CN219351281U - Main terminal wiring protection circuit of driver - Google Patents
Main terminal wiring protection circuit of driver Download PDFInfo
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- CN219351281U CN219351281U CN202320135578.2U CN202320135578U CN219351281U CN 219351281 U CN219351281 U CN 219351281U CN 202320135578 U CN202320135578 U CN 202320135578U CN 219351281 U CN219351281 U CN 219351281U
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Abstract
The utility model discloses a connection protection circuit of a main terminal of a driver, which comprises the following components: the device comprises a terminal unit, a rectifying unit, a capacitor unit, a soft start unit and a brake unit, wherein the terminal unit, the rectifying unit, the capacitor unit, the soft start unit and the brake unit are connected with output terminals of the capacitor unit and the brake unit. The utility model utilizes the positive temperature coefficient characteristic of PTC to limit the current and reduce the impact current of the device. The circuit and the method can automatically protect the fault line after the fault line is connected with the protection circuit and automatically recover the fault line after the fault is eliminated. The circuit is simple and practical, and protects sensitively. The problem that the driver is finally burnt out due to wiring errors caused by different definitions of main terminals of drivers and low standardization in the industry is effectively solved.
Description
Technical Field
The utility model belongs to the field of industrial automatic variable frequency drivers and servo drivers (hereinafter referred to as drivers for short), and relates to a protection circuit after a main terminal of the driver is connected with a fault line.
Background
The driver is an electric energy control device which converts a power frequency power supply into another frequency by utilizing the on-off action of the power semiconductor device, and can realize the functions of soft start, variable frequency speed regulation, operation precision improvement, power factor change, overcurrent/overvoltage/overload protection and the like of the alternating current asynchronous motor.
In the field of drives, the definition of main terminal connections is different from one home to another for various reasons. So that an accident of wrong connection often occurs in the process of electrician connection. The driver manufacturers have no protection in this regard and only a few manufacturers add fuses at the input. However, the protection time of the fuse is relatively short and uncontrollable, and finally, the internal power device is damaged, so that the fuse has the defects of irrecoverability, high cost, low reliability and the like. And the main terminals are all strong currents with the voltage of more than 220V, so that the main terminals have the characteristics of high voltage and high current, and after the main terminals are connected with wrong lines, a light person burns out the machine, so that a factory trips, and a heavy person can possibly cause a safety accident. And mental and physical losses are brought to enterprises and electric operators.
Disclosure of Invention
For this situation, a simple and practical safety protection circuit is proposed. The utility model aims to provide a circuit and a method which can automatically protect wires after being connected with wrong wires and automatically recover after the faults are eliminated. The circuit has simple structure and short response time, and does not need to increase a lot of cost.
The aim of the utility model is achieved by the following technical scheme:
a driver main terminal wiring protection circuit comprising:
a terminal unit including dc bus input terminals p+ and P-, an ac input terminal R, S, T, and a brake unit output terminal PB;
the rectification unit adopts a three-phase full-bridge rectification or a single-phase rectification bridge and is connected with an alternating current input terminal R, S, T;
the capacitor unit comprises direct current bus capacitors C1 and C2 and resistors R5 and R6;
the soft start unit comprises a soft start relay power supply VCC, soft start relays KM1 (contactor) and KM2 (contactor), positive direct current bus PTC resistors R1 and R2 and negative direct current bus PTC resistors R3 and R4; PTC resistors R1 and R2 are connected in series at the positive end of a direct current bus, a direct current bus input terminal P+ is led out from between the PTC resistors R1 and R2 between the positive end of a rectifier bridge and the positive end of a direct current bus capacitor C1; PTC resistors R3 and R4 are connected in series with the negative end of the direct current bus, and a direct current bus input terminal P-is led out from between the PTC resistors R3 and R4 between the negative end of the rectifier bridge and the negative end of the direct current bus capacitor C2; one end of a first pair of normally open contacts of the soft start relay KM1 is connected to the connection part of the PTC resistor R1 and the positive end of the rectifier bridge, and the other end of the first pair of normally open contacts is connected to the connection part of the PTC resistors R1 and R2; one end of a second pair of normally open contacts of the soft start relay KM1 is connected to the connection part of the PTC resistors R1 and R2, and the other end of the second pair of normally open contacts is connected with the connection part of the PTC resistor R2 and the positive electrode of the direct current bus capacitor C1; one end of a first pair of normally open contacts of the soft start relay KM2 is connected to the connection part of the PTC resistor R3 and the negative end of the rectifier bridge, and the other end of the first pair of normally open contacts is connected to the connection part of the PTC resistors R3 and R4; one end of a second pair of normally open contacts of the soft start relay KM2 is connected to the connection part of the PTC resistors R3 and R4, and the other end of the second pair of normally open contacts is connected with the connection part of the PTC resistor R4 and the negative electrode of the direct current bus capacitor C2;
and the braking unit is connected with the capacitor unit and the braking unit output terminal PB.
Further, the terminal unit includes dc bus input terminals p+ and P-, ac input terminals R, S, T, and a brake unit output terminal PB; the rectifying unit adopts three-phase full-bridge rectification and comprises rectifying diodes D1, D2, D3, D4, D5 and D6.
The ac input terminal R, S, T is connected to the junction between the anode of the rectifying diode D1 and the cathode of the rectifying diode D2, the junction between the anode of the rectifying diode D3 and the cathode of the rectifying diode D3, and the junction between the anode of the rectifying diode D5 and the cathode of the rectifying diode D6, respectively.
The 1 end of the PTC resistor R1 is connected to the connection part of the cathodes of the rectifying diode D1, the rectifying diode D3 and the rectifying diode D5, the 2 end of the PTC resistor R1 is connected with the 1 end of the PTC resistor R2, and the 2 end of the PTC resistor R2 is connected with the anode of the direct current bus capacitor C1; the 1 end of the PTC resistor R3 is connected to the connection part of the anodes of the rectifying diode D2, the rectifying diode D4 and the rectifying diode D6, the 2 end of the PTC resistor R3 is connected with the 1 end of the PTC resistor R4, and the 2 end of the PTC resistor R4 is connected to the negative electrode of the direct current bus capacitor C2.
Soft start relays KM1 and KM2 have two or more pairs of normally open contacts.
Soft start relay power VCC supplies power to soft start relays KM1 and KM2 with a supply voltage of DC24V.
Further, the braking unit comprises a single-tube chopper braking IGBT module D8 and an anti-parallel freewheel diode D7; the C pole of the chopping braking IGBT module D8 is connected to the output terminal PB of the braking unit, the E pole of the chopping braking IGBT module D8 is connected to the negative pole of the direct current bus capacitor C2, the anode of the anti-parallel freewheeling diode D7 is connected to the C pole of the chopping braking IGBT module D8, and the cathode of the anti-parallel freewheeling diode D7 is connected to the E pole of the chopping braking IGBT module D8.
Compared with the prior art, the utility model has the following advantages:
1. the utility model utilizes the positive temperature coefficient characteristic of PTC to limit the current and reduce the impact current of the device. Meanwhile, the voltage value of the direct current bus voltage is limited by utilizing the characteristic that the PTC resistor rapidly grows along with the temperature, so that the internal power supply of the driver cannot work normally, the relay cannot work, the resistors R1, R2, R3 and R4 cannot be bypassed, then the voltages on the resistors R1, R2, R3 and R4 are large, and the internal power supply of the driver cannot work continuously, so that positive feedback is formed. As long as the fault does not disappear, it will not work.
2. The protection circuit adopted by the utility model can also reduce the impact current of the rectifier bridges D1, D2, D3, D4, D5 and D6. The impact current can be ensured to be within the range regulated by the rectifier bridge by adjusting the resistance value, so that the service life of the rectifier bridge is prolonged.
3. The protection circuit can also reduce the rush current of the direct current capacitors C1 and C2. The impact current can be ensured to be within the range specified by the direct current bus capacitor by adjusting the resistance value, so that the service life of the direct current bus capacitor is prolonged.
4. The protection circuit of the utility model only adds a group of PTC resistor and relay on the original circuit, and the cost is less increased, but the protection circuit is much improved compared with the original driver in the aspects of safety and customer experience, and the cost performance is very high.
5. The main terminal wiring protection circuit of the driver has the characteristics of simple structure, fast protection action and long short-circuit time. And after the miswiring is changed, the driver can work normally.
Drawings
Fig. 1 shows the temperature characteristic of a PTC resistor;
FIG. 2 is a schematic diagram of a main terminal wiring protection circuit of the driver of the present utility model;
fig. 3 is a circuit diagram showing another main terminal connection protection circuit of the driver according to the present utility model.
Detailed Description
The present utility model will be described in detail with reference to the accompanying drawings.
Fig. 2 is a block diagram of a main terminal connection protection circuit of the driver according to the present utility model, which includes a terminal unit, a rectifying unit, a soft start unit, a braking unit, and a capacitor unit. Wherein: the rectifying unit comprises six rectifying diodes D1, D2, D3, D4, D5 and D6, the soft start unit comprises PTC resistors R1, R2, R3 and R4, the relays KM1 and KM2 with double normally open contacts, the braking unit comprises a single-tube chopper braking IGBT module D8 and an anti-parallel freewheeling diode D7, and the direct-current bus capacitor unit comprises capacitors C1 and C2 and resistors R5 and R6. The terminal unit includes dc bus input terminals p+ and P-, ac input terminal R, S, T, and brake unit output terminal PB.
The resistors R1, R2, R3, R4 are PTC resistors, and their characteristic is that the resistance increases sharply with increasing temperature, as shown in fig. 1. The power supply voltage of the relays KM1 and KM2 is DC24V.
With reference to fig. 2, the connection point of the PTC resistors R1 and R2 at the connection point of the main terminal p+ in the circuit and the connection point of the PTC resistors R3 and R4 at the connection point of the main terminal P-in the circuit, so that the terminals p+ and P-and R, S, T, PB can be effectively separated by the PTC resistors R1, R2, R3 and R4, and the rapid increase of the continuous energy caused by the wire connection fault is eliminated by limiting the current between the fault connection phases, thereby effectively protecting the components.
The rectifying unit includes, but is not limited to, three-phase full-bridge rectification shown in fig. 2, and a single-phase rectifying bridge shown in fig. 3 may also be used.
When two phases in R, S, T are connected to P+, P-, for example R, S two phases are electrically connected to the P+, P-terminals, respectively. The voltage on R2 is U RS The current is I R2 ＝U RS R2; the voltage on R1 is U RT The current is I R1 ＝U RS R1; the voltage on R3 is U ST The current is I R3 ＝U ST And R3, each loop is provided with a resistor for current limiting and protection, and the damage of the rectifier bridge caused by excessive current can be avoided. The protection principle of other forms of fault connection wires is the same, and the basic principle is to limit the rapid increase of short circuit current and limit short circuit energy by utilizing the resistance value of the PTC resistor along with the temperature characteristic.
The basic principle is as follows:
1) When current flows through the PTC resistors R1, R2, R3 and R4, the power generated by the resistors is as follows:
I R ＝U R /R (1)
P R ＝U R /R*U R ＝U R ^2/R (2)
T R ＝P R *R θ (3)
I R : resistance current
U R : voltage across resistor
P R : resistive power
T R : temperature of resistor
R θ : thermal resistance of the resistor, unit ℃/W;
2) If the driver user is connected with the wrong line, a large current is generated on the resistor, and the electric energy on the resistor is converted into heat energy (see formulas 1 and 2). The temperature of the resistors R1, R2, R3, R4 increases rapidly, here we use PTC resistors, where the resistance increases sharply with increasing temperature (see fig. 1). The PTC resistors R1, R2, R3, and R4 have increased resistance values, and as shown in formula (1), the current flowing through the resistor decreases as the resistance increases. The impact current is reduced, the driver is protected, and the terminal is prevented from being ignited.
3) Along with the increase of the resistor, the voltage of the resistor is higher, the input voltage is constant, so that the voltage on the direct current bus capacitor is reduced, the power supply in the driver cannot work, the electromagnetic relays KM1 and KM2 cannot act, the normally open contacts are kept in an open state, PTC resistors R1, R2, R3 and R4 cannot be short-circuited, and the circuit safety can be further guaranteed.
4) When the circuit returns to normal, the currents in the PTC resistors R1, R2, R3, R4 are small, and the resistance value does not rise rapidly to a very high value. When the bus voltage rises to the level that the internal power supply of the driver can be maintained to work, the electromagnetic relays KM1 and KM2 act, normally open contacts are closed, PTC resistors R1, R2, R3 and R4 are short-circuited, and the circuit can work normally.
The specific protection mode of the utility model after the driver main terminal is connected in a staggered way is as follows:
1) When the current is normally connected, the positive end of the current rectifying unit flows through the capacitors C1 and C2 through the PTC resistors R1 and R2, then flows through the PTC resistors R3 and R4, flows into the negative end of the rectifying unit, and flows back to the power grid to form a finished loop. When the two ends of the capacitor C1 and the capacitor C2 reach a certain voltage value, the relays KM1 and KM2 are attracted, and the driver works normally after the PTC resistors R1 and R2 and the PTC resistors R3 and R4 are bypassed.
2) When p+ is misconnected to any of the phases R, S, T, for example: when the R phase voltage is sine wave crest, current flows in from P+ and flows into the capacitors C1 and C2 after passing through the PTC resistor R2, flows into the rectifier bridge after passing through the PTC resistors R3 and R4, and flows into the power grid. When the R-phase voltage is a sine wave trough, the current is rectifiedThe inflow of diodes D3 and D5 flows into the R phase through PTC resistor R1. Since the voltage drop of the rectifying diodes D3, D5 is small, the voltage across R1 is equal to the phase voltage value (U between R, S RS ) The current flowing into R1 will be very large (Ir 1)
I R1 ＝U RS /R1 (4)
P R1 ＝I R1 ^2*R1 (5)
P R1 Heating power of resistor R1
According to the formulas 4 and 5, the heating value of R1 is proportional to the square of the current, and meanwhile, the resistance value of R1 is increased sharply along with the temperature rise (as shown in figure 1), so that the current of R1 can be reduced, and the current limiting effect is achieved. Thereby protecting the diodes D3, D5.
3) When two phases in RST are attached to P+, P-. Columns are connected electrically to the P+ and P-terminals, respectively, as in R, S. At the moment of power-on, the capacitors C1 and C2 are equivalent to short circuits, and the voltages on R2 and R4 are U RS The current is I R2 ＝U RS /(r2+r4); the voltage on R1 is U RT The current is I R1 ＝U RS R1; the voltage on R3 is U ST The current is I R3 ＝U ST R3. Therefore, each loop is provided with a resistor for current limiting and protection, and the rectifier bridge cannot be damaged due to overlarge current.
The above embodiments are only for illustrating the technical solution of the present utility model, and not for limiting the same; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present utility model.
Claims (7)
1. A driver main terminal wiring protection circuit, characterized in that the driver main terminal wiring protection circuit comprises:
the terminal unit comprises a direct current bus input terminal P+ and P-, an alternating current input terminal and a brake unit output terminal;
the rectification unit adopts a three-phase full-bridge rectification or a single-phase rectification bridge and is connected with an alternating current input terminal;
the capacitor unit comprises direct current bus capacitors C1 and C2 and resistors R5 and R6;
the soft start unit comprises a soft start relay power supply VCC, soft start relays KM1 and KM2, positive direct current bus PTC resistors R1 and R2 and negative direct current bus PTC resistors R3 and R4; PTC resistors R1 and R2 are connected in series at the positive end of a direct current bus, a direct current bus input terminal P+ is led out from between the PTC resistors R1 and R2 between the positive end of a rectifier bridge and the positive end of a direct current bus capacitor C1; PTC resistors R3 and R4 are connected in series with the negative end of a direct current bus, and a direct current bus input terminal P-is led out from between the PTC resistors R3 and R4 between the negative end of a rectifier bridge B1 and the negative end of a direct current bus capacitor C2; one end of a first pair of normally open contacts of the soft start relay KM1 is connected to the connection part of the PTC resistor R1 and the positive end of the rectifier bridge, and the other end of the first pair of normally open contacts is connected to the connection part of the PTC resistors R1 and R2; one end of a second pair of normally open contacts of the soft start relay KM1 is connected to the connection part of the PTC resistors R1 and R2, and the other end of the second pair of normally open contacts is connected with the connection part of the PTC resistor R2 and the positive electrode of the direct current bus capacitor C1; one end of a first pair of normally open contacts of the soft start relay KM2 is connected to the connection part of the PTC resistor R3 and the negative end of the rectifier bridge, and the other end of the first pair of normally open contacts is connected to the connection part of the PTC resistors R3 and R4; one end of a second pair of normally open contacts of the soft start relay KM2 is connected to the connection part of the PTC resistors R3 and R4, and the other end of the second pair of normally open contacts is connected with the connection part of the PTC resistor R4 and the negative electrode of the direct current bus capacitor C2;
and the braking unit is connected with the capacitor unit and the output terminal of the braking unit.
2. The driver main terminal wiring protection circuit according to claim 1, wherein the terminal unit includes dc bus input terminals p+ and P-, ac input terminals R, S, T, and a brake unit output terminal PB; the rectifying unit adopts three-phase full-bridge rectification and comprises rectifying diodes D1, D2, D3, D4, D5 and D6.
3. The driver main terminal connection protection circuit according to claim 2, wherein the ac input terminal R, S, T is connected to a junction of an anode of the rectifying diode D1 and a cathode of the rectifying diode D2, a junction of an anode of the rectifying diode D3 and a cathode of the rectifying diode D3, and a junction of an anode of the rectifying diode D5 and a cathode of the rectifying diode D6, respectively.
4. The connection protection circuit for the main terminal of the driver according to claim 3, wherein the 1 end of the PTC resistor R1 is connected to the cathode connection of the rectifying diode D1, the rectifying diode D3 and the rectifying diode D5, the 2 end of the PTC resistor R1 is connected to the 1 end of the PTC resistor R2, and the 2 end of the PTC resistor R2 is connected to the positive electrode of the dc bus capacitor C1; the 1 end of the PTC resistor R3 is connected to the connection part of the anodes of the rectifying diode D2, the rectifying diode D4 and the rectifying diode D6, the 2 end of the PTC resistor R3 is connected with the 1 end of the PTC resistor R4, and the 2 end of the PTC resistor R4 is connected to the negative electrode of the direct current bus capacitor C2.
5. The driver main terminal wiring protection circuit of claim 4, wherein the soft start relays KM1 and KM2 have two or more pairs of normally open contacts.
6. The driver main terminal connection protection circuit of claim 5, wherein the soft start relay power supply VCC has a voltage of 24V.
7. The driver main terminal wiring protection circuit of claim 6, wherein the braking unit comprises a single tube chopper braking IGBTD8 module, an anti-parallel freewheel diode D7; the C pole of the single-tube chopping braking IGBTD8 module is connected to the output terminal PB of the braking unit, the E pole of the single-tube chopping braking IGBTD8 module is connected to the negative pole of the direct-current bus capacitor C2, the anode of the anti-parallel freewheeling diode D7 is connected to the C pole of the single-tube chopping braking IGBTD8 module, and the cathode of the anti-parallel freewheeling diode D7 is connected to the E pole of the single-tube chopping braking IGBTD8 module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320135578.2U CN219351281U (en) | 2023-02-07 | 2023-02-07 | Main terminal wiring protection circuit of driver |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320135578.2U CN219351281U (en) | 2023-02-07 | 2023-02-07 | Main terminal wiring protection circuit of driver |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN219351281U true CN219351281U (en) | 2023-07-14 |
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ID=87105144
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202320135578.2U Active CN219351281U (en) | 2023-02-07 | 2023-02-07 | Main terminal wiring protection circuit of driver |
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|---|---|
| CN (1) | CN219351281U (en) |
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2023
- 2023-02-07 CN CN202320135578.2U patent/CN219351281U/en active Active
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