High-voltage high-power capacitor pre-charging device

Abstract

The utility model belongs to the field of airplane electromechanical control, and relates to a high-voltage high-power capacitor pre-charging device. The circuit comprises a front end voltage sampling circuit (1), a rear end voltage sampling circuit (2), a voltage comparator (3), a contactor driving circuit (4), an MOS driving circuit (5), a power tube (6), a bus film capacitor (7), a pre-charging resistor (8), a field effect transistor (9) and a contactor (10). The pre-charging function is completely realized by a hardware circuit, and the device has the advantages of high integration and reliability and the like. Meanwhile, the pre-charging resistor branch is connected in series with the field effect transistor, so that the pre-charging resistor can be completely cut off after the pre-charging function is completed, and the charging resistor is prevented from being damaged due to overheating. The integration and the reliability of the system are improved; the pre-charging device and the power inverter are integrally installed on the heat dissipation cold plate, the heat dissipation function of a high-power device is considered, the structure is simple, and maintenance is convenient.

Description

Technical Field

[0001] This utility model belongs to the field of aircraft electromechanical control and relates to a high-voltage, high-power capacitor pre-charging device. Background Technology

[0002] In airborne high-voltage, high-power motor controllers, a large-capacity holding capacitor is connected in parallel at the DC bus input terminal for filtering, absorbing pulsating voltage and current from the high-voltage DC voltage. In airborne environments, this capacitor is typically a film capacitor, and its capacitance is usually proportional to the controller's operating power. This project uses a 540V-powered high-voltage, high-power motor controller, therefore an 800μF film capacitor is selected for the bus input side. At the moment of power-on, due to the very low internal resistance of the film capacitor, the inrush current exceeds 2000A, which can easily cause malfunctions in the overcurrent protection devices at the system power supply front end. Furthermore, the large inrush current can adversely affect the system. Therefore, this project requires the design of a high-power pre-charge device to reduce the inrush current at power-on and prevent system power supply malfunctions.

[0003] The capacitor pre-charging device in this project adopts a combination of contactor, charging resistor and charging MOSFET, and is combined with controller voltage comparator to control the drive signal, which has the characteristics of integration and high reliability. Utility Model Content

[0004] The purpose of this invention is to provide a bus input capacitor pre-charging device for a 540V high-voltage high-power driver. The pre-charging function is entirely implemented through hardware circuitry, offering advantages such as high integration and reliability. Furthermore, by connecting a field-effect transistor in series with the pre-charging resistor branch, the pre-charging resistor can be completely disconnected after the pre-charging function is completed, preventing overheating and damage to the charging resistor.

[0005] The technical solution of this utility model:

[0006] A high-voltage, high-power capacitor pre-charging device includes a front-end voltage sampling circuit (1), a back-end voltage sampling circuit (2), a voltage comparator (3), a contactor drive circuit (4), a MOS drive circuit (5), a power transistor (6), a bus thin-film capacitor (7), a pre-charging resistor (8), a field-effect transistor (9), and a contactor (10). The core function of this device is: when the system is powered on, the signal of the MOS drive circuit (5) is at a high level, the field-effect transistor (9) is turned on, and the 540V power supply charges the bus thin-film capacitor (7) through the pre-charging resistor (8), thereby controlling the power-on inrush current within an effective range. Meanwhile, the controller collects voltage data from the 540V front-end voltage (1) and the back-end voltage (2), and sends the collected voltage to the voltage comparator (3) for comparison. When the comparison value reaches the set threshold, the comparator outputs a high level and sends it to the contactor drive circuit (4), which drives the contactor (10) connected in parallel with the pre-charging resistor and the field-effect transistor to close. At the same time, the output signal of the voltage comparator is flipped, and the signal of the MOS drive circuit (5) is set to a low level, disconnecting the pre-charging resistor branch to avoid overheating and damage to the pre-charging resistor after it flows a large current during motor operation.

[0007] The front-end voltage sampling circuit (1) and the back-end voltage sampling circuit (2) use a voltage divider circuit to perform voltage division sampling. After voltage division, the sampled voltage is sent to a linear isolation amplifier to generate an output voltage which is sent to a voltage comparator (3). The voltage comparator compares the front-end and back-end voltages for subsequent processing and can also take into account voltage protection processing.

[0008] The MOS drive circuit (5) is used to switch the field-effect transistor (9) connected in series in the pre-charge resistor branch. When the 540V voltage is applied, the drive signal is high, the field-effect transistor is turned on, and the pre-charge resistor is activated. When the voltage comparator (3) reaches the set threshold, the drive signal is low, the field-effect transistor is turned off, and the pre-charge resistor branch is completely short-circuited, avoiding overcurrent and overheating damage to the pre-charge resistor. This provides flexibility and real-time performance. At the same time, a discharge resistor is connected in parallel on the back-end bus capacitor side, so that the internal circuit can be quickly de-energized after the 540V power is cut off.

[0009] Both the MOS drive circuit (5) and the contactor drive circuit (4) are processing the command signal given by the voltage comparator (3). Since the drive current of the comparator is small, it cannot reliably turn on or off the field-effect transistor and the contactor. Therefore, the drive signal uses a Darlington optocoupler for drive signal isolation and amplification, which has the advantage of strong drive capability and ensures the reliable operation of the field-effect transistor (9) and the contactor (10).

[0010] Based on the output of the voltage comparator (3), the turn-on and turn-off sequence of the drive signal is specified. When the voltage comparison reaches the set threshold, the contactor drive circuit (4) signal is turned on first, and then the MOS drive circuit (5) signal is turned off through the level flipping circuit, thus avoiding the bus voltage impact when the contactor branch is closed.

[0011] The pre-charge contactor (10) is connected in series with the forward branch of the bus capacitor (7) in terms of structure, and is also integrated with the motor inverter (6) and installed on the heat dissipation surface of the cold plate. This takes into account the heat dissipation function of high-power devices, making the structure simple and the operation reliable.

[0012] Advantages of this invention: This invention operates entirely in hardware, making control relatively simple, and also includes bus voltage protection, improving system integration and reliability; at the same time, the pre-charging device and power inverter are integrated and mounted on a heat dissipation plate, taking into account the heat dissipation function of high-power devices, resulting in a simple structure and easy maintenance. Attached Figure Description

[0013] Figure 1 This is a structural diagram of the pre-charging device;

[0014] Figure 2 This is a circuit diagram for sampling capacitor voltage.

[0015] Figure 3 This is a Darlington optocoupler driver circuit.

[0016] Figure 4 Circuit diagram for the pre-charging circuit that also serves as a discharge resistor;

[0017] Figure 5 This is a design drawing for the integrated pre-charging device and inverter. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of the embodiments of this utility model will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar components or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this utility model. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model. The embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0019] The specific implementation of this utility model will be further described below with reference to the accompanying drawings.

[0020] This invention provides a pre-charging device for a 540V high-voltage high-power motor controller. The device is hardware-wise composed of a pre-charging resistor, a field-effect transistor, and a contactor. It can acquire the voltages at the front and rear ends of the 540V pre-charging device and send them to a voltage comparator. The comparator compares the bus voltage thresholds at the front and rear ends and generates a drive command to drive the pre-charging device. It also provides fault protection for the bus voltage and adds a bleed resistor on the capacitor side to ensure rapid power cut-off inside the controller after a 540V power outage. Furthermore, the contactor, inverter, and capacitor are integrated to ensure heat dissipation of the high-power components. The system structure is simple, and the device has high reliability. This invention provides a general description of the principle and method, including the core inventive points of this invention.

[0021] The capacitor pre-charging device includes a front-end voltage sampling circuit (1), a back-end voltage sampling circuit (2), a voltage comparator (3), a contactor drive circuit (4), a MOS drive circuit (5), a power transistor (6), a bus film capacitor (7), a pre-charging resistor (8), a field-effect transistor (9), and a contactor (10). When the system is powered on, the given MOS drive circuit signal is high, the field-effect transistor is turned on, and the 540V power supply charges the bus film capacitor through the pre-charging resistor, controlling the power-on inrush current within an effective range. Simultaneously, the controller acquires voltage data from the 540V front-end and back-end, and sends the acquired voltage to a voltage comparator for processing. The voltage comparator compares the front-end and back-end voltages. When the comparison value reaches a set threshold, the contactor drive signal is set to high level, closing the contactor connected in parallel with the pre-charging resistor and the field-effect transistor. At the same time, the MOS drive circuit signal is set to low level, disconnecting the pre-charging resistor branch. When the power supply voltage drops, if the acquired bus voltage is lower than a certain threshold, the contactor drive signal is set to low level, disconnecting the contactor branch. At the same time, the MOS drive signal is set to high level, conducting the pre-charging resistor branch for pre-charging.

[0022] Figure 2 The circuit shown is a 540V voltage sampling circuit, which consists of a resistor divider circuit, an isolation amplifier circuit, and a conditioning circuit. Resistors R50, R51, and R53 to R56 are 540V voltage divider sampling resistors. After passing through the RC filter composed of R57 and C27, the voltage is sent to the input side of the linear isolation amplifier U4. After being linearly isolated and amplified by U4, the output is sent to the operational amplifier U5 for conditioning. The output voltage of U5 is then sent to the input pin of the voltage comparator for voltage sampling and processing. This circuit can sample bus voltages of up to 1000V.

[0023] Figure 3To drive the signal amplification circuit, the drive control command output by the voltage comparator is amplified by the U16 Darlington optocoupler before driving the contactor and MOSFET. When the voltage comparator output command CON_PWM_Y1 is low, pin 4 of U16 outputs a low level; when CON_PWM_Y1 is high, pin 4 of U16 outputs a high level. This circuit uses an opto-isolated coupler, featuring strong driving capability and reliable operation.

[0024] Figure 4 This diagram shows the pre-charging main power circuit, which also functions as a bleeder resistor. When the 540V power supply is applied, the 540V input voltage charges through the pre-charging resistor R79. At this time, the MOSFET Q13, connected in series in the pre-charging resistor branch, is conducting. After the controller sets a threshold, it drives MOSFET Q14 to conduct, the contactor closes, and MOSFET Q13 opens, ending the pre-charging process. Simultaneously, resistors R81, R83, R85, and R88~R90 are connected in parallel across the bus capacitor to quickly discharge the voltage inside the controller when the power supply is interrupted.

[0025] Figure 5 This diagram shows an integrated structure of the pre-charging device, three-phase inverter, and bus capacitor. The pre-charging circuit is integrated into the power board printed circuit board, with the bus capacitor fixed on top of the power board. The pre-charging capacitor and contactor are connected to the power board via copper busbars. The pre-charging resistor, contactor, and three-phase inverter are fixed to a heat sink. This structure features integration while also addressing heat dissipation for high-power devices. The system structure is simple and the logic is clear.

[0026] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein. The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this invention. It should be understood that the above descriptions are merely specific embodiments of this invention and are not intended to limit this invention. Within the spirit and principles of this invention, any person skilled in the art may modify or alter the disclosed technical content to create equivalent embodiments applicable to other fields. However, any simple modifications, equivalent changes, alterations, modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of this invention without departing from the content of the technical solution of this invention should be included within the protection scope of this invention.

Claims

1. A high-voltage, high-power capacitor pre-charging device, characterized in that, It includes a front-end voltage sampling circuit, a back-end voltage sampling circuit, a voltage comparator, a contactor drive circuit, a MOSFET drive circuit, a power transistor, a bus film capacitor, a pre-charging resistor, a MOSFET, and a contactor. When the system is powered on, the MOSFET drive circuit signal is high, the MOSFET is turned on, and the 540V power supply charges the bus film capacitor through the pre-charging resistor, keeping the power-on inrush current within an effective range. The controller samples the 540V front-end and back-end voltages and sends the sampled voltages to the voltage comparator for comparison. When the comparison value reaches the set threshold, the comparator outputs a high level and sends it to the contactor drive circuit, driving the contactor connected in parallel with the pre-charging resistor and the MOSFET to close. At the same time, the voltage comparator output signal is flipped, the MOSFET drive circuit signal is set to low, and the pre-charging resistor branch is disconnected to prevent the pre-charging resistor from overheating and being damaged when the motor is running due to large current.

2. The apparatus as claimed in claim 1, characterized in that, The front-end voltage sampling circuit and the back-end voltage sampling circuit use a voltage divider circuit for voltage division sampling. After voltage division, the sampled voltage is sent to a linear isolation amplifier to generate an output voltage, which is then sent to a voltage comparator. The voltage comparator compares the front-end and back-end voltages for subsequent processing steps.

3. The apparatus as described in claim 2, characterized in that, The MOS drive circuit is used to provide the switching command signal for the field-effect transistor connected in series in the pre-charge resistor branch. When the 540V voltage is applied, the drive signal is high, the field-effect transistor is turned on, and the pre-charge resistor is activated. When the voltage comparator reaches the set threshold, the drive signal is low, and the field-effect transistor is turned off. A bleeder resistor is connected in parallel on the rear bus capacitor side, so that the internal circuit can be quickly powered off after the 540V power is cut off.

4. The apparatus as described in claim 3, characterized in that, Both the MOS drive circuit and the contactor drive circuit process the command signal given by the voltage comparator, and the optocoupler isolates and amplifies the drive signal, which has the advantage of strong driving capability and ensures the reliable operation of the field-effect transistor and the contactor.

5. The apparatus as described in claim 4, characterized in that, Based on the output of the voltage comparator, the turn-on and turn-off sequence of the drive signal is specified. When the voltage comparison reaches the set threshold, the contactor drive circuit signal is turned on first, and then the MOS drive circuit signal is turned off through the level flipping circuit, thus avoiding the bus voltage surge when the contactor branch is closed.

6. The apparatus as claimed in claim 5, characterized in that, The pre-charge contactor is structurally designed to connect the contactor in series with the forward branch of the bus capacitor and integrate it with the motor inverter, mounting it on the heat dissipation surface of the cold plate.

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