A high voltage direct current SSPC and method with capacitive load

Abstract

This invention provides a high-voltage DC SSPC and a method for charging capacitive loads, enabling the high-voltage SSPC to carry capacitive loads. The capacitive load circuit of this invention can adaptively distinguish whether the downstream load is short-circuited or capacitive. At the same time, this invention can adaptively adjust the upper limit of the capacitive load based on the power selection of the hardware current-limiting resistor. When the capacitive load of the downstream load exceeds the upper limit of the SSPC's capacitive load capacity, it can identify and shut down, protecting the capacitive load circuit from damage.

Description

Technical Field

[0001] This invention pertains to aviation power distribution systems, specifically to the field of SSPC (Supervisory Service PC) with capacitive loads, and relates to a high-voltage DC SSPC and a method for using it with capacitive loads. Background Technology

[0002] A solid-state power controller (SSPC) is an intelligent switching device with protective functions. Its function is similar to a traditional circuit breaker, fuse, and relay combination, or other control and protection devices, but its performance and functionality are significantly superior. It can control the on / off state of the load and has overcurrent and short-circuit protection functions. Furthermore, the SSPC can collect the load's current and voltage values, as well as the channel's on / off status, trip (protection) status, light load / full load status, etc., and perform channel self-testing based on each status.

[0003] For high-voltage DC SSPCs, the downstream load characteristics have a large capacitive characteristic. Therefore, high-voltage DC SSPCs are specifically required to have the ability to carry capacitive loads. Generally, the design uses a pre-charge circuit for the capacitor, which limits the charging current through a current-limiting power resistor to complete the charging of the downstream capacitor within a specified time. However, due to the need to consider extreme conditions such as short circuits in the downstream load, the power resistor of the pre-charge circuit is generally large, which results in a larger weight and volume. Moreover, the load-carrying capacity for capacitive loads is only based on open-loop control with a fixed pre-charge time, and cannot achieve dynamic adaptive adjustment.

[0004] In summary, it is necessary to design a more efficient capacitive load circuit that combines the characteristics of SSPC, thereby reducing the size and weight of the precharge circuit power resistor, and enabling dynamic adaptation and identification of downstream capacitive loads. Summary of the Invention

[0005] The purpose of this invention is to design a high-voltage DC SSPC and a method for carrying capacitive loads, so as to achieve better device selection and the realization of capacitive load functionality.

[0006] The first aspect of this invention provides a high-voltage DC SSPC, comprising: an MCU, a main power circuit, and a pre-charge circuit; The MCU is used to, when a short circuit protection occurs, obtain the power on the power resistor of the pre-charge circuit based on the power output current, and determine whether the preset maximum energy has been reached; if so, it determines whether the power output voltage has reached the preset percentage of the input voltage; if not, it controls the main power circuit to conduct.

[0007] Optionally, the resistance value of the pre-charge circuit power resistor is determined based on the input voltage and the preset maximum capacitive load value.

[0008] Optionally, the resistance value of the pre-charge circuit power resistor is proportional to the preset maximum energy Qmax; where, U is the input voltage, and C is the preset maximum capacitive load value.

[0009] Optionally, the MCU is used to apply a formula when a short circuit occurs. To obtain the energy Q on the power resistor of the pre-charge circuit; I is the power output current, R is the resistance of the power resistor in the pre-charge circuit, and Δt is the conduction time of the pre-charge circuit.

[0010] Optional, the default percentage is 10%.

[0011] A second aspect of the present invention provides a method for using a high-voltage DC SSPC with a capacitive load, employing a high-voltage DC SSPC as described in any one of the first aspects, the method comprising: When a short circuit occurs, the energy on the power resistor in the pre-charge circuit is obtained based on the power output current to determine whether the preset maximum energy has been reached. If yes, then determine whether the power output voltage reaches the preset percentage of the input voltage; if no, then control the main power circuit to turn on.

[0012] Optionally, the method further includes: The actual equivalent capacitance value is obtained based on the power on the power resistor of the pre-charge circuit. The actual equivalent capacitance value is taken as the minimum equivalent capacitance of the capacitive load.

[0013] Optionally, the method further includes: The precharge circuit is shut off when the power on the precharge circuit power resistor does not reach the preset maximum energy.

[0014] Optionally, the method further includes: The precharge circuit is shut off when the power output voltage does not reach the preset percentage of the input voltage.

[0015] The beneficial effects of this invention are: Based on the characteristic of SSPC's ability to quickly acquire and output analog quantities, this invention develops a method for handling capacitive loads, which enables more reasonable selection of current-limiting resistors, reduces product weight and cost, and also enhances SSPC's ability to determine the state of the back-end load, further improving the intelligence of SSPC. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. 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.

[0017] Figure 1 This is a schematic diagram of the circuit principle of the present invention.

[0018] Figure 2 This is the relevant program flow diagram of the present invention. Detailed Implementation

[0019] 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.

[0020] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0021] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0023] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0025] Specifically, such as Figure 1 and Figure 2 As shown, this invention proposes a high-voltage DC SSPC, comprising: an MCU, a main power circuit, and a pre-charge circuit; The MCU is used to, when a short circuit protection occurs, obtain the power on the power resistor of the pre-charge circuit based on the power output current, and determine whether the preset maximum energy has been reached; if so, it determines whether the power output voltage has reached the preset percentage of the input voltage; if not, it controls the main power circuit to conduct.

[0026] Optionally, the resistance value of the pre-charge circuit power resistor is determined based on the input voltage and the preset maximum capacitive load value.

[0027] Optionally, the resistance value of the pre-charge circuit power resistor is proportional to the preset maximum energy Qmax; where, U is the input voltage, and C is the preset maximum capacitive load value.

[0028] Optionally, the MCU is used to apply a formula when a short circuit occurs. To obtain the energy Q on the power resistor of the pre-charge circuit; I is the power output current, R is the resistance of the power resistor in the pre-charge circuit, and Δt is the conduction time of the pre-charge circuit.

[0029] Optional, the default percentage is 10%.

[0030] For example, based on the capacitive load requirements of the product, the power of the current-limiting resistor in the pre-charge circuit is selected. The selection criterion is that, without considering heat dissipation from the resistor, the power resistor can withstand [the load]. (C is the capacitive load capacity, and U is the power voltage) Energy is sufficient.

[0031] For example, the application software for SSPC should have specified the maximum load it can carry, i.e., the maximum energy that the current-limiting resistor can withstand.

[0032] For example, when the SSPC receives the activation command, the SSPC first activates the precharge circuit driver. Once the precharge circuit is connected, the power input charges the downstream load capacitor through the current-limiting power resistor.

[0033] For example, at this time, the SSPC will periodically collect the analog output current and analog output voltage for subsequent capacitive load determination.

[0034] For example, SSPC calculates the energy carried by the power resistor in the precharge circuit based on analog current. When the energy is below the Qmax that the power resistor can withstand, the SSPC channel can continue to conduct.

[0035] For example, the SSPC is based on the analog output voltage. The output voltage should gradually increase. When the output voltage no longer increases, it indicates that the precharge circuit can no longer supply power to the back-end capacitor and load, and the main circuit drive should be turned on.

[0036] For example, when the SSPC calculates that the energy the pre-charge power resistor can withstand reaches Qmax, the capacitance of the downstream capacitor has exceeded the maximum capacitive load requirement. The output voltage value is then further determined. If the output voltage is not very small, although it is still unstable, the main circuit can be turned on. At this point, there is a possibility of a short circuit. If a short circuit occurs, the SSPC should perform normal short-circuit protection and record the cause as excessive downstream capacitive load exceeding the SSPC's designed capacitive load capacity. If no short circuit occurs, the SSPC can normally turn on the main circuit drive.

[0037] For example, under the operating conditions in step 7, if the output voltage is very small, for example, less than 10% of the input voltage, it indicates that the back-end load is approximately in a short-circuit condition. In this case, the SSPC should directly shut down the precharge circuit drive and report the short circuit.

[0038] The implementation process of this invention is as follows: (a) The SSPC determines the withstand energy value Qmax based on the selected precharge circuit power resistor and embeds the energy value in the SSPC; (b) When the SSPC receives the activation command, the SSPC outputs the precharge circuit to drive A_DRV to the activation state. Then the precharge circuit realizes the path of DC input → current limiting power resistor R1 → power MOSFET V2 → sampling resistor R2 → DC output to charge the downstream load capacitively. (c) SSPC determines the current value by collecting the voltage across the sampling resistor R2 and determines the power output voltage by collecting the voltage value of the DC output.

[0039] (d) The SSPC determines the status of the back-end load based on the collected output current and output voltage values. The most common status is that the power on the power resistor R1 of the pre-charge circuit has not reached the set value Qmax, and the voltage of the back-end load has basically stabilized. This indicates that the capacitor is basically fully charged. In this case, the SSPC output main circuit drive M_DRV is turned on, and the power supply directly supplies the back-end load through the path of DC input → power MOSFET V1 → sampling resistor R2 → DC output, which means that the pre-charge circuit is bypassed.

[0040] (e) When the SSPC determines that the power on the pre-charge circuit power resistor R1 has reached the set value Qmax, it further determines whether the output voltage is normal. If the output voltage is very small, for example, less than 10% of the input voltage, it indicates that the downstream load is approximately under short-circuit conditions. In this case, the pre-charge circuit should be directly shut off, and a short circuit should be reported. If the output voltage is not very small, although the output voltage is still not stable, the main circuit can be opened. However, there is a possibility of a short circuit at this time. If a short circuit occurs, the SSPC should perform short-circuit protection normally and record that the cause of the short circuit is that the downstream capacitive load is too large, exceeding the capacitive load capacity designed by the SSPC.

[0041] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A high-voltage DC SSPC, characterized in that, include: MCU, main power circuit, and precharge circuit; The MCU is used to determine whether the energy on the power resistor in the pre-charge circuit has been reached when a short circuit protection occurs, based on the power output current. If so, it determines whether the power output voltage has reached a preset percentage of the input voltage. If not, it controls the main power circuit to turn on.

2. The high-voltage DC SSPC according to claim 1, characterized in that, The resistance value of the pre-charge circuit power resistor is determined based on the input voltage and the preset maximum capacitive load value.

3. The high-voltage DC SSPC according to claim 2, characterized in that, The resistance value of the power resistor in the pre-charge circuit is proportional to the preset maximum energy Qmax; where, U is the input voltage, and C is the preset maximum capacitive load value.

4. The high-voltage DC SSPC according to claim 1, characterized in that, The MCU is used to apply a formula when a short circuit occurs. To obtain the energy Q on the power resistor of the pre-charge circuit; I is the power output current, R is the resistance of the power resistor in the pre-charge circuit, and Δt is the conduction time of the pre-charge circuit.

5. The high-voltage DC SSPC according to claim 1, characterized in that, The default percentage is 10%.

6. A method for a high-voltage DC SSPC with a capacitive load, characterized in that, The method, employing a high-voltage DC SSPC as described in any one of claims 1-5, comprises: When a short circuit occurs, the energy on the power resistor in the pre-charge circuit is obtained based on the power output current to determine whether the preset maximum energy has been reached. If yes, then determine whether the power output voltage reaches the preset percentage of the input voltage; if no, then control the main power circuit to turn on.

7. The method with a capacitive load according to claim 6, characterized in that, The method further includes: The actual equivalent capacitance value is obtained based on the power on the power resistor of the pre-charge circuit. The actual equivalent capacitance value is taken as the minimum equivalent capacitance of the capacitive load.

8. The method with a capacitive load according to claim 6, characterized in that, The method further includes: The precharge circuit is shut off when the power on the precharge circuit power resistor does not reach the preset maximum energy.

9. The method for a capacitive load according to claim 6, characterized in that, The method further includes: The precharge circuit is shut off when the power output voltage does not reach the preset percentage of the input voltage.

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