A contactor abnormality detection circuit

Abstract

The present invention relates to the technical field of circuit design, and particularly to an abnormal detection circuit for a contactor, which is arranged in the power supply system of an electric vehicle. The power supply system includes a power supply, a main contactor Re1 and a load connected in sequence. The abnormal detection circuit for the contactor is arranged between the main contactor Re1 and the load. The abnormal detection circuit for the contactor includes a controller and an optocoupler U2, an optocoupler U3, a contactor Re2 and a contactor Re3 that are connected in parallel with each other. The control terminals of the main contactor Re1, the contactor Re2 and the contactor Re3 are respectively controlled by the controller, and the input terminal of the controller is electrically connected to the output signals of the optocoupler U2 and the optocoupler U3 respectively. The controller collects the on and off states of the contactor in real time and feeds them back to the battery system and the vehicle system. Once an abnormal contact of the contactor is detected, the operation is stopped to ensure that the entire system will not cause other concurrent failures due to abnormal on and off of the contactor.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit design, and particularly to a contactor abnormal detection circuit. Background Art

[0002] With the continuous emergence and advancement of new energy electric vehicles, each component on the vehicle needs to have its own protection means and cannot cause damage to other devices, so as to ensure the reliability of the whole vehicle. Among them, the pre-charge circuit of the high-voltage battery component, as a common current-limiting protection circuit, its reliability directly affects the reliability of the whole vehicle.

[0003] The pre-charge circuit generally targets high-voltage batteries and electrical equipment, taking the motor controller as an example of the electrical equipment. The high-voltage battery system supplies power to the motor controller through its own contactor. The motor controller places a pre-charge circuit at the high-voltage input port, and a energy storage capacitor is connected to the back end of the pre-charge circuit. This capacitor provides a buffer power supply for the back-end switch inverter circuit. Due to the existence of the capacitor, the pre-charge current-limiting circuit must be effective and reasonably controlled. Otherwise, at the moment when the battery contactor closes, the back end of the battery will be in a short-circuit state instantly, generating a large impact current, which may cause other more serious risks such as the adhesion of the battery contactor and the blowing of the fuse. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to provide a contactor abnormal detection circuit, by detecting the abnormality of the contactor, solve the driving abnormality caused by the abnormal failure of the contactor in the pre-charge circuit, and improve the reliability of the battery system.

[0005] To solve the above technical problem, the technical solution adopted by the present invention is: a contactor abnormal detection circuit is arranged in the power supply system of an electric vehicle. The power supply system includes a power supply, a main contactor Re1 and a load connected in sequence. The contactor abnormal detection circuit is arranged between the main contactor Re1 and the load. The contactor abnormal detection circuit includes a controller and an optocoupler U2, an optocoupler U3, a contactor Re2 and a contactor Re3 connected in parallel with each other. The control terminals of the main contactor Re1, the contactor Re2 and the contactor Re3 are respectively controlled by the controller. The input terminal of the controller is electrically connected to the output signals of the optocoupler U2 and the optocoupler U3 respectively;

[0006] The controller is configured to control the opening and closing states of the main contactor Re1, the contactor Re2 and the contactor Re3 according to the output signals of the optocoupler U2 and the optocoupler U3.

[0007] The beneficial effects of the present invention are as follows: An abnormal detection circuit for a contactor provided by the present invention generates three isolated power supplies through a transformer to supply power to the abnormal detection circuit of the contactor. During the operation of the pre-charge circuit, the controller collects the on-off state of the contactor in real time and feeds it back to the battery system and the vehicle system. Once it detects that the contactor contacts are stuck or abnormally out of control, the pre-charge operation is stopped to ensure that the entire system will not cause other concurrent failures due to the abnormality of the contactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic circuit connection diagram of an abnormal detection circuit for a contactor of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0009] To describe in detail the technical content, the achieved objectives and the effects of the present invention, the following is described in conjunction with the embodiments and with reference to the drawings.

[0010] Please refer to Figure 1 , an abnormal detection circuit for a contactor provided by the present invention is arranged in the power supply system of an electric vehicle. The power supply system includes a power supply, a main contactor Re1 and a load connected in sequence. The abnormal detection circuit of the contactor is arranged between the main contactor Re1 and the load. The abnormal detection circuit of the contactor includes a controller and optocouplers U2, U3, contactor Re2 and contactor Re3 connected in parallel with each other. The control ends of the main contactor Re1, the contactor Re2 and the contactor Re3 are respectively controlled by the controller. The input end of the controller is electrically connected to the output signals of the optocoupler U2 and the optocoupler U3 respectively;

[0011] The controller is configured to control the opening and closing states of the main contactor Re1, the contactor Re2 and the contactor Re3 according to the output signals of the optocoupler U2 and the optocoupler U3.

[0012] As can be seen from the above description, the beneficial effects of the present invention are as follows: The controller collects the output signals of the optocoupler U2 and the optocoupler U3 in real time, identifies the abnormal conditions of the contactor according to the collected signals, thereby detecting the faults of the pre-charge circuit, and by controlling the on-off states of the main contactor Re1, the contactor Re2 and the contactor Re3, the on-off of the high-voltage power supply and the on-off of the pre-charge circuit are adjusted in real time to ensure that the entire system will not cause other concurrent failures due to the abnormal on-off of the contactor Re2 and the contactor Re3 in the pre-charge circuit.

[0013] Further, the sixth pin of the optocoupler U2 is electrically connected to the 5V power supply and the sixth pin of the optocoupler U2 is used to output a signal. The fourth pin of the optocoupler U2 is grounded. The first pin of the optocoupler U2 is electrically connected to the positive electrode of the first 15V power supply, the fourth pin of the contactor Re2, the fourth pin of the contactor Re3, the first pin of the optocoupler U3, the third pin of the main contactor Re1, and the positive electrode of the second 15V power supply respectively. The third pin of the optocoupler U2 is electrically connected to the negative electrode of the first 15V power supply, the third pin of the contactor Re2, the third pin of the contactor Re3, the third pin of the optocoupler U3, and the negative electrode of the second 15V power supply respectively. The sixth pin of the optocoupler U3 is electrically connected to the second 5V power supply and the sixth pin of the optocoupler U3 is used to output a signal. The fourth pin of the optocoupler U3 is grounded.

[0014] As can be seen from the above description, the sixth pin and the fourth pin of the optocoupler U2 are the secondary side of the optocoupler. One end of the secondary side of the optocoupler U2 is connected to the first 5V power supply and outputs the first signal to the controller, and the other end of the secondary side of the optocoupler U2 is grounded. The first pin and the third pin of the optocoupler U2 are the primary side of the optocoupler. Both ends of the primary side of the optocoupler U2 are respectively connected to the positive and negative electrodes of the first 15V power supply, and are connected in parallel with the contactor Re2, the contactor Re3, and the optocoupler U3. The sixth pin and the fourth pin of the optocoupler U3 are the secondary side of the optocoupler. One end of the secondary side of the optocoupler U3 is connected to the second 5V power supply and outputs the second signal to the controller, and the other end of the secondary side of the optocoupler U3 is grounded. The first pin and the third pin of the optocoupler U3 are the primary side of the optocoupler. Both ends of the primary side of the optocoupler U3 are respectively connected to the positive and negative electrodes of the second 15V power supply, and are connected in parallel with the contactor Re2, the contactor Re3, and the optocoupler U2.

[0015] Further, it also includes a resistor R5. The third pin of the contactor Re2 is electrically connected to the third pin of the contactor Re3 through the resistor R5.

[0016] As can be seen from the above description, the electrical connection between the contactor Re2, the contactor Re3, and the resistor R5 forms a pre-charge circuit. The resistor R5 acts as a pre-charge resistor in the circuit to limit the magnitude of the pre-charge current and prevent the capacitor C4 at the back end from being short-circuited instantaneously, causing contactor adhesion, blown fuse, etc.

[0017] Further, it also includes a capacitor C4. The third pin of the optocoupler U2 is electrically connected to the negative electrode of the power supply through the capacitor C4.

[0018] As can be seen from the above description, the capacitor C4 is used as an energy storage capacitor, which provides a buffer power supply for the back-end switch inverter circuit.

[0019] Further, it further includes a fuse F1. The third pin of the main contactor Re1 is electrically connected to the first pin of the optocoupler U2, the fourth pin of the contactor Re2, the fourth pin of the contactor Re3, and the first pin of the optocoupler U3 through the fuse F1.

[0020] As can be seen from the above description, the fuse is connected to the rear end of the power supply through the main contactor Re1, preventing damage to the devices on the circuit when the current output by the power supply is too large, thus timely disconnecting the circuit to protect the safety of the power supply circuit.

[0021] Further, it further includes a resistor R3, a resistor R4, a resistor R6, and a resistor R7;

[0022] The sixth pin of the optocoupler U2 is electrically connected to one end of the resistor R3, and the other end of the resistor R3 is electrically connected to the 5V power supply;

[0023] The first pin of the optocoupler U2 is electrically connected to one end of the resistor R4, and the other end of the resistor R4 is electrically connected to the positive pole of the first 15V power supply;

[0024] The sixth pin of the optocoupler U3 is electrically connected to one end of the resistor R7, and the other end of the resistor R7 is electrically connected to the 5V power supply;

[0025] The first pin of the optocoupler U3 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to the positive pole of the second 15V power supply.

[0026] As can be seen from the above description, the resistors R4 and R3 are respectively connected to the primary and secondary sides of the optocoupler U2, and the resistors R6 and R7 are respectively connected to the primary and secondary sides of the optocoupler U3, and are respectively used to limit the current for the power supply of the optocoupler U2 and the optocoupler U3. The optocoupler U2 and the optocoupler U3 output the first signal and the second signal respectively by detecting the voltage at one end of the resistors R3 and R7.

[0027] Further, it further includes an isolated power supply circuit;

[0028] The isolated power supply circuit includes a chip U1, a MOS transistor M1, a transformer T1, a first AC-DC conversion circuit, a second AC-DC conversion circuit, and a third AC-DC conversion circuit;

[0029] The external 24V power supply is respectively electrically connected to one end of the primary side winding of the transformer T1 and the first pin of the chip U1. The other end of the primary side winding of the transformer T1 is electrically connected to the drain of the MOS transistor M1. The gate of the M1 is electrically connected to the eighth pin of the chip U1. The source of the MOS transistor M1, the fourth pin of the chip U1, and the fifth pin of the chip U1 are all grounded;

[0030] A first secondary winding, a second secondary winding, and a third secondary winding are provided on the transformer T1, and the turns ratio of the first secondary winding, the second secondary winding, and the third secondary winding is 1:3:3. The first secondary winding is electrically connected to the sixth pin of the chip U1, the other end of the resistor R3, and the other end of the resistor R7 through a first AC-DC conversion circuit. The two ends of the second secondary winding after passing through a second AC-DC conversion circuit are respectively electrically connected to the other end of the resistor R4 and the third pin of the optocoupler U2. The two ends of the third secondary winding after passing through a third AC-DC conversion circuit are respectively electrically connected to the other end of the resistor R6 and the third pin of the optocoupler U3.

[0031] As can be seen from the above description, a first secondary winding, a second secondary winding, and a third secondary winding are provided on the transformer T1, and the turns ratio is 1:3:3 respectively, so as to divide the 24V power supply of the peripheral device into three isolated power supply circuits, namely the first AC-DC conversion circuit, the second AC-DC conversion circuit, and the third AC-DC conversion circuit. And the voltages of the first AC-DC conversion circuit, the second AC-DC conversion circuit, and the third AC-DC conversion circuit are 5V, 15V1, and 15V2 respectively according to the turns ratio. And connect the 5V first AC-DC conversion circuit to the secondary sides of the optocoupler U2 and the optocoupler U3 to supply power to the detection circuits where they are located, and connect the 15V1 second AC-DC conversion circuit and the 15V2 third AC-DC conversion circuit to the primary sides of the optocoupler U2 and the optocoupler U3 respectively to supply power to the detection circuits where they are located.

[0032] Further, the first AC-DC conversion circuit includes a rectifier diode D1 and a filter capacitor C1. One end of the first secondary winding is grounded, and the other end of the first secondary winding is electrically connected to the positive electrode of the rectifier diode D1. The negative electrode of the rectifier diode D1 is respectively electrically connected to the other end of the resistor R3 and one end of the filter capacitor C1, and the other end of the filter capacitor C1 is grounded;

[0033] The second AC-DC conversion circuit includes a rectifier diode D2 and a filter capacitor C2. One end of the second secondary winding is respectively electrically connected to one end of the filter capacitor C2 and the third pin of the optocoupler U2. The other end of the second secondary winding is electrically connected to the positive electrode of the rectifier diode D2. The negative electrode of the rectifier diode D2 is respectively electrically connected to the other end of the filter capacitor C2 and the other end of the resistor R4;

[0034] The third AC-DC conversion circuit includes a rectifier diode D3 and a filter capacitor C3. One end of the third secondary winding is respectively electrically connected to one end of the filter capacitor C3 and the third pin of the optocoupler U3. The other end of the third secondary winding is electrically connected to the positive electrode of the rectifier diode D3. The negative electrode of the rectifier diode D3 is respectively electrically connected to the other end of the filter capacitor C3 and the other end of the resistor R6.

[0035] As described above, the first AC-DC conversion circuit converts alternating current into direct current through the rectifier diode D1 and the filter capacitor C1, and outputs the converted DC power supply to the secondary circuits of the optocouplers U2 and U3; the second AC-DC conversion circuit converts alternating current into direct current through the rectifier diode D2 and the filter capacitor C2, and outputs the converted DC power supply to the primary circuit of the optocoupler U2; the third AC-DC conversion circuit converts alternating current into direct current through the rectifier diode D3 and the filter capacitor C3, and outputs the converted DC power supply to the primary circuit of the optocoupler U3.

[0036] Furthermore, it also includes a resistor R1 and a resistor R2. The negative pole of the rectifier diode D1 is electrically connected to one end of the resistor R1. The other end of the resistor R1 is respectively electrically connected to the sixth pin of the chip U1 and one end of the resistor R2. The other end of the resistor R2 is grounded.

[0037] As described above, the first AC-DC conversion circuit converts alternating current into direct current through the rectifier diode D1 and the filter capacitor C1. This direct current feeds back the voltage signal to the sixth pin of the chip U1 through the resistor R1 and the resistor R2. The chip U1 adjusts the duty cycle of its eighth pin according to the voltage signal fed back by the sixth pin until the output voltage of the first AC-DC conversion circuit is adjusted to 5V.

[0038] Furthermore, the positive pole of the power supply is electrically connected to the fourth pin of the main contactor Re1.

[0039] As described above, the contactor Re1 is electrically connected to the power supply to control the on-off of the power supply circuit.

[0040] Please refer to Figure 1 , Embodiment 1 of the present invention is:

[0041] An abnormal detection circuit for a contactor provided by the present invention is arranged in the power supply system of an electric vehicle. The power supply system includes a power supply, a main contactor Re1, and a load connected in sequence. The contactor abnormal detection circuit is arranged between the main contactor Re1 and the load. The contactor abnormal detection circuit includes a controller and optocouplers U2, U3, contactors Re2, and Re3 that are connected in parallel with each other.

[0042] The power supply is a high-voltage battery. Among them, the positive pole of the power supply is electrically connected to the fourth pin of the main contactor Re1 ( Figure 1 the pin marked as 4 on the contactor Re1), the third pin of the main contactor Re1 ( Figure 1 the pin marked as 3 on the contactor Re1) is connected to one end of the fuse F1 to form a power supply circuit to provide high-voltage power supply for the load. The load is a motor controller on a new energy electric vehicle. The first pin of the main contactor Re1 (Figure 1 The pin labeled 1 on the main contactor Re1) is electrically connected to the control terminal (con1) of the main contactor Re1, and the second pin of the coil of the main contactor Re1 ( Figure 1 The pin labeled 2 on the main contactor Re1) is grounded (GND). The first pin of the coil of the contactor Re2 ( Figure 1 The pin labeled 1 on the contactor Re2) is electrically connected to the control terminal (con2) of the contactor Re2, and the second pin of the coil of the contactor Re2 ( Figure 1 The pin labeled 2 on the contactor Re2) is grounded (GND). The first pin of the coil of the contactor Re3 ( Figure 1 The pin labeled 1 on the contactor Re3) is electrically connected to the control terminal (con3) of the contactor Re3, and the second pin of the coil of the contactor Re3 ( Figure 1 The pin labeled 2 on the contactor Re3) is grounded (GND).

[0043] The sixth pin on the secondary side of the optocoupler U2 ( Figure 1 The pin labeled 6 on the optocoupler U2) is electrically connected to the 5V power supply and the sixth pin on the secondary side of the optocoupler U2 is used to output a signal (Con1St), and the fourth pin on the secondary side of the optocoupler U2 ( Figure 1 The pin labeled 4 on the optocoupler U2) is grounded, and the first pin on the primary side of the optocoupler U2 ( Figure 1 The pin labeled 1 on the optocoupler U2) is respectively electrically connected to the positive pole of the first 15V power supply, the fourth pin of the contactor Re2 ( Figure 1 The pin labeled 4 on the contactor Re2), the fourth pin of the contactor Re3 ( Figure 1 The pin labeled 4 on the contactor Re3), the first pin on the primary side of the optocoupler U3 ( Figure 1 The pin labeled 1 on the optocoupler U3), the third pin of the main contactor Re1 ( Figure 1 The pin labeled 3 on the contactor Re1) and the positive pole of the second 15V power supply, and the third pin on the primary side of the optocoupler U2 ( Figure 1 The pin labeled 3 on the optocoupler U3) is respectively electrically connected to the negative pole of the first 15V power supply, the third pin of the contactor Re2 ( Figure 1 The pin labeled 3 on the contactor Re2), the third pin of the contactor Re3 ( Figure 1 The pin labeled 3 on the contactor Re3), the third pin on the primary side of the optocoupler U3 ( Figure 1 The pin labeled 3 on the optocoupler U3) and the negative pole of the second 15V power supply, and the sixth pin on the secondary side of the optocoupler U3 ( Figure 1The pin labeled 6 on the optocoupler U3 is electrically connected to the second 5V power supply, and the sixth pin on the secondary side of the optocoupler U3 is used to output the signal (Con2St). The fourth pin on the secondary side of the optocoupler U3 ( Figure 1 the pin labeled 4 on the optocoupler U3) is grounded.

[0044] In this embodiment, it further includes a controller. The control end (con1) of the main contactor Re1, the control end (con2) of the contactor Re2, and the control end (con3) of the contactor Re3 are respectively electrically connected to the output end of the controller and are controlled by the controller. The input end of the controller is respectively electrically connected to the output signal (Con1St) of the optocoupler U2 and the output signal (Con2St) of the optocoupler U3;

[0045] The controller is configured to control the opening and closing states of the main contactor Re1, the contactor Re2, and the contactor Re3 according to the output signals of the optocoupler U2 and the optocoupler U3. The controller is connected to the battery system and the vehicle system through a can communication interface, and reports the detected output signals of the optocoupler U2 and the optocoupler U3 to the battery system and the vehicle system.

[0046] In this embodiment, it further includes a resistor R5. The third pin ( Figure 1 the pin labeled 3 on the contactor Re2) of the contactor Re2 is electrically connected to the third pin of the contactor Re3 through the resistor R5 ( Figure 1 the pin labeled 3 on the contactor Re3). The electrical connection among the contactor Re2, the contactor Re3, and the resistor R5 forms a pre-charge circuit. One end of the resistor R5 is electrically connected to the positive electrode of the capacitor C4, and the third pin ( Figure 1 the pin labeled 3 on the optocoupler U2) of the optocoupler U2 is electrically connected to the negative electrode of the power supply through the capacitor C4.

[0047] In this embodiment, it further includes an isolated power supply circuit;

[0048] The isolated power supply circuit includes a chip U1, a mos tube M1, a transformer T1, a first AC-DC conversion circuit, a second AC-DC conversion circuit, and a third AC-DC conversion circuit;

[0049] The external 24V power supply is respectively connected to one end of the primary side winding of the transformer T1 and the first pin ( Figure 1 the pin labeled 1 on the chip U1) of the chip U1. The other end of the primary side winding of the transformer T1 is electrically connected to the drain of the mos tube M1. The gate of the mos tube M1 is electrically connected to the eighth pin ( Figure 1 the pin labeled 8 on the chip U1) of the chip U1. The source of the mos tube M1 and the fourth pin ( Figure 1The pin labeled 4 on the chip U1) and the fifth pin of the chip U1 ( Figure 1 The pin labeled 5 on the chip U1) are both grounded;

[0050] The eighth pin of the U1 chip controls the on and off of the MOS transistor M1 by outputting a switching signal with a certain duty cycle, thereby generating an alternating power supply on the primary winding of the transformer T1. The second pin of the transformer T1 ( Figure 1 The pin labeled 2 on the transformer T1) and the ninth pin ( Figure 1 The pin labeled 9 on the transformer T1) on the secondary winding, the fourth pin ( Figure 1 The pin labeled 4 on the transformer T1) and the fifth pin ( Figure 1 The pin labeled 5 on the transformer T1) on the secondary winding and the sixth pin ( Figure 1 The pin labeled 6 on the transformer T1) and the seventh pin ( Figure 1 The pin labeled 7 on the transformer T1) on the secondary winding, after the secondary winding senses an alternating voltage, generates 3 paths of alternating voltage.

[0051] The transformer T1 is provided with a first secondary winding, a second secondary winding and a third secondary winding, and the turns ratio of the first secondary winding, the second secondary winding and the third secondary winding is 1:3:3. The first secondary winding is respectively electrically connected to the sixth pin of the chip U1 ( Figure 1 The pin labeled 6 on the chip U1), the other end of the resistor R3 and the other end of the resistor R7 through a first AC-DC conversion circuit. The two ends of the second secondary winding after passing through a second AC-DC conversion circuit are respectively electrically connected to the other end of the resistor R4 and the third pin of the optocoupler U2. The two ends of the third secondary winding after passing through a third AC-DC conversion circuit are respectively electrically connected to the other end of the resistor R6 and the third pin of the optocoupler U3.

[0052] Because the first secondary winding, the second secondary winding and the third secondary winding of the transformer T1 respectively correspond to the secondary windings on the second pin and the ninth pin of the transformer T1, the secondary windings on the fourth pin and the fifth pin, and the sixth pin and the seventh pin. Because the turns ratio of the first secondary winding, the second secondary winding and the third secondary winding is 1:3:3, the ratio of the alternating voltages generated on the first secondary winding, the second secondary winding and the third secondary winding is 1:3:3.

[0053] In this embodiment, the first AC-DC conversion circuit includes a rectifier diode D1 and a filter capacitor C1. One end of the first secondary winding is grounded, and the other end of the first secondary winding is electrically connected to the positive electrode of the rectifier diode D1. The negative electrode of the rectifier diode D1 is electrically connected to the other end of the resistor R3 and one end of the filter capacitor C1 respectively, and the other end of the filter capacitor C1 is grounded. The first AC-DC conversion circuit rectifies the alternating voltage generated by the first secondary winding of the transformer T1 into a DC voltage through the rectifier diode D1 and the filter capacitor C1. This DC voltage then feeds back the voltage signal to the sixth pin of the chip U1 through the resistor R1 and the resistor R2. The chip U1 continuously adjusts the duty cycle of its eighth pin according to the voltage signal fed back from its sixth pin until the DC voltage output by the first AC-DC conversion circuit is adjusted to 5V (5V+).

[0054] The second AC-DC conversion circuit includes a rectifier diode D2 and a filter capacitor C2. One end of the second secondary winding is electrically connected to one end of the filter capacitor C2 and the third pin of the optocoupler U2 respectively, and the other end of the second secondary winding is electrically connected to the positive electrode of the rectifier diode D2. The negative electrode of the rectifier diode D2 is electrically connected to the other end of the filter capacitor C2 and the other end of the resistor R4 respectively. The second AC-DC conversion circuit rectifies the alternating voltage generated on the second secondary winding into a DC voltage through the rectifier diode D2 and the filter capacitor C2, and obtains it according to the turns ratio of the first winding. The DC voltage converted on the second secondary winding is 15V. And this 15V DC voltage is output to the primary side of the optocoupler U2 as the first 15V power supply (15V1) to supply power to the detection circuit where the optocoupler U2 is located.

[0055] The third AC-DC conversion circuit includes a rectifier diode D3 and a filter capacitor C3. One end of the third secondary winding is electrically connected to one end of the filter capacitor C3 and the third pin of the optocoupler U3 respectively, and the other end of the third secondary winding is electrically connected to the positive electrode of the rectifier diode D3. The negative electrode of the rectifier diode D3 is electrically connected to the other end of the filter capacitor C3 and the other end of the resistor R6 respectively. The third AC-DC conversion circuit rectifies the alternating voltage generated on the third secondary winding into a DC voltage through the rectifier diode D3 and the filter capacitor C3, and obtains it according to the turns ratio of the first winding. The DC voltage converted on the third secondary winding is 15V. And this 15V DC voltage is output to the primary side of the optocoupler U3 as the second 15V power supply (15V2) to supply power to the detection circuit where the optocoupler U3 is located.

[0056] In this embodiment, a fuse F1 is further included. The third pin of the main contactor Re1 is electrically connected to the first pin of the optocoupler U2, the fourth pin of the contactor Re2, the fourth pin of the contactor Re3, and the first pin of the optocoupler U3 through the fuse F1. The fuse is connected to the rear end of the power supply through the main contactor Re1 to prevent damage to the devices on the circuit when the current output by the power supply is too large, so as to disconnect the circuit in time and protect the safety of the power supply circuit.

[0057] The working principle of the above contactor abnormal detection circuit is as follows:

[0058] 1. After the main contactor Re1 in the power supply circuit where the power supply is located is closed, the output voltage is connected to two circuits. One circuit is connected to the positive pole of the capacitor C4 through the contact of the contactor Re2, and the other circuit is connected to the positive pole of the capacitor C4 through the contact of the contactor Re3 and the resistor R5.

[0059] 2. After the external 24V power supply is powered on, the control terminals (con1) of the main contactor Re1, the control terminal (con2) of the contactor Re2, and the control terminal (con3) of the contactor Re3 receive a voltage signal of 0V output by the controller and control the main contactor Re1, the contactor Re2, and the contactor Re3 to disconnect.

[0060] 3. Detect the output signals (Con1St) of the optocoupler U2 and the output signals (Con2St) of the optocoupler U3 on the pre-charge circuit:

[0061] When the contact of the contactor Re2 is normally separated, the primary side of the optocoupler U2 is turned on, and the secondary side is also turned on. The output signal (Con1St) of the optocoupler U2 is 0V. If the contact of the contactor Re2 is abnormally closed, the primary side of the optocoupler U2 is not turned on, and the secondary side is also not turned on. The output signal (Con1St) of the optocoupler U2 is 5V;

[0062] When the contact of the contactor Re3 is normally separated, the primary side of the optocoupler U3 is turned on, and the secondary side is also turned on. The output signal (Con2St) of the optocoupler U3 is 0V. If the contact of the contactor Re3 is abnormally closed, the primary side of the optocoupler U3 is not turned on, and the secondary side is also not turned on. The output signal (Con2St) of the optocoupler U3 is 5V.

[0063] After the controller detects the output signal (Con1St) of optocoupler U2 and the output signal (Con2St) of optocoupler U3, it reports them to the battery system and the vehicle system in real time through CAN communication. When the vehicle system reads that the output signal (Con1St) of optocoupler U2 is 5V, the vehicle reports a serious fault and the vehicle is not allowed to run; when the vehicle system reads that the output signal (Con1St) of optocoupler U2 is 0V but the output signal (Con2St) of optocoupler U3 is 5V, the vehicle reports a minor fault, the vehicle is allowed to run, and a reminder for maintenance is given.

[0064] 4. When the battery system reads that the output signal (Con1St) of optocoupler U2 is 0V, it indicates that the battery rear-end circuit is not in a short-circuit state. The battery system controls the control terminal (con1) of main contactor Re1 to close main contactor Re1 and output voltage to the rear end. When the battery system reads that the output signal (Con1St) of optocoupler U2 is 5V, it indicates that the battery rear-end circuit is in a short-circuit state. The battery system controls the control terminal (con1) of main contactor Re1 to keep main contactor Re1 open to prevent impact current from being generated at the rear end.

[0065] 5. When high voltage is detected at the input end of the pre-charge circuit, the controller controls the control terminal (con3) of contactor Re3 to close pre-charge contactor Re3, and then pre-charges through resistor R5; during the pre-charge process, when the voltages at both ends of the contacts of contactor Re2 are the same, it indicates that the pre-charge is completed. The controller controls the control terminal (con2) of contactor Re2 to close contactor Re2, and at this time, no impact current is generated; after contactor Re2 closes, the controller then controls the control terminal (con3) of contactor Re3 to open pre-charge contactor Re3 to prevent resistor R5 from being burned out due to abnormal disconnection of contactor Re2 during vehicle operation.

[0066] 6. After the controller controls the control terminal (con2) of contactor Re2 to close contactor Re2, the controller detects the output signal (Con1St) of optocoupler U2. If the output signal (Con1St) of optocoupler U2 is 0V, it indicates that contactor Re2 fails to close abnormally, then the battery system is notified to disconnect main contactor Re1, and the vehicle system reports a serious fault and the vehicle is not allowed to run; if the output signal (Con1St) of optocoupler U2 is 5V, it indicates that contactor Re2 has closed normally and the entire pre-charge process is completed.

[0067] In summary, a contactor abnormal detection circuit provided by the present invention generates three isolated power supplies through a transformer to supply power to the contactor abnormal detection circuits on optocoupler U2 and optocoupler U3. During the operation of the pre-charge circuit, the controller collects the open and closed states of the contactor in real time and feeds them back to the battery system and the vehicle system. Once it is detected that the contactor contacts are stuck or abnormally out of control, the pre-charge work is stopped to ensure that the entire system will not cause other concurrent faults due to abnormal on / off of the contactor.

[0068] The above are only embodiments of the present invention, and thus do not limit the patent scope of the present invention. Any equivalent transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in the related technical fields, shall similarly be included within the patent protection scope of the present invention.

Claims

1. An abnormal detection circuit for a contactor, which is arranged in the power supply system of an electric vehicle. The power supply system includes a power supply, a main contactor Re1 and a load connected in sequence. It is characterized in that, The contactor anomaly detection circuit is arranged between the main contactor Re1 and the load. The contactor anomaly detection circuit includes a controller and optocouplers U2, U3, contactor Re2, and contactor Re3 that are connected in parallel. The control terminals of the main contactor Re1, contactor Re2, and contactor Re3 are respectively controlled by the controller, and the input terminals of the controller are electrically connected to the output signals of the optocoupler U2 and the optocoupler U3; The controller is configured to control the opening and closing states of the main contactor Re1, contactor Re2, and contactor Re3 according to the output signals of the optocoupler U2 and the optocoupler U3; The sixth pin of the optocoupler U2 is electrically connected to the 5V power supply and the sixth pin of the optocoupler U2 is used to output a signal. The fourth pin of the optocoupler U2 is grounded. The first pin of the optocoupler U2 is respectively electrically connected to the positive pole of the first 15V power supply, the fourth pin of the contactor Re2, the fourth pin of the contactor Re3, the first pin of the optocoupler U3, the third pin of the main contactor Re1, and the positive pole of the second 15V power supply. The third pin of the optocoupler U2 is respectively electrically connected to the negative pole of the first 15V power supply, the third pin of the contactor Re2, the third pin of the contactor Re3, the third pin of the optocoupler U3, and the negative pole of the second 15V power supply. The sixth pin of the optocoupler U3 is electrically connected to the second 5V power supply and the sixth pin of the optocoupler U3 is used to output a signal. The fourth pin of the optocoupler U3 is grounded; It further includes a resistor R5. The third pin of the contactor Re2 is electrically connected to the third pin of the contactor Re3 through the resistor R5; It further includes a capacitor C4. The third pin of the optocoupler U2 is electrically connected to the negative pole of the power supply through the capacitor C4; The positive pole of the power supply is electrically connected to the fourth pin of the main contactor Re1.

2. The abnormal detection circuit for a contactor according to claim 1, characterized in that, It further includes a fuse F1. The third pin of the main contactor Re1 is electrically connected to the first pin of the optocoupler U2, the fourth pin of the contactor Re2, the fourth pin of the contactor Re3, and the first pin of the optocoupler U3 through the fuse F1.

3. The abnormal detection circuit for a contactor according to claim 1, characterized in that, It further includes resistors R3, R4, R6, and R7; The sixth pin of the optocoupler U2 is electrically connected to one end of the resistor R3, and the other end of the resistor R3 is electrically connected to the 5V power supply; The first pin of the optocoupler U2 is electrically connected to one end of the resistor R4, and the other end of the resistor R4 is electrically connected to the positive pole of the first 15V power supply; The sixth pin of the optocoupler U3 is electrically connected to one end of the resistor R7, and the other end of the resistor R7 is electrically connected to the 5V power supply; The first pin of the optocoupler U3 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to the positive pole of the second 15V power supply.

4. The abnormal detection circuit for a contactor according to claim 3, characterized in that, It further includes an isolated power supply circuit; The isolated power supply circuit includes a chip U1, a mos tube M1, a transformer T1, a first AC-DC conversion circuit, a second AC-DC conversion circuit, and a third AC-DC conversion circuit; The 24V power supply of the peripheral device is electrically connected to one end of the primary winding of the transformer T1 and the first pin of the chip U1 respectively. The other end of the primary winding of the transformer T1 is electrically connected to the drain of the MOS transistor M1. The gate of the M1 is electrically connected to the eighth pin of the chip U1. The source of the MOS transistor M1, the fourth pin of the chip U1, and the fifth pin of the chip U1 are all grounded; The transformer T1 is provided with a first secondary winding, a second secondary winding, and a third secondary winding, and the turns ratio of the first secondary winding, the second secondary winding, and the third secondary winding is 1:3:

3. The first secondary winding is electrically connected to the sixth pin of the chip U1, the other end of the resistor R3, and the other end of the resistor R7 respectively through a first AC-DC conversion circuit. The two ends of the second secondary winding after passing through the second AC-DC conversion circuit are respectively electrically connected to the other end of the resistor R4 and the third pin of the optocoupler U2. The two ends of the third secondary winding after passing through the third AC-DC conversion circuit are respectively electrically connected to the other end of the resistor R6 and the third pin of the optocoupler U3.

5. The abnormal detection circuit for a contactor according to claim 4, characterized in that, The first AC-DC conversion circuit includes a rectifier diode D1 and a filter capacitor C1. One end of the first secondary winding is grounded. The other end of the first secondary winding is electrically connected to the positive pole of the rectifier diode D1. The negative pole of the rectifier diode D1 is electrically connected to the other end of the resistor R3 and one end of the filter capacitor C1 respectively. The other end of the filter capacitor C1 is grounded; The second AC-DC conversion circuit includes a rectifier diode D2 and a filter capacitor C2. One end of the second secondary winding is electrically connected to one end of the filter capacitor C2 and the third pin of the optocoupler U2 respectively. The other end of the second secondary winding is electrically connected to the positive pole of the rectifier diode D2. The negative pole of the rectifier diode D2 is electrically connected to the other end of the filter capacitor C2 and the other end of the resistor R4 respectively; The third AC-DC conversion circuit includes a rectifier diode D3 and a filter capacitor C3. One end of the third secondary winding is electrically connected to one end of the filter capacitor C3 and the third pin of the optocoupler U3 respectively. The other end of the third secondary winding is electrically connected to the positive pole of the rectifier diode D3. The negative pole of the rectifier diode D3 is electrically connected to the other end of the filter capacitor C3 and the other end of the resistor R6 respectively.

6. The abnormal detection circuit for a contactor according to claim 5, characterized in that, It also includes a resistor R1 and a resistor R2. The negative pole of the rectifier diode D1 is electrically connected to one end of the resistor R1. The other end of the resistor R1 is electrically connected to the sixth pin of the chip U1 and one end of the resistor R2 respectively. The other end of the resistor R2 is grounded.

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