Alternating-current solid-state power distribution zero-cross detection circuit

Abstract

The utility model discloses an AC solid-state power distribution zero-crossing detection circuit, comprising a voltage and current sampling circuit, a zero-crossing comparison circuit connected with the voltage and current sampling circuit, and a zero-crossing logic circuit connected with the zero-crossing comparison circuit, the voltage and current sampling circuit is composed of a voltage sampling conditioning circuit and a current sampling conditioning circuit, the voltage sampling conditioning circuit comprises a first-stage differential proportion operation circuit and a second-stage differential proportion operation circuit. According to the utility model, du / dt and di / dt of the MOSFET in the switching-on and switching-off processes can be eliminated, current impact when a capacitive load is switched on and voltage impact when an inductive load is switched off can be reduced, the conventional AC solid-state power distribution based on silicon controlled rectifiers can be replaced, the circuit development cost and period can be reduced, the zero-cross detection function of the preceding-stage drive of the AC solid-state power distribution based on the MOSFET can be realized, and the reliability of the AC solid-state power distribution based on the MOSFET can be improved. And the reliability of overall alternating-current solid-state power distribution is improved.

Description

Technical Field

[0001] This utility model relates to the field of AC solid-state power distribution detection in aviation equipment, specifically an AC solid-state power distribution zero-crossing detection circuit. Background Technology

[0002] Currently, aircraft AC power systems come in two types: constant frequency and variable frequency. Most commonly, 115V / 200V 400Hz three-phase AC power is used. Traditional relays or contactors are often used on board for power input control. However, solid-state AC power distribution has the advantages of no contacts, no electric arc, no noise, fast response, low electromagnetic interference, long life, and high reliability compared to traditional devices. In recent years, due to the increase in electrical equipment and the improvement of automation, aircraft are developing towards more electric aircraft and all-electric aircraft, and aircraft power distribution systems are gradually developing towards solid-state power distribution systems.

[0003] However, this type of AC solid-state power distribution is usually achieved through thyristors. Thyristors have disadvantages such as high heat generation, large size, poor anti-interference ability and short life. Implementing this function through MOSFETs can improve the above problems. However, during the AC channel turn-on / turn-off process, MOSFETs are accompanied by large du / dt and di / dt. There are current surges when capacitive loads are turned on and voltage surges when inductive loads are turned off. Utility Model Content

[0004] The purpose of this invention is to provide an AC solid-state power distribution zero-crossing detection circuit to solve the problems mentioned in the background art, such as high heat generation, large size, poor anti-interference ability and short lifespan of existing AC solid-state power distribution using thyristors.

[0005] To achieve the above objectives, this utility model provides the following technical solution: an AC solid-state power distribution zero-crossing detection circuit, comprising a voltage and current sampling circuit, a zero-crossing comparison circuit connected to the voltage and current sampling circuit, and a zero-crossing logic circuit connected to the zero-crossing comparison circuit. The voltage and current sampling circuit consists of a voltage sampling conditioning circuit and a current sampling conditioning circuit. The voltage sampling conditioning circuit includes a first-stage differential proportional operation circuit and a second-stage differential proportional operation circuit connected to the first-stage differential proportional operation circuit and used to condition its output voltage. The zero-crossing comparison circuit includes a window comparison circuit and capacitors C2 and C3 connected to the window comparison circuit for waveform compensation. A diode assembly and a resistor assembly are connected in parallel at the output terminals of capacitors C2 and C3. The zero-crossing logic circuit includes an optocoupler, a MOS transistor connected to the optocoupler, and a dual D flip-flop connected to the MOS transistor. The dual D flip-flop is used to provide a zero-crossing drive signal for the detection circuit.

[0006] Furthermore, the first-stage differential proportional operational circuit includes resistors R298, R306, R274, and R287, and an operational amplifier. The resistance values ​​of resistors R298 and R306 are equal, and the resistance values ​​of resistors R274 and R287 are the same. The second-stage differential proportional operational circuit includes resistors R289 and R290, and an operational amplifier. The non-inverting input of the operational amplifier is connected to the output of the operational amplifier through resistors R303 and R302 connected in series. A capacitor C137 is connected between resistors R302 and R303, and the output of capacitor C137 is connected to the output of the operational amplifier. A capacitor C138 is connected between the non-inverting input of the operational amplifier and resistor R303. The output of capacitor C138 is directly grounded (GND), and a capacitor C135 and resistor R299 are connected in parallel at the output of the operational amplifier.

[0007] Furthermore, the window comparison circuit is provided in two sets, which are divided into a first window comparison circuit and a second window comparison circuit. The first window comparison circuit includes a first window comparator, and the second window comparison circuit includes a second window comparator. The diode assembly consists of diodes D1 and D2, and the resistor assembly consists of resistors R3, R4, and R5.

[0008] Furthermore, the non-inverting input of the first window comparator is connected to the inverting input of the second window comparator, the output of the first window comparator is connected to capacitor C2, and the output of the second window comparator is connected to capacitor C3; the inverting input of the first window comparator is connected to the non-inverting input of the second window comparator.

[0009] Furthermore, the MOS transistor is an N39 MOS transistor. The base of the MOS transistor is connected to the optocoupler through resistor R283, and the collector of the MOS transistor is connected to the optocoupler through resistor R278. The emitter of the MOS transistor is connected to a dual D flip-flop. Resistor R286 is connected between resistor R283 and the optocoupler. The output terminal of resistor R286 is directly grounded. 15VCC_A is connected between the optocoupler and resistor R278.

[0010] The beneficial effects of this utility model are as follows: This utility model uses a MOSFET to eliminate the du / dt and di / dt during the MOSFET turn-on and turn-off process, reducing the current surge when capacitive loads are turned on and the voltage surge when inductive loads are turned off. Furthermore, it utilizes common and low-cost electronic components to achieve zero-crossing detection, which can replace the existing AC solid-state power distribution based on thyristors, reducing circuit development costs and time. It realizes the zero-crossing detection function of the front-end drive of MOSFET-based AC solid-state power distribution, solving the problems of large size, short lifespan and excessive heat, and improving the overall reliability of AC solid-state power distribution. It has extremely high practical promotion and application value. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the principle of this utility model;

[0012] Figure 2 This is a voltage sampling and conditioning circuit diagram of the present invention;

[0013] Figure 3 This is a diagram of the zero-crossing comparator circuit of this utility model;

[0014] Figure 4 This is the zero-crossing logic circuit diagram of this utility model.

[0015] In the diagram: 1 Voltage sampling and conditioning circuit, 11 Operational amplifier 1, 12 Operational amplifier 2, 2 Current sampling and conditioning circuit, 3 Zero-crossing comparator circuit, 31 Window comparator 1, 32 Window comparator 2, 4 Zero-crossing logic circuit, 41 Optocoupler, 42 MOS transistor, 43 Dual D flip-flop. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Please see Figure 1-4This invention provides a technical solution for an AC solid-state power distribution zero-crossing detection circuit, comprising a voltage and current sampling circuit, a zero-crossing comparison circuit 3 connected to the voltage and current sampling circuit, and a zero-crossing logic circuit 4 connected to the zero-crossing comparison circuit 3. The voltage and current sampling circuit consists of a voltage sampling conditioning circuit 1 and a current sampling conditioning circuit 2. The voltage sampling conditioning circuit 1 includes a first-stage differential proportional operation circuit and a second-stage differential proportional operation circuit connected to the first-stage differential proportional operation circuit and used to condition its output voltage. The zero-crossing comparison circuit 3 includes a window comparison circuit and capacitors C2 and C3 connected to the window comparison circuit for waveform compensation. A diode assembly and a resistor assembly are connected in parallel at the output terminals of capacitors C2 and C3. The zero-crossing logic circuit 4 includes an optocoupler 41, a MOS transistor 42 connected to the optocoupler 41, and a dual D flip-flop 43 connected to the MOS transistor 42. The dual D flip-flop 43 is used to provide a zero-crossing drive signal for the detection circuit.

[0018] In this embodiment, the first-stage differential proportional operational circuit includes resistors R298, R306, R274, and R287, and operational amplifier 11. The resistance values ​​of resistors R298 and R306 are equal, and the resistance values ​​of resistors R274 and R287 are the same. The second-stage differential proportional operational circuit includes resistors R289 and R290, and operational amplifier 12. The non-inverting input of operational amplifier 12 is connected to the output of operational amplifier 11 through resistors R303 and R302 connected in series. A capacitor C137 is connected between resistors R302 and R303, and the output of capacitor C137 is connected to the output of operational amplifier 12. A capacitor C138 is connected between the non-inverting input of operational amplifier 12 and resistor R303. The output of capacitor C138 is directly grounded (GND), and a capacitor C135 and resistor R299 are connected in parallel to the output of operational amplifier 12.

[0019] It should be noted that the voltage sampling conditioning circuit 1 and the current sampling conditioning circuit 2 operate on the same principle. The difference is that the comparison signal of the voltage sampling conditioning circuit 1 is directly taken from the AC voltage input and output terminals of the channel, while the comparison signal of the current sampling conditioning circuit 2 is taken from both ends of the detection resistor. According to the "virtual short and virtual open" behavior of operational amplifiers 11 and 12, the output voltage is determined by the difference between the resistance and the input voltage, with an amplification factor A = -(R298 / R306). Since the output of the voltage sampling conditioning circuit 1 is directly connected to the control circuit, to minimize the impact of the power side on the control circuit, a resistor with the largest possible resistance (megaohm level) should be selected at the input. Therefore, the first-stage differential proportional operational circuit is a reduction circuit, A < 1. The amplification factor of the second-stage proportional operational circuit is A = 1 + R289 / R290, which is used to condition the output voltage of the preceding stage for normal identification by the subsequent window comparator circuit.

[0020] In this embodiment, the mentioned window comparison circuit is provided in two sets, namely a first window comparison circuit and a second window comparison circuit. The first window comparison circuit includes a first window comparator 31, and the second window comparison circuit includes a second window comparator 32. The diode assembly consists of diodes D1 and D2, and the resistor assembly consists of resistors R3, R4, and R5. The non-inverting input terminal of the first window comparator 31 is connected to the inverting input terminal of the second window comparator 32, and the output terminal of the first window comparator 31 is connected to capacitor C2. The output of comparator 32 is connected to capacitor C3; the inverting input of window comparator 31 is connected to the non-inverting input of window comparator 32; the zero-crossing comparator circuit 3 compares the input signal with the GND signal. Since the input of the first window comparator circuit is an AC signal, the zero-crossing comparator circuit 3 can realize the function of outputting a high level at the zero-crossing voltage point or the overcurrent point. The capacitors C2 and C3 can be used for waveform compensation. According to the characteristic of capacitors "passing high frequencies and blocking low frequencies", the output voltage waveform of the window comparator circuit is shaped into a pulse waveform for the control of the zero-crossing logic circuit 4.

[0021] In this embodiment, the MOS transistor 42 in the zero-crossing logic circuit 4 is an N39 MOS transistor. The base of the MOS transistor 42 is connected to the optocoupler 41 through a resistor R283, and the collector of the MOS transistor 42 is connected to the optocoupler 41 through a resistor R278. The emitter of the MOS transistor 42 is connected to the dual D flip-flop 43. A resistor R286 is connected between the resistor R283 and the optocoupler 41. The output terminal of the resistor R286 is directly grounded. A 15VCC_A is connected between the optocoupler 41 and the resistor R278.

[0022] This AC solid-state power distribution zero-crossing detection circuit performs zero-voltage turn-on as follows: When optocoupler 41 is turned on, the external control signal is valid and outputs signals to pins D1, RESET1, and RESET2 of the dual D flip-flop 43 via MOSFET 42. If the AC voltage is not zero, no pulse signal is input to pin CL1 of the dual D flip-flop 43, and pin Q2 of the dual D flip-flop 43 does not output a high signal, rendering subsequent drive ineffective. When the AC voltage is zero, the zero-crossing comparator 3 outputs a pulse to pin CL1 of the dual D flip-flop 43. According to the truth table of the dual D flip-flop 43, pin Q2 of the dual D flip-flop 43 outputs a high signal for subsequent drive. The high signal output continues even after the pulse disappears, thus achieving the zero-voltage turn-on function. This function is independent of the CL1 pin of the dual D flip-flop 43. 2. Pin Influence; Zero Current Turn-Off: When optocoupler 41 is not turned on, external control signals are invalid, and signals are input to pins D1, RESET1, and RESET2 of the dual D flip-flop via MOSFET 42. If the AC current is not zero, no pulse signal is input to pin CL2 of the dual D flip-flop 43, and pin Q2 of the dual D flip-flop 43 does not output a low signal, while the subsequent drive remains effective. When the AC current is zero, the zero-crossing comparator circuit 3 outputs a pulse to pin CL2 of the dual D flip-flop 43. According to the truth table of the dual D flip-flop 43, a low signal is output at pin Q2 of the dual D flip-flop 43 for subsequent turn-off drive. After the pulse disappears, the output of the low signal will not stop, thus realizing the zero current turn-off function. This function is not affected by pin CL1 of the dual D flip-flop 43.

[0023] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0024] The above embodiments only illustrate preferred embodiments of the present utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be understood that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present utility model, and these all fall within the protection scope of the present utility model. In the present utility model, unless otherwise explicitly specified and limited, the terms "installation", "connection", "joining", "fixing", etc. should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components. Among them, there are various ways of detachable installation, such as by plugging and snapping, or by bolt connection, etc.

[0025] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An alternating current solid state power distribution zero crossing detection circuit, characterized by: The system includes a voltage and current sampling circuit, a zero-crossing comparator circuit connected to the voltage and current sampling circuit, and a zero-crossing logic circuit connected to the zero-crossing comparator circuit. The voltage and current sampling circuit consists of a voltage sampling conditioning circuit and a current sampling conditioning circuit. The voltage sampling conditioning circuit includes a first-stage differential proportional operation circuit and a second-stage differential proportional operation circuit connected to the first-stage differential proportional operation circuit and used to condition its output voltage. The zero-crossing comparator circuit includes a window comparator circuit and capacitors C2 and C3 connected to the window comparator circuit for waveform compensation. A diode assembly and a resistor assembly are connected in parallel at the output terminals of capacitors C2 and C3. The zero-crossing logic circuit includes an optocoupler, a MOSFET connected to the optocoupler, and a dual D flip-flop connected to the MOSFET. The dual D flip-flop is used to provide a zero-crossing drive signal for the detection circuit.

2. An AC solid state power distribution zero-crossing detection circuit according to claim 1, wherein: The first-stage differential proportional operational circuit includes resistors R298, R306, R274, and R287, and an operational amplifier. Resistors R298 and R306 have the same resistance value, and resistors R274 and R287 have the same resistance value. The second-stage differential proportional operational circuit includes resistors R289 and R290, and an operational amplifier. The non-inverting input of the operational amplifier is connected to the output of the operational amplifier through resistors R303 and R302 connected in series. A capacitor C137 is connected between resistors R302 and R303, and the output of capacitor C137 is connected to the output of the operational amplifier. A capacitor C138 is connected between the non-inverting input of the operational amplifier and resistor R303. The output of capacitor C138 is directly grounded (GND), and a capacitor C135 and resistor R299 are connected in parallel to the output of the operational amplifier.

3. An AC solid state power distribution zero-crossing detection circuit according to claim 1, wherein: The window comparison circuit is provided in two sets, which are divided into a first window comparison circuit and a second window comparison circuit. The first window comparison circuit includes a first window comparator, and the second window comparison circuit includes a second window comparator. The diode assembly consists of diodes D1 and D2, and the resistor assembly consists of resistors R3, R4, and R5.

4. An AC solid state power distribution zero-crossing detection circuit according to claim 3, wherein: The non-inverting input of the first window comparator is connected to the inverting input of the second window comparator. The output of the first window comparator is connected to capacitor C2, and the output of the second window comparator is connected to capacitor C3. The inverting input of the first window comparator is connected to the non-inverting input of the second window comparator.

5. An AC solid state power distribution zero-crossing detection circuit according to claim 1, wherein: The MOSFET is an N39-MOSFET. The base of the MOSFET is connected to the optocoupler through resistor R283, and the collector of the MOSFET is connected to the optocoupler through resistor R278. The emitter of the MOSFET is connected to a dual D flip-flop. Resistor R286 is connected between resistor R283 and the optocoupler. The output of resistor R286 is directly grounded. 15VCC_A is connected between the optocoupler and resistor R278.

Images