CN113394751B - Circuit system and method for realizing vehicle motor driving and self-protection - Google Patents
Circuit system and method for realizing vehicle motor driving and self-protection Download PDFInfo
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- CN113394751B CN113394751B CN202110665371.1A CN202110665371A CN113394751B CN 113394751 B CN113394751 B CN 113394751B CN 202110665371 A CN202110665371 A CN 202110665371A CN 113394751 B CN113394751 B CN 113394751B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
- H02H7/085—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
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Abstract
The invention relates to a circuit system for realizing vehicle motor drive and self-protection, which comprises a micro control unit, a first relay, a second relay, an NMOS (N-channel metal oxide semiconductor) tube, a motor, a storage battery, a sampling resistor and a TVS (transient voltage suppressor), wherein the forward and reverse rotation directions of the motor are controlled by the first relay and the second relay, the NMOS tube controls the on-off of the current of a loop grounding end of the motor, the micro control unit processes control logic related to the motor, the suction or the off of the first relay and the second relay are respectively controlled by signals, the micro control unit controls the on or the off of the NMOS tube by control signals, and the TVS tube carries out transient voltage suppression on a drain electrode of the NMOS tube and clamps the voltage to a safe voltage range. The invention also relates to a method for realizing the motor drive and self-protection control for the vehicle. The circuit system and the method for realizing the motor drive and the self-protection for the vehicle can effectively reduce the design cost, greatly prolong the electrical service life of the motor drive circuit and prevent the abnormal connection of the motor interface from damaging the internal circuit.
Description
Technical Field
The invention relates to the field of automobile embedded development, in particular to the field of hardware diagnosis and protection of automobile motor driving circuits, and specifically relates to a circuit system and a method for realizing automobile motor driving and self-protection.
Background
The motor for vehicles, such as a direct current motor for windows, door locks, etc., usually works in a 12V system or a 24V system, and the existing driving circuit technology usually adopts two schemes: 1. the intelligent power device scheme is as follows: the integrated circuit chip is used for realizing the integrated functions of control, diagnosis and protection of the motor drive, has the advantages of high safety and reliability integration level, and has the defects of higher practical application cost and lower upper limit of current drive capability, and the chip voltage resistance limit is only common in 12V systems and has failure risk when being applied to 24V truck systems; 2. the relay scheme is as follows: the H-bridge driving circuit is built through 2 single-pole double-throw relays, and the H-bridge driving circuit has the advantages of simple software control logic, low cost of a 12V system relay and high cost of a 24V system relay; an effective diagnosis protection circuit is lacked, and the risk of adhesion of relay contacts or fuse of fuses exists after the motor interface is short-circuited; in addition, the working current of the motor is large, the reliable electrical service life of the relay is only about 10 ten thousand times, and the mechanical service life of the relay is shortened by more than 5 times.
Nowadays, in the field of automotive electronics, requirements for reliability and cost control of an electronic control unit are higher and higher, and in order to improve market competitiveness, quality three-pack claim mileage and age limit required by various automobile manufacturers for parts are continuously increased, so that if the electronic control unit is short in service life, poor in self-protection capability and high in cost, the electronic control unit is inevitably eliminated in the future competitive development trend.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a circuit system and a method for realizing vehicle motor driving and self-protection, which have the advantages of good reliability, low cost and strong self-protection capability.
In order to achieve the above object, the circuit system and method for realizing the driving and self-protection of the vehicle motor of the present invention are as follows:
the circuit system for realizing the driving and the self-protection of the vehicle motor is mainly characterized by comprising a micro control unit, a first relay, a second relay, an NMOS (N-channel metal oxide semiconductor) tube, a motor, a storage battery, a sampling resistor and a TVS (transient voltage suppressor), wherein the drain electrode of the NMOS tube and a first relay K 1 And a second relay K 2 The normally closed contact is connected, the grid electrode is connected with the micro control unit, the control signal Mos _ Ctrl is received, the source electrode is connected with one end of the sampling resistor and also connected with a second analog signal acquisition end of the micro control unit, the other end of the sampling resistor is grounded, one end of the TVS tube is connected with the drain electrode of the NMOS tube, the other end of the TVS tube is grounded, the normally closed contact is also connected with two ends of the motor, and the first relay K is connected with the other end of the motor 1 And a second relay K 2 The normally open contact of the battery is connected with the storage battery,
the micro control unit controls the positive and negative rotation direction of the motor through the first relay and the second relay, the NMOS tube is used for controlling the current on-off of a loop grounding end of the motor, the micro control unit is used for processing control logic related to the motor, the attracting or the disconnection of the first relay and the second relay are respectively controlled through an M + _ Ctrl signal and an M- _ Ctrl signal, the micro control unit controls the connection or the disconnection of the NMOS tube through a control signal Mos _ Ctrl, and the TVS tube carries out transient voltage suppression on a drain electrode of the NMOS tube and clamps the voltage to a safe voltage range.
Preferably, the circuit further comprises a second resistor, a third resistor and a fourth resistor, the drain of the NMOS transistor is connected to one end of the second resistor and one end of the third resistor, the other end of the second resistor is connected to the storage battery, the other end of the third resistor is connected to the first analog signal acquisition end of the micro control unit and to one end of the fourth resistor, and the other end of the fourth resistor is grounded.
Preferably, the first relay and the second relay both include coils, one end of each coil is connected to the storage battery, and the other end of each coil is connected to the micro control unit, and receives the control signals M + _ Ctrl and M- _ Ctrl from the micro control unit.
The method for realizing the motor drive and the self-protection control for the vehicle by utilizing the system is mainly characterized by comprising the following steps of:
the micro control unit judges the short circuit or open circuit of the motor interface according to the voltage state of the motor interface in each control time sequence;
the contact adhesion of the relay is prevented by controlling the time sequence of the NMOS tube;
and the micro control unit calculates the time point of the system parameter for disconnecting the current of the NMOS tube and performs overcurrent and overheat protection on the NMOS tube.
Preferably, the step of determining the short circuit or the open circuit of the motor interface specifically includes the following processing steps:
(1-1) the micro control unit judges whether the motor interface is abnormal or not by detecting the voltage value of the first analog signal acquisition end, and if so, the step (1-2) is continued; otherwise, continuing the step (1-3);
(1-2) judging the motor interface voltage V according to a calculation formula of the voltage value of the first analog signal acquisition end MOTOR Short-circuit to power supply or ground, and recovering to the initial stateRetrying the step (1-1) after timing a certain time;
and (1-3) adjusting the voltage division values of the second resistor, the third resistor and the fourth resistor according to a calculation formula of the voltage value of the first analog signal acquisition end, so that the conventional sampling range of the power supply voltage is within the sampling range of the first analog signal acquisition end.
Preferably, the steps further include the following processes:
(1-4) controlling the relay to be closed, judging whether the voltage value of the first analog signal acquisition end is greater than 4.5V or not, and if so, judging that the circuit state is normal; otherwise, the circuit state is abnormal, fault recording is carried out, the initial state is recovered, and the step (1-1) is retried after timing for a certain time.
Preferably, the step of preventing the relay contact from being adhered by controlling the time sequence of the NMOS transistor specifically includes the following steps:
after the relay contacts are closed, delaying at least 1 relay contact switching period, and opening the NMOS tube to conduct the current of the motor loop;
when the current of the motor loop is closed, the NMOS tube is closed, the current of the motor loop is cut off, at least 1 relay contact switching period is delayed, and the relay is controlled to be switched off.
Preferably, the step of calculating the time point of the system parameter to turn off the NMOS transistor current specifically includes the following processing steps:
(3-1) acquiring the voltage value of the second analog signal acquisition end at intervals, and calculating the current value I passing through the NMOS tube n ；
(3-2) judging the current value I of the NMOS tube n Whether the current is less than the safe working current I of the NMOS tube s If yes, calculating the time t from starting to shutting off the NMOS tube c (ii) a Judging the current value I of the NMOS tube n Whether the safe working current I is larger than or equal to that of the NMOS tube s And less than or equal to short circuit judgment threshold current I max If yes, calculating the time t from starting to shutting off the NMOS tube c (ii) a Judging the current value I of the NMOS tube n Whether or not it is larger than the short-circuit judgment threshold current I max If so, the MCU interrupts through the bottom layerImmediately processing, judging the short-circuit protection, and controlling the disconnection current of the NMOS tube;
(3) If the circuit state is overcurrent or short circuit, a period of time is delayed, and the NMOS is conducted again.
Preferably, when the motor interface is abnormal in the step (1-2), the voltage value of the first analog signal acquisition end is calculated, specifically:
calculating the voltage value of the first analog signal acquisition end when the motor interface is abnormal according to the following formula:
wherein, V AD1 For the voltage value, V, of the first analog signal acquisition terminal BATT For the supply voltage, R 2 Is the resistance value of the second resistor, R 3 Is the resistance value of the third resistor, R 4 Is the resistance of the fourth resistor.
Preferably, the step (1-3) is performed by calculating a voltage value of the first analog signal collecting terminal when the motor interface is abnormal, specifically:
calculating the voltage value of the first analog signal acquisition end when the motor interface is abnormal according to the following formula:
wherein, V AD1 Is the voltage value, V, of the first analog signal acquisition terminal MOTOR Is the motor interface voltage, R 2 Is the resistance value of the second resistor, R 3 Is the resistance value of the third resistor, R 4 Is the resistance of the fourth resistor.
Preferably, the current value I of the NMOS transistor is calculated in the step (3-2) n Whether the safe working current I is larger than or equal to that of the NMOS tube s And less than or equal to short circuit judgment threshold current I max Time from start-up to turn-off of NMOS tube c The method specifically comprises the following steps:
calculating the time t from starting to shutting off of the NMOS tube according to the following formula c ：
Wherein K is a heat dissipation dynamic adjustment coefficient, R DS(ON) Is DS on-resistance of MOS, T max To the highest withstanding junction temperature, T room Is the ambient temperature, T R Is the thermal resistivity of MOS.
The circuit system and the method for realizing the motor drive and the self-protection for the vehicle can effectively reduce the design cost, greatly prolong the electrical service life of the motor drive circuit and prevent the abnormal connection of the motor interface from damaging the internal circuit. The invention has the advantage of cost, and simultaneously has the self-protection function of the driving circuit, thereby avoiding the damage of the driving circuit or the fusing of the fuse caused by the short circuit of the motor interface.
Drawings
Fig. 1 is a schematic circuit diagram of a circuit system for realizing vehicle motor driving and self-protection according to the present invention.
Fig. 2 is a flowchart of a method for implementing the motor driving and self-protection control for the vehicle according to the present invention.
Detailed Description
In order that the technical contents of the present invention can be more clearly described, the present invention will be further described with reference to specific embodiments.
Referring to fig. 1, the circuit system for implementing driving and self-protection of a vehicle motor according to the present invention includes a micro control unit, a first relay, a second relay, an NMOS transistor, a motor, a storage battery, a sampling resistor, and a TVS transistor, wherein a drain of the NMOS transistor and a first relay K are connected to a drain of the NMOS transistor 1 And a second relay K 2 The normally closed contact is connected, the grid electrode is connected with the micro control unit, the control signal Mos _ Ctrl is received, the source electrode is connected with one end of the sampling resistor and also connected with a second analog signal acquisition end of the micro control unit, the other end of the sampling resistor is grounded, one end of the TVS tube is connected with the drain electrode of the NMOS tube, the other end of the TVS tube is grounded, the normally closed contact is also connected with two ends of the motor, and the first relay K is connected with the other end of the motor 1 And a second relay K 2 The normally open contact of the battery is connected with the storage battery,
the micro control unit controls the positive and negative rotation direction of the motor through the first relay and the second relay, the NMOS tube is used for controlling the current on-off of a loop grounding end of the motor, the micro control unit is used for processing control logic related to the motor, the attracting or the disconnection of the first relay and the second relay are respectively controlled through an M + _ Ctrl signal and an M- _ Ctrl signal, the micro control unit controls the connection or the disconnection of the NMOS tube through a control signal Mos _ Ctrl, and the TVS tube carries out transient voltage suppression on a drain electrode of the NMOS tube and clamps the voltage to a safe voltage range.
As a preferred embodiment of the present invention, the circuit further includes a second resistor, a third resistor, and a fourth resistor, the drain of the NMOS transistor is connected to one end of the second resistor and one end of the third resistor, the other end of the second resistor is connected to the battery, the other end of the third resistor is connected to the first analog signal acquisition end of the micro control unit, and is also connected to one end of the fourth resistor, and the other end of the fourth resistor is grounded.
As the preferred embodiment of the invention, the first relay and the second relay both internally comprise coils, one end of each coil is connected with the storage battery, the other end of each coil is connected with the micro-control unit, and the control signals M + _ Ctrl and M- _ Ctrl of the micro-control unit are received.
Referring to fig. 2, the method for implementing vehicle motor driving and self-protection control by using the above system of the present invention includes the following steps:
the micro control unit judges the short circuit or open circuit of the motor interface according to the voltage state of the motor interface in each control time sequence;
the contact adhesion of the relay is prevented by controlling the time sequence of the NMOS tube;
and the micro control unit calculates the time point of the system parameter for disconnecting the current of the NMOS tube and performs overcurrent and overheat protection on the NMOS tube.
As a preferred embodiment of the present invention, the step of determining a short circuit or an open circuit of the motor interface specifically includes the following processing steps:
(1-1) the micro control unit judges whether the motor interface is abnormal or not by detecting the voltage value of the first analog signal acquisition end, and if so, the step (1-2) is continued; otherwise, continuing the step (1-3);
(1-2) judging the motor interface voltage V according to a calculation formula of the voltage value of the first analog signal acquisition end MOTOR Restoring the initial state to the power supply short circuit or the ground short circuit, and retrying the step (1-1) after timing a certain time;
and (1-3) adjusting the voltage division values of the second resistor, the third resistor and the fourth resistor according to a calculation formula of the voltage value of the first analog signal acquisition end, so that the conventional sampling range of the power supply voltage is within the sampling range of the first analog signal acquisition end.
(1-4) controlling the relay to be closed, judging whether the voltage value of the first analog signal acquisition end is larger than 4.5V or not, and if so, judging that the circuit state is normal; otherwise, the circuit state is abnormal, fault recording is carried out, the initial state is recovered, and the step (1-1) is retried after timing for a certain time.
As a preferred embodiment of the present invention, the step of preventing the relay contact from being stuck by controlling the timing of the NMOS transistor specifically includes the following steps:
after the relay contacts are closed, delaying at least 1 relay contact switching period, and opening the NMOS tube to conduct the current of the motor loop;
when the motor loop current is closed, the NMOS tube is closed, the motor loop current is cut off, at least 1 relay contact switching period is delayed, and the relay is controlled to be switched off.
As a preferred embodiment of the present invention, the step of calculating the time point of the system parameter to turn off the NMOS transistor current specifically includes the following processing procedures:
(3-1) acquiring the voltage value of the second analog signal acquisition end at intervals, and calculating the current value I passing through the NMOS tube n ；
(3-2) judging the current value I of the NMOS tube n Whether the current is less than the safe working current I of the NMOS tube s If yes, calculating the time t from starting to shutting off the NMOS tube c (ii) a Judging the current value I of the NMOS tube n Whether the safe working current I is larger than or equal to that of the NMOS tube s And less than or equal to short circuit judgment threshold current I max If yes, calculating the time t from starting to shutting off the NMOS tube c (ii) a Judging the current value I of the NMOS tube n Whether or not it is larger than the short-circuit judgment threshold current I max If yes, the micro control unit immediately processes through bottom layer interruption, judges that short-circuit protection is achieved, and controls the cut-off current of the NMOS tube; wherein, I max If the current is the short circuit judgment threshold current, the current is immediately cut off if the current exceeds the short circuit judgment threshold current;
(3) If the circuit state is overcurrent or short circuit, the time is delayed for a period of time, and the NMOS is conducted again.
As a preferred embodiment of the present invention, when there is no abnormality in the motor interface in step (1-2), the step of calculating the voltage value of the first analog signal acquisition end specifically includes:
calculating the voltage value of the first analog signal acquisition end when the motor interface is abnormal according to the following formula:
wherein, V AD1 For the voltage value, V, of the first analog signal acquisition terminal BATT For the supply voltage, R 2 Is the resistance value of the second resistor, R 3 Is the resistance value of the third resistor, R 4 Is the resistance of the fourth resistor.
As a preferred embodiment of the present invention, in the step (1-3), when the motor interface is abnormal, the voltage value of the first analog signal collecting terminal is calculated, specifically:
calculating the voltage value of the first analog signal acquisition end when the motor interface is abnormal according to the following formula:
wherein, V AD1 Is the voltage value, V, of the first analog signal acquisition terminal MOTOR For motor interfaceVoltage, R 2 Is the resistance value of the second resistor, R 3 Is the resistance value of the third resistor, R 4 Is the resistance of the fourth resistor.
As a preferred embodiment of the present invention, in the step (3-2), the current value I of the NMOS transistor is calculated n Whether the safe working current I is larger than or equal to that of the NMOS tube s And less than or equal to short circuit judgment threshold current I max Time from start-up to turn-off of NMOS tube c The method specifically comprises the following steps:
calculating the time t from starting to shutting off of the NMOS tube according to the following formula c ：
Wherein K is a heat dissipation dynamic adjustment coefficient, R DS(ON) Is DS on-resistance, T, of MOS max To maximum withstanding junction temperature, T room Is the ambient temperature, T R Is the thermal resistivity of MOS.
In a specific embodiment of the present invention, the motor driving circuit includes a micro control unit MCU, a relay unit, and an N-channel MOSFET, and the self-protection system includes: MCU, current diagnostic circuit, motor interface voltage detection circuit, overvoltage crowbar. The method comprises the following steps:
the method 1 is a method for realizing short circuit and open circuit diagnosis through the voltage state of a motor interface in each control time sequence;
method 2, a method for preventing relay contact adhesion by specific logic control time sequence of NMOS;
Fig. 1 shows a motor driving circuit and a corresponding self-protection circuit, and fig. 2 shows a driving circuit working logic, which includes 3 self-protection methods. In the description of the invention and the accompanying drawings, the MCU refers to a Micro Controller Unit, namely a Micro control Unit; BATT refers to Battery, i.e., a storage Battery; AD refers To Analog To Digital, i.e., the amount of Analog To Digital signals; NMOSAn N-Channel MOSFET, namely an N-Channel MOSFET; t is R Thermal Resistance, i.e., thermal Resistance; r DS(ON) Refer to Drain-to-Source On Resistance, DS On Resistance.
The system circuit connection mode of the present invention is shown in fig. 1, and the related driving circuit passes through a first relay K 1 And a second relay K 2 Build an H-bridge circuit and control a motor M 1 The direction is rotated positively and negatively; NMOS tube Q 1 The current on-off control circuit is used for controlling the current on-off of the grounding end of the whole motor loop; MCU-U 1 Processing the control logic related to the motor, and respectively controlling the first relay K through M + _ Ctrl and M- _ Ctrl signals 1 And a second relay K 2 Closing or opening, and Mos _ Ctrl controls the NMOS tube Q 1 Conducting or disconnecting, and acquiring 0-5V analog signals through AD1 and AD2 to obtain key data of a protection algorithm; TVS tube D 1 To NMOS tube Q 1 The end D of the transformer carries out transient voltage suppression, and the voltage is clamped to a safe voltage range.
Under the normal initial state (the motor interface has no short circuit or abnormal connection), the NMOS tube Q 1 End D and first relay K 1 And a second relay K 2 The normally closed contacts are connected, and the normally closed contacts are connected with a Motor + and a Motor-of an external Motor; first relay K 1 And a second relay K 2 The normally open contact of (3) is connected with BATT; one end of the relay coil is connected with BATT, and the other end is connected with MCU-U 1 The control signals M + Ctrl and M-Ctrl are connected; NMOS tube Q 1 The G end of the NMOS tube Q is connected with the MCU control signal Mos _ Ctrl 1 S terminal and sampling resistor R 1 One end is connected with the MCU-AD2 port; r 1 The other end is connected with the ground; TVS tube D 1 One end of the NMOS transistor Q 1 The end D of the switch is connected with the ground, and the other end of the switch is connected with the ground; r 2 One end is connected with BATT, and the other end is connected with NMOS tube Q 1 Is connected to the D terminal of R 3 Are connected at one end to R 3 Is connected with MCU-AD1 and R 4 Are connected to one end of R 4 The other end of which is connected to ground.
The self-protection method 1 is a software control strategy, and the MCU judges whether a motor interface is abnormal or not by detecting the voltage value of the AD1, because the NMOS is not turned onOpening, V AD1 Not in a grounded state;
when the motor interface is not abnormal,
wherein V BATT For supply voltage, if the selected MCU is paired with V AD1 The sampling range of the port is 0-5V (the sampling range is related to the MCU power supply voltage, the conventional voltage is 3.3V or 5V), R 2 、R 3 、R 4 For dividing the resistance, V is limited by reasonable voltage dividing value AD1 Corresponds to V BATT Is located at V AD1 The port is within a sampling range (a typical range is 1.5V to 3.5V) and there is enough voltage interval to distinguish the full bias.
When the motor interface is shorted to power or ground,
if V is detected AD1 If the voltage is more than 4.5V, the motor interface voltage V is judged MOTOR For power supply short circuit, if V is detected AD1 Less than 0.5V, determining the voltage V of the motor interface MOTOR And (4) short circuit to the ground, and the software system returns to the initial state after recording the short circuit event and counts a certain time to allow retry.
In the logic, if the motor interface judges that no abnormity exists and the relay is controlled to be closed, V MOTOR Close to V BATT The software judges according to formula 2 when V AD1 If the voltage is more than 4.5V, the voltage is a correct value, otherwise, the voltage is judged to be abnormal, fault records are made, the initial state is recovered, and retry is allowed after a certain time is timed.
The self-protection method 2 is a control time sequence of the MCU, is used for preventing the relay contact from being adhered, and comprises the following two points: 1. the NMOS must be turned on to turn on the current of the motor loop by delaying at least 1 switching cycle (typically 10 ms) after the relay contacts are closed. 2. When the motor loop current is closed, the NMOS is closed firstly, the motor loop current is cut off, and then the relay is controlled to be switched off after at least 1 relay contact switching period is delayed.
The self-protection method 3 is a software control algorithm and strategy, and the MCU calculates the time point of the system for disconnecting the NMOS current according to system parameters to prevent the NMOS from being damaged by overheating. The specific algorithm and strategy are as follows:
(1) The AD2 voltage V is collected once every a period of time AD2 Calculating the value of the current through the NMOS
(2) Assuming that the safe working current of NMOS in the full temperature range is I s When I is n <I s When NMOS turns on to turn off for time t c ＝t max (a typical value is 8 seconds after start-up).
(3) When I is s ≤I n ≤I max Time, calculate
K is a heat dissipation dynamic adjustment coefficient, and calibration is required according to the number of layers of the PCB and the heat dissipation condition; tmax is the highest tolerated junction temperature (typically 175 ℃); troom is the environmental temperature (usually set according to the highest test requirement of the product requirement, and the typical value of the automobile parts is 85 ℃); t is a unit of R Is the thermal resistivity of the MOS; r is DS(ON) Is the DS on-resistance of the MOS. When the detected current is continuously in the interval and the accumulated time exceeds t c And when the current is over-current, the MCU judges that the current is over-current protection and controls the NMOS to cut off the current.
(4) When I is n ＞I max And meanwhile, the MCU immediately processes the interruption of the bottom layer, judges the short-circuit protection is carried out, and controls the NMOS to cut off the current.
(5) Once it is judged that the current is over-current or short-circuit, it needs to be delayed for a period of time t int (typically 30 seconds) to allow the NMOS to turn on again.
In the invention, the relay contact is protected by the self-protection method 1, the self-protection method 2 and the switching characteristic of the NMOS, and the self-protection method 3 protects the NMOS from being damaged in overcurrent and short circuit. Therefore, the invention can effectively prolong the service life of the easily damaged relay contact in the motor driving circuit and also ensure that the NMOS can still recover to work normally after passing through extreme working conditions.
The invention can greatly prolong the electric service life of the motor driving circuit and prevent the abnormal connection of the motor interface from damaging the internal circuit while effectively reducing the design cost. Taking only one automobile part as an example, the annual output is 10 ten thousand, the selling price is 500 yuan, the three-pack claim rate is 3-fold selling price, and the claim rate caused by the motor control circuit failure before the technical improvement is 1%, so that the claim amount generated in one year is 100000 × 500 × 0.01 × 3=150 ten thousand. After the technology of the invention is improved, the claim rate caused by the motor fault is reduced by 0.01%, and the claim amount generated in one year is 100000 multiplied by 500 multiplied by 0.0001 multiplied by 3=1.5 ten thousand, and the economic benefit is 148.5 ten thousand.
The circuit system and the method for realizing the motor drive and the self-protection for the vehicle can effectively reduce the design cost, greatly prolong the electrical service life of the motor drive circuit and prevent the abnormal connection of the motor interface from damaging the internal circuit. The invention has the advantage of cost, and simultaneously has the self-protection function of the driving circuit, thereby avoiding the damage of the driving circuit or the fusing of the fuse caused by the short circuit of the motor interface.
In this specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.
Claims (6)
1. A method for realizing vehicle motor drive and self-protection control based on a circuit system for realizing vehicle motor drive and self-protection comprises the following steps:
the system comprises a micro control unit, a first relay, a second relay, an NMOS (N-channel metal oxide semiconductor) tube, a motor, a storage battery, a sampling resistor and a TVS (transient voltage suppressor), wherein a drain electrode of the NMOS tube and a first relay K 1 And a second relay K 2 The grid electrode is connected with the micro-controlThe system unit is connected with the signal receiving unit, receives a control signal Mos _ Ctrl, the source electrode is connected with one end of the sampling resistor and is also connected with the second analog signal acquisition end of the micro control unit, the other end of the sampling resistor is grounded, one end of the TVS tube is connected with the drain electrode of the NMOS tube, the other end of the TVS tube is grounded, the normally closed contact is also connected with the two ends of the motor, and the first relay K is connected with the two ends of the motor 1 And a second relay K 2 The normally open contact of the battery is connected with the storage battery,
the micro control unit controls the forward and reverse rotation direction of the motor through a first relay and a second relay, the NMOS tube is used for controlling the on-off of the current of a loop grounding end of the motor, the micro control unit is used for processing the relevant control logic of the motor, the attraction or the disconnection of the first relay and the second relay are respectively controlled through an M + _ Ctrl signal and an M- _ Ctrl signal, the micro control unit controls the on-off of the NMOS tube through a control signal Mos _ Ctrl, and the TVS tube carries out transient voltage suppression on the drain electrode of the NMOS tube and clamps the voltage to a safe voltage range;
the circuit further comprises a second resistor, a third resistor and a fourth resistor, wherein the drain electrode of the NMOS tube is connected with one end of the second resistor and one end of the third resistor, the other end of the second resistor is connected with the storage battery, the other end of the third resistor is connected with a first analog signal acquisition end of the micro control unit and is simultaneously connected with one end of the fourth resistor, and the other end of the fourth resistor is grounded;
the first relay and the second relay both comprise coils, one end of each coil is connected with the storage battery, the other end of each coil is connected with the micro control unit, and control signals M + _ Ctrl and M- _ Ctrl of the micro control unit are received;
the method is characterized by comprising the following steps:
the micro control unit judges the short circuit or open circuit of the motor interface according to the voltage state of the motor interface in each control time sequence;
the contact adhesion of the relay is prevented by controlling the time sequence of the NMOS tube;
the micro control unit calculates the time point of the current of the NMOS tube to carry out overcurrent and overheating protection on the NMOS tube;
the step of calculating the time point of the system parameter to switch off the NMOS tube current specifically comprises the following processing steps:
(3-1) collecting the voltage value of the second analog signal collecting end at intervals, and calculating the current value passing through the NMOS tube
；
(3-2) determining the value of the current of the NMOS transistor
Whether the current is less than the safe working current of the NMOS tube
If yes, calculating the time from starting to shutting off the NMOS tube
(ii) a Judging the current value of the NMOS tube
Whether the safe working current is more than or equal to that of the NMOS tube
And less than or equal to the short circuit judgment threshold current
If yes, calculating the time from starting to shutting off the NMOS tube
When the detected current is continuously in the interval and the accumulated time exceeds the interval
Judging the current is overcurrent protection and controlling the NMOS tube to be disconnectedCurrent, at which time the circuit state is overcurrent; judging the current value of the NMOS tube
Whether it is larger than the short-circuit judgment threshold current
If yes, the micro control unit immediately processes through bottom layer interruption, judges that short circuit protection is achieved, controls the disconnection current of the NMOS tube, and at the moment, the circuit state is short circuit;
(3-3) when the circuit state is overcurrent or short circuit, delaying for a period of time, and turning on the NMOS again;
calculating the current value of the NMOS tube in the step (3-2)
Whether the safe working current is more than or equal to that of the NMOS tube
And is less than or equal to the short circuit judgment threshold current
Time from start-up to turn-off of NMOS transistor
The method specifically comprises the following steps:
calculating the time from starting to shutting off of the NMOS tube according to the following formula
：
Wherein K is a dynamic adjustment coefficient of heat dissipation,
is the DS on-resistance of the MOS,
in order to be the highest tolerant junction temperature,
is at the temperature of the surroundings and is,
is the thermal resistivity of MOS.
2. The method as claimed in claim 1, wherein the step of determining whether the motor interface is short-circuited or open-circuited includes the following steps:
(1-1) the micro control unit judges whether the motor interface is abnormal or not by detecting the voltage value of the first analog signal acquisition end, and if so, the step (1-2) is continued; otherwise, continuing the step (1-3);
(1-2) judging the voltage of the motor interface according to a calculation formula of the voltage value of the first analog signal acquisition end
Restoring the initial state to the power supply short circuit or the ground short circuit, and retrying the step (1-1) after timing a certain time;
and (1-3) adjusting the voltage division values of the second resistor, the third resistor and the fourth resistor according to a calculation formula of the voltage value of the first analog signal acquisition end, so that the conventional sampling range of the voltage of the power supply is positioned in the sampling range of the first analog signal acquisition end.
3. The method for realizing motor drive and self-protection control for a vehicle according to claim 2, wherein the steps further comprise the following processes:
(1-4) controlling the relay to be closed, judging whether the voltage value of the first analog signal acquisition end is larger than 4.5V or not, and if so, judging that the circuit state is normal; otherwise, the circuit state is abnormal, fault recording is carried out, the initial state is recovered, and the step (1-1) is retried after timing for a certain time.
4. The method for realizing vehicle motor drive and self-protection control according to claim 2, wherein the step (1-3) of calculating the voltage value of the first analog signal acquisition terminal when the motor interface is abnormal specifically comprises:
calculating the voltage value of the first analog signal acquisition end when the motor interface is abnormal according to the following formula:
wherein,
is the voltage value of the first analog signal acquisition end,
in order to supply the voltage of the power supply,
is the resistance value of the second resistor and is,
is the resistance value of the third resistor and is,
is the resistance of the fourth resistor.
5. The method according to claim 2, wherein the step (1-2) of calculating the voltage value of the first analog signal collecting terminal when the motor interface is abnormal specifically comprises:
calculating the voltage value of the first analog signal acquisition end when the motor interface is abnormal according to the following formula:
wherein,
is the voltage value of the first analog signal acquisition end,
is the voltage of the interface of the motor,
is the resistance value of the second resistor and is,
is a resistance value of the third resistor, and,
is the resistance of the fourth resistor.
6. The method of claim 1, wherein the step of preventing the relay contact from being stuck by controlling the timing of the NMOS transistor comprises the following steps:
after the relay contacts are closed, delaying at least 1 relay contact switching period, and opening an NMOS (N-channel metal oxide semiconductor) tube to conduct the current of the motor loop;
when the motor loop current is closed, the NMOS tube is closed, the motor loop current is cut off, at least 1 relay contact switching period is delayed, and the relay is controlled to be switched off.
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| CN106896755B (en) * | 2015-12-18 | 2020-01-14 | 联创汽车电子有限公司 | Load driving circuit for single-low end control of vehicle |
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| CN108695833A (en) * | 2018-06-30 | 2018-10-23 | 昌辉汽车电气系统（安徽）有限公司 | Vehicle-mounted relay protection control circuit in 24V bodywork systems and method |
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