A DC load drive protection circuit

Abstract

The invention discloses a DC load drive protection circuit, including a power control circuit, a current signal acquisition and conditioning circuit, a comparison circuit and a logic judgment circuit; the power control circuit controls the MOSFET power tube to be turned on and off through a photoelectric coupler and a voltage-dividing resistor, and the power circuit adopts a MOSFET power tube and a power relay series structure; the current signal acquisition and conditioning circuit converts the current signal into a voltage signal through an isolated current sensor, and the voltage signal enters the comparison circuit after being processed by a differential amplifier circuit; the comparison circuit compares the overcurrent signal voltage value with the overcurrent threshold value and outputs an overcurrent protection signal; the logic judgment circuit receives the overcurrent protection signal, and after performing an OR operation with the CPU circuit output control signal, outputs the MOSFET power tube control signal to the power control circuit to control the MOSFET power tube to turn off the protection. The invention has strong real-time performance, simple circuit design and high reliability.

Description

Technical Field

[0001] The invention belongs to the field of electrical technology and relates to a direct current load drive protection circuit. Background Art

[0002] With the replacement of airborne products, traditional mechanical transmission has been replaced by electric transmission. Power transmission is completed through electrical wires in the form of electrical energy transmission. Electric transmission not only reduces the weight of airborne products and reduces ground maintenance equipment, but also has strong fault tolerance, which greatly improves the reliability, maintainability and economy of aircraft. At present, the actuators of electric transmission mainly include actuators, electric valves, intelligent valves, etc. In order to ensure the reliability and life of the actuators, higher requirements are put forward for the drive protection circuit. At present, the actuators are developing towards intelligent and integrated drive components, that is, the actuators not only integrate power circuits, but also control circuits and processing circuits. Due to the structural space limitations of the actuators, a large number of acquisition circuits and processing circuits cannot be used. Therefore, in order to meet the design requirements of new actuators, it is necessary to design a simple, reliable and fast protection drive protection circuit. Summary of the invention

[0003] (I) Purpose of the invention

[0004] The purpose of the present invention is to provide a DC load drive protection circuit which is simple in design, reliable and capable of rapid protection.

[0005] (II) Technical solution

[0006] In order to solve the above technical problems, the present invention provides a DC load drive protection circuit, including a power control circuit, a current signal acquisition and conditioning circuit, a comparison circuit and a logic judgment circuit; the power control circuit controls the opening and closing of a MOSFET power tube through a photoelectric coupler and a voltage-dividing resistor, and the power circuit adopts a MOSFET power tube and a power relay series structure; the current signal acquisition and conditioning circuit converts the current signal into a voltage signal through an isolated current sensor, and the voltage signal enters the comparison circuit after being processed by a differential amplifier circuit; the comparison circuit compares the overcurrent signal voltage value with the overcurrent threshold value and outputs an overcurrent protection signal; the logic judgment circuit receives the overcurrent protection signal, and after performing an OR operation with the CPU circuit logic control signal, outputs the MOSFET power tube control signal to the power control circuit to control the MOSFET power tube to shut down the protection.

[0007] Among them, the power control circuit includes a photocoupler U1, a power relay K1, and a MOSFET power tube V1. The photocoupler U1 receives a logic control signal CON_B, and the output of the photocoupler U1 is connected to the MOSFET power tube V1 to achieve isolation and driving functions; the power relay K1 receives a logic control signal CON_C and is connected in series with the MOSFET power tube V1 to avoid a single power tube failure causing the power circuit to be unable to disconnect the protection in time, thereby achieving reliable control of the power output terminal POUT.

[0008] The power control circuit also includes a current limiting resistor R1, a voltage dividing resistor R2, a voltage dividing resistor R3, a voltage regulator tube V2, a freewheeling diode V3, a resistor R4 and a capacitor C1. One end of the current limiting resistor R1 is connected to the input terminal 1 of the photocoupler U1, and the other end of the current limiting resistor R1 is connected to the +5V power supply. The logic control signal CON_B is connected to the input terminal 2 of the photocoupler U1. One end of the voltage dividing resistor R2 is connected to the output terminal 3 of the photocoupler U1, and the other end of the voltage dividing resistor R2 is connected to the Q15V power supply. One end of the voltage dividing resistor R3 is connected to the output terminal 4 of the photocoupler U1, the cathode of the voltage regulator tube V2 and the MOSFET power The gate pin 1 of the tube V1 and the other end of the voltage-dividing resistor R3 are connected to the anode of the voltage-stabilizing tube V2, the source pin 3 of the MOSFET power tube V1, one end of the resistor R4 and the power terminal QGND, the drain pin 2 of the MOSFET power tube V1 is connected to the contact terminal pin 1 of the power relay K1 and one end of the capacitor C1, the other end of the capacitor C1 is connected to the resistor R4, the contact terminal pin 2 of the power relay K1 is connected to the DC28V power supply, the coil terminal pin 4 of the power relay K1 is connected to the logic control signal CON_C and the cathode of the freewheeling diode V3, and the coil terminal pin 3 of the power relay K1 is connected to the anode of the freewheeling diode V3 and the power ground AGND.

[0009] Among them, the gate 1 pin and the source 3 pin of the MOSFET power tube V1 are connected to the voltage regulator tube V2 to prevent overvoltage breakdown between the gate and the source of the MOSFET power tube.

[0010] Among them, the current signal acquisition and conditioning circuit includes an isolated current sensor U2 and an operational amplifier U3. The isolated current sensor U1 converts the power loop current into a voltage signal AOUT. After the voltage signal AOUT and the reference voltage REF2.5V output by the isolated current sensor U2 pass through a differential amplifier circuit composed of the operational amplifier U3, the reference voltage in the voltage signal AOUT is changed from 2.5V to 0V and amplified to output a voltage signal BOUT.

[0011] Among them, the current signal acquisition and conditioning circuit also includes a decoupling capacitor C2, a resistor R5 and a resistor R6, one end of the resistor R5 is connected to the reference voltage terminal 9 pin (REF2.5V) of the isolated current sensor U2, the other end of the resistor R5 is connected to the input terminal 1 pin of the operational amplifier U3 and one end of the resistor R6, the other end of the resistor R6 is connected to the output terminal 3 pin of the operational amplifier U3 and the voltage signal BOUT, one end of the decoupling capacitor C2 is connected to the power supply terminal 11 pin of the isolated current sensor U2 and the signal ground SGND, the other end of the capacitor C2 is connected to the power supply terminal 12 pin of the isolated current sensor U2 and the +5V power supply, the output terminal 10 of the isolated current sensor U2 is connected to the input terminal 2 pin of the operational amplifier U3 and the voltage signal AOUT, the power input terminals 1 pin, 3 pin, 5 pin and 7 pin of the isolated current sensor U2 are connected to the power terminal QGND, the power output terminals 2 pin, 4 pin, 6 pin and 8 pin of the isolated current sensor U2 are connected to the power output terminal POUT, and the operational amplifier U3 is powered by a +5V power supply.

[0012] Among them, the comparison circuit includes a comparator U4, a resistor R7, a resistor R8 and a pull-up resistor R9, one end of the resistor R7 is connected to the voltage signal BOUT, the other end of the resistor R7 is connected to the input terminal 2 of the comparator U4 and one end of the resistor R8, the other end of the resistor R8 is connected to the output terminal 3 of the comparator U4, the overcurrent protection signal CON_OVER and one end of the resistor R9, the other end of the resistor R9 is connected to a +5V power supply, the input terminal 1 of the comparator U4 is connected to the overcurrent threshold signal REF_B, and the comparator U4 is powered by a +5V power supply.

[0013] Among them, the comparison circuit compares the voltage signal BOUT with the overcurrent threshold signal REF_B. When the voltage signal BOUT is higher than the overcurrent threshold signal REF_B, the overcurrent protection signal CON_OVER is output as a high level and an overcurrent phenomenon exists. Otherwise, it is a low level and there is no overcurrent phenomenon.

[0014] Among them, the logic judgment circuit includes an OR gate U5. After the OR gate U5 performs an OR operation on the CPU circuit logic control signal CON_A and the overcurrent protection signal CON_OVER, it outputs the logic control signal CON_B to the power control circuit. The input terminal 1 pin of the OR gate U5 is connected to the CPU circuit output control signal, the input terminal 2 pin of the OR gate U5 is connected to the overcurrent protection signal CON_OVER, and the output terminal 3 pin of the OR gate U5 is connected to the input terminal 2 pin of the photocoupler U1.

[0015] Among them, the current sensor adopts an isolated sensor to isolate the power signal to be collected by the current sensor from the small voltage signal output by the current sensor.

[0016] (III) Beneficial effects

[0017] The DC load drive protection circuit provided by the above technical solution adopts a structure in which a MOSFET power tube is connected in series with a power relay, realizes the power circuit overcurrent protection function through a current signal acquisition and conditioning circuit, a comparison circuit and a logic judgment circuit, realizes overcurrent judgment and outputs a control signal through a hardware circuit, and the CPU processing circuit participates in the judgment, thereby reducing the burden of the CPU processing circuit and reducing the output delay of the overcurrent protection signal, thereby improving the real-time performance of the circuit. At the same time, the circuit design is simple, compact and highly reliable, and is suitable for occasions where the circuit board structure space is small, such as actuators. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the application of the driving protection circuit of the present invention.

[0019] Figure 2 This is the driving protection circuit diagram of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0021] See also Figure 1 As shown, the DC load drive protection circuit of this embodiment is applied to the actuator control circuit, and the CPU processing circuit outputs the logic control signal CON_A to the logic judgment circuit; the power control circuit receives the logic control signal CON_B output by the logic judgment circuit and the logic control signal CON_A output by the CPU processing circuit to control the on and off of the power circuit; the power control circuit outputs the power current to the power output terminal POUT through the current signal acquisition and conditioning circuit, and the current signal acquisition and conditioning circuit isolates the current signal and converts it into a voltage signal BOUT, and the power output terminal POUT is connected to the DC load; the comparison circuit compares the voltage signal BOUT with the overcurrent threshold, outputs the overcurrent protection signal CON_OVER to the logic judgment circuit, and outputs the logic control signal CON_B to the power control circuit after logic judgment, controls the power circuit to be turned off, and realizes the overcurrent protection function.

[0022] See also Figure 2As shown, the present invention specifically includes an embodiment of a DC load drive protection circuit, including a power control circuit, a current signal acquisition and conditioning circuit, a comparison circuit and a logic judgment circuit; the power control circuit controls the MOSFET power tube to be turned on and off through a photoelectric coupler and a voltage-dividing resistor, and the power circuit adopts a MOSFET power tube and a power relay series structure; the current signal acquisition and conditioning circuit converts the current signal into a voltage signal through an isolated current sensor, and the voltage signal enters the comparison circuit after being processed by a differential amplifier circuit; the comparison circuit compares the overcurrent signal voltage value with the overcurrent threshold value and outputs an overcurrent protection signal; the logic judgment circuit receives the overcurrent protection signal, and after performing an OR operation with the CPU circuit logic control signal, outputs the MOSFET power tube control signal to the power control circuit to control the MOSFET power tube to turn off the protection.

[0023] The power control circuit includes a photocoupler U1, a power relay K1, and a MOSFET power tube V1. The photocoupler U1 receives a logic control signal CON_B, and the output of the photocoupler U1 is connected to the MOSFET power tube V1 to achieve isolation and driving functions; the power relay K1 receives a logic control signal CON_C and is connected in series with the MOSFET power tube V1 to avoid the failure of a single power tube to cause the power circuit to be unable to disconnect the protection in time, thereby achieving reliable control of the power output terminal POUT.

[0024] The power control circuit also includes a current limiting resistor R1, a voltage dividing resistor R2, a voltage dividing resistor R3, a voltage regulator tube V2, a freewheeling diode V3, a resistor R4 and a capacitor C1. One end of the current limiting resistor R1 is connected to the input terminal 1 of the photocoupler U1, and the other end of the current limiting resistor R1 is connected to the +5V power supply. The logic control signal CON_B is connected to the input terminal 2 of the photocoupler U1. One end of the voltage dividing resistor R2 is connected to the output terminal 3 of the photocoupler U1, and the other end of the voltage dividing resistor R2 is connected to the Q15V power supply. One end of the voltage dividing resistor R3 is connected to the output terminal 4 of the photocoupler U1, the cathode of the voltage regulator tube V2 and the MOSFET power tube V The gate pin 1 of 1, the other end of the voltage-dividing resistor R3 is connected to the anode of the voltage-regulating tube V2, the source pin 3 of the MOSFET power tube V1, one end of the resistor R4 and the power terminal QGND, the drain pin 2 of the MOSFET power tube V1 is connected to the contact terminal pin 1 of the power relay K1 and one end of the capacitor C1, the other end of the capacitor C1 is connected to the resistor R4, the contact terminal pin 2 of the power relay K1 is connected to the DC28V power supply, the coil terminal pin 4 of the power relay K1 is connected to the logic control signal CON_C and the cathode of the freewheeling diode V3, and the coil terminal pin 3 of the power relay K1 is connected to the anode of the freewheeling diode V3 and the power ground AGND.

[0025] The power control circuit prevents overvoltage breakdown between the gate and source of the MOSFET power tube by connecting a voltage regulator tube V2 between the gate 1 pin and the source 3 pin of the MOSFET power tube V1.

[0026] The current signal acquisition and conditioning circuit includes an isolated current sensor U2 and an operational amplifier U3. The isolated current sensor U1 converts the power loop current into a voltage signal AOUT. After the voltage signal AOUT and the reference voltage REF2.5V output by the isolated current sensor U2 pass through a differential amplifier circuit composed of the operational amplifier U3, the reference voltage in the voltage signal AOUT is changed from 2.5V to 0V and amplified to output a voltage signal BOUT.

[0027] The current signal acquisition and conditioning circuit also includes a decoupling capacitor C2, a resistor R5 and a resistor R6. One end of the resistor R5 is connected to the reference voltage terminal 9 pin (REF2.5V) of the isolated current sensor U2, the other end of the resistor R5 is connected to the input terminal 1 pin of the operational amplifier U3 and one end of the resistor R6, the other end of the resistor R6 is connected to the output terminal 3 pin of the operational amplifier U3 and the voltage signal BOUT, one end of the decoupling capacitor C2 is connected to the power supply terminal 11 pin of the isolated current sensor U2 and the signal ground SGND, the other end of the capacitor C2 is connected to the power supply terminal 12 pin of the isolated current sensor U2 and the +5V power supply, the output terminal 10 of the isolated current sensor U2 is connected to the input terminal 2 pin of the operational amplifier U3 and the voltage signal AOUT, the power input terminals 1 pin, 3 pin, 5 pin and 7 pin of the isolated current sensor U2 are connected to the power terminal QGND, the power output terminals 2 pin, 4 pin, 6 pin and 8 pin of the isolated current sensor U2 are connected to the power output terminal POUT, and the operational amplifier U3 is powered by a +5V power supply.

[0028] The comparison circuit includes a comparator U4, a resistor R7, a resistor R8 and a pull-up resistor R9. One end of the resistor R7 is connected to the voltage signal BOUT, the other end of the resistor R7 is connected to the input terminal 2 of the comparator U4 and one end of the resistor R8, the other end of the resistor R8 is connected to the output terminal 3 of the comparator U4, the overcurrent protection signal CON_OVER and one end of the resistor R9, the other end of the resistor R9 is connected to a +5V power supply, the input terminal 1 of the comparator U4 is connected to the overcurrent threshold signal REF_B, and the comparator U4 is powered by a +5V power supply.

[0029] The comparison circuit compares the voltage signal BOUT with the overcurrent threshold signal REF_B. When the voltage signal BOUT is higher than the overcurrent threshold signal REF_B, the overcurrent protection signal CON_OVER is output at a high level and an overcurrent phenomenon exists. Otherwise, it is at a low level and there is no overcurrent phenomenon.

[0030] The logic judgment circuit includes an OR gate U5. After the OR gate U5 performs an OR operation on the CPU circuit logic control signal CON_A and the overcurrent protection signal CON_OVER, it outputs the logic control signal CON_B to the power control circuit. The input terminal 1 pin of the OR gate U5 is connected to the CPU circuit output control signal, the input terminal 2 pin of the OR gate U5 is connected to the overcurrent protection signal CON_OVER, and the output terminal 3 pin of the OR gate U5 is connected to the input terminal 2 pin of the photocoupler U1.

[0031] The current sensor adopts an isolated sensor to isolate the power signal to be collected by the current sensor from the small voltage signal output by the current sensor.

[0032] The present invention adds a hardware overcurrent protection control circuit on the basis of the driving circuit, reduces the delay of the CPU processing circuit, uses fewer components, and effectively improves the real-time performance, reliability and economy of the circuit.

[0033] The technical solution of the present invention adopts the structure of MOSFET power tube and power relay in series, and realizes the overcurrent protection function of the power circuit through the current signal acquisition and conditioning circuit, the comparison circuit and the logic judgment circuit. Compared with the previous drive protection circuit, the overcurrent judgment is realized through the hardware circuit and the control signal is output, and the CPU circuit logic judgment is not required to realize the rapid overcurrent protection of the power circuit. The whole circuit has strong versatility, simple circuit design and typical promotion value.

[0034] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A DC load drive protection circuit, characterized in that: It includes a power control circuit, a current signal acquisition and conditioning circuit, a comparison circuit and a logic judgment circuit; the power control circuit and the logic judgment circuit are externally connected to a CPU processing circuit, and the power control circuit includes a power loop formed by a MOSFET power tube and a power relay in series; the CPU processing circuit outputs a logic control signal CON_A to the logic judgment circuit; the power control circuit receives a logic control signal CON_B output by the logic judgment circuit and a logic control signal CON_C output by the CPU processing circuit to control the on and off of the power loop; the power control circuit outputs power electricity to a power output terminal POUT through a current signal acquisition and conditioning circuit, and the current signal acquisition and conditioning circuit isolates and converts the current signal into a voltage signal BOUT, and the power output terminal POUT is connected to a DC load; the comparison circuit compares the voltage signal BOUT with an overcurrent threshold, outputs an overcurrent protection signal CON_OVER to the logic judgment circuit, and outputs a logic control signal CON_B to the power control circuit after logic judgment to control the power loop to be turned off, thereby realizing an overcurrent protection function; The power control circuit includes a photocoupler U1, a power relay K1, and a MOSFET power tube V1. The photocoupler U1 receives a logic control signal CON_B, and the output of the photocoupler U1 is connected to the MOSFET power tube V1 to achieve isolation and driving functions; the power relay K1 receives a logic control signal CON_C and is connected in series with the MOSFET power tube V1 to avoid a single power tube failure causing the power circuit to be unable to disconnect the protection in time, thereby achieving reliable control of the power output terminal POUT; The power control circuit also includes a current limiting resistor R1, a voltage dividing resistor R2, a voltage dividing resistor R3, a voltage regulator tube V2, a freewheeling diode V3, a resistor R4 and a capacitor C1. One end of the current limiting resistor R1 is connected to the input terminal 1 pin of the photocoupler U1, and the other end of the current limiting resistor R1 is connected to the +5V power supply. The logic control signal CON_B is connected to the input terminal 2 pin of the photocoupler U1. One end of the voltage dividing resistor R2 is connected to the output terminal 3 pin of the photocoupler U1, and the other end of the voltage dividing resistor R2 is connected to the Q15V power supply. One end of the voltage dividing resistor R3 is connected to the output terminal 4 pin of the photocoupler U1, the cathode of the voltage regulator tube V2 and the MOSFET power tube The gate pin 1 of V1 and the other end of the voltage divider resistor R3 are connected to the anode of the voltage regulator tube V2, the source pin 3 of the MOSFET power tube V1, one end of the resistor R4 and the power terminal QGND, the drain pin 2 of the MOSFET power tube V1 is connected to the contact terminal pin 1 of the power relay K1 and one end of the capacitor C1, the other end of the capacitor C1 is connected to the resistor R4, the contact terminal pin 2 of the power relay K1 is connected to the DC28V power supply, the coil terminal pin 4 of the power relay K1 is connected to the logic control signal CON_C and the cathode of the freewheeling diode V3, and the coil terminal pin 3 of the power relay K1 is connected to the anode of the freewheeling diode V3 and the power ground AGND; The gate 1 pin and source 3 pin of the MOSFET power tube V1 are connected to the voltage regulator tube V2 to prevent overvoltage breakdown between the gate and source of the MOSFET power tube; The current signal acquisition and conditioning circuit includes an isolated current sensor U2 and an operational amplifier U3. The isolated current sensor U1 converts the power loop current into a voltage signal AOUT. After the voltage signal AOUT and the reference voltage REF2.5V output by the isolated current sensor U2 are passed through a differential amplifier circuit composed of the operational amplifier U3, the reference voltage in the voltage signal AOUT is changed from 2.5V to 0V and amplified, and the voltage signal BOUT is output; The current signal acquisition and conditioning circuit also includes a decoupling capacitor C2, a resistor R5 and a resistor R6, one end of the resistor R5 is connected to the reference voltage terminal 9 pin of the isolated current sensor U2, the other end of the resistor R5 is connected to the input terminal 1 pin of the operational amplifier U3 and one end of the resistor R6, the other end of the resistor R6 is connected to the output terminal 3 pin of the operational amplifier U3 and the voltage signal BOUT, one end of the decoupling capacitor C2 is connected to the power supply terminal 11 pin of the isolated current sensor U2 and the signal ground SGND, the other end of the capacitor C2 is connected to the power supply terminal 12 pin of the isolated current sensor U2 and a +5V power supply, the output terminal 10 of the isolated current sensor U2 is connected to the input terminal 2 pin of the operational amplifier U3 and the voltage signal AOUT, the power input terminals 1 pin, 3 pin, 5 pin and 7 pin of the isolated current sensor U2 are connected to the power terminal QGND, the power output terminals 2 pin, 4 pin, 6 pin and 8 pin of the isolated current sensor U2 are connected to the power output terminal POUT, and the operational amplifier U3 is powered by a +5V power supply; The comparison circuit includes a comparator U4, a resistor R7, a resistor R8 and a pull-up resistor R9, one end of the resistor R7 is connected to the voltage signal BOUT, the other end of the resistor R7 is connected to the input terminal 2 pin of the comparator U4 and one end of the resistor R8, the other end of the resistor R8 is connected to the output terminal 3 pin of the comparator U4, the overcurrent protection signal CON_OVER and one end of the resistor R9, the other end of the resistor R9 is connected to a +5V power supply, the input terminal 1 pin of the comparator U4 is connected to the overcurrent threshold signal REF_B, and the comparator U4 is powered by a +5V power supply; The comparison circuit compares the voltage signal BOUT with the overcurrent threshold signal REF_B. When the voltage signal BOUT is higher than the overcurrent threshold signal REF_B, the overcurrent protection signal CON_OVER is output as a high level and an overcurrent phenomenon exists. Otherwise, it is a low level and there is no overcurrent phenomenon. The logic judgment circuit includes an OR gate U5, which performs an OR operation on the CPU circuit logic control signal CON_A and the overcurrent protection signal CON_OVER, and outputs a logic control signal CON_B to the power control circuit, an input terminal pin 1 of the OR gate U5 is connected to the CPU circuit output control signal, an input terminal pin 2 of the OR gate U5 is connected to the overcurrent protection signal CON_OVER, and an output terminal pin 3 of the OR gate U5 is connected to an input terminal pin 2 of the photoelectric coupler U1; The current sensor adopts an isolation type sensor to isolate the power signal to be collected by the current sensor from the small output voltage signal of the current sensor.

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