High-voltage interlocking circuit with diagnosis function

Abstract

The invention provides a high-voltage interlocking circuit with a diagnosis function. The high-voltage interlocking circuit comprises a detection circuit, a reference power supply circuit, a comparison circuit and a filtering recovery circuit. Through circuit voltage division, the detection circuit divides different voltage values to be compared with a reference voltage under the working conditions of normal, open circuit, short ground and short power supply of the interlocking connector, outputs corresponding high and low levels through the comparison circuit, and finally transmits the high and low levels to the MCU through the RC filtering recovery circuit so as to realize high-voltage interlocking state detection. A traditional high-voltage interlocking circuit does not have a diagnosis function, when an interlocking connector has power supply short circuit or ground short circuit, an MCU cannot detect the short circuit, and a detection fault is likely to be misreported; compared with a traditional high-voltage interlocking circuit, the circuit has the function of detecting the power supply to the ground, the situation that faults cannot be detected and are misreported during short circuit is avoided, and a new energy automobile is safer and more reliable.

Description

Technical Field

[0001] This invention relates to the field of motor controllers, and more specifically to a high-voltage interlock detection circuit with diagnostic functions. Background Technology

[0002] In the electric drive system of new energy vehicles, the normal operation of the motor controller is extremely important. A malfunction in the motor controller can lead to system abnormalities at best, and vehicle destruction and fatalities at worst. The condition of the controller's high-voltage connectors is even more crucial, making high-voltage interlock testing an unavoidable task. Common high-voltage interlock detection circuits cannot diagnose whether the interlock connectors are short-circuited to ground or power, often reporting false faults that severely impact the controller. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide a high-voltage interlock detection circuit with diagnostic function, which solves the problem that the existing technology cannot diagnose the working conditions of short circuit to ground or power supply, and avoids false alarms.

[0004] To achieve the above objectives, the present invention employs the following technical means:

[0005] A high-voltage interlock circuit with diagnostic function is characterized by comprising a detection circuit, a reference power supply circuit, a comparison circuit, and a filter sampling circuit. The detection circuit divides the voltage to compare different voltage values ​​with the reference voltage under several operating conditions of the interlock connector: normal, open circuit, short ground, and short power supply. The comparison circuit outputs the corresponding high and low levels, and finally transmits the data to the MCU through the RC filter sampling circuit to realize the detection of the high-voltage interlock status.

[0006] Furthermore, the detection circuit includes a first resistor (R1), a second resistor (R2), a third resistor (R3), and a fourth resistor (R4), a first capacitor (C1), a second capacitor (C2), a first ferrite bead (L1), and a second ferrite bead (L2); the signal terminals HVIL1+CN and HVIL1-CN of the external interlock connector are filtered by the first capacitor (C1), the second capacitor (C2), the first ferrite bead (L1), and the second ferrite bead (L2), and then connected to the second resistor (R2) and the third resistor (R3), respectively. After being divided by the first resistor (R1) and the fourth resistor (R4), they are connected to the input terminals of the first comparator U1A and the second comparator U1B.

[0007] In this circuit, one end of the first resistor (R1) is connected to the MCU control signal HVIL1_CTRL_uC, and the other end is connected in series with the second resistor (R2) to form a high-side voltage divider circuit. The first ferrite bead L1 and the second capacitor (C2) form an LC filter (L1 / C2). One end of the fourth resistor (R4) is connected to GND, and the other end is connected in series with the third resistor (R3) to form a low-side voltage divider circuit. The second ferrite bead (L2) and the first capacitor (C1) form an LC filter (L2 / C1).

[0008] Furthermore, the reference power supply circuit includes a ninth resistor (R9), a tenth resistor (R10), and an eleventh resistor (R11); the ninth resistor (R9) and the tenth resistor (R10) form a high-side reference voltage REF_H, which is connected to the first comparator U1A; the tenth resistor (R10) and the eleventh resistor (R11) form a low-side reference voltage REF_L, which is connected to the second comparator U1B.

[0009] Furthermore, the comparison circuit includes a first comparator U1A, a second comparator U1B, a first TVS diode (D1), a second TVS diode (D2), a third filter capacitor C3, a fourth filter capacitor (C4), a sixth filter capacitor (C6), a seventh filter capacitor (C7), a fifth pull-up resistor (R5), and a seventh pull-up resistor (R7). The third pin of the positive input terminal of the first comparator U1A is connected to the high-side reference voltage REF_H after being filtered by the fourth filter capacitor (C4). The second pin of the negative input terminal of the first comparator U1A is connected to the high-side voltage divider point of the detection circuit after being protected by the first TVS diode (D1) and filtered by the third filter capacitor (C3). The first pin of the output terminal of the first comparator U1A is connected to the fifth pull-up resistor (R5), and after being RC filtered by the sixth resistor (R6) and the fifth capacitor (C5), it is connected to the MCU.

[0010] The positive input pin 5 of the second comparator U1B is connected to the low-side reference voltage REF_L after being filtered by the seventh capacitor (C7). The negative input pin 6 of the second comparator U1B is connected to the low-side voltage divider point of the detection circuit after being protected by the second TVS diode (D2) and filtered by the sixth capacitor (C6). The output pin 7 of the second comparator U1B is connected to the seventh pull-up resistor (R7), and after being filtered by the eighth resistor (R8) and the eighth capacitor (C8), it is connected to the MCU.

[0011] Furthermore, the filtering and sampling circuit includes a sixth resistor (R6), an eighth resistor (R8), a fifth capacitor (C5), and an eighth capacitor (C8); one end of the sixth resistor (R6) is connected to pin 1 of the output of the first comparator (U1A), and the other end is connected to the fifth capacitor (C5), and after RC filtering, it is connected to the MCU; one end of the eighth resistor (R8) is connected to pin 7 of the output of the second comparator (U1B), and the other end is connected to the eighth capacitor (C8), and after RC filtering, it is connected to the MCU.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. Using the above scheme, a high-voltage interlock detection circuit with diagnostic function is formed by a comparator and several resistors and capacitors. The detection circuit outputs a corresponding PWM wave according to the interlock connector's operating conditions: normal, open circuit, short power supply, and short ground. This PWM wave, along with the high and low side reference power supplies, is input to the comparator. After being flipped by the comparator, the output PWM wave is filtered by RC and sent to the MCU for sampling. This avoids the false triggering of high-voltage interlock protection caused by the inability to diagnose short circuit conditions to ground or power supply, and has a high level of safety.

[0014] 2. Compared with traditional high-voltage interlock circuits, this circuit has a power supply to ground detection function, avoiding the inability to detect short circuits and false alarms, making new energy vehicles safer and more reliable. This detection circuit is ingeniously conceived, rationally designed, simple in structure, and low in cost. Attached Figure Description

[0015] Figure 1 This is a circuit diagram of the high-voltage interlock detection circuit with diagnostic function of the present invention. Detailed Implementation

[0016] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0017] like Figure 1 As shown, this invention provides a high-voltage interlock detection circuit with diagnostic function, comprising a detection circuit, a reference power supply circuit, a comparison circuit, and a filter sampling circuit. The detection circuit uses voltage division to determine different voltage values ​​under various operating conditions of the interlock connector: normal, open circuit, short-to-ground, and short-to-power supply. These values ​​are compared with the reference voltage, and the comparison circuit outputs corresponding high and low levels. Finally, the data is transmitted to the MCU via the RC filter sampling circuit, thus realizing the detection of the high-voltage interlock status.

[0018] The detection circuit includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4; a first capacitor C1 and a second capacitor C2; a first ferrite bead L1 and a second ferrite bead L2; and an external interlock connector, after being filtered by the first capacitor C1, the second capacitor C2, and the first and second ferrite beads L1 and L2, is connected to the second resistor R2 and the third resistor R3 respectively. After being divided by the first resistor R1 and the fourth resistor R4, it is connected to the input terminals of the first comparator U1A and the second comparator U1B. The ferrite beads are filtering devices.

[0019] In this circuit, one end of the first resistor R1 is connected to the MCU's control signal (PWM signal) HVIL1_CTRL_uC, and the other end is connected in series with the second resistor R2 to form a high-side voltage divider circuit. The first ferrite bead L1 and the second capacitor form an LC filter (L1 / C2). One end of the fourth resistor R4 is connected to GND, and the other end is connected in series with the third resistor R3 to form a low-side voltage divider circuit. The second ferrite bead L2 and the first capacitor C1 form an LC filter (L2 / C1).

[0020] One end of the second resistor R2 is connected to the voltage divider resistor R1, and the other end is filtered by the first ferrite bead L1 and the second capacitor C2 before being connected to the interlock connector. The voltage divider of the first resistor R1 and the second resistor R2 is then connected to pin 2 of the negative input terminal of the first comparator U1A. One end of the third resistor R3 is connected to the voltage divider resistor R4, and the other end is filtered by the first ferrite bead L2 and the second capacitor C2 before being connected to the interlock connector. One end of the fourth resistor R4 is connected to the voltage divider resistor R3, and the other end is connected to GND. The voltage divider of the third resistor R3 and the fourth resistor R4 is then connected to pin 6 of the negative input terminal of the second comparator U1B.

[0021] The reference power supply circuit includes a ninth resistor R9, a tenth resistor R10, and an eleventh resistor R11. The ninth resistor R9 and the tenth resistor R10 form a high-side reference voltage REF_H, which is connected to the first comparator U1A. The eleventh resistor R11 forms a low-side reference voltage REF_L, which is connected to the second comparator U1B.

[0022] Among them, the tenth resistor R10 and the eleventh resistor R11 are connected in series and divided by the ninth resistor R9 to form the high-side reference. After being filtered by the fourth capacitor C4, it is connected to the third pin of the positive input terminal of the first comparator U1A; the ninth resistor R9, the tenth resistor R10 and the eleventh resistor R11 are divided to form the low-side reference. After being filtered by the seventh capacitor C7, it is connected to the fifth pin of the positive input terminal of the second comparator U1B.

[0023] The comparison circuit includes a first comparator U1A and a second comparator U1B, a first TVS diode (D1), a second TVS diode (D2), a third filter capacitor C3, a fourth filter capacitor C4, a sixth filter capacitor C6, a seventh filter capacitor C7, a fifth pull-up resistor R5, and a seventh pull-up resistor R7. The third pin of the positive input terminal of the first comparator U1A is connected to the high-side reference voltage REF_H after being filtered by the fourth filter capacitor C4. The second pin of the negative input terminal of the first comparator U1A is connected to the high-side voltage divider point of the detection circuit after being filtered by the first TVS diode (D1) under forward protection and the third filter capacitor C3. The output pin 1 of comparator U1A is connected to the fifth pull-up resistor R5, and after RC filtering via the sixth resistor R6 and the fifth capacitor C5, it is connected to the MCU. The positive input pin 5 of the second comparator U1B is connected to the low-side reference voltage REF_L after being filtered by the seventh capacitor C7. The negative input pin 6 of the second comparator U1B is connected to the low-side voltage divider point of the detection circuit after being filtered by the second TVS diode (D2) for leakage protection and the sixth capacitor C6. The output pin 7 of the second comparator U1B is connected to the seventh pull-up resistor R7, and after RC filtering via the eighth resistor R8 and the eighth capacitor C8, it is connected to the MCU.

[0024] The power supply pin 8 of the first comparator U1A is connected to a +15VDC power supply, and the low pin 4 of the first comparator U1A is connected to GND.

[0025] Among them, the negative input terminals of the first comparator U1A and the second comparator U1B are respectively provided with a submerged protection TVS transistor (D1\D2) and a filter capacitor (C3\C6) between them and the high and low side voltage divider circuits.

[0026] Filter capacitors (C4 and C7) are provided between the positive input terminals of the first comparator U1A and the second comparator U1B and the high and low side reference power supplies, respectively.

[0027] An RC filter circuit (R6\C5) is added to the first pin output of the first comparator U1A, and an RC filter circuit (R8\C8) is added to the seventh pin output of the second comparator U1B.

[0028] The filtering and sampling circuit includes a sixth resistor R6, an eighth resistor R8, a fifth capacitor C5, and an eighth capacitor (C8). One end of the sixth resistor R6 is connected to the first output pin 1 of the first comparator U1A, and the other end is connected to the fifth capacitor C5. After RC filtering, it is connected to the MCU. One end of the eighth resistor R8 is connected to the seventh output pin of the second comparator U1B, and the other end is connected to the eighth capacitor C8. After RC filtering, it is connected to the MCU.

[0029] The high-voltage interlock detection circuit with diagnostic function of the present invention is used to test the interlock connector under normal connection, open circuit, short power supply and short ground conditions respectively.

[0030] During normal connection, the high-side voltage divider is:

[0031]

[0032] Under normal connection, the low-side voltage divider is:

[0033]

[0034] When the circuit is broken, the voltage drop across the high side is:

[0035]

[0036] When the circuit is open, the voltage drop across the lower side is:

[0037]

[0038] When the interlock connector is shorted to ground, the high-side voltage divider is applied:

[0039]

[0040] When the interlock connector is shorted to ground, the low-side voltage divider is applied:

[0041]

[0042] When the interlock connector is short-circuited, the high-side voltage divider is as follows:

[0043]

[0044] When the interlock connector is short-circuited, the low-side voltage divider is applied:

[0045]

[0046] High-side reference voltage:

[0047]

[0048] Low-side reference voltage:

[0049]

[0050] V PWM A PWM wave with an amplitude of 5V and a duty cycle of 50%, when the interlock connector is properly connected:

[0051] The high-side voltage is V H =3V PWM, low-side voltage divider is V L =1V PWM, high-side reference voltage REF_H =4.14V, low-side reference voltage REF_L =0.54V; VH <REF_H, the first comparator U1A outputs a high level on its first pin, which is then filtered by the RC filter composed of the sixth resistor R6 and the fifth capacitor C5 before being transmitted to the MCU; 0 <REF_L <V L The first comparator U1A outputs a PWM wave from its seventh pin, which is then filtered by an RC filter consisting of an eighth resistor R8 and an eighth capacitor C8 before being transmitted to the MCU.

[0052] V PWM For a PWM wave with an amplitude of 5V and a duty cycle of 50%, when the interlock connector is open:

[0053] The high-side voltage is V H =5V PWM, low-side voltage divider is V L =0V, high-side reference voltage REF_H =4.14V, low-side reference voltage REF_L =0.54V; 0 < REF_H < V H The first comparator U1A outputs a PWM wave at its first pin. After being filtered by the RC system consisting of the sixth resistor R6 and the fifth capacitor C5, the PWM wave is transmitted to the MCU. When 0 < REF_L, the first comparator U1A outputs a high level at its seventh pin. After being filtered by the RC system consisting of the eighth resistor R8 and the eighth capacitor C8, the high level is transmitted to the MCU.

[0054] V PWM For a PWM wave with an amplitude of 5V and a duty cycle of 50%, when the interlock connector is short-circuited to ground:

[0055] The high-side voltage is V H =1.67V PWM, low-side voltage divider is V L =0V, high-side reference voltage REF_H =4.14V, low-side reference voltage REF_L =0.54V; V H <REF_H, the first comparator U1A outputs a high level on its first pin, which is then filtered by the RC filter composed of the sixth resistor R6 and the fifth capacitor C5 before being transmitted to the MCU; 0<REF_L, the first comparator U1A outputs a high level on its seventh pin, which is then filtered by the RC filter composed of the eighth resistor R8 and the eighth capacitor C8 before being transmitted to the MCU.

[0056] V PWM For a PWM wave with an amplitude of 5V and a duty cycle of 50%, when the interlock connector is short-circuited to the power supply:

[0057] The high-side voltage is V H =5V PWM, low-side voltage divider is V L =2.5V PWM, high-side reference voltage REF_H =4.14V, low-side reference voltage REF_L =0.54V; 0 < REF_H < V HThe first comparator U1A outputs a PWM wave from its first pin. After being filtered by the RC filter composed of the sixth resistor R6 and the fifth capacitor C5, the wave is transmitted to the MCU; REF_L < V L The first comparator U1A outputs a low level on pin 7, which is then filtered by the RC filter composed of resistor R8 and capacitor C8 and transmitted to the MCU.

[0058] In this embodiment, the first comparator U1A is an LM2903A-SO1R-S, the first resistor R1 is 20KΩ, the second resistor R2, the third resistor R3, the fourth resistor R4, and the tenth resistor R10 are 10KΩ, the fifth resistor R5 and the seventh resistor R7 are 4.7KΩ, the sixth resistor R6 and the eighth resistor R8 are 1KΩ, the ninth resistor R9 is 2.4KΩ, and the eleventh resistor R11 is 1.5KΩ; the first capacitor C1, the second capacitor C2, the fourth capacitor C4, the fifth capacitor C5, the seventh capacitor C7, and the eighth capacitor C8 are 10nF, and the third capacitor C3 and the sixth capacitor C6 are 1nF.

[0059] This invention establishes a high-voltage interlock detection circuit with diagnostic function, consisting of a comparator, several resistors, and capacitors. The detection circuit outputs a corresponding PWM wave based on the interlock connector's operating conditions: normal, open circuit, short power supply, and short ground. This PWM wave, along with the high and low side reference power supplies, is input to the comparator. After being flipped by the comparator, the output PWM wave is filtered by an RC filter and sent to the MCU for sampling. This avoids false triggering of the high-voltage interlock protection due to the inability to diagnose short circuits to ground or power supply, thus providing a high level of safety.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A high-voltage interlock circuit with diagnostic function, characterized in that, It includes a detection circuit, a reference power supply circuit, a comparison circuit, and a filter sampling circuit. The detection circuit divides the voltage to compare different voltage values ​​with the reference voltage under several operating conditions of the interlock connector: normal, open circuit, short ground, and short power supply. The comparison circuit outputs the corresponding high and low levels, and finally transmits them to the MCU through the RC filter sampling circuit to realize the detection of high voltage interlock status.

2. The high-voltage interlock circuit with diagnostic function according to claim 1, characterized in that, The detection circuit includes a first resistor (R1), a second resistor (R2), a third resistor (R3), and a fourth resistor (R4), a first capacitor (C1), a second capacitor (C2), a first ferrite bead (L1), and a second ferrite bead (L2). The signal terminals HVIL1+CN and HVIL1-CN of the external interlock connector are filtered by the first capacitor (C1), the second capacitor (C2), the first ferrite bead (L1), and the second ferrite bead (L2) and are then connected to the second resistor (R2) and the third resistor (R3), respectively. After being divided by the first resistor (R1) and the fourth resistor (R4), they are connected to the input terminals of the first comparator U1A and the second comparator U1B. In this circuit, one end of the first resistor (R1) is connected to the MCU control signal HVIL1_CTRL_uC, and the other end is connected in series with the second resistor (R2) to form a high-side voltage divider circuit. The first ferrite bead L1 and the second capacitor (C2) form an LC filter (L1 / C2). One end of the fourth resistor (R4) is connected to GND, and the other end is connected in series with the third resistor (R3) to form a low-side voltage divider circuit. The second ferrite bead (L2) and the first capacitor (C1) form an LC filter (L2 / C1).

3. The high-voltage interlock circuit with diagnostic function according to claim 1, characterized in that, The reference power supply circuit includes a ninth resistor (R9), a tenth resistor (R10), and an eleventh resistor (R11). The ninth resistor (R9) and the tenth resistor (R10) form a high-side reference voltage REF_H, which is connected to the first comparator U1A. The tenth resistor (R10) and the eleventh resistor (R11) form a low-side reference voltage REF_L, which is connected to the second comparator U1B.

4. The high-voltage interlock circuit with diagnostic function according to claim 1, characterized in that, The comparison circuit includes a first comparator U1A, a second comparator U1B, a first TVS diode (D1), a second TVS diode (D2), a third filter capacitor C3, a fourth filter capacitor (C4), a sixth filter capacitor (C6), a seventh filter capacitor (C7), a fifth pull-up resistor (R5), and a seventh pull-up resistor (R7). The positive input pin 3 of the first comparator U1A is connected to the high-side reference voltage REF_H after being filtered by the fourth filter capacitor (C4). The negative input pin 2 of the first comparator U1A is connected to the high-side voltage divider point of the detection circuit after being protected by the first TVS diode (D1) and filtered by the third filter capacitor (C3). The output pin 1 of the first comparator U1A is connected to the fifth pull-up resistor (R5), and after being RC filtered by the sixth resistor (R6) and the fifth capacitor (C5), it is connected to the MCU. The positive input pin 5 of the second comparator U1B is connected to the low-side reference voltage REF_L after being filtered by the seventh capacitor (C7). The negative input pin 6 of the second comparator U1B is connected to the low-side voltage divider point of the detection circuit after being protected by the second TVS diode (D2) and filtered by the sixth capacitor (C6). The output pin 7 of the second comparator U1B is connected to the seventh pull-up resistor (R7), and after being filtered by the eighth resistor (R8) and the eighth capacitor (C8), it is connected to the MCU.

5. The high-voltage interlock circuit with diagnostic function according to claim 1, characterized in that, The filtering and sampling circuit includes a sixth resistor (R6), an eighth resistor (R8), a fifth capacitor (C5), and an eighth capacitor (C8). One end of the sixth resistor (R6) is connected to the first output pin of the first comparator (U1A), and the other end is connected to the fifth capacitor (C5). After RC filtering, it is connected to the MCU. One end of the eighth resistor (R8) is connected to the seventh output pin of the second comparator (U1B), and the other end is connected to the eighth capacitor (C8). After RC filtering, it is connected to the MCU.

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