A circuit and an EPS system with a multiple motor protection mechanism

Abstract

A circuit and an EPS system with a multiple motor protection mechanism, which relate to the technical field of automotive steering assistance. Among them, a circuit with a multiple motor protection mechanism includes a first control circuit, a second control circuit, a switching circuit and a motor. The first control circuit and the second control circuit are connected to the motor through the same switching circuit. The first control circuit includes a control unit, a pre-driver unit and a power bridge connected in sequence. The second control circuit includes a detection circuit and a selection circuit connected in sequence. The power bridge and the selection circuit are respectively connected to the switching circuit. The detection circuit is used to receive the PWM signal sent by the control unit and the back electromotive force signal from the motor. The selection circuit is also connected to the pre-driver unit. The present invention can disconnect the switching circuit through a separate hardware circuit when the control unit is abnormal, timely turn off the motor, and avoid motor jamming. Moreover, the present invention can reduce common cause failures and cascading failures, and improve system safety.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive steering assist, and particularly to a circuit and an EPS system with a multiple motor protection mechanism. Background Art

[0002] In an EPS system, generally, a single-chip microcomputer sends a driving signal to a pre-driver circuit. The pre-driver circuit charges and discharges the gate capacitance of the MOSFET in the power bridge, amplifies the received PWM pulse to a level sufficient to drive the power bridge transistor, performs switching power amplification, so as to respond to a weak input signal, drive the power bridge, and then control the normal operation of the motor. Since the motor and its control unit therein mainly serve as the execution unit of the human-vehicle interaction interface, the protection and preventive design thereof are particularly important. Currently, there are mainly the following three types of motor protection mechanisms adopted in the EPS system.

[0003] First, as Figure 1 shown, the pre-driver circuit has a diagnostic function. When the motor gets stuck, the pre-driver circuit detects the motor failure, sends the fault information to the single-chip microcomputer, and then through the switch circuit controlled by the single-chip microcomputer, such as a phase breaker, a relay, an isolator, etc., disconnects the motor to achieve the protection effect.

[0004] Second, as Figure 2 shown, the pre-driver circuit does not have a diagnostic function. When the motor gets stuck, the single-chip microcomputer judges whether the motor fails by detecting the motor phase current, the low-end bus current, the high-end bus current, etc. When the motor fails, the single-chip microcomputer outputs a PWM signal to the pre-driver circuit to turn off the pre-driver circuit. At the same time, the switch circuit controlled by the single-chip microcomputer, such as a phase breaker, a relay, an isolator, etc., disconnects the motor, and then stops the motor from working, preventing the motor from getting stuck and thus preventing harm to driving safety.

[0005] Third, as Figure 3 shown, a dual-redundancy design is carried out through a dual-chip scheme. One path is the actuator for driving the motor to work normally, and the other path is the management mechanism (monitoring unit) for detecting whether the actuator works normally when controlling the motor; when the management mechanism (monitoring unit) identifies that the actuator fails when controlling the motor to work, it directly cuts off the switch circuit.

[0006] However, the first two protection mechanisms need to be based on the normal operation of the single-chip microcomputer or the pre-driver circuit. When the single-chip microcomputer crashes, the program runs wild, or the pre-driver chip is abnormal, the motor cannot be directly disconnected through the hardware circuit, which has the disadvantages of slow reaction speed and inability to protect the motor in time. The protection mechanism of the third dual-chip design scheme includes an actuator and a management mechanism (monitoring unit). There are many interaction signals between them, the algorithm is complex, and the volume is large. It is not suitable for being arranged in places with strict space requirements such as automobiles. Moreover, compared with the single-chip design, the dual-chip design has a higher cost. Summary of the Invention

[0007] One of the purposes of the present invention is to provide a circuit with a multiple motor protection mechanism, which independently controls the on / off of the switch circuit by adding a set of hardware control circuits. Moreover, the added set of hardware control circuits can timely disconnect the switch circuit when the control unit fails, the program runs wild, crashes and other abnormal conditions occur, thereby turning off the motor to achieve the purpose of protecting the motor. And the added set of hardware control circuits shares a set of switch circuits with the original control circuit, with simple control and low cost.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions: A circuit with a multiple motor protection mechanism, including a first control circuit, a second control circuit, a switch circuit, and a motor U5. The first control circuit and the second control circuit are connected to the motor U5 through the same switch circuit. The first control circuit includes a control unit, a pre-driver unit, and a power bridge U2 connected in sequence. The second control circuit includes a detection circuit and a selection circuit connected in sequence. The power bridge U2 and the selection circuit are respectively connected to the switch circuit. The detection circuit is used to receive the PWM signal sent by the control unit and the back electromotive force signal from the motor U5. The selection circuit is also connected to the pre-driver unit. The pre-driver unit can control the output of the sel signal according to whether the detection circuit detects the PWM signal. And the selection circuit can select a suitable signal for output according to different sel signals, thereby triggering the first control circuit to control the switch circuit or triggering the second control circuit to control the switch circuit. When the detection circuit detects the PWM signal, the on / off of the switch circuit is controlled by the first control circuit. When the detection circuit does not detect the PWM signal, the on / off of the switch circuit is controlled by the second control circuit.

[0009] Preferably, the detection circuit includes a differential switch circuit, an integration switch circuit, a back electromotive force switch circuit, and a back electromotive force identification circuit. The control terminal of the differential switch circuit is connected to the PWM signal sent by the control unit. The input terminal of the differential switch circuit is connected to the power supply voltage VCC. The output terminal of the differential switch circuit is connected to the control terminal of the integration switch circuit. The input terminal of the integration switch circuit is connected to the power supply voltage VCC in series with a resistor R1. The control terminal of the back electromotive force switch circuit is connected between the input terminal of the integration switch circuit and the resistor R1. The output terminal of the back electromotive force switch circuit is connected to the ground in common with the output terminal of the integration switch circuit after being connected in series with a resistor R2. The input terminal of the back electromotive force switch circuit is connected to the output terminal of the back electromotive force identification circuit through an ELV circuit. The input terminal of the back electromotive force identification circuit is connected to the motor U5. The switch circuit is connected between the motor U5 and the power bridge U2, and the switch circuit can receive different signals sent by the selection circuit to trigger the first control circuit to control the switch circuit or trigger the second control circuit to control the switch circuit.

[0010] Preferably, the differential switch circuit includes a resistor R7, a capacitor C2, and a triode V2. One end of the capacitor C2 is connected to the base of the triode V2. The other end of the capacitor C2 and one end of the resistor R7 are connected in common and then connected to the PWM signal. The emitter of the triode V2 and the other end of the resistor R7 are connected in common and then connected to the power supply voltage VCC. The collector of the triode V2 is connected to the control terminal of the integration switch circuit.

[0011] Preferably, the integration switch circuit includes a resistor R3, a capacitor C1, and a triode V3. One end of the resistor R3 is connected to the collector of the triode V2. The other end of the resistor R3, one end of the capacitor C1, and the base of the triode V3 are connected in common. The other end of the capacitor C1 and the emitter of the triode V3 are both grounded to GND. One end of the resistor R1 is connected to the power supply voltage VCC. The collector of the triode V3 and the other end of the resistor R1 are connected in common and then connected to the control terminal of the back electromotive force switch circuit.

[0012] Preferably, the selection circuit includes a selector U4. Port 1 of the selector U4 is connected to the power supply voltage VCC. Port 3 of the selector U4 is connected to the pre-driver unit. The back electromotive force switch circuit includes a triode V1. The base of the triode V1, the other end of the resistor R1, and the collector of the triode V3 are connected in common. The emitter of the triode V1 and one end of the resistor R2 are connected in common and then connected to port 2 of the selector U4. The other end of the resistor R2 and the emitter of the triode V3 are connected in common and then grounded to GND. The collector of the triode V1 is connected to one end of the ELV circuit.

[0013] Preferably, the back electromotive force identification circuit includes a resistor R4, a resistor R5, and a resistor R6. The motor U5 is connected in series with the resistors R4, R5, and R6 connected in parallel, and then connected to the other end of the ELV circuit.

[0014] Preferably, the switch circuit includes a relay K1 and a relay K2. The relay K1 and the relay K2 are connected in parallel between the motor U5 and the power bridge U2. The two ends of the parallel-connected relay K1 and relay K2 are respectively connected to port 2 and port 4 of the selector U4. The OUT signal and the CTRL signal are sent to the relay K1 and the relay K2 through port 2 and port 4 of the selector U4 to control the suction and disconnection of the relay.

[0015] Preferably, both the triode V1 and the triode V3 are NPN type triodes with a resistor, and the triode V2 is a PNP type triode with a resistor. A resistor is connected between the base and the emitter of the triode V1, between the base and the emitter of the triode V2, and between the base and the emitter of the triode V3 respectively. A resistor is also connected to the base of the triode V1, the base of the triode V2, and the base of the triode V3 respectively.

[0016] Preferably, the control unit is a single-chip microcomputer U1, and a watchdog is built in the single-chip microcomputer U1. The PWM signal is sent by the watchdog. The pre-driver unit is a pre-driver chip U3, and a pre-driver circuit is built in the pre-driver chip U3. The sel signal is sent by the pre-driver circuit.

[0017] Another object of the present invention is to provide an EPS system with a multiple motor protection mechanism, which includes the above-mentioned circuit with a multiple motor protection mechanism.

[0018] The present invention detects the PWM signal provided by the control unit through a detection circuit to trigger whether the switch circuit is controlled by the first control circuit or the second control circuit. When the control unit is normal, the detection circuit identifies that the PWM signal is valid, the pre-drive signal sel is at a high level, the selection circuit outputs an a signal, closes the switch circuit, and shields the back electromotive force signal of the motor. At this time, the control unit sends a drive signal to the pre-driver unit, and the pre-driver unit controls the power bridge through amplification, and then controls the normal operation of the motor through the switch circuit. When the control unit fails or the program runs away, freezes, or other abnormal conditions occur, the pre-driver unit cannot work normally, the control unit stops providing the PWM signal, the detection circuit identifies that the PWM signal is invalid, the pre-drive signal sel is at a low level, the selection circuit selects a b signal, and at this time, the back electromotive force is triggered for control, so as to disconnect the switch circuit and protect the motor from being stuck.

[0019] The present invention independently controls the on / off of a switch circuit by adding a set of hardware control circuits (the second control circuit). Moreover, the added set of hardware control circuits can timely disconnect the switch circuit when the control unit of the original control circuit (the first control circuit) fails, the program runs amok, freezes, or other situations occur, thereby turning off the motor to achieve the purpose of protecting the motor. Additionally, the added set of hardware control circuits shares a set of switch circuits with the original control circuit, which is simple to control and has a low cost. Among them, when the control unit is working normally, the on / off of the switch circuit is still controlled by the control unit. When the control unit is abnormal, the on / off of the switch circuit can be controlled by an independent hardware circuit (the second control circuit), with a faster response speed and the ability to protect the motor in a timely manner. In addition, the control logic in the present invention is simpler, consisting of two sets of control circuits and a set of actuator systems (switch circuits). The circuit is easy to control, reduces the failure of the entire system, and has a low cost. Moreover, the present invention adopts a compatible decision-making system. When one set of control logic in the system is normal, the other set of control logic waits. The two sets of control logics complement each other from the signal source end and the system execution end of the system, reducing failures such as common cause failures and cascade failures, and improving the safety and safety level of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 FIG. is a framework diagram of the first motor protection mechanism in the prior art.

[0021] Figure 2 FIG. is a framework diagram of the second motor protection mechanism in the prior art.

[0022] Figure 3 FIG. is a framework diagram of the third motor protection mechanism in the prior art.

[0023] Figure 4 FIG. is a framework diagram of the circuit with multiple motor protection mechanisms in this embodiment.

[0024] Figure 5 FIG. is a circuit diagram of the circuit with multiple motor protection mechanisms in this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] The difference between this circuit and the traditional circuit lies in that: in the case of the failure of the single-chip microcomputer or the program running amok in the traditional circuit, the motor cannot be directly disconnected through the hardware circuit, with a slow response speed and the inability to protect the motor in a timely manner. In this circuit, when the entire watchdog of the single-chip microcomputer is normal, the single-chip microcomputer controls the suction and disconnection of the relay; if the single-chip microcomputer has abnormal situations such as running amok or freezing, the suction and disconnection of the relay are controlled by an independent hardware drive circuit. In the traditional design, generally two sets of systems are used for management and monitoring. This design uses one set of systems, with a simple control logic, easy circuit control, reduced failure of the entire system, and low cost.

[0026] For the convenience of those skilled in the art, the present invention will be further described below in conjunction with embodiments and the accompanying drawings. The content mentioned in the embodiments does not limit the present invention.

[0027] As Figure 4 、 Figure 5 shown, a circuit with a multiple motor protection mechanism includes a first control circuit, a second control circuit, a switching circuit, and a motor U5. The first control circuit and the second control circuit are connected to the motor U5 through the same switching circuit. The first control circuit includes a control unit, a pre-driver unit, and a power bridge U2 connected in sequence. The second control circuit includes a detection circuit and a selection circuit connected in sequence. The power bridge U2 and the selection circuit are respectively connected to the switching circuit. The detection circuit is used to receive the PWM signal sent by the control unit and the back electromotive force signal from the motor U5. The selection circuit is also connected to the pre-driver unit. The pre-driver unit can control the output of the sel signal according to whether the PWM signal is detected by the detection circuit, and the selection circuit can select a suitable signal for output according to different sel signals, so as to trigger the first control circuit to control the switching circuit or trigger the second control circuit to control the switching circuit. When the detection circuit detects the PWM signal, the on / off of the switching circuit is controlled by the first control circuit. When the detection circuit does not detect the PWM signal, the on / off of the switching circuit is controlled by the second control circuit.

[0028] In this embodiment, the detection circuit includes a differential switching circuit, an integral switching circuit, a back electromotive force switching circuit, and a back electromotive force identification circuit. The control end of the differential switching circuit is connected to the PWM signal sent by the control unit. The input end of the differential switching circuit is connected to the power supply voltage VCC. The output end of the differential switching circuit is connected to the control end of the integral switching circuit. The input end of the integral switching circuit is connected to the power supply voltage VCC in series with a resistor R1. The control end of the back electromotive force switching circuit is connected between the input end of the integral switching circuit and the resistor R1. The output end of the back electromotive force switching circuit is connected to the output end of the integral switching circuit in series with a resistor R2 and grounded. The input end of the back electromotive force switching circuit is connected to the output end of the back electromotive force identification circuit through an ELV circuit. The input end of the back electromotive force identification circuit is connected to the motor U5. The switching circuit is connected between the motor U5 and the power bridge U2, and the switching circuit can receive different signals sent by the selection circuit to trigger the first control circuit to control the switching circuit or trigger the second control circuit to control the switching circuit.

[0029] This embodiment also provides an EPS system with a multiple motor protection mechanism, which includes the aforementioned circuit with a multiple motor protection mechanism.

[0030] In the circuit with a multiple motor protection mechanism provided in the above embodiment, when the control terminal of the differential switch circuit receives a PWM signal, the differential switch circuit will generate a square wave signal with a voltage amplitude equal to the power supply voltage VCC and a frequency the same as that of the PWM signal and send it to the integral switch circuit. The integral switch circuit then shapes the square wave signal into a DC signal. At this time, the back electromotive force switch circuit is open, the output of the pre-driver unit sel is high, the selection circuit outputs signal a, closes the switch circuit, and shields the back electromotive force signal of the motor U5. The control unit sends a drive signal to the pre-driver unit, and the pre-driver unit controls the power bridge U2 through amplification and then controls the normal operation of the motor U5 through the switch circuit. Conversely, when the control terminal of the differential switch circuit does not receive a PWM signal, the differential switch circuit is open, the integral switch circuit is open, the back electromotive force switch circuit is closed, the output of the pre-driver unit sel is low, the selection circuit selects signal b, and through back electromotive force trigger control, the switch circuit is disconnected to protect the motor from jamming. It should be noted that when the control unit is in a normal working state, the on / off of the switch circuit is still controlled by the first control circuit, and the back electromotive force signal of the motor is shielded. When the control unit is in an abnormal state, the pre-driver unit cannot work properly either. At this time, the on / off of the switch circuit changes to be controlled by the second control circuit, and the switch circuit is disconnected through the back electromotive force of the motor to achieve the purpose of protecting the motor.

[0031] It can be easily seen from the above content that compared with the traditional technical solution, the circuit and EPS system with a multiple motor protection mechanism provided in this embodiment add a new detection mechanism, and the detection mechanism uses a heterogeneous method, which can solve common cause failures and cascading failures, and completely solves the problem that the switch circuit cannot be disconnected in time due to various reasons in the system, resulting in motor jamming and affecting driving safety. Moreover, usually, the failure rate of the entire switch circuit in the EPS system is low, and only one set of the final actuator (switch circuit) is used in the entire control logic of the present invention, and the same switch circuit is controlled by two sets of logics, thus simplifying the system circuit and saving costs.

[0032] When the present invention selects the selection circuit, switch circuit, differential switch circuit, integral switch circuit, back electromotive force switch circuit, and back electromotive force identification circuit, there are many ways to achieve it, which can be but not limited to the following ways. Next, the specific structures of each circuit will be described in detail.

[0033] In this embodiment, the differential switch circuit includes a resistor R7, a capacitor C2, and a triode V2. One end of the capacitor C2 is connected to the base of the triode V2, the other end of the capacitor C2 is connected to one end of the resistor R7 and then receives the PWM signal, the emitter of the triode V2 is connected to the other end of the resistor R7 and then connected to the power supply voltage VCC, and the collector of the triode V2 is connected to the control terminal of the integral switch circuit.

[0034] In this embodiment, the integrating switch circuit includes a resistor R3, a capacitor C1, and a triode V3. One end of the resistor R3 is connected to the collector of the triode V2. The other end of the resistor R3, one end of the capacitor C1, and the base of the triode V3 are collinear. The other end of the capacitor C1 and the emitter of the triode V3 are both grounded to GND. One end of the resistor R1 is connected to the power supply voltage VCC. The collector of the triode V3 and the other end of the resistor R1 are collinear and then connected to the control end of the back electromotive force switch circuit.

[0035] In this embodiment, the selection circuit includes a selector U4. Port 1 of the selector U4 is connected to the power supply voltage VCC. Port 3 of the selector U4 is connected to the pre-driving unit. The back electromotive force switch circuit includes a triode V1. The base of the triode V1, the other end of the resistor R1, and the collector of the triode V3 are collinear. The emitter of the triode V1 and one end of the resistor R2 are collinear and then connected to port 2 of the selector U4. The other end of the resistor R2 and the emitter of the triode V3 are collinear and then grounded to GND. The collector of the triode V1 is connected to one end of the ELV circuit.

[0036] In this embodiment, the back electromotive force identification circuit includes a resistor R4, a resistor R5, and a resistor R6. The motor U5 is connected in series with the resistors R4, R5, and R6 connected in parallel and then connected to the other end of the ELV circuit.

[0037] In this embodiment, the switch circuit includes a relay K1 and a relay K2. The relay K1 and the relay K2 are connected in parallel between the motor U5 and the power bridge U2. The two ends of the relay K1 and the relay K2 connected in parallel are respectively connected to port 2 and port 4 of the selector U4. The OUT signal and the CTRL signal are sent to the relay K1 and the relay K2 through port 2 and port 4 of the selector U4 to control the suction and disconnection of the relay.

[0038] Considering the stability of the triode, a resistor can be respectively connected between the base and the emitter of the triode V1, between the base and the emitter of the triode V2, and between the base and the emitter of the triode V3. A resistor is also respectively connected to the base of the triode V1, the base of the triode V2, and the base of the triode V3.

[0039] In this embodiment, both the triode V1 and the triode V3 are NPN type triodes with built-in resistors, and the triode V2 is a PNP type triode with a built-in resistor.

[0040] In this embodiment, the pre-driving unit is a pre-driving chip U3, which amplifies the input weak electrical signal to form a strong electrical signal for external devices and drives the power bridge U2 to work normally. Among them, a pre-driving circuit is built in the pre-driving chip U3, and the sel signal is sent by the pre-driving circuit.

[0041] In this embodiment, the control unit is a single-chip microcomputer U1, which has a built-in watchdog, and the PWM signal is sent by the watchdog. When the single-chip microcomputer U1 works normally, the output PWM signal is a square wave signal, and the watchdog is fed in real time by sending the PWM signal; when the single-chip microcomputer U1 fails, the output PWM signal is a high level or a low level.

[0042] Among them, when the single-chip computer U1 outputs a PWM signal (square wave signal), the differential circuit composed of resistor R7 and capacitor C2 is used for calculation, and the transistor V2 is turned on. At this time, the collector output of the transistor V2 is equal to the amplitude of the battery VCC. Then, the square wave signal is rectified into a DC signal through the integration circuit composed of resistor R3 and capacitor C1, and input to the base of the transistor V3, turning on the transistor V3. At this time, the base of the transistor V1 is pulled low, the transistor V1 is turned off, and the OUT output is 0; when the single-chip computer U1 outputs a high level or a low level, the transistor V2 is turned off, and the collector output of the transistor V2 is 0, which is input to the base of the transistor V3, and the transistor V3 is turned off. At this time, the base of VCC is pulled high through the resistor R1, turning on the transistor V1, and the OUT output is ELV.

[0043] In this embodiment, the power bridge U2 is composed of six MOSFETs but is not limited to MOSFET switch components. The on and off of the three phases of the motor are controlled by controlling the gates of the MOSFETs.

[0044] In this embodiment, the selector U4 selects the output signal by receiving the driver chip signal. When the driver chip works normally, the sel signal selects a and outputs out=a. When the driver chip does not work normally, the sel signal selects b and outputs out=b.

[0045] In this embodiment, the relays K1 and K2 constituting the switch circuit are controlled to be closed and opened by the OUT signal and the CTRL signal.

[0046] The present invention detects the PWM signal provided by the single-chip microcomputer U1 through a detection circuit to trigger whether the switch circuit is controlled by the first control circuit or the second control circuit. When the single-chip microcomputer U1 is normal, the detection circuit identifies that the PWM signal is valid, the pre-drive signal sel is high level, the selection circuit outputs a signal, closes the switch circuit, and shields the back electromotive force signal of the motor. At this time, the single-chip microcomputer U1 sends a drive signal to the pre-drive chip U3, and the pre-drive chip U3 controls the power bridge U2 after amplification, and then controls the motor U5 to work normally after passing through the switch circuit; when the single-chip microcomputer U1 fails or the program runs away, crashes, and other abnormal conditions occur, the pre-drive chip U3 cannot work normally, the single-chip microcomputer U1 stops providing the PWM signal, the detection circuit identifies that the PWM signal is invalid, the pre-drive signal sel is low level, and the selection circuit selects the b signal. At this time, the back electromotive force triggers the control, thereby disconnecting the switch circuit to protect the motor U5 from being stuck.

[0047] In the present invention, a new set of hardware control circuit (the second control circuit) is added to independently control the on-off of the switch circuit. Moreover, when the single-chip microcomputer U1 of the original control circuit (the first control circuit) fails, or the program runs away or freezes, etc., the newly added hardware control circuit can timely disconnect the switch circuit, thereby turning off the motor U5, achieving the purpose of protecting the motor U5. In addition, the newly added hardware control circuit shares a set of switch circuits with the original control circuit, with simple control and low cost. Among them, when the single-chip microcomputer U1 works normally, the on-off of the switch circuit is still controlled by the single-chip microcomputer U1. When the single-chip microcomputer U1 is abnormal, the on-off of the switch circuit can be controlled by an independent hardware circuit (the second control circuit), with a faster response speed and timely protection of the motor U5. In addition, the control logic in the present invention is simpler, consisting of two sets of control circuits and a set of actuator systems (switch circuits), which is easy to control, reduces the failure of the entire system, and has a low cost. It is worth mentioning that the present invention adopts a compatible decision-making system. When one set of control logic is normal in the system decision, the other set of control logic waits. The two sets of control logics complement each other from the signal source end and the system execution end of the system, solving the personal injuries caused by failures such as common cause failures and cascading failures, and improving the safety and safety level of the entire system.

[0048] It should be noted that the present invention adopts a watchdog mechanism in the detection mechanism, so that the system can make conditional selections based on the entire watchdog to trigger the single-chip microcomputer U1 to control the switch circuit or trigger the back electromotive force of the motor U5 to control the switch circuit.

[0049] The above is only the preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Although the present invention has been disclosed as the preferred embodiment above, it is not used to limit the product form and style of the present invention. Any person skilled in the art can make some changes or modifications into equivalent embodiments of equivalent changes within the scope of the technical solution of the present invention. However, as long as it does not depart from the technical solution of the present invention, it belongs to the patent scope of the technical solution of the present invention.

Claims

1. A circuit with a multiple motor protection mechanism, characterized in that: It includes a first control circuit, a second control circuit, a switching circuit and a motor. The first control circuit and the second control circuit are connected to the motor through the same switching circuit. The first control circuit includes a control unit, a pre-driver unit and a power bridge connected in sequence. The second control circuit includes a detection circuit and a selection circuit connected in sequence. The power bridge and the selection circuit are respectively connected to the switching circuit. The detection circuit is used to receive the PWM signal sent by the control unit and the back electromotive force signal from the motor. The selection circuit is also connected to the pre-driver unit. The pre-driver unit can control the output of the sel signal according to whether the PWM signal is detected by the detection circuit, and the selection circuit can select a suitable signal for output according to different sel signals, so as to trigger the first control circuit to control the switching circuit or trigger the second control circuit to control the switching circuit. When the detection circuit detects the PWM signal, the on-off of the switching circuit is controlled by the first control circuit. When the detection circuit does not detect the PWM signal, the on-off of the switching circuit is controlled by the second control circuit.

2. The circuit with a multiple motor protection mechanism according to claim 1, characterized in that: The detection circuit includes a differential switching circuit, an integral switching circuit, a back electromotive force switching circuit and a back electromotive force identification circuit. The control end of the differential switching circuit is connected to the PWM signal sent by the control unit. The input end of the differential switching circuit is connected to the power supply voltage VCC. The output end of the differential switching circuit is connected to the control end of the integral switching circuit. The input end of the integral switching circuit is connected to the power supply voltage VCC in series with a resistor R1. The control end of the back electromotive force switching circuit is connected between the input end of the integral switching circuit and the resistor R1. The output end of the back electromotive force switching circuit is connected to the ground in series with a resistor R2 and is collinear with the output end of the integral switching circuit. The input end of the back electromotive force switching circuit is connected to the output end of the back electromotive force identification circuit through an ELV circuit. The input end of the back electromotive force identification circuit is connected to the motor. The switching circuit is connected between the motor and the power bridge, and the switching circuit can receive different signals sent by the selection circuit to trigger the first control circuit to control the switching circuit or trigger the second control circuit to control the switching circuit.

3. The circuit with multiple motor protection mechanisms according to claim 2, characterized in that: The differential switching circuit includes a resistor R7, a capacitor C2 and a triode V2. One end of the capacitor C2 is connected to the base of the triode V2. The other end of the capacitor C2 is connected to the resistor R7 and then accesses the PWM signal. The emitter of the triode V2 is connected to the power supply voltage VCC after being collinear with the other end of the resistor R7. The collector of the triode V2 is connected to the control end of the integral switching circuit.

4. The circuit with a multiple motor protection mechanism according to claim 3, characterized in that: The integral switching circuit includes a resistor R3, a capacitor C1 and a triode V3. One end of the resistor R3 is connected to the collector of the triode V2. The other end of the resistor R3, one end of the capacitor C1 and the base of the triode V3 are collinear. The other end of the capacitor C1 and the emitter of the triode V3 are both grounded to GND. One end of the resistor R1 is connected to the power supply voltage VCC. The collector of the triode V3 is connected to the control end of the back electromotive force switching circuit after being collinear with the other end of the resistor R1.

5. The circuit with a multiple motor protection mechanism according to claim 4, characterized in that: The selection circuit includes a selector. Port 1 of the selector is connected to the power supply voltage VCC, and port 3 of the selector is connected to the pre-driver unit. The back electromotive force switch circuit includes a triode V1. The base of the triode V1, the other end of the resistor R1, and the collector of the triode V3 are collinear. The emitter of the triode V1 is collinear with one end of the resistor R2 and then connected to port 2 of the selector. The other end of the resistor R2 is collinear with the emitter of the triode V3 and then grounded to GND. The collector of the triode V1 is connected to one end of the ELV circuit.

6. The circuit with a multiple motor protection mechanism according to claim 5, wherein: The back electromotive force identification circuit includes a resistor R4, a resistor R5, and a resistor R6. The motor is connected in series with the resistors R4, R5, and R6 connected in parallel and then connected to the other end of the ELV circuit.

7. The circuit with a multiple motor protection mechanism according to claim 6, characterized in that: The switch circuit includes a relay K1 and a relay K2. The relay K1 and the relay K2 are connected in parallel between the motor and the power bridge. The two ends of the relay K1 and the relay K2 connected in parallel are respectively connected to port 2 and port 4 of the selector. OUT signals and CTRL signals are sent to the relay K1 and the relay K2 through port 2 and port 4 of the selector to control the suction and disconnection of the relay.

8. The circuit with multiple motor protection mechanisms according to claim 7, characterized in that: Both the triode V1 and the triode V3 are NPN type transistors with resistors, and the triode V2 is a PNP type transistor with a resistor. A resistor is respectively connected between the base and the emitter of the triode V1, between the base and the emitter of the triode V2, and between the base and the emitter of the triode V3. A resistor is also respectively connected to the base of the triode V1, the base of the triode V2, and the base of the triode V3.

9. The circuit with a multiple motor protection mechanism according to any one of claims 1 to 8, characterized in that: The control unit is a single-chip microcomputer. A watchdog is built in the single-chip microcomputer, and the PWM signal is sent by the watchdog. The pre-driver unit is a pre-driver chip. A pre-driver circuit is built in the pre-driver chip, and the sel signal is sent by the pre-driver circuit.

10. An EPS system with a multiple motor protection mechanism, characterized in that: It includes the circuit with a multiple motor protection mechanism according to any one of claims 1 to 9.

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