Electromagnetic chuck driving and protecting circuit and method based on H bridge

Abstract

The application discloses an electromagnetic chuck driving and protection circuit and method based on an H-bridge, and belongs to the technical field of electromagnetic chucks. The circuit comprises an H-bridge driving unit, a first energy storage unit, a second energy storage unit, a discharge unit, a voltage detection unit, a current detection unit and a control unit. The H-bridge structure is combined with IGBT switching tubes to realize positive and negative excitation and demagnetization control of the electromagnetic chuck, the first capacitor is used for storing and releasing the reverse demagnetization energy, and a double protection mechanism is used to effectively inhibit the kilovolt-level reverse electromotive force generated when power is cut off. The application has the advantages of fast response speed, long service life, high safety, low energy consumption and the like, solves the problems of workpiece release delay and reverse electromotive force hazards caused by the magnetic hysteresis effect of traditional electromagnetic chucks, and is suitable for electromagnetic control applications in the fields of mechanical machining and automatic handling.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic chuck technology, and particularly relates to an electromagnetic chuck driving and protection circuit and method based on an H-bridge. Background Technology

[0002] An electromagnetic chuck is a device that uses an energized coil to generate a magnetic field to attract magnetically conductive workpieces. Its core advantage lies in the fact that the presence or absence of magnetism is controlled by the switching of current; the magnitude of the magnetism has a linear response to the excitation current; and the polarity of the magnetic field can be dynamically switched by changing the direction of the current. These characteristics give it significant technological advantages in machining, logistics handling, and automated production lines. Traditional electromagnetic chuck drive circuits use contact switches or other contact switches for control, but the contacts in such circuits are prone to burning and have a short lifespan. Furthermore, when the electromagnetic chuck is powered off after the material is released, the inherent inductance of the electromagnetic coil (L values ​​are typically in the range of 1-10H) generates a back electromotive force of up to kilovolts at the moment of disconnection. Due to the hysteresis effect, the magnetic force continues to exist, resulting in a significant time delay in workpiece release, leading to low efficiency and a high failure rate.

[0003] In the patent document "202311414614.X An electromagnetic chuck control device and a control method for the electromagnetic chuck control device", this method achieves the functions of excitation, reverse demagnetization and rectification by adjusting the conduction angle of the thyristor. It adopts real-time current monitoring and fault identification to effectively avoid the occurrence of risks. However, this method can only be used under the condition that the circuit is powered on throughout, and it does not address how to deal with the reverse electromotive force generated by the electromagnetic chuck after the circuit is powered off. Summary of the Invention

[0004] To address the problems of existing technologies, the present invention aims to propose an electromagnetic chuck driving and protection circuit and method based on an H-bridge. The electromagnetic chuck is driven by combining an H-bridge with an IGBT, and the reverse electromotive force generated at a level of up to kilovolts during the moment of power failure of the circuit is dually protected and utilized. It features fast control response speed, long service life, high safety and low power consumption.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] This invention proposes an electromagnetic chuck driving and protection circuit based on an H-bridge, the circuit comprising: an H-bridge driving unit, a first energy storage unit, a second energy storage unit, a discharge unit, a voltage detection unit, a current detection unit, and a control unit;

[0007] The H-bridge drive unit is connected to the first energy storage unit, the discharge unit, the voltage detection unit, and the current detection unit. The first energy storage unit is connected to the second energy storage unit, the discharge unit, and the voltage detection unit. The second energy storage unit, the voltage detection unit, and the current detection unit are all connected to the control unit. The control unit is connected to the H-bridge drive unit, the first energy storage unit, and the discharge unit.

[0008] The H-bridge drive unit includes a first switch, a second switch, a third switch, and a fourth switch; the first energy storage unit includes a fifth switch, a first diode, a second diode, and a first capacitor; the second energy storage unit includes a second capacitor; the discharge unit includes a sixth switch and a first resistor; the voltage detection unit includes a second resistor; and the current detection unit includes a third resistor and a fourth resistor.

[0009] Furthermore, in the H-bridge drive unit, the switching electrode of the first switching transistor is connected to the signal output terminal of the control unit, the first electrode of the first switching transistor is connected to the voltage detection unit, and the second electrode of the first switching transistor is connected to the first electrode of the third switching transistor; the switching electrode of the second switching transistor is connected to the signal output terminal of the control unit, the first electrode of the second switching transistor is connected to the first electrode of the first switching transistor, and the second electrode of the second switching transistor is connected to the first electrode of the fourth switching transistor; the switching electrode of the third switching transistor is connected to the signal output terminal of the control unit, the first electrode of the third switching transistor is connected to one end of the electromagnetic chuck, and the second electrode of the third switching transistor is connected to the current detection unit; the switching electrode of the fourth switching transistor is connected to the signal output terminal of the control unit, the first electrode of the fourth switching transistor is connected to the other end of the electromagnetic chuck, and the second electrode of the fourth switching transistor is connected to the current detection unit.

[0010] Furthermore, in the first energy storage unit, the switching electrode of the fifth switching transistor is connected to the signal output terminal of the control unit, the first electrode of the fifth switching transistor is connected to the cathode of the first diode, and the second electrode of the fifth switching transistor is connected to the cathode of the second diode; the anode of the first diode is connected to the DC power input terminal, and the cathode of the first diode is connected to the voltage detection unit; the anode of the second diode is connected to the anode of the first diode, and the cathode of the second diode is connected to the positive terminal of the first capacitor; the negative terminal of the first capacitor is connected to the ground terminal.

[0011] In the second energy storage unit, the positive terminal of the second capacitor is connected to the power input terminal of the control unit, and the negative terminal of the second capacitor is connected to the ground terminal.

[0012] Furthermore, in the discharge unit, the switching electrode of the sixth switching transistor is connected to the signal output terminal of the control unit, the first electrode of the sixth switching transistor is connected to the H-bridge drive unit, and the second electrode of the sixth switching transistor is connected to one end of the first resistor; the other end of the first resistor is connected to the ground terminal.

[0013] Furthermore, in the voltage detection unit, one end of the second resistor is connected to the signal input terminal of the control unit and the first energy storage unit, and the other end of the second resistor is connected to the signal input terminal of the control unit and the ground terminal;

[0014] In the current detection unit, one end of the third resistor is connected to the signal input terminal and the ground terminal of the control unit, and the other end of the third resistor is connected to the signal input terminal of the control unit, the H-bridge drive unit, and one end of the fourth resistor; one end of the fourth resistor is connected to the signal input terminal of the control unit, and the other end of the fourth resistor is connected to the signal input terminal of the control unit and the H-bridge drive unit.

[0015] Furthermore, the anode of the third diode is connected to the positive terminal of the first capacitor, and the cathode of the third diode is connected to the positive terminal of the second capacitor.

[0016] Furthermore, the switching transistor is an insulated gate bipolar transistor (IGBT), with the gate of the IGBT serving as the switching electrode, the collector of the IGBT serving as the first electrode, and the emitter of the IGBT serving as the second electrode; the diode is a power-stage diode; and the first resistor R1 is a power-stage aluminum-cased resistor.

[0017] This invention proposes an electromagnetic chuck driving method based on an H-bridge, comprising the following steps:

[0018] When the circuit is input voltage, the control unit monitors the voltage value of the second resistor. When the voltage value of the second resistor reaches the preset opening value, the control unit outputs a drive signal to turn on the first switch and the fourth switch. The electromagnetic chuck and the DC power supply form a positive path and generate a positive magnetic force.

[0019] When the circuit is disconnected from the voltage, it enters the protection process of the circuit; after the protection process of the circuit is completed, it enters the reverse demagnetization process of the circuit. The control unit outputs a drive signal to turn on the second switch and the third switch. The electromagnetic chuck and the first capacitor form a reverse path and generate a reverse magnetic force.

[0020] Furthermore, the reverse demagnetization process is configured with a reverse current value. The control unit monitors the current values ​​of the third resistor and the fourth resistor. When the second switch is turned on, if the current value of the third resistor is higher than the preset reverse current value, the second switch is turned off. When the second switch is turned off, if the current value of the fourth resistor is lower than the preset reverse current value, the second switch is turned on.

[0021] This invention proposes a method for protecting an electromagnetic chuck based on an H-bridge, comprising the following steps:

[0022] First layer of protection: The control unit monitors the voltage value of the second resistor. When the voltage value of the second resistor reaches the preset shutdown value, the control unit outputs a drive signal to turn off the first switch. The current of the circuit is consumed along the parasitic diodes of the fourth switch and the third switch.

[0023] Second layer of protection: The control unit monitors the current value of the fourth resistor. When the current value of the fourth resistor is lower than the preset safe current value, the control unit outputs a drive signal to turn off the fourth switch and turn on the sixth switch.

[0024] The control unit monitors the voltage value of the second resistor. When the voltage value of the second resistor is lower than the preset safe voltage value, the control unit outputs a drive signal to turn off the sixth switch and turn on the fifth switch, thus completing the protection process.

[0025] The beneficial effects of this invention are:

[0026] (1) The present invention drives the electromagnetic chuck by combining H-bridge with IGBT. Compared with the common method of using contactors and other contact switches, it has the characteristics of high switching frequency, low switching loss and long service life.

[0027] (2) This invention provides dual protection and utilization for the reverse electromotive force generated at the moment of power failure of the circuit, which is as high as kilovolts, thereby improving the safety of the circuit and reducing power loss.

[0028] (3) When the circuit is de-energized, the first capacitor provides reverse demagnetizing charge, which solves the problem of significant time delay in workpiece release caused by hysteresis effect of electromagnetic chuck and speeds up control response.

[0029] (4) In this invention, the first capacitor (high voltage and large capacity) and the second capacitor (high voltage and small capacity) are connected by a third diode to form a unidirectional conduction. After the circuit completes reverse demagnetization, the first capacitor discharges its charge, while the second capacitor still has charge, thus ensuring the normal operation of the drive and protection circuit. Attached Figure Description

[0030] Figure 1This is a schematic diagram of an electromagnetic chuck driving and protection circuit based on an H-bridge according to an embodiment of the present invention;

[0031] Figure 2 This is a circuit diagram of an electromagnetic chuck driving and protection circuit based on an H-bridge according to an embodiment of the present invention. Specific implementation steps

[0032] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0033] like Figure 1 The diagram shown is a schematic representation of an H-bridge-based electromagnetic chuck driving and protection circuit according to an embodiment of the present invention. Figure 1 In this embodiment of the invention, an electromagnetic chuck driving and protection circuit structure based on an H-bridge includes: an H-bridge driving unit, a first energy storage unit, a second energy storage unit, a discharge unit, a voltage detection unit, a current detection unit, and a control unit;

[0034] The H-bridge drive unit is connected to the first energy storage unit, the discharge unit, the voltage detection unit, and the current detection unit. The first energy storage unit is connected to the second energy storage unit, the discharge unit, and the voltage detection unit. The second energy storage unit, the voltage detection unit, and the current detection unit are all connected to the control unit. The control unit is connected to the H-bridge drive unit, the first energy storage unit, and the discharge unit.

[0035] like Figure 2 The diagram shown is a schematic diagram of an electromagnetic chuck driving and protection circuit based on an H-bridge according to an embodiment of the present invention.

[0036] In Figure 2 In this embodiment of the invention, the H-bridge driving unit includes a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4; the first energy storage unit includes a fifth switch Q5, a first diode D1, a second diode D2, and a first capacitor C1; the second energy storage unit includes a second capacitor C2; the discharge unit includes a sixth switch Q6 and a first resistor R1; the voltage detection unit includes a second resistor R2; and the current detection unit includes a third resistor R3 and a fourth resistor R4.

[0037] In the H-bridge drive unit, the switching electrode of the first switch Q1 is connected to the signal output terminal of the control unit, the first electrode of the first switch Q1 is connected to the voltage detection unit, and the second electrode of the first switch Q1 is connected to the first electrode of the third switch Q3; the switching electrode of the second switch Q2 is connected to the signal output terminal of the control unit, the first electrode of the second switch Q2 is connected to the first electrode of the first switch Q1, and the second electrode of the second switch Q2 is connected to the first electrode of the fourth switch Q4; the switching electrode of the third switch Q3 is connected to the signal output terminal of the control unit, the first electrode of the third switch Q3 is connected to one end of the electromagnetic chuck, and the second electrode of the third switch Q3 is connected to the current detection unit; the switching electrode of the fourth switch Q4 is connected to the signal output terminal of the control unit, the first electrode of the fourth switch Q4 is connected to the other end of the electromagnetic chuck, and the second electrode of the fourth switch Q4 is connected to the current detection unit.

[0038] In the first energy storage unit, the switching electrode of the fifth switching transistor Q5 is connected to the signal output terminal of the control unit, the first electrode of the fifth switching transistor Q5 is connected to the cathode of the first diode D1, and the second electrode of the fifth switching transistor Q5 is connected to the cathode of the second diode D2; the anode of the first diode D1 is connected to the DC power input terminal, and the cathode of the first diode D1 is connected to the voltage detection unit; the anode of the second diode D2 is connected to the anode of the first diode D1, and the cathode of the second diode D2 is connected to the positive terminal of the first capacitor C1; the negative terminal of the first capacitor C1 is connected to the ground terminal.

[0039] In the second energy storage unit, the positive terminal of the second capacitor C2 is connected to the power input terminal of the control unit, and the negative terminal of the second capacitor C2 is connected to the ground terminal.

[0040] In the bleeder unit, the switching electrode of the sixth switch Q6 is connected to the signal output terminal of the control unit, the first electrode of the sixth switch Q6 is connected to the H-bridge drive unit, and the second electrode of the sixth switch Q6 is connected to one end of the first resistor R1; the other end of the first resistor R1 is connected to the ground terminal.

[0041] In the voltage detection unit, one end of the second resistor R2 is connected to the signal input terminal of the control unit and the first energy storage unit, and the other end of the second resistor R2 is connected to the signal input terminal of the control unit and the ground terminal.

[0042] In the current detection unit, one end of the third resistor R3 is connected to the signal input terminal and the ground terminal of the control unit, and the other end of the third resistor R3 is connected to the signal input terminal of the control unit, the H-bridge drive unit, and one end of the fourth resistor R4; one end of the fourth resistor R4 is connected to the signal input terminal of the control unit, and the other end of the fourth resistor R4 is connected to the signal input terminal of the control unit and the H-bridge drive unit.

[0043] In this configuration, the anode of the third diode D3 is connected to the positive terminal of the first capacitor C1, and the cathode of the third diode D3 is connected to the positive terminal of the second capacitor C2.

[0044] Specifically, the first capacitor C1 (high voltage, large capacity) and the second capacitor C2 (high voltage, small capacity) are connected by the third diode D3 to form a unidirectional conduction circuit. After the circuit completes reverse demagnetization, the first capacitor C1 is discharged, while the second capacitor C2 still has charge, ensuring the normal operation of the drive and protection circuit.

[0045] In this embodiment of the invention, the switching transistor is an insulated gate bipolar transistor (IGBT), with the gate of the IGBT serving as the switching electrode, the collector of the IGBT serving as the first electrode, and the emitter of the IGBT serving as the second electrode; the diode is a power stage diode; and the first resistor R1 is a power stage aluminum-cased resistor.

[0046] Specifically, the first capacitor C1 is a large-capacity, high-voltage capacitor, and the second capacitor C2 is a small-capacity, high-voltage capacitor.

[0047] An embodiment of the present invention provides an electromagnetic chuck driving method based on an H-bridge, comprising:

[0048] When the circuit input voltage is applied, the control unit monitors the voltage value of the second resistor R2. When the voltage value of the second resistor R2 reaches the preset opening value, the control unit outputs a drive signal to turn on the first switch Q1 and the fourth switch Q4. The electromagnetic chuck forms a positive path with the DC power supply, generating a positive magnetic force.

[0049] When the circuit is disconnected from the voltage, it enters the circuit protection process; after the circuit protection process is completed, it enters the circuit reverse demagnetization process. The control unit outputs a drive signal to turn on the second switch Q2 and the third switch Q3. The electromagnetic chuck and the first capacitor C1 form a reverse path and generate a reverse magnetic force.

[0050] Specifically, compared to the forward excitation stage, the electromagnetic chuck stores less energy during the reverse demagnetization stage. Furthermore, to prevent electric shock to workers after reverse demagnetization, the high charge stored in the first capacitor C1 needs to be discharged rather than re-stored. To improve efficiency, only the sixth switch Q6 needs to be turned on, and the second resistor R2 is used to discharge the charge in the first capacitor C1 and the reverse electromotive force generated by the electromagnetic chuck. The charge in the second capacitor C2 is relatively small, and after all the working steps are completed, the charge will be consumed to below the safe voltage.

[0051] In this embodiment of the invention, a reverse current value is set during the reverse demagnetization process. The control unit monitors the current values ​​of the third resistor R3 and the fourth resistor R4. When the second switch Q2 is turned on, if the current value of the third resistor R3 is higher than the preset reverse current value, the second switch Q2 is turned off. When the second switch Q2 is turned off, if the current value of the fourth resistor R4 is lower than the preset reverse current value, the second switch Q2 is turned on.

[0052] Specifically, when the second switch Q2 is turned on, the first capacitor C1 acts as a power source, and the current gradually increases along the second switch Q2 and the third switch Q3; when the second switch Q2 is turned off, there is no power source, and the current gradually decreases along the parasitic diodes of the third switch Q3 and the fourth switch Q4.

[0053] Specifically, the reason for setting the reverse current value in the reverse demagnetization process is that if the reverse current value is too high, the reverse magnetic force will be too large, which will cause the released workpiece to be re-adsorbed; if the reverse current value is too low, the reverse magnetic force will be too small, which will result in a weak force to push away the unreleased workpiece, and the purpose of reverse demagnetization cannot be achieved.

[0054] An embodiment of the present invention provides an electromagnetic chuck protection method based on an H-bridge, comprising:

[0055] First layer of protection: The control unit monitors the voltage value of the second resistor R2. When the voltage value of the second resistor R2 reaches the preset shutdown value, the control unit outputs a drive signal to turn off the first switch Q1. The current of the circuit is consumed along the parasitic diodes of the fourth switch Q4 and the third switch Q3.

[0056] Specifically, the first layer of protection is mainly used to suppress the rate of change of current when the electromagnetic chuck is de-energized. Based on Faraday's law of electromagnetic induction and Lenz's law, the back electromotive force generated by the inductor is determined by the inductance and the rate of change of current. Therefore, reducing the rate of change of current when the electromagnetic chuck is de-energized can effectively reduce the back electromotive force and ensure circuit safety.

[0057] Second layer of protection: The control unit monitors the current value of the fourth resistor R4. When the current value of the fourth resistor R4 is lower than the preset safe current value, the control unit outputs a drive signal to turn off the fourth switch Q4 and turn on the sixth switch Q6.

[0058] Specifically, the second layer of protection is mainly used to discharge the reverse electromotive force generated after the electromagnetic chuck is de-energized to below the circuit's safe value.

[0059] Specifically, this step fully utilizes the reverse electromotive force generated by the de-energization of the electromagnetic chuck after discharge to charge the first capacitor C1, as follows:

[0060] The control unit monitors the voltage value of the second resistor R2. When the voltage value of the second resistor R2 is lower than the preset safe voltage value, the control unit outputs a drive signal to turn off the sixth switch Q6 and turn on the fifth switch Q5, thus completing the protection process.

[0061] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A H-bridge based electromagnetic chuck drive and protection circuit, characterized in that, The circuit comprises an H-bridge driving unit, a first energy storage unit, a second energy storage unit, a discharge unit, a voltage detection unit, a current detection unit and a control unit; The H-bridge driving unit is connected to the first energy storage unit, the discharge unit, the voltage detection unit and the current detection unit; the first energy storage unit is connected to the second energy storage unit, the discharge unit and the voltage detection unit; the second energy storage unit, the voltage detection unit and the current detection unit are all connected to the control unit; and the control unit is connected to the H-bridge driving unit, the first energy storage unit and the discharge unit. The H-bridge driving unit comprises a first switch tube Q1, a second switch tube Q2, a third switch tube Q3 and a fourth switch tube Q4; the first energy storage unit comprises a fifth switch tube Q5, a first diode D1, a second diode D2 and a first capacitor C1; the second energy storage unit comprises a second capacitor C2; the discharge unit comprises a sixth switch tube Q6 and a first resistor R1; the voltage detection unit comprises a second resistor R2; and the current detection unit comprises a third resistor R3 and a fourth resistor R4. In the H-bridge driving unit, the switch pole of the first switch tube Q1 is connected to the signal output end of the control unit, the first pole of the first switch tube Q1 is connected to the voltage detection unit, and the second pole of the first switch tube Q1 is connected to the first pole of the third switch tube Q3; the switch pole of the second switch tube Q2 is connected to the signal output end of the control unit, the first pole of the second switch tube Q2 is connected to the first pole of the first switch tube Q1, and the second pole of the second switch tube Q2 is connected to the first pole of the fourth switch tube Q4; the switch pole of the third switch tube Q3 is connected to the signal output end of the control unit, the first pole of the third switch tube Q3 is connected to one end of an electromagnetic chuck, and the second pole of the third switch tube Q3 is connected to the current detection unit; and the switch pole of the fourth switch tube Q4 is connected to the signal output end of the control unit, the first pole of the fourth switch tube Q4 is connected to the other end of the electromagnetic chuck, and the second pole of the fourth switch tube Q4 is connected to the current detection unit. In the first energy storage unit, the switch pole of the fifth switch tube Q5 is connected to the signal output end of the control unit, the first pole of the fifth switch tube Q5 is connected to the cathode of the first diode D1, and the second pole of the fifth switch tube Q5 is connected to the cathode of the second diode D2; the anode of the first diode D1 is connected to a direct-current power supply input end, and the cathode of the first diode D1 is connected to the voltage detection unit; the anode of the second diode D2 is connected to the anode of the first diode D1, and the cathode of the second diode D2 is connected to the positive pole of the first capacitor C1; and the negative pole of the first capacitor C1 is connected to a ground end. In the second energy storage unit, the positive pole of the second capacitor C2 is connected to the power supply input end of the control unit, and the negative pole of the second capacitor C2 is connected to a ground end.

2. The H-bridge based electromagnetic chuck drive and protection circuit according to claim 1, wherein, The sixth switch tube Q6 is connected to the signal output end of the control unit, the first pole of the sixth switch tube Q6 is connected to the H-bridge driving unit, and the second pole of the sixth switch tube Q6 is connected to one end of the first resistor R1.

3. The H-bridge-based electromagnetic chuck driving and protection circuit according to claim 2, characterized in that, In the voltage detection unit, one end of the second resistor R2 is connected to the signal input end of the control unit and the first energy storage unit, and the other end of the second resistor R2 is connected to the signal input end of the control unit and the ground end. In the current detection unit, one end of the third resistor R3 is connected to the signal input end of the control unit and the ground end, the other end of the third resistor R3 is connected to the signal input end of the control unit, the H-bridge driving unit and one end of the fourth resistor R4, one end of the fourth resistor R4 is connected to the signal input end of the control unit, and the other end of the fourth resistor R4 is connected to the signal input end of the control unit and the H-bridge driving unit.

4. The H-bridge based electromagnetic chuck drive and protection circuit of claim 3, wherein, The anode of the third diode D3 is connected to the positive pole of the first capacitor C1, and the cathode of the third diode D3 is connected to the positive pole of the second capacitor C2.

5. The H-bridge based electromagnetic chuck drive and protection circuit of claim 4, wherein, The switch tube is an insulated gate bipolar transistor (IGBT), the gate of the IGBT serves as the switch pole of the switch tube, the collector of the IGBT serves as the first pole of the switch tube, and the emitter of the IGBT serves as the second pole of the switch tube; the diode is a power-level diode; and the first resistor R1 is a power-level aluminum shell resistor.

6. A method for driving an electromagnetic chuck based on an H-bridge, applied to the circuit according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: When the circuit input voltage, the control unit monitors the voltage value of the second resistor R2, when the voltage value of the second resistor R2 reaches the preset opening value, the control unit outputs a driving signal to open the first switch tube Q1 and the fourth switch tube Q4, the electromagnetic chuck and the DC power supply form a forward path, and a forward magnetic force is generated; When the circuit is disconnected, the protection process of the circuit is entered; After waiting for the protection process of the circuit to complete, the reverse demagnetization process of the circuit is entered, the control unit outputs a driving signal to open the second switch tube Q2 and the third switch tube Q3, the electromagnetic chuck and the first capacitor C1 form a reverse path, and a reverse magnetic force is generated.

7. The H-bridge-based electromagnetic chuck driving method according to claim 6, wherein, The reverse demagnetization process sets a reverse current value, the control unit monitors the current values of the third resistor R3 and the fourth resistor R4, when the second switch tube Q2 is opened, the current value of the third resistor R3 is higher than the preset reverse current value, and the second switch tube Q2 is closed; when the second switch tube Q2 is closed, the current value of the fourth resistor R4 is lower than the preset reverse current value, and the second switch tube Q2 is opened.

8. A method for protecting an H-bridge based electromagnetic chuck, applied to the circuit according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: First heavy protection: the control unit monitors the voltage value of the second resistor R2, when the voltage value of the second resistor R2 reaches the preset closing value, the control unit outputs the driving signal, closes the first switch tube Q1, and the current of the circuit is consumed along the parasitic diode of the fourth switch tube Q4 and the third switch tube Q3; Second heavy protection: the control unit monitors the current value of the fourth resistor R4, when the current value of the fourth resistor R4 is lower than the preset safety current value, the control unit outputs the driving signal, closes the fourth switch tube Q4, and opens the sixth switch tube Q6; The control unit monitors the voltage value of the second resistor R2, when the voltage value of the second resistor R2 is lower than the preset safety voltage value, the control unit outputs the driving signal, closes the sixth switch tube Q6 and opens the fifth switch tube Q5, and the protection process is completed.

Images