CN110932238B - Overcurrent and short-circuit protection circuit for electromagnetic brake - Google Patents
Overcurrent and short-circuit protection circuit for electromagnetic brake Download PDFInfo
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- CN110932238B CN110932238B CN201911263638.3A CN201911263638A CN110932238B CN 110932238 B CN110932238 B CN 110932238B CN 201911263638 A CN201911263638 A CN 201911263638A CN 110932238 B CN110932238 B CN 110932238B
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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
Abstract
The invention discloses an overcurrent and short-circuit protection circuit for an electromagnetic brake, which comprises an overcurrent detection module and a trap protection module, wherein the overcurrent detection module is used for detecting whether the driving current of the electromagnetic brake exceeds the maximum current upper limit and whether the duration time of exceeding the maximum current upper limit exceeds a preset time threshold, and the trap protection module is used for generating a trapping signal when a short circuit is detected or after being triggered by the overcurrent detection module so as to cut off the power of an external execution circuit to protect other peripheral circuits. The invention adopts the integrating circuit to realize the threshold judgment and the overcurrent duration judgment of the overcurrent protection, can quickly respond and process overcurrent faults and can also realize the automatic recovery of the overcurrent protection capability, thereby reducing the maintenance and repair cost of the industrial quick door controller.
Description
Technical Field
The invention belongs to the technical field of electromechanical control, and particularly relates to an overcurrent and short-circuit protection circuit for an electromagnetic brake.
Background
An Electromagnetic Brake (Electromagnetic Brake) is a mechanical part for stopping or decelerating moving parts in a machine, commonly called a Brake or a barrier, and mainly comprises a Brake frame, a Brake part, an operating device and the like.
The electromagnetic brake is a very important part in machines such as industrial quick doors, elevators, ships, metallurgy and hoisting machinery. However, in the existing mechanical equipment, the real-time detection of the braking force and the braking process is rarely performed, and the maintenance and the adjustment are performed manually and regularly, so that accidental faults such as short circuit, overcurrent and the like in the use process of the brake cannot be discovered and prevented in time. Once the electromagnetic brake has short circuit or overcurrent fault, the electromagnetic brake or a matching circuit is extremely easy to be permanently damaged.
In equipment such as industry sliding lift door, industry quick door, banister, electromagnetic braking device's overcurrent protection generally adopts the fuse, and chinese utility model patent that publication number is CN201425074Y discloses an electromagnetic brake control circuit, and it is equipped with the protective tube between "transformer (1) and rectifier circuit (2)" to "can play good short circuit protection function". However, the utility model has two significant problems: 1. after the fuse in the fuse tube is fused and protected under the short-circuit condition, the fuse tube can not be recovered after being electrified again, and the whole circuit can be recovered after a new fuse tube is required to be replaced. 2. The protective tube can only protect short-circuit faults, and the protective tube and the whole technical scheme in the utility model can not accurately detect and protect overcurrent faults.
A PTC (Positive Temperature Coefficient) recoverable fuse is an overcurrent electronic protection element. The traditional fuse overcurrent protection can only protect once and is blown to be replaced, and the self-recovery fuse has the dual functions of overcurrent and overheat protection and automatic recovery. However, in soa (safe of area) of the PTC recoverable fuse, the overcurrent response time often exceeds 100 milliseconds or even more than 10 seconds, and easily causes damage to current sensitive components in the circuit, so that the PTC recoverable fuse cannot be used for short-circuit protection.
The PTC-based recoverable fuse is slow in heat dissipation but fast in heating, and in the field of industrial fast door control, when an electromagnetic brake is started and stopped frequently, the PTC recoverable fuse easily causes an overload fault, and the continuous working capacity of equipment is reduced. However, with a PTC recoverable fuse having a higher current rating, the overload detection capability of the PTC recoverable fuse on the execution circuit will be reduced or lost. In addition, overcurrent, overheat, and fusing of fuses and PTC resettable fuses is temperature dependent. The industrial sliding doors, the industrial quick doors and the gates are often installed in outdoor environments, outdoor temperature changes are large, fuses cannot be blown out at low temperature in an overcurrent mode, and fuses can be blown out only by normal working current in high-temperature environments. The above-mentioned problems reduce the environmental adaptability of the device and also cause poor reliability of some devices.
Disclosure of Invention
In view of the above drawbacks and needs of the prior art, the present invention provides an over-current and short-circuit protection circuit for an electromagnetic brake, which is used for implementing over-current and short-circuit protection of the electromagnetic brake.
In order to achieve the above object, the present invention provides an overcurrent and short-circuit protection circuit for an electromagnetic brake, including an overcurrent detection module and a trap protection module, wherein the overcurrent detection module is configured to detect whether a driving current of the electromagnetic brake exceeds a maximum current upper limit and whether a duration time of exceeding the maximum current upper limit exceeds a preset time threshold, and the trap protection module is configured to generate a trap signal when a short circuit is detected or after being triggered by the overcurrent detection module, so as to power off an external execution circuit to protect other peripheral circuits; wherein:
the overcurrent detection circuit module is formed by sequentially connecting an overcurrent voltage comparison unit, an overcurrent integration unit and an overcurrent time threshold value determination unit, wherein the overcurrent voltage comparison unit is used for determining whether the driving current of the electromagnetic brake exceeds the maximum current upper limit or not by detecting the voltage change;
the trap protection module is composed of a trap protection unit, a power-on protection unit and a trap signal output port, the trap protection unit is used for generating a trapping signal after being triggered by the overcurrent detection module, the power-on protection unit is used for preventing the trigger of the overcurrent detection module from being activated when the electromagnetic brake is powered on, and the trap signal output port is used for outputting the trapping signal to an external execution circuit.
In an embodiment of the present invention, the over-current voltage comparing unit is composed of a first over-current detecting arm, a voltage dividing circuit and a first voltage comparator, wherein the first over-current detecting arm is connected to a negative input port of the first voltage comparator through a first resistor, and is configured to input a voltage of the over-current detecting point to the first voltage comparator, the voltage dividing circuit is configured to generate a reference comparison voltage, an input end of the voltage dividing circuit is connected to a high level, an output end of the voltage dividing circuit is connected to a positive input port of the first voltage comparator, and an output port of the first voltage comparator is connected to an input end of the over-current integrating circuit.
In an embodiment of the present invention, the over-current integration unit is composed of a second resistor, an integration capacitor, and a third resistor, one end of the second resistor is connected to an output port of the first voltage comparator, the other end of the second resistor is grounded through the integration capacitor, the other end of the second resistor is also connected to a high level through the third resistor, and a charging time of the integration capacitor is determined by a resistance ratio of the second resistor to the third resistor, where the charging time is a time period from an over-current start to a trigger trap.
In one embodiment of the invention, the third resistor to the integrating capacitor form a forward integrating path for charging the integrating capacitor, the integrating capacitor to the second resistor form a reverse integrating path for discharging the integrating capacitor, and the speed of the reverse integration for releasing the energy of the integrating capacitor after the electromagnetic brake is stopped is far faster than the speed of the forward integration charging.
In an embodiment of the invention, the third resistor is connected in parallel with a first diode, a cathode of the first diode is connected with a high level, an anode of the first diode is connected with an integrating capacitor, the first diode is used for power-down protection, the integrating capacitor is released to discharge in time when power is turned off, and the capacitor can be charged again through the integrating circuit after the next power-up is prepared to realize overcurrent detection.
In an embodiment of the present invention, the overcurrent time threshold determination unit is a second voltage comparator, a negative input port of the second voltage comparator is connected to an integrating capacitor in the overcurrent integrating unit, and a positive input port of the second voltage comparator is connected to a preset voltage point in the voltage dividing circuit.
In an embodiment of the present invention, the power-on protection unit includes a fourth resistor, a second diode, and a second capacitor, where one end of the fourth resistor is connected to a high level, the other end of the fourth resistor is connected to an anode of the second diode, the other end of the fourth resistor is further connected to an output end of the overcurrent time threshold determination unit, and the other end of the fourth resistor is further grounded through the second capacitor.
In an embodiment of the invention, the trap protection unit includes a first triode and a second triode, wherein a base of the first triode is connected to the short-circuit detection point through a fifth resistor, the short-circuit detection point is connected to a negative electrode of the second diode, a collector of the first triode is connected to a base of the second triode through a sixth resistor, a base of the first triode is connected to a collector of the second triode through a seventh resistor, an emitter of the first triode is connected to the trap signal output port through a third capacitor, an emitter of the second triode is connected to the trap signal output port, and the emitter of the first triode is further grounded.
In an embodiment of the invention, a switch control module is connected in series to the emitter of the second triode, a control end of the switch control module is connected with the MCU and used for receiving a control signal of the MCU, the switch control module is turned on when the control signal of the MCU is not received, and is turned off shortly after receiving the control signal of the MCU, and the switch control module is used for enabling the trap protection module to be triggered by the MCU after entering the protection state and recover from the protection state to the non-protection state.
In an embodiment of the present invention, the negative input port of the first voltage comparator is further grounded through a filter capacitor, so as to eliminate noise interference generated by other circuits or electricity in the electromagnetic controller.
Generally, compared with the prior art, the technical scheme of the invention has the following beneficial effects:
(1) the invention adopts the integrating circuit to realize the threshold judgment and the overcurrent duration judgment of the overcurrent protection, can quickly respond and process overcurrent faults and can also realize the automatic recovery of the overcurrent protection capability, thereby reducing the maintenance and repair cost of the industrial quick door controller.
(2) The invention adds an overcurrent detection arm in the trap protection circuit, and can immediately and directly make power-off response to more serious overcurrent faults such as short circuit and the like. The defect that the integrating circuit still has a small delay when the integrating circuit faces serious overcurrent faults is overcome.
(3) The invention also arranges a power-on protection circuit and a power-off protection circuit, improves the accuracy and reliability of overcurrent protection, not only can realize that the trap protection circuit is not touched by mistake during power-on, but also can timely release the electric quantity in the integrating capacitor during power-off and reliably start the detection function of the integrating circuit during power-on.
Drawings
Fig. 1 is a schematic structural diagram of an overcurrent and short-circuit protection circuit for an electromagnetic brake according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
As shown in fig. 1, the present invention provides an overcurrent and short-circuit protection circuit for an electromagnetic brake, including an overcurrent detection module and a trap protection module, where the overcurrent detection module is configured to detect whether a driving current of the electromagnetic brake exceeds a maximum current upper limit and whether a duration time of exceeding the maximum current upper limit exceeds a preset time threshold, and the trap protection module is configured to generate a trap signal when a short circuit is detected or after being triggered by the overcurrent detection module, so as to power off an external execution circuit to protect other peripheral circuits; wherein:
the overcurrent detection circuit module is formed by sequentially connecting an overcurrent voltage comparison unit, an overcurrent integration unit and an overcurrent time threshold value determination unit, wherein the overcurrent voltage comparison unit is used for determining whether the driving current of the electromagnetic brake exceeds the maximum current upper limit or not by detecting the voltage change;
the trap protection module is composed of a trap protection unit, a power-on protection unit and a trap signal output port, wherein the trap protection unit is used for generating a trapping signal when a short circuit is detected or after being triggered by the overcurrent detection module, the power-on protection unit is used for preventing the trigger of the overcurrent detection module from being activated when the electromagnetic brake is powered on, and the trap signal output port is used for outputting the trapping signal to an external execution circuit.
Specifically, as shown in fig. 1, the over-current voltage comparison unit is composed of a first over-current detection arm, a voltage division circuit and a first voltage comparator (U1-a), wherein the first over-current detection arm is connected to a negative input port of the first voltage comparator (U1-a) through a first resistor R9(10K) for inputting the voltage of the over-current detection point to the first voltage comparator (U1-a), the voltage division circuit is used for generating a reference comparison voltage, an input end of the voltage division circuit is connected to a high level (+5V), an output end of the voltage division circuit is connected to a positive input port of the first voltage comparator (U1-a), and an output port of the first voltage comparator (U1-a) is connected to an input end of the over-current integration.
IN the embodiment of the present invention, the first overcurrent detecting arm is connected to an overcurrent detecting point (IN _ ISENS), and the resistance value of the first resistor R9 is 10K. The negative input port of the first voltage comparator (U1-A) is also grounded through a filter capacitor C6(0.1 muF) for eliminating noise interference generated by other circuits or electricity in the electromagnetic controller.
In the embodiment of the invention, the high level connected with the input end of the voltage division circuit is +5V, the voltage division circuit is used for generating a thirty-one reference comparison voltage of +5V, and the first voltage comparator (U1-A) is used for comparing the voltage of the over-current detection point with the thirty-one reference comparison voltage of +5V and replacing the detection of the current change by the detection of the voltage change.
Specifically, in the embodiment of the present invention, the voltage dividing circuit has a structure that four resistors R8(10K), R10(10K), R11(10K), and R15(1K) are sequentially connected in series, a front end of the resistor R8 is connected to a high level, a rear end of the resistor R15 is grounded, and a front end of the resistor R15 is connected to a positive input port of the first voltage comparator (U1-a); thus, the input voltage of the positive input port of the first voltage comparator (U1-a) is one thirty-one of the high level (divided voltage generated by four resistors R3, R7, R11, R15, R15/(R8+ R10+ R11+ R15)). Furthermore, the rear end of the resistor R8 may be grounded through a capacitor, and the rear end of the resistor R10 may be grounded through a capacitor.
As shown in fig. 1, the overcurrent integrating unit is composed of a second resistor R18(30K), an integrating capacitor C157(10 μ F) and a third resistor R275(2M), one end of the second resistor R18 is connected to the output port of the first voltage comparator (U1-a), the other end of the second resistor R18 is grounded through the integrating capacitor C157, the other end of the second resistor R18 is also connected to a high level through the third resistor R275, the charging time of the integrating capacitor C157 (charging time corresponds to the integration time, which can be adjusted by the magnitude of the resistor resistance value and the capacitor capacitance on the forward integrating circuit, but is generally set at the millisecond level and much shorter than the overcurrent response time of the PTC recoverable fuse) is determined by the ratio of the resistances of the two resistors of the second resistor R18 and the third resistor R275, which is the length of time from the start of overcurrent to the triggering of trapping.
The second resistor R18, the integrating capacitor C157 and the third resistor R275 form an asymmetric integrating circuit, specifically: the third resistor R275 to the integrating capacitor C157 form a forward integrating path for charging the integrating capacitor C157, the integrating capacitor C157 to the second resistor R18 form a reverse integrating path for discharging the integrating capacitor C157, and the rate of reverse integration releasing the energy of the integrating capacitor C157 after the electromagnetic brake is stopped is much faster than the forward integrating charging rate. The asymmetric integration circuit has the following effects: 1: the above configuration allows the integrating capacitor C157 not to be erroneously charged when the electromagnetic brake is frequently turned on and off. Effect 2: the overload protection can be automatically recovered after the overload protection due to the quick reverse integration, and the overload protection can be recovered without power failure.
Further, as shown in fig. 1, the third resistor R275 is further connected in parallel with a first diode D4, a negative electrode of the first diode D4 is connected to a +5V high level, a positive electrode of the first diode D4 is connected to the integrating capacitor C157, the first diode D4 is used for power-down protection, the integrating capacitor C157 is released to discharge in time when power is turned off, and the capacitor can be charged again through the integrating circuit after the next power-up is prepared to realize overcurrent detection.
Further, as shown in fig. 1, the overcurrent time threshold determination unit is a second voltage comparator (U1-B), a negative input port of the second voltage comparator (U1-B) is connected to the integrating capacitor C157 in the overcurrent integrating unit, and a positive input port of the second voltage comparator (U1-B) is connected to a preset voltage point in the voltage dividing circuit. In the embodiment of the invention, the positive input port of the second voltage comparator (U1-B) is connected with the rear end of the resistor R10 in the voltage division circuit.
Further, as shown in the figure, in the trap protection module, the power-on protection unit is composed of a fourth resistor R17(1K), a second diode D1 and a second capacitor C8, wherein one end of the fourth resistor R17 is connected to +5V, the other end of the fourth resistor R17 is connected to the anode of the second diode D1, the other end of the fourth resistor R17 is further connected to the output end of the overcurrent time threshold determination unit, and the other end of the fourth resistor R17 is further connected to the ground through the second capacitor C8. The second capacitor C8 is grounded and is a soft-start capacitor for storing energy during power-on to prevent excessive power-on current.
The main body of the trap protection unit is two triodes, wherein the base of the first triode Q3 is connected with a short-circuit detection point (the same as the overcurrent detection point) through a fifth resistor R5(10K), specifically, connected with the short-circuit detection point through a second overcurrent detection arm. The short-circuit detection point is connected with the cathode of the second diode D1, and is also grounded through a third capacitor C1. The collector of the first triode Q3 is connected with the base of the second triode Q4 through a sixth resistor R13(100), the base of the first triode Q3 is connected with the collector of the second triode Q4 through a seventh resistor R14(100), the emitter of the first triode Q3 is connected with the trap signal output port through a third capacitor C7, the emitter of the second triode Q4 is connected with the trap signal output port, and the emitter of the first triode Q3 is also grounded.
Further, the base of the first transistor Q3 is also grounded through a fourth capacitor C3, and the base of the first transistor Q3 is also grounded through an eighth resistor R6 (150K).
Further, the base of the second transistor Q4 is further connected to the trap signal output port through a fifth capacitor C10, and the base of the second transistor Q4 is further connected to the trap signal output port (OU _ FAULT) through a ninth resistor R20 (15K).
Specifically, a trap signal output port (OU _ FAULT) for outputting the trap signal to an external execution circuit.
In view of safety concerns in industrial fast door control, electromagnetic brakes are embodied as power-off brakes that lock up due to power loss when a trap signal is output.
Further, a switch control module may be connected in series to the emitter of the second transistor Q4, a control end of the switch control module is connected to the MCU for receiving a control signal of the MCU, the switch control module may specifically be an optocoupler or a PMOS (PMOS refers to an n-type substrate, a p-channel, and an MOS transistor that carries current by the flow of a cavity) switch device, the switch control module is turned on when the MCU control signal (positive voltage pulse) is not received, and is turned off shortly after the MCU control signal (positive voltage pulse) is received. The switch control module is used for enabling the trap protection module to be triggered by the MCU to recover from a protection state to a non-protection state after entering the protection state.
In the embodiment of the present invention, the first transistor Q3 is an NPN transistor, and the second transistor Q4 is a PNP transistor.
Furthermore, the working principle of the overcurrent and short-circuit protection circuit for the electromagnetic brake is as follows:
(1) and overcurrent protection: the negative input port of the first voltage comparator (U1-A) is connected with a first overcurrent detection arm (overcurrent detection point) through a resistor, if the overcurrent detection point connected with the first overcurrent detection arm is overcurrent, the voltage value of the negative input port of the first voltage comparator (U1-A) is reduced, the voltage value of the positive input port of the first voltage comparator (U1-A) is one-thirty-one of +5V (reference voltage value, particularly the reference voltage value can be adjusted by adjusting each resistance value in a voltage division circuit under different application scenes), and when the voltage value of the negative input port is lower than that of the positive input port, the first voltage comparator (U1-A) outputs high level;
at this time, the integrating capacitor C157 is charged, the voltage of the negative input port of the second voltage comparator is continuously increased, and when the voltage of the negative input port of the second voltage comparator exceeds the voltage of the positive input port of the second voltage comparator, the output port of the second voltage comparator outputs a low level.
At this time, the first transistor Q3 is not conductive, and the second transistor Q4 is also not conductive, the trap signal output port (OU _ FAULT) outputs a low level.
In a normal working state, when an overcurrent detection point connected with the first overcurrent detection arm is not overcurrent, the output of the second voltage comparator is a high level, the first triode Q3 and the second triode Q4 are both conducted, and the trap signal output port (OU _ FAULT) outputs the high level;
so when the output of the trap signal output port (OU _ FAULT) changes from high level to low level, the overcurrent protection is realized;
(2) and short-circuit protection: the base of the first transistor Q3 is connected to a short detection point (IN _ ISENS, which is the same as the over-current detection point) through a fifth resistor R5.
When a short circuit occurs, since the integrating circuit of the over-current detection circuit module needs to be charged for a period of time to output an over-current signal, the device may be damaged, and therefore the device needs to be immediately turned off when the short circuit condition is detected.
Specifically, when a short circuit detection point (the same as an overcurrent detection point) is short-circuited, the voltage value at the short circuit detection point is 0, that is, the base voltage of the first triode Q3 is zero, at this time, the first triode Q3 is not conducted, and the second triode Q4 is also not conducted, so that the trap signal output port (OU _ FAULT) outputs a low level, thereby implementing overcurrent protection.
It is further noted that: the values of the relevant devices are exemplified in the embodiment of the present invention, but making small adjustments (without changing the operating principles of the circuit and the devices) on the values of the devices in practical application does not result in improvements on the present invention, and under the principles of the present invention, the circuits or the devices may be replaced or adjusted according to the practical application requirements, and the improvements do not exceed the protection scope of the present invention.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (8)
1. An overcurrent and short-circuit protection circuit for an electromagnetic brake is characterized by comprising an overcurrent detection module and a trap protection module, wherein the overcurrent detection module is used for detecting whether the driving current of the electromagnetic brake exceeds the maximum current upper limit and whether the duration time of exceeding the maximum current upper limit exceeds a preset time threshold, and the trap protection module is used for generating a trapping signal when a short circuit is detected or after being triggered by the overcurrent detection module so as to cut off the power of an external execution circuit to protect other peripheral circuits; wherein:
the overcurrent detection circuit module is formed by sequentially connecting an overcurrent voltage comparison unit, an overcurrent integration unit and an overcurrent time threshold value determination unit, wherein the overcurrent voltage comparison unit is used for determining whether the driving current of the electromagnetic brake exceeds the maximum current upper limit or not by detecting the voltage change; the overcurrent voltage comparison unit consists of a first overcurrent detection arm, a voltage division circuit and a first voltage comparator, wherein the first overcurrent detection arm is connected with a negative input port of the first voltage comparator through a first resistor and is used for inputting the voltage of an overcurrent detection point to the first voltage comparator;
the trap protection module consists of a trap protection unit, a power-on protection unit and a trap signal output port, wherein the trap protection unit is used for generating a trapping signal after being triggered by the overcurrent detection module, the power-on protection unit is used for preventing the triggering of the overcurrent detection module from being activated when the electromagnetic brake is powered on, and the trap signal output port is used for outputting the trapping signal to an external execution circuit; the trap protection unit comprises a first triode and a second triode, wherein the base of the first triode is connected with the short-circuit detection point through a fifth resistor, the short-circuit detection point is connected with the negative electrode of the second diode, the collector of the first triode is connected with the base of the second triode through a sixth resistor, the base of the first triode is connected with the collector of the second triode through a seventh resistor, the emitter of the first triode is connected with the trap signal output port through a third capacitor, the emitter of the second triode is connected with the trap signal output port, and the emitter of the first triode is grounded.
2. The overcurrent and short-circuit protection circuit for an electromagnetic brake as set forth in claim 1, wherein said overcurrent integration unit is composed of a second resistor, an integration capacitor and a third resistor, one end of the second resistor is connected to the output port of the first voltage comparator, the other end of the second resistor is grounded via the integration capacitor, the other end of the second resistor is connected to a high level via the third resistor, and the charging time of the integration capacitor is determined by the ratio of the resistances of the second resistor and the third resistor, and the charging time is the length of time from the start of overcurrent to the time of triggering trap.
3. The overcurrent and short-circuit protection circuit for an electromagnetic brake as set forth in claim 2, wherein said third resistor forms a forward integration path to said integrating capacitor for charging said integrating capacitor, said integrating capacitor forms a reverse integration path to said second resistor for discharging said integrating capacitor, and said reverse integration releases energy from said integrating capacitor after said electromagnetic brake is stopped at a rate substantially faster than a rate of said forward integration charging.
4. The overcurrent and short-circuit protection circuit as claimed in claim 3, wherein the third resistor is connected in parallel with a first diode, the cathode of the first diode is connected to a high level, the anode of the first diode is connected to an integrating capacitor, the first diode is used for power-down protection, the integrating capacitor is released when power is turned off so as to discharge in time, and the capacitor can be charged again through the integrating circuit after the next power-up is prepared so as to realize overcurrent detection.
5. The overcurrent and short-circuit protection circuit for an electromagnetic brake as set forth in claim 1, wherein said overcurrent time threshold determination unit is a second voltage comparator, a negative input port of the second voltage comparator is connected to an integrating capacitor in the overcurrent integrating unit, and a positive input port of the second voltage comparator is connected to a preset voltage point in said voltage dividing circuit.
6. The overcurrent and short-circuit protection circuit for an electromagnetic brake as claimed in claim 1, wherein said power-on protection unit is composed of a fourth resistor, a second diode and a second capacitor, wherein one end of the fourth resistor is connected to a high level, the other end of the fourth resistor is connected to the anode of the second diode, the other end of the fourth resistor is further connected to the output end of the overcurrent time threshold determination unit, and the other end of the fourth resistor is further grounded through the second capacitor.
7. The over-current and short-circuit protection circuit for the electromagnetic brake as claimed in claim 1, wherein a switch control module is connected in series to the emitter of the second triode, a control terminal of the switch control module is connected to the MCU for receiving a control signal of the MCU, the switch control module is turned on when the MCU control signal is not received, and turned off when the MCU control signal is received, the switch control module is configured to enable the trap protection module to be triggered by the MCU after entering the protection state and to be restored from the protection state to the non-protection state.
8. The overcurrent and short-circuit protection circuit for an electromagnetic brake as set forth in claim 1, wherein said negative input port of said first voltage comparator is further grounded via a filter capacitor for eliminating noise interference generated by other circuits or electricity in said electromagnetic controller.
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|---|---|---|---|---|
| CN1829031A (en) * | 2005-03-03 | 2006-09-06 | 中兴通讯股份有限公司 | Short-circuit protection circuit with self-recovering function |
| CN102629751A (en) * | 2012-04-26 | 2012-08-08 | 深圳市汉拓数码有限公司 | Over-current protection circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110932238A (en) | 2020-03-27 |
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