A self-built-in voltage grid-connected circuit for an aviation low-voltage DC generator controller

Abstract

This invention discloses a self-built-up voltage circuit for an aviation low-voltage DC generator controller, including a buck circuit, a switching circuit, and a comparator circuit. When the DC generator begins self-built-up voltage, the residual magnetism voltage is insufficient to power the controller, the buck circuit has no +5V output, the normally closed contact of relay U4 operates, and the residual magnetism voltage is directly supplied to the excitation winding, causing the motor terminal voltage to begin to rise. When the motor terminal voltage rises to the operating voltage of the buck circuit, it is still less than the window voltage of the comparator circuit, so the comparator circuit outputs a low level, and the buck circuit and the switching circuit begin to operate. The use of an open-collector output comparator and pull-up resistors ensures that the motor terminal voltage rises steadily during the self-built-up process, avoiding controller failure caused by excessive voltage overshoot time, and improving the power supply quality and efficiency of the low-voltage DC power supply system.

Description

Technical Field

[0001] This invention relates to the field of motor controller design technology, specifically to a self-built-in voltage grid-connected circuit for an aviation low-voltage DC generator controller. Background Technology

[0002] Currently, most low-voltage DC generators used in aviation exhibit voltage spikes during the initial voltage build-up phase. The transient output voltage fails to meet relevant national standards, and the prolonged voltage overshoot time triggers overvoltage protection on the controller, leading to malfunctions in the aviation low-voltage DC power supply system. For example, patent application CN102611374A discloses a method and circuit for controlling voltage build-up in a three-phase AC generator. Based on the natural voltage build-up process using its own regulation mechanism, a reference voltage circuit is added to control a certain overshoot voltage. This allows for dynamic changes during voltage build-up. While the voltage regulator is activated, the reference voltage gradually changes from a very small value to the final set steady-state reference voltage. This process ensures that the electromagnetic field of the main generator gradually increases, preventing rapid changes and reducing the occurrence of overshoot and other adverse phenomena during voltage build-up. However, its method of increasing the reference voltage through RC charging results in low output accuracy and unstable output. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention provides a self-built-in voltage grid-connected circuit for an aviation low-voltage DC generator controller.

[0004] This invention is achieved through the following technical solution:

[0005] A self-built voltage circuit for an aviation low-voltage DC generator controller includes a step-down circuit, a switching circuit, and a comparator circuit. The input terminal of the step-down circuit is connected to the motor terminal voltage, and the output terminal of the step-down circuit is connected to the switching circuit and the comparator circuit. The switching circuit is connected to the comparator circuit.

[0006] The step-down circuit includes a chip U1. The IN pin of chip U1 is connected to a +28V power supply and is connected to 28V ground via capacitors C1, C2, and C3. The RON pin is connected to the +28V power supply and the IN pin via resistor R1. The EN pin is connected to the +28V power supply and the IN pin via resistor R2, and is also grounded via resistor R3. The LX pin of chip U1 is connected to the FB pin via inductor L1 and capacitor C6. The LX pin is also connected to the FB pin via inductor L1 and resistor R5. The LX pin is also connected to the VCC pin via inductor L1 and diode D1, with the anode of diode D1 connected to inductor L1. The negative terminal of D2 is connected to the VCC pin. The BS pin of chip U1 is connected to the LX pin through capacitor C4. The VCC pin of chip U1 is also connected to 28V ground through capacitor C5. The LX pin of chip U1 is also connected to the ECAP pin and 28V ground through inductor L1, resistor R5, and resistor R4 respectively. The +5V output is connected to 5V ground through capacitors C10 and C11 respectively. The +5V output is also connected to one end of capacitors C7, C8, and C9 through inductor F1. The other end of capacitors C7, C8, and C9 is connected to 28V ground, and is also connected to capacitors C10 and C11 through inductor F2. Inductor F1 is connected to inductor L1.

[0007] Furthermore, the comparison circuit includes comparator U2, wherein the non-inverting input terminal of comparator U2 is connected to the motor voltage input terminal through resistor R7, and to the +5V voltage through resistor R9. The non-inverting input terminal of comparator U2 is also connected to 28V ground through capacitor C12 and resistor R6. The inverting input terminal of comparator U2 is connected to 28V ground through capacitor C13, Zener diode D2, and resistor R8. The cathode of Zener diode D2 is connected to the inverting input terminal of comparator U2, and the anode of Zener diode D2 is connected to 28V ground. Resistors R6 and R7 are connected, and resistors R8 and R9 are connected. A resistor R10 is connected across the non-inverting input terminal and the output terminal of comparator U2. The VCC pin of comparator U2 is connected to the +5V voltage, and the GND pin is connected to 28V ground.

[0008] Furthermore, the switching circuit includes relays U3 and U4, MOSFETs Q1, Q2, and Q3. The IN+ pin of relay U3 is connected to the +5V input terminal via resistors R17 and R18. The gate of MOSFET Q1 is connected to the +5V input terminal via resistors R12 and R11, and the drain of MOSFET Q1 is connected to the +5V input terminal via resistor R15. The gate of MOSFET Q2 is connected to the voltage build-up enable signal via resistor R14, and the gate of MOSFET Q2 is connected to 28V ground via resistors R14 and R13. The drain of MOSFET Q2 is connected to the drain of MOSFET Q1. The gate of MOSFET Q3 is connected to the drains of MOSFETs Q1 and Q2, and the gate of MOSFET Q3 is also connected to relays U3 and U4. The IN+ pin of relay 3 is connected, and the source of MOSFET Q3 is connected to the IN- pin of relay U3. The motor voltage input terminal is connected to the OUT+ pin of relay U3 and the 3rd pin of relay U4. The FB pin of relay U3 is connected to the 1st pin of relay U4 through diode D3 and resistor R19 and diode D3 and resistor R20, respectively. The anode of diode D3 is connected to the FB pin of relay U3, and the cathode of diode D3 is connected to resistor R19 and resistor R20, respectively. The 2nd pin of relay U4 is connected to the +5V voltage input terminal, and the 5th pin of relay U4 is connected to 28V ground. The +5V voltage input terminal and 28V ground are connected through diode D4, with the anode of diode D4 connected to 28V ground and the cathode of diode D4 connected to the +5V voltage input terminal.

[0009] The sources of MOSFETs Q1, Q2, and Q3, and the OUT- pin of relay U3 are connected to 28V ground, respectively. The +5V voltage input terminal is connected to 28V ground through capacitors C14 and C15, respectively.

[0010] Furthermore, relay U3 is an optical MOS relay with a set of normally closed contacts, and relay U4 is a medium-power sealed electromagnetic relay with a set of changeover contacts.

[0011] The beneficial effects of this invention are as follows: The self-built voltage grid-connected circuit of the aviation low-voltage DC generator controller adopts a step-down circuit, a comparator circuit, and a switching circuit. The comparator circuit uses an open-collector output comparator and a pull-up resistor, which makes the motor terminal voltage rise steadily during the self-built voltage process, avoiding controller failure caused by excessive voltage overshoot time, and improving the power supply quality and efficiency of the low-voltage DC power supply system. After the self-built voltage is completed, the controller can cut off the self-built voltage circuit and enter the normal power generation process after grid connection, which improves the output stability of the motor during the self-built voltage process. Attached Figure Description

[0012] Figure 1 This is a schematic block diagram illustrating the principle of the present invention;

[0013] Figure 2 This is the step-down circuit diagram of the present invention;

[0014] Figure 3 This is a comparison circuit and a switching circuit diagram of the present invention. Detailed Implementation

[0015] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0016] like Figure 1 As shown, when the DC generator begins to build up voltage, the residual magnetism voltage is insufficient to power the controller, meaning the buck circuit has no +5V output. The normally closed contact of relay U4 operates, and the residual magnetism voltage is directly supplied to the excitation winding, causing the motor terminal voltage to start rising. When the motor terminal voltage rises to the operating voltage of the buck circuit, it is still less than the window voltage of the comparator circuit. Therefore, the comparator circuit outputs a low level, and the buck circuit and switching circuit begin to operate. The buck circuit outputs +5V, relay U4 switches to its normally open contact, and the normally closed contact of the opto-MOS relay U3 begins to operate, causing the motor terminal voltage to continue rising. When the motor terminal voltage rises to a certain value that causes the voltage at the non-inverting input of comparator U2 to exceed the voltage at the inverting input of the comparator, the comparator circuit slowly outputs a high level until the switching circuit operates normally. The normally closed contact of the opto-MOS relay then opens, the controller cuts off the self-building voltage circuit, and the normal power generation process begins.

[0017] Based on the above working principle, the specific design is as follows: A self-built-in voltage circuit for an aviation low-voltage DC generator controller includes a step-down circuit, a switching circuit, and a comparator circuit. The step-down circuit includes a chip U1. The IN pin of chip U1 is connected to a +28V power supply and is connected to 28V ground through capacitors C1, C2, and C3. The RON pin is connected to the +28V power supply and the IN pin through resistor R1. The EN pin is connected to the +28V power supply and the IN pin through resistor R2, and the EN pin is also grounded through resistor R3. The LX pin of chip U1 is connected to the FB pin through inductor L1 and capacitor C6. The LX pin is also connected to the FB pin through inductor L1 and resistor R5. The LX pin is also connected to the FB pin through inductor L1 and diode D1. The VCC connection is as follows: the positive terminal of diode D1 is connected to inductor L1, and the negative terminal of diode D2 is connected to the VCC pin. The BS pin of chip U1 is connected to the LX pin through capacitor C4. The VCC pin of chip U1 is also connected to 28V ground through capacitor C5. The LX pin of chip U1 is also connected to the ECAP pin and 28V ground through inductor L1, resistor R5, and resistor R4, respectively. The +5V output is connected to 5V ground through capacitors C10 and C11. The +5V output is also connected to one end of capacitors C7, C8, and C9 through inductor F1. The other end of capacitors C7, C8, and C9 is connected to 28V ground, and is also connected to capacitors C10 and C11 through inductor F2. Inductor F1 is connected to inductor L1.

[0018] The circuit consists of inductor L1, resistors R4 and R5, capacitor C6, and diode D1. When the circuit is on, inductor L1 is magnetized, simultaneously charging capacitor C6 and providing energy to resistors R4 and R5. When the circuit is off, inductor L1 discharges through diode D1 to reduce the inductor current. Simultaneously, the +5V output of the buck circuit is filtered between the +5V output and +5V ground via inductors F1 and F2, and capacitors C7, C8, C9, C10, and C11. When the motor terminal voltage rises to a certain value, making V_EN = 1.5VDC (i.e., the EN voltage at the pin of chip U1 is 1.5 times the VCC voltage), the turn-on voltage of chip U1 is reached, and the buck circuit starts working. The buck circuit outputs 5V, which, after filtering by the filter circuit, becomes +5V.

[0019] The comparison circuit includes comparator U2, wherein the non-inverting input terminal of comparator U2 is connected to the motor voltage input terminal through resistor R7, and to the +5V voltage through resistor R9. The non-inverting input terminal of comparator U2 is also connected to 28V ground through capacitor C12 and resistor R6. The inverting input terminal of comparator U2 is connected to 28V ground through capacitor C13, Zener diode D2, and resistor R8. The cathode of Zener diode D2 is connected to the inverting input terminal of comparator U2, and the anode of Zener diode D2 is connected to 28V ground. Resistors R6 and R7 are connected, and resistors R8 and R9 are connected. A resistor R10 is connected across the non-inverting input terminal and the output terminal of comparator U2. The VCC pin of comparator U2 is connected to the +5V voltage, and the GND pin is connected to 28V ground.

[0020] The switching circuit includes relays U3 and U4, and MOSFETs Q1, Q2, and Q3. The IN+ pin of relay U3 is connected to the +5V input terminal via resistors R17 and R18. The gate of MOSFET Q1 is connected to the +5V input terminal via resistors R12 and R11, and the drain of MOSFET Q1 is connected to the +5V input terminal via resistor R15. The gate of MOSFET Q2 is connected to the voltage build-up enable signal via resistor R14, and the gate of MOSFET Q2 is connected to 28V ground via resistors R14 and R13. The drain of MOSFET Q2 is connected to the drain of MOSFET Q1. The gate of MOSFET Q3 is connected to the drains of MOSFETs Q1 and Q2, and the gate of MOSFET Q3 is also connected to the relay U3. The IN+ pin is connected, and the source of MOSFET Q3 is connected to the IN- pin of relay U3. The motor voltage input terminal is connected to the OUT+ pin of relay U3 and pin 3 of relay U4. The FB pin of relay U3 is connected to pin 1 of relay U3 through diode D3 and resistor R19 and diode D3 and resistor R20, respectively. The positive terminal of diode D3 is connected to the FB pin of relay U3, and the negative terminal of diode D3 is connected to resistor R19 and resistor R20, respectively. Pin 2 of relay U4 is connected to the +5V voltage input terminal, and pin 5 of relay U4 is connected to 28V ground. The +5V voltage input terminal and 28V ground are connected through diode D4, with the positive terminal of diode D4 connected to 28V ground and the negative terminal of diode D4 connected to the +5V voltage input terminal.

[0021] The sources of MOSFETs Q1, Q2, and Q3, and the OUT- pin of relay U3 are connected to 28V ground, respectively. The +5V voltage input terminal is connected to 28V ground through capacitors C14 and C15, respectively.

[0022] The relay U3 is an optical MOS relay with a set of normally closed contacts, optical isolation, power MOSFET output, and strong overload capacity. The relay U4 is a medium-power sealed electromagnetic relay with a set of changeover contacts.

[0023] In actual operation, the situation is divided into two categories: controller without emergency power supply and controller with emergency power supply.

[0024] When the controller has no emergency power:

[0025] The DC generator begins to build up voltage, but the residual magnetism voltage is insufficient to power the controller. The buck circuit has no +5V output, the normally closed contact of relay U4 operates, and the residual magnetism voltage is directly supplied to the excitation winding, causing the motor terminal voltage to start to rise. When the motor terminal voltage rises to the operating voltage of the buck circuit (16V-18V), it is still less than the window voltage of the comparator circuit (18V-21V). The comparator circuit outputs a low level, the buck circuit and the switching circuit start to work, the buck circuit outputs +5V, relay U4 switches to its normally open contact, MOSFETs Q1 and Q2 are not conducting, MOSFET Q3 is conducting, the normally closed contact of the opto-MOSFET relay U3 starts to operate, and the motor terminal voltage continues to rise.

[0026] When the motor terminal voltage is greater than the window voltage (18V-21V) of the comparator circuit, since the comparator used in the comparator circuit is an open collector output stage, the comparator circuit has the ability to slowly output a high level through the pull-up resistor R11, while clamping the motor terminal voltage between 21V-24V. When the motor terminal voltage rises to the normal operating level of the switching circuit, MOSFET Q1 is turned on, MOSFETs Q2 and Q3 are not turned on, the normally closed contact of the opto-MOSFET relay U3 is opened, the controller cuts off the self-built voltage circuit, and enters the normal power generation process.

[0027] When the controller has an emergency power supply: it outputs a voltage build-up enable signal, the buck circuit works normally, outputs +5V voltage, and the optoMOSFET relays U3 and U4 are in the normally open state. At this time, the controller directly cuts off the self-voltage build-up circuit and further controls the excitation current through the output PWM to enter the normal power generation process.

Claims

1. A self-built-in voltage circuit for an aviation low-voltage DC generator controller, characterized in that, It includes a step-down circuit, a switching circuit, and a comparator circuit. The input terminal of the step-down circuit is connected to the motor terminal voltage, and the output terminal of the step-down circuit is connected to the switching circuit and the comparator circuit. The switching circuit is connected to the comparator circuit. The comparison circuit includes comparator U2, wherein the non-inverting input terminal of comparator U2 is connected to the motor voltage input terminal through resistor R7, and the inverting input terminal of comparator U2 is connected to +5V voltage through resistor R9. The non-inverting input terminal of comparator U2 is also connected to 28V ground through capacitor C12 and resistor R6. The inverting input terminal of comparator U2 is connected to 28V ground through capacitor C13, Zener diode D2, and resistor R8. The cathode of Zener diode D2 is connected to the inverting input terminal of comparator U2, and the anode of Zener diode D2 is connected to 28V ground. Resistors R6 and R7 are connected, and resistors R8 and R9 are connected. A resistor R10 is connected across the non-inverting input terminal and the output terminal of comparator U2. The VCC pin of comparator U2 is connected to +5V voltage, and the GND pin is connected to 28V ground. The switching circuit includes relays U3 and U4, MOSFETs Q1, Q2, and Q3. The IN+ pin of relay U3 is connected to the +5V input terminal via resistors R17 and R18. The gate of MOSFET Q1 is connected to the +5V input terminal via resistors R12 and R11. The junction of resistors R11 and R12 is connected to the output terminal of comparator U2. The drain of MOSFET Q1 is connected to the +5V input terminal via resistor R15. The gate of MOSFET Q2 is connected to the voltage build-up enable signal via resistor R14. The gate of MOSFET Q2 is connected to 28V ground via resistors R14 and R13. The drain of MOSFET Q2 is connected to the drain of MOSFET Q1. The gate of MOSFET Q3 is connected to the drains of MOSFETs Q1 and Q2, and the drain of MOSFET Q3 is also connected to the IN+ pin of relay U3. The source of MOSFET Q3 is connected to the IN+ pin of relay U3. The IN- pin of relay U3 is connected to the OUT+ pin of relay U3 and the OUT- pin of relay U4. The FB pin of relay U3 is connected to pin 1 of relay U3 via diode D3 and resistor R19, and diode D3 and resistor R20, respectively. The positive terminal of diode D3 is connected to the FB pin of relay U3, and the negative terminal of diode D3 is connected to resistor R19 and resistor R20, respectively. Pin 2 of relay U4 is connected to the +5V voltage input terminal. Pin 5 of relay U4 is connected to 28V ground. The +5V voltage input terminal and 28V ground are connected via diode D4, with the positive terminal of diode D4 connected to 28V ground and the negative terminal of diode D4 connected to the +5V voltage input terminal. The sources of MOSFETs Q1, Q2, and Q3 and the OUT- pin of relay U3 are all connected to 28V ground. The +5V voltage input terminal is connected to 28V ground via capacitors C14 and C15, respectively.

2. The self-built-in voltage circuit of an aviation low-voltage DC generator controller according to claim 1, characterized in that, The step-down circuit includes a chip U1. The IN pin of chip U1 is connected to a +28V power supply and is connected to 28V ground via capacitors C1, C2, and C3. The RON pin is connected to the +28V power supply and the IN pin via resistor R1. The EN pin is connected to the +28V power supply and the IN pin via resistor R2, and is also grounded via resistor R3. The LX pin of chip U1 is connected to the FB pin via inductor L1 and capacitor C6. The LX pin is also connected to the FB pin via inductor L1 and resistor R5. The LX pin is also connected to the VCC pin via inductor L1 and diode D1, with the anode of diode D1 connected to inductor L1 and the cathode of diode D1 connected to the VCC pin. With C-connection, the BS pin of chip U1 is connected to the LX pin through capacitor C4. The VCC pin of chip U1 is also connected to 28V ground through capacitor C5. The LX pin of chip U1 is also connected to pin ECAP and 28V ground through inductor L1, resistor R5, and resistor R4 respectively. The +5V output is connected to 5V ground through one end of capacitor C10 and one end of capacitor C11. The +5V output is also connected to one end of capacitor C7, capacitor C8, and capacitor C9 through inductor F1. The other end of capacitors C7, capacitor C8, and capacitor C9 is connected to 28V ground, and at the same time, it is connected to the other end of capacitor C10 and the other end of capacitor C11 through inductor F2. Inductor F1 is connected between inductor L1 and +5V.

3. The self-built-in voltage circuit of an aviation low-voltage DC generator controller according to claim 1, characterized in that, The relay U3 is an optical MOS relay with a set of normally closed contacts, and the relay U4 is a medium-power sealed electromagnetic relay with a set of changeover contacts.

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