CN108879593A - A kind of list comparator overcurrent protection driving circuit and generator voltage controller - Google Patents
A kind of list comparator overcurrent protection driving circuit and generator voltage controller Download PDFInfo
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- CN108879593A CN108879593A CN201810881341.2A CN201810881341A CN108879593A CN 108879593 A CN108879593 A CN 108879593A CN 201810881341 A CN201810881341 A CN 201810881341A CN 108879593 A CN108879593 A CN 108879593A
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Classifications
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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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- 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
- H02H3/02—Details
- H02H3/06—Details with automatic reconnection
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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
- H02H7/06—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 generators; for synchronous capacitors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
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Abstract
A kind of list comparator overcurrent protection driving circuit,Including the first comparing unit (101),Power cell (102),Energy-storage units (103),Timing circuit (104),Clamp circuit (105),The non-inverting input terminal of first comparing unit receives reference voltage Vref,First comparing unit (A1) output end connects energy-storage units input terminal,The power cathode end of energy-storage units is grounded,Energy-storage units output end connects timing circuit input terminal,The power cathode end of timing circuit is grounded,The power cathode end of timing circuit is grounded,Timing circuit output end connects the inverting input terminal of clamper circuit output end and the first comparing unit simultaneously,The input terminal of the output end connection power cell of first comparing unit,The power cathode end of power cell is grounded,The input terminal of the output end connection clamp circuit of power cell is used to be the first comparing unit feedback power device saturation voltage drop signal,The output end of power cell is also used to control the power cathode of external loading.
Description
Technical Field
The invention belongs to the technical field of electromechanical control, and particularly relates to a single comparator overcurrent protection driving circuit and a generator voltage regulator.
Background
Electromechanical devices require power control circuits, such as operation of various electrical machine devices, generator field winding control, and the like. When the control circuit operates, the power device is often overloaded and over-current, so that the power tube is overheated, even breaks down, leaks electricity, burns out and the like, and even serious short-circuit accidents occur. For generator excitation, the power tube is overloaded due to the open circuit and overcurrent of the exciting winding, and a driving circuit with overcurrent protection function is required to be designed to prevent the power tube from being damaged.
However, the existing overcurrent protection circuit has disadvantages, which are mainly expressed as:
1. the overcurrent protection driving circuit of the main circuit current sampling method comprises the following steps: the method is commonly used for sampling the current by connecting the low-resistance high-power resistor in series at the high current position of the trunk circuit, but the high-power sampling resistor connected in series in the method consumes electric power, generates a large amount of heat, occupies a large circuit board area, and increases the material cost and the process cost.
2. The overcurrent protection driving circuit directly samples the saturation voltage drop of the power tube: compared with the first circuit, the circuit omits a high-power sampling resistor, but the circuit needs to process the sampled saturation voltage drop signal, and a more complex processing circuit is adopted, including a comparator, an operational amplifier, an analog-to-digital conversion circuit, a cpu and the like, so that a signal flow link of the protection circuit is too complex, serial logic may exist between hardware protection and processing software, the protection is affected or disabled in case of one problem, and the circuit is complex, occupies a larger area of a circuit board, increases the fault probability and increases the cost.
3. The overcurrent protection driving circuit of the special chip comprises: such circuits are costly and expensive.
Therefore, it is necessary to design an overcurrent protection driving circuit with a simple circuit, safety and reliability.
Disclosure of Invention
The invention aims to design a power driving circuit which has an overcurrent protection function and directly samples the saturation voltage drop of a power tube to perform overcurrent protection by adopting a simple single comparator circuit, is used for driving load devices such as a motor and the like, and is particularly used for an overcurrent protection type generator voltage regulator which directly samples the saturation voltage drop of the power tube and has a simpler structure circuit.
According to a first aspect of the present invention, there is provided a single comparator over-current protection driving circuit, which is characterized in that it comprises a first comparing unit, a power unit, an energy storage unit, a delay circuit, and a clamping circuit,
the first comparing unit has a non-inverting input terminal, an inverting input terminal and an output terminal,
the power unit is provided with an input end, an output end and a power supply negative end,
the energy storage unit is provided with an input end, an output end and a power supply negative end,
the delay loop is provided with an input end, an output end and a power supply negative end,
the clamping circuit has an input terminal and an output terminal,
wherein,
the non-inverting input end of the first comparing unit is used for being connected with a peripheral reference voltage circuit and receiving a reference voltage, the output end of the first comparing unit is connected with the input end of the energy storage unit, the negative power end of the energy storage unit is grounded, the output end of the energy storage unit is connected with the input end of the delay loop, the negative power end of the delay loop is grounded, the output end of the delay loop is simultaneously connected with the output end of the clamping circuit and the inverting input end of the first comparing unit,
the output end of the first comparing unit is connected with the input end of the power unit, the power supply cathode end of the power unit is grounded, the output end of the power unit is connected with the input end of the clamping circuit and is used for feeding back a power device saturation voltage drop signal for the first comparing unit, the output end of the power unit is also used for controlling the power supply cathode of an external load,
when the power unit is normally conducted, the saturation voltage drop of the power device of the power unit pulls down the potential of the reverse phase input end of the first comparison unit through a clamping loop, so that the potential of the reverse phase input end is lower than the reference voltage potential received by the in-phase input end, the first comparison unit outputs high potential to enable the power device to be in a stable conduction state, when the power device is subjected to overcurrent, the saturation voltage drop exceeds a set value, the potential of the reverse phase input end of the first comparison unit is higher than the reference voltage potential of the in-phase input end through the clamping loop, the first comparison unit is turned over to output low potential to enable the power device to be immediately cut off to be protected, the energy storage unit maintains the protection state of the cut-off of the power device through a time delay circuit, the energy storage and discharge process of the energy storage unit is carried out, and when the potential of the reverse, and the comparison unit is turned to output high potential again, so that the power unit is conducted again, the reverse phase input end potential of the comparison unit is lower than the same phase input end potential through the clamping circuit, the normal conduction is recovered if the overcurrent is removed, and the protection state is entered again if the overcurrent continues.
According to a second aspect of the present invention there is provided a generator voltage regulator characterised by comprising a single comparator over-current protection driver circuit as described in the first aspect.
Preferably, the generator voltage regulator is characterized by comprising a sampling unit, a first threshold unit, a second threshold unit and a single comparator overcurrent protection driving circuit, wherein the sampling unit is connected with a positive electrode and a negative electrode of a power supply of the voltage regulator, an output end of the sampling unit is connected with an inverted input end of the first comparison unit through the second threshold unit, the first threshold unit is connected with the positive electrode and the negative electrode of the power supply, an output end of the first threshold unit is connected with a non-inverted input end of the first comparison unit, and the first threshold unit is used for generating the reference voltage.
Further, the generator voltage regulator is characterized in that the second threshold unit is a voltage stabilizing diode.
Preferably, the generator voltage regulator is characterized by comprising a sampling unit, a first threshold unit, a second threshold unit and a single comparator overcurrent protection driving circuit, wherein the sampling unit is connected with the positive electrode and the negative electrode of a voltage regulator power supply, the output end of the sampling unit is connected with the input end of the second threshold unit, the grounding end of the second threshold unit is grounded, the output end of the second threshold unit is connected with the non-inverting input end of the first comparison unit or the output end of the first comparison unit, the first threshold unit is connected with the positive electrode and the negative electrode of the power supply, the output end of the first threshold unit is connected with the non-inverting input end of the first comparison unit, the first threshold unit is used for generating the reference voltage, and the second threshold unit is a controlled three-terminal voltage stabilization integrated circuit.
Preferably, the generator voltage regulator is characterized by comprising a sampling unit, a first threshold unit, a second comparison unit and a single comparator overcurrent protection driving circuit, wherein the first threshold unit is connected with a positive electrode and a negative electrode of a power supply, an output end of the first threshold unit is connected with a non-inverting input end of the first comparison unit, the sampling unit is connected with the positive electrode and the negative electrode of the power supply of the voltage regulator, an output end of the sampling unit is connected with an inverting input end of the second comparison unit, the non-inverting input end of the second comparison unit is connected with an output end of the first threshold unit, the first threshold unit is used for generating the reference voltage, and an output end of the second comparison unit is connected with an output end of the first comparison unit.
Preferably, the voltage regulator for the generator is characterized by comprising a sampling unit, a first threshold unit, a third threshold unit, a second comparison unit and a single comparator overcurrent protection driving circuit, wherein the first threshold unit is connected with a positive electrode and a negative electrode of a power supply, an output end of the first threshold unit is connected with a non-inverting input end of the first comparison unit, the third threshold unit is connected with the positive electrode and the negative electrode of the power supply, an output end of the third threshold unit is connected with a non-inverting input end of the second comparison unit, the sampling unit is connected with the positive electrode and the negative electrode of the power supply, an output end of the sampling unit is connected with an inverting input end of the second comparison unit, the first threshold unit is used for generating the reference voltage Vref, and an output end of the second comparison unit is connected.
The invention has the advantages that the overcurrent protection driving circuit directly sampling the saturation voltage drop of the power tube: compared with the first circuit, the circuit saves a high-power sampling resistor, adopts a single comparator to carry out comparison amplification of overcurrent saturation voltage drop, positive feedback inversion and grid voltage drive disconnection, and is compared with a protection circuit which is processed by an operational amplifier, an analog-digital conversion circuit, a cpu and the like. When the technical scheme is integrated, the overcurrent protection function is realized by a smaller chip area.
Drawings
Fig. 1 is a schematic diagram of a single comparator overcurrent protection driving circuit according to an embodiment of the present invention,
figure 2 is a schematic diagram of a first generator voltage regulator including a single-comparator overcurrent protection driver circuit according to an embodiment of the present invention,
figure 3 is a schematic diagram of a second generator voltage regulator including a single comparator overcurrent protection driver circuit according to an embodiment of the present invention,
figure 4 is a schematic diagram of a third generator voltage regulator including a single comparator overcurrent protection driver circuit according to an embodiment of the present invention,
figure 5 is a schematic diagram of a fourth generator voltage regulator including a single-comparator overcurrent protection driver circuit according to an embodiment of the present invention,
fig. 6 is a schematic structural diagram of a fifth generator voltage regulator including a single-comparator overcurrent protection driving circuit according to an embodiment of the present invention.
Detailed Description
The invention aims to design a power driving circuit which has an overcurrent protection function and directly samples the saturation and voltage drop of a power tube to perform overcurrent protection by adopting a simple single comparator circuit, is used for driving load devices such as a motor and the like, and particularly is used for constructing an overcurrent protection type generator voltage regulator which has a simpler circuit and directly samples the saturation and voltage drop of the power tube so as to adapt to the harsh requirements of the generator voltage regulator on reliability and small volume.
In a first aspect, a single comparator over-current protection driving circuit is provided, as described in embodiment 1.
Example 1
A single comparator overcurrent protection driving circuit is shown in FIG. 1, and comprises a first comparing unit 101, a power unit 102, an energy storage unit 103, a delay circuit 104, a clamping circuit 105,
the first comparing unit has a non-inverting input terminal, an inverting input terminal and an output terminal,
the power unit is provided with an input end, an output end and a power supply negative end,
the energy storage unit is provided with an input end, an output end and a power supply negative end,
the delay loop is provided with an input end, an output end and a power supply negative electrode end,
the clamping circuit has an input terminal and an output terminal,
wherein,
the non-inverting input end of the first comparing unit (comparator A1) is used for being connected with a peripheral reference voltage circuit and receiving a reference voltage Vref, the output end of the first comparing unit (comparator) A1 is connected with the input end of the energy storage unit, the power supply negative end of the energy storage unit is grounded (namely, the power supply negative pole Gnd), the output end of the energy storage unit is connected with the input end of the delay loop, the power supply negative end of the delay loop is grounded, the output end of the delay loop is simultaneously connected with the output end (the positive pole end of the diode D2) of the clamping circuit (diode D2) and the inverting input end of the first comparing unit,
the output end of the first comparison unit is connected with the input end of the power unit, the power supply negative end of the power unit is grounded, the output end of the power unit is connected with the input end of the clamping circuit (the negative end of the diode D2) and used for feeding back a saturation voltage drop signal of the power device for the first comparison unit, and the output end (Vout) of the power unit is also used for controlling the power supply negative end of an external load.
In fig. 1, the energy storage unit 1003 includes a diode D2 and a capacitor C1, an anode of the diode D2 serves as an input end of the energy storage unit, a cathode of the diode D2 is connected to one end of the capacitor C1 as an output end of the energy storage unit, and the other end of the capacitor C1 serves as a power supply cathode end and is grounded. The delay loop 104 comprises resistors R1 and R2 connected in series, the connection node of the resistors R1 and R2 is used as the output end of the delay loop, the other end of the resistor R1 is used as the input end of the delay loop and is connected with the output end of the energy storage unit 103, and the other end of the resistor R2 is used as the negative end of the power supply of the delay loop and is grounded. Of course, the voltage comparator a1 also needs to be connected to the positive power supply (B +) and ground (Gnd).
The working process is as follows:
when a power tube (fig. 1 takes a field effect transistor as an example) of a power unit is normally turned on, the saturation voltage drop pulls down the potential of the reverse-phase input end of the first comparing unit through a clamping loop diode D1, so that the potential of the reverse-phase input end is lower than the reference voltage potential Vref received by the in-phase input end, the first comparing unit outputs a high potential, the gate of the power tube obtains a driving voltage, so that the power device is in a stable on state, when the power tube is subjected to overcurrent, the saturation voltage drop Uds exceeds a set value, and the potential of the reverse-phase input end of the first comparing unit is higher than the reference voltage potential of the in-phase input end through a clamping loop: uds + UD1 is more than Vref, in the formula, UD1 is forward conduction voltage drop of the diode D1, at this time, the first comparison unit is turned over to output low potential, the grid voltage of the power tube is pulled to low potential, and the power device is immediately cut off and protected. At this time, the drain of the power tube has an external load which is pulled up to the positive electrode potential of the power supply, so that the diode D1 is cut off in a reverse bias way, the capacitor C1 stores charges, the capacitor C1 discharges through the resistors R1 and R2 and the circuit in the inverting input end of the comparator A1, theoretically, the internal resistance of the input end of the comparator is infinite, in practice, current is consumed, of course, the discharging path is mainly formed by the resistors R1 and R2, the energy storage unit maintains the protection state that the power device is cut off through the delay circuit, and as the energy storage leakage process of the energy storage unit progresses, when the stored energy is discharged until the potential of the reverse-phase input end of the comparison unit is lower than the reference voltage Vref, the comparison unit is turned to output high potential again, so that the power unit is conducted again, the potential of the reverse-phase input end of the comparison unit is lower than the potential of the same-phase input end through the clamping circuit, if the overcurrent is removed, the normal conduction is recovered, and if the overcurrent continues, the protection state is entered again.
It can be seen that the circuit structure is simple, and when overcurrent protection occurs, because of the following processes: the reverse-phase input end potential ↓ → the comparator output end potential ↓ → the power tube gate potential ↓ → the power tube drain potential ↓ → the comparator a1 reverse-phase input end potential × (ii) through D1, which is a strong positive feedback process, the market circuit is turned over sharply to the state that the power tube is cut off, the action is rapid, and the protection is stable and reliable.
In a second aspect, there is provided a generator voltage regulator comprising the single comparator overcurrent protection drive circuit of the first aspect.
Example 2
A generator voltage regulator is disclosed, as shown in fig. 2, and comprises a sampling unit 107, a first threshold unit 106, a second threshold unit 108 and a single comparator overcurrent protection driving circuit, wherein the sampling unit formed by connecting resistors R7 and R8 in series is connected with the positive and negative electrodes of a power supply of the voltage regulator, the output end of the sampling unit is connected with the inverting input end of the first comparison unit through a voltage stabilizing diode D4 of the second threshold unit, the first threshold unit formed by connecting a resistor R5 and a voltage stabilizing diode D3 in series is connected with the positive and negative electrodes of the power supply, the output end of the first threshold unit is connected with the non-inverting input end of the first comparison unit, and the first threshold unit is used for generating a reference voltage Vref.
In the circuit of this embodiment, a resistor R6 is added to the inverting input terminal of the comparator a1, so that an "overvoltage signal" from the sampling unit and the voltage regulator tube D4 is additionally input to the inverting input terminal of the comparator a1, and the comparator is controlled by the generator output voltage, thereby simplifying the structure of the voltage regulator.
When the output voltage of the generator is lower than a set value, the diode D4 is cut off, the single comparator overcurrent protection driving circuit can enter a normally-on excitation state as in the embodiment 1, and overcurrent protection can be implemented when overcurrent occurs.
When the output voltage of the generator is higher than a set value, the sampling unit outputs an 'overvoltage signal' through the voltage stabilizing tube D4, so that the inverting input end of the comparator A1 obtains a voltage signal higher than the reference voltage Vref of the inverting input end, the comparator turns over, the power tube is cut off, the generator quits excitation, and then the discharging process of the capacitor C1 in the 'overcurrent protection' process is continued, in the discharging process, the power tube is cut off until the discharging is finished, and when the output voltage of the generator falls back to be lower than the set value, the comparator A1 starts to turn over to output a high-level state, and the power tube restores excitation again, so that the excitation frequency of the voltage regulator is influenced by the time constants of the capacitor C1 and a delay loop, the excitation frequency of the generator can be restricted, and the phenomenon that the excitation frequency is too high or too low as the traditional voltage regulator can not occur, this is also an excellent excitation technical effect brought by the present invention.
Example 3
A generator voltage regulator is shown in fig. 3 and comprises a sampling unit 107, a first threshold unit 106, a second threshold unit N1 and a single comparator overcurrent protection driving circuit, wherein the sampling unit is connected with the anode and cathode of a voltage regulator power supply, the output end of the sampling unit is connected with the input end of a second threshold unit N1, the second threshold unit is a controlled three-end voltage stabilization integrated circuit containing reference voltage inside, such as AZ431 and the like, the ground end of the second threshold unit is grounded, the output end of the second threshold unit is connected with the non-inverting input end of the first threshold unit, the first threshold unit is connected with the anode and cathode of the power supply, the output end of the first threshold unit is connected with the non-inverting input end of the first threshold unit, and the first threshold unit is used for generating the reference voltage Vre.
When the output voltage of the generator is lower than a set value, the output signal voltage of the sampling unit is lower than the trigger threshold voltage (for example, 2.45V taking AZ431 as an example) of the input end of the second threshold unit, the circuit in the output end of the second threshold unit N1 is in a high-resistance open-circuit state, and has no influence on a single-comparator overcurrent protection driving circuit which is formed by taking a comparator a1 as a core, and the single-comparator overcurrent protection driving circuit can drive an excitation winding to obtain normal excitation current. When the power tube is normally conducted, the potential UA1 at the inverting input terminal of the comparator a1 is inverted to Uds + UD1, where Uds is the saturation voltage drop (generally below 0.8V) of the power tube, UD1 is the forward conduction voltage drop (generally below 0.6V) of the diode D1, and the potential UA1 at the inverting input terminal of the comparator a1 is inverted to generally below 1.5V (not limited to the voltage at this point, but only exemplified here).
When the output voltage of the generator exceeds a set value, the sampling unit signal triggers the second threshold unit N1 to be turned on, and the anode voltage UN1 of the N1 after being turned on is generally below 0.8V (the turn-on current of the N1 comes from the resistor R5, and the current is generally in milliampere, so the turn-on voltage drop is very low), that is: UN1 < UA1 is reversed, so that the comparator A1 is turned over to output at a low level, the grid electrode potential of a power tube is pulled down, excitation is cut off, and the comparator A1 is turned over again to output at a high level to restore excitation until the output voltage of the generator is lower than a set value and the discharging of the capacitor C1 is finished.
Example 4
As shown in fig. 4, a generator voltage regulator includes a sampling unit 107, a first threshold unit 106, a second threshold unit N1, and the single comparator overcurrent protection driving circuit, where the sampling unit is connected to positive and negative electrodes of a voltage regulator, an output end of the sampling unit is connected to an input end of a second threshold unit N1, the second threshold unit is a controlled three-terminal voltage-stabilized integrated circuit containing a reference voltage therein, such as AZ431, a ground end of the second threshold unit is grounded, an output end of the second threshold unit is connected to an output end of the first threshold unit, the first threshold unit is connected to the positive and negative electrodes of the power supply, an output end of the first threshold unit is connected to a non-inverting input end of the first threshold unit, and the first threshold unit is configured to generate a reference voltage Vref.
When the output voltage of the generator is lower than a set value, the output signal voltage of the sampling unit is lower than the trigger threshold voltage (for example, 2.45V taking AZ431 as an example) of the input end of the second threshold unit, the circuit in the output end of the second threshold unit N1 is in a high-resistance open-circuit state, and has no influence on a single-comparator overcurrent protection driving circuit which is formed by taking a comparator a1 as a core, and the single-comparator overcurrent protection driving circuit can drive an excitation winding to obtain normal excitation current.
When the output voltage of the generator exceeds the set value, the sampling unit signal triggers the second threshold unit N1 to be switched on, the grid electrode potential of the power tube is pulled down, excitation is cut off, and the comparator A1 is turned over again to high level to output and recover excitation until the output voltage of the generator is lower than the set value and the capacitor C1 finishes discharging.
Example 5
A generator voltage regulator is shown in fig. 5 and comprises a sampling unit 107, a first threshold unit 106, a second comparison unit A2 and a single comparator overcurrent protection driving circuit, wherein the first threshold unit is connected with a positive electrode and a negative electrode of a power supply, an output end of the first threshold unit is connected with a non-inverting input end of a first comparison unit A1, the sampling unit is connected with the positive electrode and the negative electrode of the voltage regulator, an output end of the sampling unit is connected with an inverting input end of a second comparison unit A2, the non-inverting input end of the second comparison unit is connected with an output end of the first threshold unit, the first threshold unit is used for generating a reference voltage Vref, and the output end of the second comparison unit is connected with an output end.
When the output voltage of the generator is lower than a set value, the output signal voltage of the sampling unit is lower than the output signal voltage Vref of the first threshold unit, the comparator A2 outputs high potential (the circuit in the output end is in a high-resistance open circuit state), no influence is caused to a single-comparator overcurrent protection driving circuit formed by taking the comparator A1 as a core, and the single-comparator overcurrent protection driving circuit can drive the excitation winding to obtain normal excitation current.
When the output voltage of the generator exceeds the set value, the sampling unit signal triggers the second comparison unit A2 to turn over, the grid potential of the power tube 102 is directly pulled down, excitation is cut off, and the comparator A1 turns over again to high level to output and recover excitation until the output voltage of the generator is lower than the set value and the discharging of the capacitor C1 is finished.
Example 6
A voltage regulator of a generator is shown in fig. 6 and comprises a sampling unit 107, a first threshold unit 106, a third threshold unit 110, a second comparison unit A2 and a single comparator overcurrent protection driving circuit, wherein the first threshold unit is connected with a positive electrode and a negative electrode of a power supply, an output end of the first threshold unit is connected with a non-inverting input end of a first comparison unit A1, the third threshold unit is connected with the positive electrode and the negative electrode of the power supply, an output end of the third threshold unit is connected with a non-inverting input end of a second comparison unit A2, the sampling unit is connected with the positive electrode and the negative electrode of the power supply, an output end of the sampling unit is connected with an inverting input end of the second comparison unit, the first threshold unit is used for generating a reference voltage Vref.
When the output voltage of the generator is lower than a set value, the output signal voltage of the sampling unit is lower than the output signal voltage of the third threshold unit, the circuit in the output end of the comparator A2 of the second comparison unit is in a high-resistance open-circuit state, no influence is caused on a single-comparator overcurrent protection driving circuit formed by taking the comparator A1 as a core, and the single-comparator overcurrent protection driving circuit can drive the excitation winding to obtain normal excitation current.
When the power tube is normally turned on, as described above, the potential UA1 at the inverting input terminal of the comparator a1 is usd + UD1, and this value is generally 1.5V or less (this is not a limitation on the voltage at this point, and this is merely an example).
When the output voltage of the generator exceeds a set value, the output signal of the sampling unit triggers the second comparison unit A2 to turn over, the voltage of the non-inverting input end of the comparator A1 is pulled down (generally lower than 0.2V), so that the comparator A1 turns over to be output at a low level, the grid potential of the power tube is pulled down, excitation is cut off, and the comparator A1 turns over to be output at a high level again to recover excitation until the output voltage of the generator is lower than the set value and the discharge of the capacitor C1 is finished.
through the description of the embodiments, the driving circuit with the overcurrent protection function can be formed by a single comparator, the driving circuit is mainly used for driving electromechanical products such as motor coil loads, resistive loads and the like, the cold end (namely the negative electrode) of the load is controlled, the driving circuit can be in direct current driving or pulse driving, and when the driving circuit is in pulse driving, the pulse period is smaller than the effective discharge time of a capacitor C1 of the overcurrent protection circuit of the single comparator.
The invention has the advantages that the overcurrent protection driving circuit directly sampling the saturation voltage drop of the power tube: compared with the first circuit, the circuit saves a high-power sampling resistor, adopts a single comparator to carry out comparison amplification of overcurrent saturation voltage drop, positive feedback inversion and grid voltage drive disconnection, and is compared with a protection circuit which is processed by an operational amplifier, an analog-digital conversion circuit, a cpu and the like. When the technical scheme is integrated, the overcurrent protection function is realized by a smaller chip area.
Claims (7)
1. A single comparator over-current protection driving circuit is characterized by comprising a first comparison unit, a power unit, an energy storage unit, a delay loop and a clamping circuit,
the first comparing unit has a non-inverting input terminal, an inverting input terminal and an output terminal,
the power unit is provided with an input end, an output end and a power supply negative end,
the energy storage unit is provided with an input end, an output end and a power supply negative end,
the delay loop is provided with an input end, an output end and a power supply negative end,
the clamping circuit has an input terminal and an output terminal,
wherein,
the non-inverting input end of the first comparing unit is used for being connected with a peripheral reference voltage circuit and receiving a reference voltage, the output end of the first comparing unit is connected with the input end of the energy storage unit, the negative power end of the energy storage unit is grounded, the output end of the energy storage unit is connected with the input end of the delay loop, the negative power end of the delay loop is grounded, the output end of the delay loop is simultaneously connected with the output end of the clamping circuit and the inverting input end of the first comparing unit,
the output end of the first comparing unit is connected with the input end of the power unit, the power supply cathode end of the power unit is grounded, the output end of the power unit is connected with the input end of the clamping circuit and is used for feeding back a power device saturation voltage drop signal for the first comparing unit, the output end of the power unit is also used for controlling the power supply cathode of an external load,
when the power unit is normally conducted, the saturation voltage drop of the power device of the power unit pulls down the potential of the reverse phase input end of the first comparison unit through a clamping loop, so that the potential of the reverse phase input end is lower than the reference voltage potential received by the in-phase input end, the first comparison unit outputs high potential to enable the power device to be in a stable conduction state, when the power device is subjected to overcurrent, the saturation voltage drop exceeds a set value, the potential of the reverse phase input end of the first comparison unit is higher than the reference voltage potential of the in-phase input end through the clamping loop, the first comparison unit is turned over to output low potential to enable the power device to be immediately cut off to be protected, the energy storage unit maintains the protection state of the cut-off of the power device through a time delay circuit, the energy storage and discharge process of the energy storage unit is carried out, and when the potential of the reverse, and the comparison unit is turned to output high potential again, so that the power unit is conducted again, the reverse phase input end potential of the comparison unit is lower than the same phase input end potential through the clamping circuit, the normal conduction is recovered if the overcurrent is removed, and the protection state is entered again if the overcurrent continues.
2. A generator voltage regulator comprising the single comparator overcurrent protection driver circuit of claim 1.
3. The generator voltage regulator according to claim 2, comprising a sampling unit, a first threshold unit, a second threshold unit and the single comparator overcurrent protection driving circuit according to claim 1, wherein the sampling unit is connected to positive and negative electrodes of a voltage regulator power supply, an output end of the sampling unit is connected to an inverting input end of the first comparison unit through the second threshold unit, the first threshold unit is connected to the positive and negative electrodes of the power supply, an output end of the first threshold unit is connected to a non-inverting input end of the first comparison unit, and the first threshold unit is configured to generate the reference voltage.
4. A generator voltage regulator according to claim 3 wherein said second threshold unit is a zener diode.
5. The generator voltage regulator according to claim 2, comprising a sampling unit, a first threshold unit, a second threshold unit, and the single comparator overcurrent protection driving circuit according to claim 1, wherein the sampling unit is connected to positive and negative electrodes of a voltage regulator power supply, an output terminal of the sampling unit is connected to an input terminal of the second threshold unit, a ground terminal of the second threshold unit is grounded, an output terminal of the second threshold unit is connected to a non-inverting input terminal of the first comparison unit or to an output terminal of the first comparison unit, the first threshold unit is connected to the positive and negative electrodes of the power supply, an output terminal of the first threshold unit is connected to the non-inverting input terminal of the first comparison unit, the first threshold unit is configured to generate the reference voltage, and the second threshold unit is a controlled three-terminal voltage stabilization integrated circuit.
6. The generator voltage regulator according to claim 2, comprising a sampling unit, a first threshold unit, a second comparison unit and the single comparator overcurrent protection driving circuit according to claim 1, wherein the first threshold unit is connected to a positive electrode and a negative electrode of a power supply, an output end of the first threshold unit is connected to a non-inverting input end of the first comparison unit, the sampling unit is connected to a positive electrode and a negative electrode of the voltage regulator, an output end of the sampling unit is connected to an inverting input end of the second comparison unit, a non-inverting input end of the second comparison unit is connected to an output end of the first threshold unit, the first threshold unit is configured to generate the reference voltage, and an output end of the second comparison unit is connected to an output end of the first comparison unit.
7. The generator voltage regulator according to claim 2, comprising a sampling unit, a first threshold unit, a third threshold unit, a second comparison unit and the single comparator overcurrent protection driving circuit, wherein the first threshold unit is connected to the positive and negative terminals of a power supply, the output terminal of the first threshold unit is connected to the non-inverting input terminal of the first comparison unit, the third threshold unit is connected to the positive and negative terminals of the power supply, the output terminal of the third threshold unit is connected to the non-inverting input terminal of the second comparison unit, the sampling unit is connected to the positive and negative terminals of the power supply, the output terminal of the sampling unit is connected to the inverting input terminal of the second comparison unit, the first threshold unit is configured to generate the reference voltage Vref, and the output terminal of the second comparison unit is connected to the non-inverting input terminal of.
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| CN201810881341.2A CN108879593A (en) | 2018-08-05 | 2018-08-05 | A kind of list comparator overcurrent protection driving circuit and generator voltage controller |
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| CN201810881341.2A CN108879593A (en) | 2018-08-05 | 2018-08-05 | A kind of list comparator overcurrent protection driving circuit and generator voltage controller |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109782668A (en) * | 2019-01-27 | 2019-05-21 | 惠州三华工业有限公司 | To the control circuit and short circuit protection system of needle type print head conduction time |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109782668A (en) * | 2019-01-27 | 2019-05-21 | 惠州三华工业有限公司 | To the control circuit and short circuit protection system of needle type print head conduction time |
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Application publication date: 20181123 |