A kind of protection device and method of servo press

Abstract

The present invention belongs to the technical field of presses, and specifically relates to a protection device and method for a servo press. The present invention connects a protection circuit composed of a rectifier bridge, a soft start circuit A, a soft start circuit B, an energy storage circuit, a three-phase full-bridge inverter circuit, a core controller, etc. to a motor, thereby realizing that the servo press does not need to be equipped with a brake, and the motor can still be controlled and run safely in the event of a sudden power failure, providing a short-term working power supply to the motor of the servo press, greatly saving costs.

Description

Technical Field

[0001] The invention belongs to the technical field of servo presses, and in particular relates to a protection device and method for a servo press. Background Art

[0002] When the servo press loses power in the factory, the servo motor will rotate freely without a brake, which may seriously hit the mold, shorten the mold life, and cause forming damage to the workpiece, directly causing economic losses to the forming equipment manufacturer. Therefore, it is necessary to solve the problem of preventing the servo motor from losing control when the servo press loses power.

[0003] CN107196404A "A UPS device and its power switching control method" proposes a device for power failure. The UPS device is currently a conventional industrial backup equipment, but because the UPS device requires a backup power supply or power battery, and the UPS device itself uses an inverter as the input of the three-phase power supply, it is expensive. Summary of the invention

[0004] The present invention aims to solve the deficiencies of the prior art and provides a protection device and method for a servo press.

[0005] The present invention is achieved through the following technical solutions:

[0006] A protection device for a servo press comprises a rectifier bridge, a soft start circuit A, a soft start circuit B, an energy storage circuit, a three-phase full-bridge inverter circuit, a core controller, and a motor, wherein: the soft start circuit A comprises a soft start resistor R1 and a soft start resistor R2 connected in parallel; the soft start circuit B comprises a soft start resistor R11 and a soft start resistor R12 connected in parallel; the energy storage circuit comprises a plurality of energy storage branches connected in parallel, a plurality of capacitors are connected in series on each energy storage branch, and each capacitor is connected in parallel with a resistor; the rectifier bridge is connected to a three-phase 380V power line, the anode of a diode D1 is connected to a single-phase 220V power line, the cathode of the diode D1 is connected to the cathode of the rectifier bridge, the cathode of the rectifier bridge is connected to one end of the soft start circuit A, the other end of the soft start circuit A is connected to the anode of a thyristor S7, one end of the soft start circuit B is connected to the anode of a capacitor in a three-phase full-bridge inverter circuit, the cathode of the thyristor S7 is connected to the The anode is connected, the cathode of the capacitor in the three-phase full-bridge inverter circuit is connected to the anode of the rectifier bridge, the anode of the energy storage circuit is connected to the anode of the thyristor S7, the cathode of the energy storage circuit is connected to the anode of the rectifier bridge, the cathode of the thyristor S7 is connected to the input of the DC-DC power module, the output of the DC-DC power module is connected to the power supply of the core controller, the voltage signal collected by the voltage sensor is input to the core controller, the current signal collected by the current sensor is input to the core controller, the upper bridge arm IGBT emitter in the three-phase full-bridge inverter circuit is connected to the three-phase input terminal of the motor through the cable, the IGBT gate level signal g in the three-phase full-bridge inverter circuit is connected to the g output signal of the core controller, the motor output shaft is connected to the crank connecting rod transmission mechanism of the press, and the press control command is input to the core controller; the cables of the three-phase 380V power line pass through the three voltage sensors respectively, and the input cables of the motor pass through the three current sensors respectively.

[0007] Preferably, the three-phase full-bridge inverter circuit includes a series capacitor composed of capacitor C1 and capacitor C2, and a topological structure composed of 6 IGBTs, and the 6 IGBTs are S1, S2, S3, S4, S5, and S6; wherein the collector of S4 is connected to the emitter of S1, the collector of S5 is connected to the emitter of S2, the collector of S6 is connected to the emitter of S3, the emitters of S1, S2, and S3 are respectively connected to the three-phase input terminals of the motor through cables, the collectors of S1, S2, and S3 are respectively connected to the cathode of the rectifier bridge, the emitters of S4, S5, and S6 are respectively connected to the anode of the rectifier bridge, and the IGBT gate-level signals g of S1, S2, S3, S4, S5, and S6 are connected to the g output signal of the core controller.

[0008] Preferably, the energy storage circuit includes four energy storage branches in parallel, namely: capacitor C3 and capacitor C4 are connected in series, capacitor C3 is connected in parallel with resistor R3, and capacitor C4 is connected in parallel with resistor R4 to form a first energy storage branch; capacitor C5 and capacitor C6 are connected in series, capacitor C5 is connected in parallel with resistor R5, and capacitor C6 is connected in parallel with resistor R6 to form a second energy storage branch; capacitor C7 and capacitor C8 are connected in series, capacitor C7 is connected in parallel with resistor R7, and capacitor C8 is connected in parallel with resistor R8 to form a third energy storage branch; capacitor C9 and capacitor C10 are connected in series, capacitor C9 is connected in parallel with resistor R9, and capacitor C10 is connected in parallel with resistor R10 to form a fourth energy storage branch.

[0009] Preferably, the voltage sensor is a through-hole voltage sensor, and the current sensor is a through-hole current sensor.

[0010] Preferably, the capacitor selection in the energy storage circuit is calculated according to the following formula:

[0011]

[0012] Among them, m is the mass of the slider; v is the average speed of the slider from the bottom dead center to the top dead center; C is the total capacitance value of the energy storage circuit; ΔU is the DC bus voltage difference.

[0013] The present invention also includes a servo press protection method, comprising the following steps:

[0014] Step 1: The voltage of the three-phase 380V power line is connected to the three-phase input side of the rectifier bridge. When the single-phase 220V voltage amplitude is in the positive half cycle, the diode D1 is turned on, and the capacitor in the three-phase full-bridge inverter circuit is charged through the soft start circuit B. When the voltage between the positive and negative DC bus reaches 540V, charging will stop;

[0015] Step 2: The DC-DC power module converts 540V to 24V and supplies power to the core controller, which sends instructions to the rectifier bridge;

[0016] Step 3: The rectifier bridge receives the instruction from the core controller and starts working, rectifying the three-phase 380V AC voltage into 540V DC voltage; the 540V DC voltage forms two branches: one branch charges the energy storage circuit through the soft start circuit A until the full voltage reaches 540V, at which point the thyristor S7 is not turned on; the other branch provides DC voltage to the three-phase full-bridge inverter circuit;

[0017] Step 4: The core controller receives the press control instruction and starts to execute the press control instruction. At the same time, combined with the feedback of the current sensor signal, the core controller outputs the PWM wave g signal to the IGBT gate level signal g of the three-phase full-bridge inverter circuit;

[0018] Step 5: After the IGBT of the three-phase full-bridge inverter circuit receives the gate-level signal g, it starts to perform the switching action. The power comes from the output voltage of the rectifier bridge, and the motor starts to rotate. During the operation of the motor, if the three-phase 380V power line is suddenly powered off, step 6 is executed;

[0019] Step 6: The three-phase 380V power line input by the rectifier bridge is suddenly powered off, and the voltage sensor feeds back the voltage signal to the core controller in real time. The core controller immediately saves the current grid voltage value to the EEPROM in the core controller, and regards the disappearance of the grid voltage at this moment as a fault, and stores it in the fault storage area FLASH in the core controller; the core controller turns on the thyristor S7, and the energy storage circuit provides input power to the DC-DC power module and continues to power the core controller. The motor controls the slider to stop urgently, and controls the motor to make the slider return to the top dead center position from any current position;

[0020] Step 7: When the motor returns to the top dead center, the control thyristor S7 is no longer turned on and no longer provides energy to the motor, completing the entire safety protection process.

[0021] The protection device of the present invention eliminates the need for a brake for the servo press. When the three-phase 380V power supply suddenly disappears during normal operation, the motor can still be controlled and run safely, providing the motor of the servo press with a short-term working power supply, so that the slider stops urgently at the current position, and immediately returns to the top dead center and stops. Compared with the situation where the motor is out of control and rotates freely due to a sudden power failure, the protection device of the present invention greatly protects the mold and the workpiece, is safe and reliable, and has great application prospects in actual working conditions. At the same time, compared with installing a brake, it does not increase any motor installation space size, and the price is reduced by about 70% compared with installing a brake, which greatly saves costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 4 is a circuit diagram of an embodiment of the present invention.

[0023] Figure 2 This is a control flow chart of an embodiment of the present invention.

[0024] In the figure, 1 is a soft start circuit A, 2 is a soft start circuit B, 3 is a three-phase full-bridge inverter circuit, and 4 is an energy storage circuit. DETAILED DESCRIPTION

[0025] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application belong to the protection scope of the present invention.

[0026] The circuit diagram of the protection device of the present invention is shown in the attached figure. Figure 1As shown, it includes a rectifier bridge, a soft start circuit A1, a soft start circuit B2, an energy storage circuit 4, a three-phase full-bridge inverter circuit 3, and a core controller.

[0027] The soft start circuit A1 includes a soft start resistor R1 and a soft start resistor R2, and the soft start resistor R1 and the soft start resistor R2 are connected in parallel.

[0028] The soft start circuit B2 includes a soft start resistor R11 and a soft start resistor R12, and the soft start resistor R11 and the soft start resistor R12 are connected in parallel.

[0029] Wherein, the three-phase full-bridge inverter circuit 3 includes a capacitor and an IGBT, and an IGBT (Insulated Gate Bipolar Transistor) is an insulated gate bipolar transistor. The three-phase full-bridge inverter circuit 3 in the present embodiment includes a series capacitor composed of a capacitor C1 and a capacitor C2, and a topological structure composed of 6 IGBTs, and the 6 IGBTs are respectively S1, S2, S3, S4, S5, and S6, and the S4 collector is connected to the S1 emitter, the S5 collector is connected to the S2 emitter, and the S6 collector is connected to the S3 emitter. The emitters of S1, S2, and S3 are connected to the three-phase input terminals of the motor through cables, and the IGBT gate-level signals g of S1, S2, S3, S4, S5, and S6 are connected to the g output signals of the core controller. The collectors of S1, S2, and S3 are connected to the cathode of the rectifier bridge, and the emitters of S4, S5, and S6 are connected to the anode of the rectifier bridge.

[0030] Among them, the energy storage circuit 4 includes a plurality of energy storage branches, and the plurality of energy storage branches are connected in parallel, and a plurality of capacitors are connected in series on each energy storage branch, and each capacitor is connected in parallel with a resistor. In this embodiment, four energy storage branches are connected in parallel to form the energy storage circuit 4, namely: capacitor C3 and capacitor C4 are connected in series, capacitor C3 is connected in parallel with resistor R3, and capacitor C4 is connected in parallel with resistor R4 to form an energy storage branch; capacitor C5 and capacitor C6 are connected in series, capacitor C5 is connected in parallel with resistor R5, and capacitor C6 is connected in parallel with resistor R6 to form an energy storage branch; capacitor C7 and capacitor C8 are connected in series, capacitor C7 is connected in parallel with resistor R7, and capacitor C8 is connected in parallel with resistor R8 to form an energy storage branch; capacitor C9 and capacitor C10 are connected in series, capacitor C9 is connected in parallel with resistor R9, and capacitor C10 is connected in parallel with resistor R10 to form an energy storage branch. The selection of capacitors in the energy storage circuit 4 here can be based on the law of conservation of energy:

[0031]

[0032]

[0033] Among them, m is the mass of the slider; v is the average speed of the slider from the bottom dead center to the top dead center; C is the total capacitance of the energy storage circuit 4; ΔU is the DC bus voltage difference, the normal DC bus voltage value is 540V, and the general DC bus voltage working minimum value is 480V. The subtraction of the above two voltage values ​​is the DC bus voltage difference of 60V here, so ΔU is generally selected as 60V based on experience.

[0034] Among them, the core controller includes CPU, FLASH, EEPROM and reset circuit.

[0035] Attached Figure 1 In the embodiment, the three-phase 380V power line is connected to the input of the rectifier bridge, the single-phase 220V power line is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the cathode of the rectifier bridge. The cathode of the rectifier bridge is connected to one end of the soft start circuit A1 composed of soft start resistors R1 and R2 in parallel, and the other end of the soft start circuit A1 is connected to the anode of the thyristor S7. One end of the soft start circuit B2 composed of soft start resistors R11 and R12 in parallel is connected to the anode of the capacitor C1, the cathode of the thyristor S7 is connected to the anode of the capacitor C1, the capacitor C1 is connected in series with the capacitor C2, and the cathode of the capacitor C2 is connected to the anode of the rectifier bridge. The anode of the energy storage circuit 4 is connected to the anode of the thyristor S7, and the cathode of the energy storage circuit 4 is connected to the anode of the rectifier bridge. The cathode of the thyristor S7 is connected to the input of the DC-DC power module, and the output of the DC-DC power module is connected to the core controller power supply. The emitters of S1, S2, and S3 are connected to the three-phase input terminals of the motor through cables, the IGBT gate level signals g of S1, S2, S3, S4, S5, and S6 are connected to the g output signals of the core controller, and the motor output shaft is connected to the crank-connecting rod transmission mechanism of the press. The press control command is input into the core controller. The cables of the three-phase 380V power line pass through three voltage sensors, and the input cables of the three-phase motor pass through three current sensors. The voltage signals collected by the three voltage sensors are input into the core controller, and the current signals of the three current sensors are input into the core controller.

[0036] Based on the protection device of the servo press of the present invention, a protection method is implemented by the following specific steps, see the attached Figure 2 :

[0037] Step 1: The voltage of the three-phase 380V power line is connected to the three-phase input side of the rectifier bridge, and the diode D1 is turned on. When the single-phase 220V voltage amplitude is in the positive half cycle, the capacitors C1 and C2 are charged through the soft start resistors R11 and R12. When the voltage between the positive and negative DC bus reaches 540V, charging will stop.

[0038] Step 2: The DC-DC power module converts 540V into 24V to power the core controller, and the core controller sends instructions to the rectifier bridge.

[0039] Step 3: The rectifier bridge receives the instruction from the core controller and starts working to rectify the three-phase 380V AC voltage into a 540V DC voltage; the core controller can detect the DC bus voltage value through the internal circuit; the 540V DC voltage forms two branches: one branch is to charge the energy storage circuit 4 through the soft start resistor R1 and the soft start resistor R2 until the full voltage reaches 540V, and the thyristor S7 is not connected from power-on to this step; the other branch is to provide DC voltage to the three-phase full-bridge inverter circuit 3.

[0040] Step 4: The core controller can now receive input signals such as press control instructions and start executing control commands. At the same time, combined with the feedback of the current sensor signal, the core controller CPU starts to calculate the motor control algorithm and outputs the PWM wave g signal from the core controller to the 6 IGBT gate-level signals g of S1, S2, S3, S4, S5, and S6.

[0041] Step 5: After receiving the gate signal g, the IGBTs from S1 to S6 start to switch, the power comes from the output voltage of the rectifier bridge, and the motor starts to rotate. If there is a sudden power outage, execute the following step 6.

[0042] Step 6: If the three-phase 380V power line input by the rectifier bridge is suddenly powered off for some reason, the DC bus voltage will not drop suddenly due to the presence of capacitors C1 and C2. The 3-way voltage sensor feeds back the grid voltage signal to the core controller in real time, and the core controller immediately performs the following actions: save the current grid voltage value to the EEPROM, and regard the disappearance of the grid voltage at this moment as a fault, and store it in the fault storage area FLASH; the core controller controls the conduction thyristor S7, and at this time, the energy storage circuit 4 composed of capacitors C3 to C10 provides input power to the DC-DC power supply module and continues to supply power to the core controller. The energy previously stored in capacitors C3 to C10 can provide electrical energy to the motor within a certain period of time, so that the motor can control the slider to stop urgently, and control the motor to make the slider return to the top dead center position from any current position.

[0043] Step 7: When the motor returns to the top dead center, thyristor S7 is turned off and no longer provides energy to the motor, completing the entire safety protection process.

[0044] The motor control algorithm includes motor current and speed data processing, Clarke and Park transformation, field oriented control, vector control and PWM wave calculation, etc. The internal control strategy of the core controller includes the above-mentioned power failure protection control strategy in addition to the conventional motor control algorithm and conventional motor control functions.

[0045] The embodiment described above is only one of the more preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A protective device for a servo press, characterized in that: The invention comprises a rectifier bridge, a soft start circuit A (1), a soft start circuit B (2), an energy storage circuit (4), a three-phase full-bridge inverter circuit (3), a core controller, and a motor, wherein: the soft start circuit A (1) comprises a soft start resistor R1 and a soft start resistor R2 connected in parallel; the soft start circuit B (2) comprises a soft start resistor R11 and a soft start resistor R12 connected in parallel; the energy storage circuit (4) comprises a plurality of energy storage branches connected in parallel, each energy storage branch is connected in series with a plurality of capacitors, and each capacitor is connected in parallel with a resistor; the rectifier bridge is connected to a three-phase 380V power line, the anode of the diode D1 is connected to a single-phase 220V power line, The cathode of the diode D1 is connected to the cathode of the rectifier bridge, the cathode of the rectifier bridge is connected to one end of the soft start circuit A (1), the other end of the soft start circuit A (1) is connected to the anode of the thyristor S7, one end of the soft start circuit B (2) is connected to the anode of the capacitor in the three-phase full-bridge inverter circuit (3), the cathode of the thyristor S7 is connected to the anode of the capacitor in the three-phase full-bridge inverter circuit (3), the cathode of the capacitor in the three-phase full-bridge inverter circuit (3) is connected to the anode of the rectifier bridge, the anode of the energy storage circuit (4) is connected to the anode of the thyristor S7, the cathode of the energy storage circuit (4) is connected to the anode of the rectifier bridge, and the cathode of the thyristor S7 is connected to the DC-DC The input of the power module is connected, the output of the DC-DC power module is connected to the power supply of the core controller, the voltage signal collected by the voltage sensor is input to the core controller, the current signal of the current sensor is input to the core controller, the IGBT emitter in the three-phase full-bridge inverter circuit (3) is respectively connected to the three-phase input terminal of the motor through a cable, the IGBT gate level signal g in the three-phase full-bridge inverter circuit (3) is connected to the g output signal of the core controller, the motor output shaft is connected to the crank connecting rod transmission mechanism of the press, and the press control command is input to the core controller; the cable of the three-phase 380V power line is provided with a voltage sensor, the motor The input cable is provided with a current sensor; the energy storage circuit (4) comprises four energy storage branches connected in parallel, namely: a first energy storage branch is formed by capacitor C3 and capacitor C4 connected in series, capacitor C3 connected in parallel with resistor R3, and capacitor C4 connected in parallel with resistor R4; a second energy storage branch is formed by capacitor C5 and capacitor C6 connected in series, capacitor C5 connected in parallel with resistor R5, and capacitor C6 connected in parallel with resistor R6; a third energy storage branch is formed by capacitor C7 and capacitor C8 connected in series, capacitor C7 connected in parallel with resistor R7, and capacitor C8 connected in parallel with resistor R8; a fourth energy storage branch is formed by capacitor C9 and capacitor C10 connected in series, capacitor C9 connected in parallel with resistor R9, and capacitor C10 connected in parallel with resistor R10.

2. The protective device for a servo press according to claim 1, characterized in that: The three-phase full-bridge inverter circuit (3) comprises a series capacitor composed of a capacitor C1 and a capacitor C2, and a topological structure composed of 6 IGBTs, wherein the 6 IGBTs are S1, S2, S3, S4, S5, and S6; wherein the collector of S4 is connected to the emitter of S1, the collector of S5 is connected to the emitter of S2, the collector of S6 is connected to the emitter of S3, the emitters of S1, S2, and S3 are respectively connected to the three-phase input terminals of the motor through cables, the IGBT gate-level signals g of S1, S2, S3, S4, S5, and S6 are connected to the g output signal of the core controller, the collectors of S1, S2, and S3 are respectively connected to the cathode of the rectifier bridge, and the emitters of S4, S5, and S6 are respectively connected to the anode of the rectifier bridge.

3. The protective device for a servo press according to claim 1, characterized in that: The voltage sensor is a through-type voltage sensor, and the current sensor is a through-type current sensor.

4. The protective device for a servo press according to claim 1, characterized in that: The capacitor type in the energy storage circuit (4) is calculated according to formula (1): Wherein, m is the mass of the slider; v is the average speed of the slider from the bottom dead center back to the top dead center; C is the total capacitance of the energy storage circuit (4); ΔU is the DC bus voltage difference.

5. According to the servo press protection device of claim 1, a servo press protection method comprises the following steps: Step 1: The voltage of the three-phase 380V power line is connected to the three-phase input side of the rectifier bridge, and the diode D1 is turned on. When the single-phase 220V voltage amplitude is in the positive half cycle, the capacitor in the three-phase full-bridge inverter circuit (3) is charged through the soft start circuit B (2). When the voltage between the positive and negative sides of the DC bus reaches 540V, charging is stopped. Step 2: The DC-DC power module converts 540V to 24V and supplies power to the core controller, which sends instructions to the rectifier bridge; Step 3: The rectifier bridge receives the instruction from the core controller and starts working, rectifying the three-phase 380V AC voltage into a 540V DC voltage; the 540V DC voltage forms two branches: one branch is used to charge the energy storage circuit (4) through the soft start circuit A (1) until the voltage is fully charged to 540V, at which point the thyristor S7 is not turned on; the other branch is used to provide a DC voltage to the three-phase full-bridge inverter circuit (3); Step 4: The core controller receives the press machine control instruction and starts to execute the press machine control instruction. At the same time, combined with the feedback of the current sensor signal, the core controller outputs the PWM wave g signal to the IGBT gate level signal g of the three-phase full-bridge inverter circuit (3); Step 5: After receiving the gate-level signal g, the IGBT of the three-phase full-bridge inverter circuit (3) starts to perform switching action, the power comes from the output voltage of the rectifier bridge, and the motor starts to rotate; during the operation of the motor, if the three-phase 380V power line is suddenly powered off, step 6 is executed; Step 6: The three-phase 380V power line input by the rectifier bridge is suddenly powered off, and the voltage sensor feeds back the voltage signal to the core controller in real time. The core controller immediately saves the current grid voltage value to the EEPROM in the core controller, and regards the disappearance of the grid voltage at this moment as a fault, and stores it in the fault storage area FLASH in the core controller; The core controller turns on the thyristor S7, and the energy storage circuit (4) provides input power to the DC-DC power module and continuously supplies power to the core controller. The motor controls the slider to stop urgently, and controls the motor to return the slider to the top dead center position from any current position. Step 7: When the motor returns to the top dead center, thyristor S7 is turned off and no longer provides energy to the motor, completing the entire safety protection process.

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