consumption of the auxiliary power supply 22. Furthermore, since the balancing circuit includes a first voltage regulator Z... bThe first voltage regulator can use its own voltage regulation function to bear a certain voltage, thereby reducing the voltage that the first resistor element in the balancing circuit needs to bear, avoiding excessive loss of the first resistor element, effectively reducing the loss of the entire balancing circuit, and realizing a low-loss balancing circuit.

[0069] Furthermore, to avoid the problem of increased losses in the balancing circuit as voltage increases, leading to difficulty in dissipating losses, the clamping capacitor C is activated after the main power device S has operated normally. a Before the voltage reaches the fifth preset voltage, the balancing circuit needs to be cut off in advance. Therefore, a third preset voltage also needs to be set. After the main power device S operates normally, the clamping capacitor C... a The voltage across the terminals no longer remains at the fourth preset voltage, but changes with the operation of the main power device S, gradually increasing from the fourth preset voltage to the fifth preset voltage that ultimately achieves voltage equalization control. This occurs when the clamping capacitor C... a When the voltage across the terminals reaches the fifth preset voltage, the entire series power device circuit reaches a stable power conversion operating state, and this can be achieved by adjusting the main power device S and / or the auxiliary power device S. a The action logic balances the clamp capacitor voltage, and the balancing circuit 21 will balance the clamp capacitor C. a When the voltage increases to the third preset voltage, it is disconnected from the series power device circuit in advance to avoid affecting the power conversion of the series power device circuit and to ensure the power conversion efficiency of the series power device circuit.

[0070] As an optional embodiment, the controller is also used for:

[0071] When all auxiliary power supplies 22 in the series power device circuit are fully started, the output drive signal is sent to the control terminal of the main power device S and / or the auxiliary power device S. a The control terminal is used to control the main power device S and / or the auxiliary power device S. a Normal operation to achieve electrical energy conversion.

[0072] Meanwhile, considering that the balancing circuit 21 only needs to be used when all auxiliary power supplies 22 have not been fully activated, when the clamping capacitor C a When the voltage is less than the first preset voltage, the auxiliary power supply 22 will be in the pre-start (not started) state, and the clamping capacitor C... a After the voltage reaches the fourth preset voltage for a certain period of time, the auxiliary power supply 22 will be fully activated. If all auxiliary power supplies 22 are fully activated, the controller can operate normally based on the power supply voltage provided by the auxiliary power supply 22, driving the main power device S and auxiliary power device S in the series unit 1 of each device. aWhen the device is turned on or off, the series unit 1 and its main power device S are in normal working condition. Then, the main power device S and / or auxiliary power device S can be adjusted. a The action logic ensures the clamping capacitor C a To achieve voltage equalization and avoid voltage oscillation, a normally open switch S can be set in the balancing circuit 21. de This controls whether the balancing circuit 21 operates or not. It remains on when the auxiliary power supply 22 is not fully activated, connecting the balancing circuit 21 to the clamping capacitor C. a The two ends are used to achieve passive control of the clamping capacitor voltage; after the auxiliary power supply 22 is fully started, the clamping capacitor C a When the voltage reaches the third preset voltage, the normally open switch S de Turn off to avoid losses caused when the balancing circuit 21 is turned on. For the first resistive element R... b The first voltage regulator Z b and normally open type switch S de The specific type and implementation method are not specifically limited in this application. The first resistive element R b This can be achieved using methods such as fixed circuits, with the first voltage regulator Z... b This can be achieved using a Zener diode or a circuit with similar voltage clamping function composed of other discrete components, such as the normally open switch S. de This can be achieved using depletion-mode MOSFETs, JFETs (Junction Field-Effect Transistors), or normally-on relays. The complete startup of the auxiliary power supply 22 refers to the completion of startup and normal operation of all auxiliary power supplies 22 corresponding to the series-connected device series unit 1 in the auxiliary power supply system. At this time, the main power devices in all series-connected power device circuits operate normally, and under the control of the controller, they will achieve alternating conduction between the two bridge arms. Taking a converter including a half-bridge circuit as an example, the complete startup of the auxiliary power supply 22 means that the controller begins to control the alternating conduction of the first and second bridge arms.

[0073] It is not difficult to understand that this application does not impose any special restrictions on the specific type and implementation method of the controller, but it can set up several driver chips that correspond one-to-one with each main power device. Figure 4The driver shown is used to control the main power devices, or multiple main power devices can share a single driver chip. Based on the device series unit 1 and the self-powered circuit 2 provided in this application, a power converter can be implemented. Meanwhile, the design of the balancing circuit 21 provides a startup process for the power converter. To prevent the auxiliary power supply 22 from oscillating, the voltage V of each clamping capacitor needs to be maintained. ci >V thi This allows the normal workflow to begin. Among them, V ci V is the voltage of the clamping capacitor in the i-th device series unit 1. thi The first preset voltage is the auxiliary power supply 22 corresponding to the i-th device series unit 1.

[0074] See Figure 9 As shown, Figure 9 This invention provides a schematic diagram of the startup process of a power converter; taking an example where both the first and second bridge arms use two series-connected devices, when power is first applied, the DC power supply pre-charges each clamping capacitor. The equivalent circuit diagram of the first bridge arm at this time is shown below. Figure 5 As shown, as the voltage of the clamping capacitor continuously increases, the clamping capacitor voltages in both the first and second series power device circuits reach the first preset voltage. At this point, the first auxiliary power supply starts first, and after a time Δt, the second auxiliary power supply starts. The equivalent circuit diagram of the first bridge arm at this time is shown below. Figure 6 As shown, if the clamping capacitor voltage in the first series power device circuit and the clamping capacitor voltage in the second series power device circuit can both be maintained above the first preset voltage, then the two auxiliary power supplies will operate stably, and the voltage across the two clamping capacitors will be stable at V. dc / 4, where V dc The output voltage of the DC power supply is shown below. The equivalent circuit diagram of the first bridge arm is as follows: Figure 7 As shown. After the auxiliary power supply 22 stabilizes, the controller starts and begins to operate the main power device S in the series unit 1. The first and second bridge arms conduct alternately. Assuming the first bridge arm is conducting, the voltage across the two clamping capacitors on the first bridge arm stabilizes at V. dc / 2, at this point, the equivalent circuit diagram of the first bridge arm is as follows: Figure 8As shown. By controlling the main power device S and / or the auxiliary power device, voltage equalization of each clamping capacitor can be achieved. This voltage equalization control alone is sufficient to ensure the stability and balance of the clamping capacitor voltage. If the clamping capacitor voltage in the first device series unit 1 and the clamping capacitor voltage in the second device series unit 1 are both lower than the corresponding first preset voltage, the corresponding auxiliary power supply 22 will be turned off, and the corresponding clamping capacitor will be pre-charged again under the action of the balancing circuit 21. This start-stop cycle is repeated until the clamping capacitor voltage can be maintained at a level greater than the first preset voltage.

[0075] As a specific embodiment, the normally open switch S de This can be implemented using a depletion-mode MOSFET device. During the initial period before power-on, between the establishment of the input voltage of the auxiliary power supply 22 and the start-up phase, the normally-on switch S... de Maintaining the default on state, connect the first resistor and the first voltage regulator Z. b The insertion circuit operates. When the voltage across the balancing circuit 21, that is, the voltage V of the corresponding clamping capacitor... ca Lower than the first voltage regulator Z b The second preset voltage V Z At that time, the voltage drop is concentrated in the first voltage regulator Z. b The branch circuit is cut off and approximately does not participate in the operation; when the voltage across the balancing circuit 21 is higher than the Zener diode voltage V... Z At that time, the first voltage regulator Z b The voltage across the terminals remains approximately V. Z The voltage across the first resistive element is V. ca -V Z At this point, the first resistive element begins to passively maintain the voltage stability of each clamping capacitor. Therefore, a second preset voltage V needs to be selected. Z The first preset voltage V is lower than that of the auxiliary power supply 22 th As pre-charging progresses, the voltage across the clamping capacitor gradually increases from zero, sequentially reaching the second preset voltage, the first preset voltage, and the fourth preset voltage. Once the clamping capacitor pre-charging is complete, and the voltage of the clamping capacitor can be stabilized using the clamping capacitor voltage sorting and balancing method by controlling the main power device and / or auxiliary power device during normal operation, the normally open switch can be turned off by the controller when the clamping capacitor reaches the third preset voltage, eliminating additional losses in the balancing circuit 21.

[0076] As one specific embodiment, see Figure 5 As shown, Figure 5 A circuit equivalent diagram of a series power device circuit and its corresponding self-powered circuit provided by this invention during the auxiliary power supply not starting stage; see [link to diagram]. Figure 6 As shown, Figure 6A circuit equivalent diagram of a series power device circuit and its corresponding self-powered circuit during the startup phase of the auxiliary power supply section, provided by this invention; see [link to diagram]. Figure 7 As shown, Figure 7 A circuit equivalent diagram of a series power device circuit and its corresponding self-powered circuit provided by this invention at the moment of full auxiliary power supply startup; see [link to relevant documentation]. Figure 8 As shown, Figure 8 The present invention provides an equivalent circuit diagram of a series power device circuit and its corresponding self-powered circuit during the normal operation phase of the series power device circuit; taking two device units 1 connected in series with small-capacity clamping capacitors as an example, the equivalent circuit diagram of the startup process of the auxiliary power supply 22 and the pre-charging process of the clamping capacitor is shown below. Figures 5 to 8 As shown, the bolded part indicates that current is flowing through it, and the presence of a drive signal (square wave) input to the switching device indicates that the corresponding switching device is activated. Figure 5 At the beginning of pre-charging, the DC bus sequentially passes through the auxiliary power device S of the first device series unit. a body diode D a1 The clamping capacitor C of the first device series unit a1 The auxiliary power device S of the second device series unit a body diode D a2 The clamping capacitor C of the second device series unit a2 The path charges the clamping capacitors in the series-connected units of the two devices, and the voltages of the two clamping capacitors rise from 0, corresponding to clamping capacitor voltages of V respectively. c1 and V c2 During this stage, the voltage across the clamping capacitor is relatively small, V c1 V c2 The voltage difference between the two is only related to the difference in parameters such as capacitance value and can be ignored. Figure 6 This means that as the voltage of the clamping capacitor increases, the balancing circuit 21 begins to consume current, passively suppressing voltage divergence of the clamping capacitor. Furthermore, as the voltage of the clamping capacitor increases, an auxiliary power supply 22 can start first. Due to the presence of the balancing circuit 21, even if the two auxiliary power supplies 22 have asynchronous starting times due to delay time differences, or V... c1 With V c2 The changes in voltage still differ, but the balancing circuit 21 can limit the changes in voltage. Although the voltages of the clamping capacitors are unbalanced, they can remain stable under the action of the balancing circuit 21. Figure 7 This is a circuit diagram showing the circuit when both auxiliary power supplies start up. At this time, the voltage V across the two clamping capacitors is... c1 With V c2All components are kept at the fourth preset voltage (the maximum voltage that the clamping capacitor can reach before the auxiliary power supply is fully started). All the series-connected components share the output voltage of the DC power supply. At this time, the voltage of each clamping capacitor is stable and balanced. Figure 8 This indicates that the auxiliary power supply is fully activated, and the device series unit 1 has entered the normal operation stage from the pre-charging stage. It can now drive the device series unit 1 to operate normally. At this time, the corresponding clamping capacitor can be controlled through the auxiliary power device, and the reactive power flowing through the device series unit 1 itself can help achieve voltage balance of the clamping capacitor. At this time, the two balancing circuits 21 can be cut off by simultaneously turning off the two normally open switches to further reduce additional losses.

[0077] Specifically, the self-powered circuit 2 provided in this application can effectively ensure the small-capacity clamping capacitor C a To ensure stability and meet practical requirements, a passive balancing method is adopted, and a first voltage regulator Z is added in series in the balancing circuit 21. b To reduce voltage equalization losses and effectively reduce or avoid the large losses caused by the first resistive element, the first voltage regulator Z is utilized. b To minimize the losses in the balancing circuit 21 during pre-charging, enabling it to reach the level of natural dissipation, a normally-on switch S is employed. de The operation of the balancing circuit 21 is controlled to optimize loss control. It can maintain the stability of the clamping capacitor voltage in the series unit 1 of each device during the asynchronous time of auxiliary power supply 22 startup, and reduce voltage equalization loss by 40% to 80% compared to a scheme without a first voltage regulator. During the pre-charging phase, a normally open switch S is used. de The balancing circuit 21 is inserted from the initial moment to ensure that the series clamping capacitors C are properly clamped during the asynchronous startup of the auxiliary power supply 22 and during the remaining pre-charging time. a The voltage remains balanced. When the series unit 1 of the devices is operating normally, all normally open switches S can be simultaneously turned off. de This is to reduce additional wear and tear during normal operation.

[0078] It is understandable that, considering the normally open switch S in the balancing circuit 21 de Additional control is also needed to determine whether the balancing circuit 21 is working. Furthermore, to ensure the normal operation of all auxiliary power supplies 22 and to avoid voltage oscillations caused by asynchronous startup of the auxiliary power supplies 22, the balancing circuit 21 will stop working only after all auxiliary power supplies 22 have fully started. Specifically, this can be achieved through a controller to detect whether the auxiliary power supplies 22 have completed startup and to control the normally open switch S. de Shutdown control.

[0079] Furthermore, in one embodiment, the controller detects the clamping capacitor C. aThe voltage is used to detect whether the auxiliary power supply 22 is fully started. When the auxiliary power supply 22 is fully started, the device series unit 1 works normally. At this time, the clamping capacitor C corresponding to each series device series unit 1 is... a This will ensure voltage equalization among the series-connected units 1 of the devices in the on state, so as to Figure 2 For example, during normal operation, the two arms of the half-bridge circuit will conduct alternately. At this time, the voltage of the N clamping capacitors corresponding to the N series-connected units 1 of the devices on a single arm is Vdc / N (that is, the fifth preset voltage), ensuring equal voltage across each series-connected unit 1. However, when the auxiliary power supply 22 is fully started, before the series-connected units 1 of the devices are working normally, the 2N clamping capacitors on the two arms share the DC bus voltage equally. Therefore, the voltage of each clamping capacitor C... a The voltages are all Vdc / 2N (i.e., the fourth preset voltage), therefore, the clamping capacitor C can be detected. a The detection of whether the device series unit 1 is working properly is achieved by checking whether the voltage reaches a third preset voltage between Vdc / 2N and the rated voltage (Vdc / N). The rated voltage refers to the voltage at which the clamping capacitor achieves voltage equalization control of the device series unit 1 when the device series unit 1 is working properly.

[0080] As an optional embodiment, the first resistive element R b The resistor is a fixed resistor, and its resistance is equal to the ratio of the square of the sixth preset voltage to the power consumption of the auxiliary power supply 22. The sixth preset voltage must be lower than the second preset voltage of the first voltage regulator.

[0081] It is easy to understand that, in order to ensure the compensation effect of the balancing circuit 21 on the current consumed by the auxiliary power supply 22, the resistance value of the fixed resistor can be set according to the constant power consumption of the auxiliary power supply 22. The first resistor element R is implemented by using a fixed resistor with a pre-set suitable resistance value. b Taking a topology of two devices connected in series (unit 1) as an example, such as... Figure 6 As shown, assume the auxiliary power supply S aps1 Prior to auxiliary power supply S aps2 Start-up, with a time difference of Δt, using auxiliary power supply S aps1 Taking a constant power load with power consumption of P1 as an example, the auxiliary power supply S aps1 The total current consumed by its corresponding balancing circuit, i c1 It can be represented as:

[0082] ;

[0083] Among them, v c1 Auxiliary power supply S aps1 The corresponding clamping capacitor C a1 The voltage across the terminals, V Z1 Clamping capacitor Ca1 The corresponding second preset voltage of the balancing circuit, R b1 Clamping capacitor C a1 The resistance value of the first resistor in the corresponding balanced circuit, based on the equality condition of the inequality, is known to be that the auxiliary power supply S... aps1 The total current consumed by its corresponding balancing circuit, i c1 In v c1 2 =R b1 The minimum value is obtained at point ×P1, and the clamping capacitor voltage corresponding to the minimum value is denoted as V. c1_crit Therefore, based on the power consumption corresponding to the auxiliary power supply, the resistance value of the first resistor element in the balancing circuit can be designed so that the current flowing through the corresponding clamping capacitor satisfies the condition of V. c1 >V c1_crit The curve decreases monotonically, and the current consumed by the balancing circuit and auxiliary power supply is greater than V1. c1_crit The time curve increases monotonically, thus maintaining the stability of the clamping capacitor voltage. Simultaneously, by increasing the V of the balancing circuit... Z1 It can reduce i c1 This reduces the total losses of the balancing circuit and auxiliary power supply, and changes V Z1 The minimum voltage point does not affect the circuit stability criterion.

[0084] Specifically, by utilizing the power consumption of the auxiliary power supply 22 when it is considered a constant power load, the first resistive element R in the balancing circuit 21 can be preset. b The resistance value is chosen such that the voltage V of the clamping capacitor corresponds to the minimum value of the total current consumed. c1_crit Not greater than the second preset voltage V of the balancing circuit z V c1_crit That is, the minimum value is located on the horizontal axis of the diagram showing the sum of the current consumed by the balancing circuit and the auxiliary power supply minus the voltage of the clamping capacitor. This ensures that the voltage of the corresponding clamping capacitor remains stable as long as the balancing circuit 21 starts working.

[0085] See Figure 10 As shown, Figure 10 A schematic diagram of a balanced circuit structure corresponding to another device series unit provided by the present invention; as an optional embodiment, the self-powered circuit further includes:

[0086] Second resistive element R c The first end is respectively connected to the first resistive element R b The first terminal, the first input terminal of the corresponding auxiliary power supply 22, and the corresponding clamping capacitor C a The first end is connected;

[0087] Second voltage regulator Z c The positive electrode is connected to the second resistive element R.c The second terminal is connected to the second voltage regulator Z. c The voltage regulation threshold is the seventh preset voltage, which is greater than the first preset voltage and less than the third preset voltage.

[0088] Controllable switch S c The first terminal is connected to the second voltage regulator Z. c The negative terminal is connected, and the second terminal is connected to the normally open switch S. de The second terminal, the second input terminal of the corresponding auxiliary power supply 22, and the corresponding clamping capacitor C a The second end is connected, and the control end is connected to the output end of the controller;

[0089] The controller is also used when the corresponding clamping capacitor C a When the voltage reaches the third preset voltage, a preset control signal is output to control the normally open switch S. de Turn off and control the controllable switch to turn on, so that the second resistive element R... c Second voltage regulator Z c and controllable switch S c Take over the voltage equalization control of the clamping capacitor.

[0090] Understandably, this is to prevent the device series unit 1 from being unable to control and maintain the clamping capacitor C after the auxiliary power supply 22 is started. a For voltage equalization, for example, when the auxiliary power device uses an uncontrollable device such as a diode, multiple sets of balancing circuits 22 can be connected in parallel in the circuit. Taking the addition of a balancing circuit as an example, a second resistor element R is added to the circuit. c Second voltage regulator Z c Controllable switch S c The second set of balanced circuits is formed when the clamping capacitor C a After the voltage reaches the fourth preset voltage and the auxiliary power supply 22 is fully turned on, the main power device S operates normally under the control of the controller. When the clamping capacitor C... a When the voltage reaches the third preset voltage, the normally open switch S de When the controller shuts down the circuit, the first set of balancing circuits is disconnected from the series power device circuit. At this time, the controller controls the controllable switch S. c When the circuit is turned on, the second set of balancing circuits is connected to the series power device circuit. The second set of balancing circuits can use its own positive resistance to ensure voltage equalization of the clamping capacitor when the main power device S is operating normally. At the same time, the second resistive element R... c The resistance value is greater than that of the first resistive element R. b The resistance value of the second balancing circuit is such that its loss is smaller than that of the first balancing circuit, minimizing its impact on the power conversion of the series power device circuit. For the second resistive element R... c Second voltage regulator Zc Controllable switch S c The specific type and implementation method of the controllable switch S are not specifically limited in this application. c The circuit can be turned on when the series power device circuit is powered on, cooperating with the first group of balancing circuits to achieve normal startup of the auxiliary power supply; after the first group of balancing circuits is disconnected, it continues to conduct to ensure voltage equalization of the clamping capacitor. Alternatively, it can be kept off by default, and turned on again under the action of the controller after the first group of balancing circuits is disconnected. For each series unit of the devices, the setting of the balancing circuit is not limited to two groups, but can also be three, four, or more groups, to achieve hierarchical control of the clamping capacitor. Starting from the first group of balancing circuits corresponding to the first resistive element, the resistance value of the resistive elements in several groups of balancing circuits gradually increases, and the time of disconnection from the series power device circuit is gradually delayed. This application does not make any special restrictions on the specific setting of the balancing circuits corresponding to each series unit of the devices in the series power device circuit. Figure 10 The diagram shows the structure when two sets of balanced circuits are set in the series unit of the device.

[0091] As an optional embodiment, the auxiliary power supply is a DC / DC converter. Specifically, it can be an isolated or non-isolated DC / DC converter with a wide input voltage range and constant output. For example... Figure 4 As shown, the auxiliary power supply 22 includes:

[0092] The transformer T's first input terminal is connected to the first terminal of the corresponding balancing circuit 21 and the corresponding clamping capacitor C, respectively. a The first end is connected, and the first output end serves as the negative power supply terminal of the auxiliary power supply 22;

[0093] The power switch K has its first terminal connected to the second input terminal of the transformer T, and its second terminal connected to the second terminal of the corresponding balancing circuit 21 and the corresponding clamping capacitor C. a The second end is connected;

[0094] The positive terminal of the unidirectional conduction module D0 is connected to the second output terminal of the transformer T, and the negative terminal serves as the positive terminal for power supply of the auxiliary power supply 22.

[0095] As an optional embodiment, the auxiliary power supply 22 further includes:

[0096] The common-mode inductor Lcm, its first input terminal is connected to the first terminal of the corresponding balancing circuit 21 and the corresponding clamping capacitor C, respectively. a The first terminal is connected, and the second input terminal is connected to the second terminal of the corresponding balancing circuit 21 and the corresponding clamping capacitor C, respectively. a The second terminal is connected to the first input terminal of transformer T, and the second output terminal is connected to the second terminal of power switch K.

[0097] And / or,

[0098] The output capacitor C12 has its first end connected to the negative terminal of the unidirectional conduction module D0, and its second end connected to the first output terminal of the transformer T.

[0099] Understandably, the specific structure of the auxiliary power supply 22 can also be flexibly configured according to actual application requirements. Specifically, it can be implemented using a flyback power supply structure, employing a transformer T as an energy storage inductor and isolation element, and directly utilizing the input clamping capacitor C. a The output power supply voltage is provided, and since the controller requires a relatively low power supply voltage, the transformer T can also serve as a step-down converter. The flyback power supply uses a power switch K to achieve power conversion. The power switch K can operate based on different duty cycles or frequencies to achieve automatic control of the auxiliary power supply's output voltage or current. A series-connected unidirectional conduction module D0 is also provided at the output to ensure a positive output of the power supply voltage. A common-mode inductor Lcm can be further added to the input side of the auxiliary power supply 22 to clamp the capacitor C. a The input voltage to the auxiliary voltage is filtered to improve the accuracy and reliability of the final output power supply voltage. An input capacitor C11 can also be added to the input side to improve the stability of the input voltage. An output capacitor C12 can also be added to the output side for filtering and voltage regulation. This application does not specifically limit the specific types and implementation methods of the transformer T, unidirectional conduction module D0, common-mode inductor Lcm, and output capacitor C12 in the auxiliary power supply 22. The unidirectional conduction module D0 can be implemented using a diode. The auxiliary power supply 22 can also be implemented using other high-dropout-ratio DC / DC converters to reduce the voltage from the clamping capacitor voltage to the power supply voltage required for auxiliary power supply.

[0100] Specifically, the auxiliary power supply 22 can be implemented using a flyback power supply structure or other methods, utilizing the energy storage of the transformer T to power the auxiliary power supply 22. The circuit structure is simple and easy to implement.

[0101] Secondly, the present invention also provides a bridge circuit, including N bridge arm structures and a self-powered circuit as described above, where N is a positive integer;

[0102] The bridge arm structure includes a first bridge arm composed of a series power device circuit and a second bridge arm composed of a series power device circuit. The self-powered circuit 2 is connected to the device series unit 1 in the series power device circuit.

[0103] As an optional embodiment, the bridge circuit also includes a first bus capacitor C1 and a second bus capacitor C2;

[0104] The first terminal of the first bus capacitor C1 is connected to the first output terminal of the power supply and the first terminal of the first bridge arm, respectively. The second terminal is connected to the first terminal of the second bus capacitor C2 and the first terminal of the load, respectively. The second terminal of the first bridge arm is connected to the second terminal of the load and the first terminal of the second bridge arm, respectively. The second terminal of the second bus capacitor C2 is connected to the second output terminal of the power supply and the second terminal of the second bridge arm, respectively. The power supply can be implemented using DC power or AC power, etc., as required.

[0105] For an introduction to the bridge circuit provided by this invention, please refer to the above-described embodiment of the self-powered circuit; further details of this invention will not be repeated here.

[0106] Thirdly, the present invention provides a power converter including the bridge circuit as described above.

[0107] For a description of the power converter provided by this invention, please refer to the above-described embodiment of the self-powered circuit; the invention will not be described again here.

[0108] Fourthly, the present invention provides a self-powered method applied to a series power device circuit. The series power device circuit includes a plurality of series-connected device series units. Each device series unit includes a main power device, an auxiliary power device, and a clamping capacitor. The main power devices in the plurality of series-connected device series units are connected in series. The first terminal of the auxiliary power device is connected to the first terminal of the main power device, the first terminal of the clamping capacitor is connected to the second terminal of the auxiliary power device, and the second terminal of the clamping capacitor is connected to the second terminal of the main power device. A plurality of self-powered circuits as described above are connected one-to-one with the plurality of device series units in the series power device circuit. The self-powered method includes:

[0109] When the clamping capacitor in the series-connected device unit is charging, energy is obtained from the corresponding clamping capacitor through the auxiliary power supply in the self-powered circuit, so that the auxiliary power supply starts after a preset delay time when the voltage of the corresponding clamping capacitor reaches the first preset voltage, and outputs voltage to the control terminal of the corresponding main power device after full startup; wherein, the input terminal of the auxiliary power supply has a negative resistance characteristic.

[0110] The energy of the corresponding clamping capacitor is consumed by the balancing circuit that is turned on in the self-powered circuit; wherein, the two ends of the balancing circuit have positive resistance characteristics, and when the balancing circuit is turned on, the positive dynamic resistance of the balancing circuit is less than the absolute value of the negative dynamic resistance of the auxiliary power supply.

[0111] After all auxiliary power supplies are fully activated, they drive each main power device to operate normally.

[0112] Furthermore, this application further verifies the function of the balancing circuit through simulation experiments. As a specific embodiment, see [link to specific embodiment]. Figure 11 As shown, Figure 11 This invention provides a schematic diagram comparing the clamping capacitor voltages of three series-connected devices before and after the installation of a balancing circuit. The dashed lines represent the clamping capacitor voltage curves of the three series-connected devices without a balancing circuit, while the solid lines represent the clamping capacitor voltage curves of the three series-connected devices with a balancing circuit. The green curve represents the clamping capacitor voltage curve of the first series-connected device, the red curve represents the clamping capacitor voltage curve of the second series-connected device, and the blue curve represents the clamping capacitor voltage curve of the third series-connected device. In this process, (a) is the charging stage when the clamping capacitor voltage is less than the second preset voltage of the corresponding balancing circuit; (b) is the process of gradually reaching the first preset voltage as the clamping capacitor voltage increases. When the clamping capacitor voltage reaches the first preset voltage, the three auxiliary power supplies start asynchronously, with the first auxiliary power supply starting before the second, and the second auxiliary power supply starting before the third. At this time, the asynchronous time between the auxiliary power supply modules is Δt1 (the start-up time difference between the first and second auxiliary power supplies) = Δt2 (the start-up time difference between the second and third auxiliary power supplies) = 10ms. Without a balancing circuit, it is easy to see that the voltage of the clamping capacitor is unstable and continues to diverge until the voltage of the first clamping capacitor drops below the minimum input voltage of the auxiliary power supply, causing the first auxiliary power supply to shut down. However, with a balancing circuit, although the voltage of each clamping capacitor still has a certain imbalance, it can remain stable. (c) is the stage after all the auxiliary power supplies have started up. At this time, the voltage of each capacitor with a balancing circuit tends to be stable and uniform, which can maintain the voltage safety of the clamping capacitor.

[0113] It should be noted that the capacitance of the clamping capacitor is not directly related to the stability of the series unit of the device, but it does affect the rate of voltage divergence of the series unit in an unstable state. For series units using small-capacity capacitors and series systems, the divergence problem in stage b cannot be ignored. In the method of passively stabilizing the clamping capacitor voltage using a balancing circuit, the loss of the balancing resistor needs to be greater than the power consumption of the auxiliary power supply to effectively compensate for the reduction in the current consumption of the auxiliary power supply. Therefore, a first voltage regulator device needs to be set in the balancing circuit to avoid the power consumption and power density loss caused by a single power supply element. When an additional first voltage regulator device is connected in series, compared with a pure first resistor element, its original stabilization capability remains unchanged, and the additional loss required for voltage equalization can be significantly reduced. In one embodiment, assuming that the number of series units of the device in each of the two bridge arms is 3, and the input DC bus voltage V dc =1.2kV, auxiliary power supply power consumption P=3W, and the resistance value R of the first resistor element. b =10kΩ, clamping capacitor value C=2μF, second preset voltage V Z=160V. To allow for a margin, the voltage across the clamping capacitor can be half of the clamping voltage (V). c =V dc When P = 200V, the loss of the first resistor in the balancing circuit is set to 4W (achieved by adjusting the resistance value of the first resistor), which is slightly greater than P = 3W. These values ​​are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0114] See Figure 12 As shown, Figure 12 This diagram illustrates the comparison of losses in the first resistive element with and without the first voltage regulator in the balancing circuit provided by this invention. By connecting the first voltage regulator in series, when the pre-charge voltage of the clamping capacitors reaches the fourth preset voltage (i.e., when the voltages of all clamping capacitors are greater than the first preset voltage) and the auxiliary power supply has started, the additional losses can be reduced by 80%. When the pre-charge of the device series unit ends and the clamping capacitor voltage rises to the fifth preset voltage, the additional losses can still be reduced by at least 40%. In this way, the balancing circuit can solve this small loss through passive heat dissipation, making it easy to integrate into the device series unit.

[0115] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. It should also be noted that in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0116] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A self-powered circuit, characterized in that, This is applied to series power device circuits, which include several series-connected device units. Each device unit includes a main power device, an auxiliary power device, and a clamping capacitor. The main power devices in the several series-connected device units are connected in series. The first terminal of the auxiliary power device is connected to the first terminal of the main power device, the first terminal of the clamping capacitor is connected to the second terminal of the auxiliary power device, and the second terminal of the clamping capacitor is connected to the second terminal of the main power device. Several self-powered circuits are connected one-to-one with the several device units in the series power device circuit. For any self-powered circuit, the self-powered circuit includes: The auxiliary power supply is used to obtain energy from the corresponding clamping capacitor. When the voltage of the corresponding clamping capacitor reaches the first preset voltage, it starts after a preset delay time. After it is fully started, it outputs voltage to the control terminal of the corresponding main power device so that the controller can drive each main power device to operate normally after all auxiliary power supplies are fully started. The output power of the auxiliary power supply is constant, and the input terminal of the auxiliary power supply has a negative resistance characteristic. A balanced circuit has positive resistance at both ends; it is used to control the on / off state based on a preset control signal. When the balancing circuit is turned on, the positive dynamic resistance of the balancing circuit is less than the absolute value of the negative dynamic resistance of the auxiliary power supply, so that the corresponding self-powered circuit exhibits positive resistance characteristics. The balancing circuit includes: The first resistor element has its first end connected to the first input terminal of the corresponding auxiliary power supply and the first end of the clamping capacitor in the corresponding device series unit, respectively. The first voltage regulator has its negative terminal connected to the second terminal of the first resistor element. The voltage regulation threshold of the first voltage regulator is a second preset voltage. The first voltage regulator is used to cut off when the voltage of the corresponding clamping capacitor is less than the second preset voltage; when the voltage of the corresponding clamping capacitor is not less than the second preset voltage, it maintains the voltage across the first resistor element at the difference between the voltage of the corresponding clamping capacitor and the second preset voltage; the second preset voltage is less than the first preset voltage. The normally open switch has its first terminal connected to the positive terminal of the first voltage regulator, its second terminal connected to the second input terminal of the corresponding auxiliary power supply and the second terminal of the corresponding clamping capacitor, and its control terminal connected to the output terminal of the controller.

2. The self-powered circuit according to claim 1, characterized in that, The normally-on switch is turned on by default; The controller is used to output a preset control signal to control the normally open switch to turn off when the voltage of the corresponding clamping capacitor reaches a third preset voltage; the third preset voltage is greater than a fourth preset voltage and less than a fifth preset voltage; wherein, the fourth preset voltage is the maximum voltage that the clamping capacitor can reach before the auxiliary power supply is fully started, and the fourth preset voltage is greater than a first preset voltage, and the fifth preset voltage is the rated voltage reached by the clamping capacitor after the main power device operates normally.

3. The self-powered circuit according to claim 1, characterized in that, The auxiliary power supply is a DC / DC converter.

4. The self-powered circuit according to claim 2, characterized in that, The controller is also used for: When all auxiliary power supplies in the series power device circuit are fully started, a drive signal is output to the control terminal of the main power device and / or the control terminal of the auxiliary power device to control the main power device and / or the auxiliary power device to operate normally and realize power conversion.

5. The self-powered circuit according to claim 2, characterized in that, The self-powered circuit also includes: The first end of the second resistor element is connected to the first end of the first resistor element, the first input end of the corresponding auxiliary power supply, and the first end of the corresponding clamping capacitor. The negative terminal of the second voltage regulator is connected to the second end of the second resistor element. The voltage regulation threshold of the second voltage regulator is a seventh preset voltage, which is greater than the first preset voltage and less than the third preset voltage. The controllable switch has its first terminal connected to the positive terminal of the second voltage regulator, its second terminal connected to the second terminal of the normally open switch, the second input terminal of the corresponding auxiliary power supply, and the second terminal of the corresponding clamping capacitor, and its control terminal connected to the output terminal of the controller. The controller is also used to output a preset control signal to control the normally open switch to turn off when the voltage of the corresponding clamping capacitor reaches a third preset voltage, and to control the controllable switch to turn on, so that the second resistive element, the second voltage regulator and the controllable switch take over the voltage equalization control of the clamping capacitor.

6. A bridge circuit, characterized in that, It includes N bridge arm structures and a self-powered circuit as described in any one of claims 1 to 5, where N is a positive integer; The bridge arm structure includes a first bridge arm composed of a series power device circuit and a second bridge arm composed of a series power device circuit, and the self-powered circuit is connected to the series unit of the device in the series power device circuit.

7. The bridge circuit according to claim 6, characterized in that, The bridge circuit also includes a first bus capacitor and a second bus capacitor. The first end of the first bus capacitor is connected to the first output terminal of the power supply and the first end of the first bridge arm, respectively. The second end is connected to the first end of the second bus capacitor and the first end of the load, respectively. The second end of the first bridge arm is connected to the second end of the load and the first end of the second bridge arm, respectively. The second end of the second bus capacitor is connected to the second output terminal of the power supply and the second end of the second bridge arm, respectively.

8. A power converter, characterized in that, Includes the bridge circuit as described in claim 6.

9. A self-powered method, characterized in that, The method is applied to a series power device circuit, which includes a plurality of series-connected device series units. Each device series unit includes a main power device, an auxiliary power device, and a clamping capacitor. The main power devices in the plurality of series-connected device series units are connected in series. A first terminal of the auxiliary power device is connected to a first terminal of the main power device, a first terminal of the clamping capacitor is connected to a second terminal of the auxiliary power device, and a second terminal of the clamping capacitor is connected to a second terminal of the main power device. A plurality of self-powered circuits as described in any one of claims 1-5 are connected one-to-one with the plurality of device series units in the series power device circuit. The self-powered method includes: When the clamping capacitor in the series-connected device unit is charged, energy is obtained from the corresponding clamping capacitor through the auxiliary power supply in the self-powered circuit, so that the auxiliary power supply starts after a preset delay time when the voltage of the corresponding clamping capacitor reaches the first preset voltage, and outputs voltage to the control terminal of the corresponding main power device after full startup; wherein, the input terminal of the auxiliary power supply has a negative resistance characteristic. The energy of the corresponding clamping capacitor is consumed by the balancing circuit that is turned on in the self-powered circuit; wherein, the two ends of the balancing circuit have positive resistance characteristics, and when the balancing circuit is turned on, the positive dynamic resistance of the balancing circuit is less than the absolute value of the negative dynamic resistance of the auxiliary power supply. After all the auxiliary power supplies are fully started, they drive each main power device to operate normally.

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