Robot joint module power device overcurrent protection circuit and protection method

Abstract

The invention relates to a robot joint module power device overcurrent protection circuit, which comprises three circuits connected in parallel and power devices and motors on the three circuits, and is characterized in that the tail ends of the first circuit, the second circuit and the third circuit are respectively connected in parallel with a fourth branch (7) and a fifth branch (8), a sixth branch (9) and a seventh branch (10), and an eighth branch (11) and a ninth branch (12); the fourth branch circuit, the sixth branch circuit and the eighth branch circuit are connected with sampling resistors R1, R2 and R3 respectively. The tail ends of the fifth branch, the seventh branch and the ninth branch are respectively connected in parallel with a first branch (13) and a second branch (14), a third branch (15) and a fourth branch (16), and a fifth branch (17) and a sixth branch (18); the second branch, the fourth branch and the sixth branch are connected with the anode ends of the diodes D4, D5 and D6 respectively, the common cathode end of the diodes D4, D5 and D6 is connected with the cathode of the operational amplifier U2 through a tail end circuit (19), and the anode of the operational amplifier U2 is provided with an over-current threshold Ref. The bidirectional overcurrent protection circuit has the advantages of bidirectional overcurrent protection and timely early warning for the power device.

Description

Technical Field

[0001] The present invention relates to the technical field of robot systems, and in particular to an overcurrent protection circuit and a protection method for power devices of a robot joint module. Background Art

[0002] Collaborative robots are now widely used in various new energy scenarios. The collaborative robot body is usually composed of joint modules, which mainly control the operation of permanent magnet brushless DC motors through driver boards. Effective overcurrent protection of MOSFET and IGBT power devices in the driver board is the key to ensuring the normal operation of the robot system.

[0003] In order to realize the over-current protection function, such as Figure 1 As shown in the figure, most of the existing solutions perform overcurrent protection by detecting the Vds voltage generated when the MOSFET is turned on or the Vce voltage when the IGBT is turned on. However, this form of protection can only protect the power device from unidirectional overcurrent, and most of them need to use a driver chip with corresponding overcurrent protection function to achieve it, which has a single function and high cost. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing overcurrent protection method only supports unidirectional protection and the cost of the chip for coordinated protection is high. A robot joint module power device overcurrent protection circuit is provided, which can output an overcurrent alarm to shut down the drive chip in time, and at the same time achieve a bidirectional overcurrent protection effect on the power device.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A robot joint module power device overcurrent protection circuit comprises a first circuit, a second circuit and a third circuit connected in parallel, the first circuit is connected with a power device Q1 and a power device Q2 in sequence, the second circuit is connected with a power device Q3 and a power device Q4 in sequence, and the third circuit is connected with a power device Q5 and a power device Q6 in sequence; The circuit between the power device Q1 and the power device Q2 is connected to the motor U through branch 1, the circuit between the power device Q3 and the power device Q4 is connected to the motor V through branch 2, and the circuit between the power device Q5 and the power device Q6 is connected to the motor W through branch 3; The ends of the first circuit are respectively connected to two parallel branches four and five, the ends of the second circuit are respectively connected to two parallel branches six and seven, and the ends of the third circuit are respectively connected to two parallel branches eight and nine; Branch 4 is connected to a sampling resistor R1, branch 6 is connected to a sampling resistor R2, branch 8 is connected to a sampling resistor R3, and branch 4, branch 6 and branch 8 are all connected to GND; The end of branch five is connected in parallel with two circuits, namely branch one and branch two; the end of branch seven is connected in parallel with two circuits, namely branch three and branch four; the end of branch nine is connected in parallel with two circuits, namely branch five and branch six; Branch two, branch four and branch six are connected to the anode terminals of diodes D4, D5 and D6 respectively, and the common cathode terminals of the three diodes are connected to the cathode of operational amplifier U2 through the terminal circuit. An overcurrent threshold Ref is set on the anode of operational amplifier U2.

[0006] Furthermore, branch one, branch three and branch five are connected to the cathode terminals of diodes D1, D2 and D3 respectively, and the common anode terminal of the three diodes is connected to the cathode of operational amplifier U3 through an inverting circuit, and an overcurrent threshold Ref is provided on the anode of operational amplifier U3.

[0007] Furthermore, the inverting circuit includes an operational amplifier U1, a cathode of the operational amplifier U1 is connected to a resistor R4 and a resistor R5 in parallel, the other end of the resistor R4 is connected to a common anode terminal of a diode D1, a diode D2 and a diode D3, the other end of the resistor R5 is connected to an output terminal of the operational amplifier U1 through a circuit, and the positive terminal of the operational amplifier U1 is grounded.

[0008] Furthermore, the terminal circuit is connected to a resistor R6, and its branch circuit is connected to a resistor R7.

[0009] Furthermore, the output terminals of the operational amplifier U2 and the operational amplifier U3 are both connected to the power supply voltage Vcc terminal, and the input terminals of the first circuit, the second circuit and the third circuit are all connected to the power supply voltage Vdd terminal.

[0010] In order to further achieve the purpose of the present invention, a method for overcurrent protection of power devices of a robot joint module is also provided. Using the above-mentioned overcurrent protection circuit, the specific steps are as follows: (1) When the current flows from the motor U, V, W to the lower bridge arm power device to GND through the power device Q2, Q4 or Q6, the current will also flow through the sampling resistor R1, R2 or R3 and generate a sampling voltage at both ends of the corresponding sampling resistor; (2) Diodes D4, D5, and D6 form a half-wave rectifier circuit. Due to half-wave rectification, the common cathode terminal voltage of diodes D4, D5, and D6 is the maximum value V+ of the sampling voltage generated by the three sampling resistors R1, R2, or R3. max ; (3) The sampled voltage value on the negative electrode of the operational amplifier U2 is the maximum current value flowing through the power devices Q2, Q4, and Q6 converted by the sampling resistors R1, R2, and R3; (4) Set the corresponding overcurrent threshold Ref on the positive electrode of the operational amplifier U2 to set the overcurrent protection conditions for different power ranges, and when V+ max When it is greater than Ref, it is determined that overcurrent occurs, and the output terminal of the operational amplifier U2 outputs a low-level alarm signal. The system receives the alarm signal and stops the operation of the entire system to protect the power devices.

[0011] Furthermore, in step (1), when the current flows out of the lower bridge arm power device from GND through the power device Q2, Q4 or Q6 and continues to flow to the motor U, V, W, the current will also flow through the sampling resistor R1, R2 or R3 and generate a sampling voltage across the corresponding sampling resistor.

[0012] Furthermore, in step (2), the diodes D1, D2, and D3 form a half-wave rectifier circuit. Due to the half-wave rectification, the common anode terminal voltage of the diodes D1, D2, and D3 is the maximum value V-1 of the sampling voltage generated by the three sampling resistors R1, R2, or R3. max .

[0013] Furthermore, in step (3), the operational amplifier U1 inverting circuit is used to convert V- max The inverted output is given to the operational amplifier U3, so that the sampled voltage value on the negative electrode of the operational amplifier U3 is the maximum current value flowing through the power devices Q2, Q4, and Q6 converted by the sampling resistor.

[0014] Furthermore, in step (4), a corresponding overcurrent threshold Ref is set on the positive electrode of the operational amplifier U3 to set the overcurrent protection conditions of different power sections, and when V- max When it is greater than Ref, it is determined that overcurrent occurs, and the output terminal of the operational amplifier U3 outputs a low-level alarm signal. The system receives the alarm signal and stops the operation of the entire system to protect the power devices.

[0015] In the technical solution of the present invention, the low-side resistor voltage is collected, and the low-side resistor voltage value is collected in real time through the rectifier circuit and an overcurrent threshold is set. When a positive or negative overcurrent occurs in a phase current value of the lower bridge arm and exceeds the set overcurrent threshold, the circuit of the present invention can output an overcurrent alarm to shut down the drive chip in time, thereby achieving bidirectional overcurrent protection for the power device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of an overcurrent protection circuit in the prior art; Figure 2 This is a circuit diagram of overcurrent protection for power devices of a robot joint module of the present invention; Figure 3 It is a schematic diagram of simulation calculation when forward overcurrent occurs in this embodiment; Figure 4 It is a schematic diagram of simulation calculation when negative overcurrent occurs in this embodiment. DETAILED DESCRIPTION

[0017] Example To make the present invention more clear, an overcurrent protection circuit and a protection method for a power device of a robot joint module of the present invention are further described below in conjunction with the accompanying drawings. The specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0018] See also Figure 2 A robot joint module power device overcurrent protection circuit comprises a first circuit 1, a second circuit 2 and a third circuit 3 connected in parallel, the first circuit 1 is connected with a power device Q1 and a power device Q2 in sequence, the second circuit 2 is connected with a power device Q3 and a power device Q4 in sequence, and the third circuit 3 is connected with a power device Q5 and a power device Q6 in sequence; the circuit between the power device Q1 and the power device Q2 is connected to a motor U through a branch 1 4, the circuit between the power device Q3 and the power device Q4 is connected to a motor V through a branch 2 5, and the circuit between the power device Q5 and the power device Q6 is connected to a motor W through a branch 3 6, characterized in that: The ends of the first circuit 1 are respectively connected to two parallel branches 4 7 and 5 8, the ends of the second circuit 2 are respectively connected to two parallel branches 6 9 and 7 10, and the ends of the third circuit 3 are respectively connected to two parallel branches 8 11 and 9 12; The branch 4 7 is connected to a sampling resistor R1, the branch 6 9 is connected to a sampling resistor R2, the branch 8 11 is connected to a sampling resistor R3, and the branch 4 7, the branch 6 9 and the branch 8 11 are all connected to GND; The end of branch five 8 is connected in parallel with two circuits, namely branch one 13 and branch two 14; the end of branch seven 10 is connected in parallel with two circuits, namely branch three 15 and branch four 16; the end of branch nine 12 is connected in parallel with two circuits, namely branch five 17 and branch six 18; The second branch 14, the fourth branch 16 and the sixth branch 18 are connected to the anode terminals of the diodes D4, D5 and D6 respectively, and the common cathode terminals of the three diodes are connected to the negative electrode of the operational amplifier U2 through the terminal circuit 19. The terminal circuit 19 is connected to a resistor R6, and its branch circuit is connected to a resistor R7. The positive electrode of the operational amplifier U2 is provided with an overcurrent threshold Ref; Branch 1 13, branch 3 15 and branch 5 17 are connected to the cathode terminals of diode D1, diode D2 and diode D3 respectively, and the common anode terminal of the three diodes is connected to the cathode of operational amplifier U3 through an inverting circuit 20, and an overcurrent threshold Ref is provided on the anode of operational amplifier U3; The inverting circuit 20 includes an operational amplifier U1, a cathode of which is connected to resistors R4 and R5 in parallel, the other end of the resistor R4 is connected to the common anode end of diodes D1, D2 and D3, the other end of the resistor R5 is connected to the output end of the operational amplifier U1 through a circuit, and the positive end of the operational amplifier U1 is grounded.

[0019] In this embodiment, the output terminals of the operational amplifier U2 and the operational amplifier U3 are connected to the power supply voltage Vcc terminal, and the input terminals of the first circuit 1, the second circuit 2 and the third circuit 3 are connected to the power supply voltage Vdd terminal.

[0020] The present invention performs overcurrent protection according to the following method: Diodes D4, D5, and D6 form a half-wave rectifier circuit. When the current flows from the motor U, V, or W into the lower arm power device to GND through the power device Q2, Q4, or Q6, Figure 2 In the direction of Q4 current, the current will also flow through the sampling resistors R1, R2 or R3, generating a sampling voltage at both ends of the sampling resistors. Due to half-wave rectification, the common cathode terminal voltage of diodes D4, D5, and D6 is the maximum value V+ of the sampling voltage generated by the three sampling resistors R1, R2 or R3. max In this way, the sampled voltage value on the negative electrode of the operational amplifier U2 is the maximum current value flowing through the power devices Q2, Q4, and Q6 converted by the sampling resistor. At the same time, by setting the corresponding overcurrent threshold Ref on the positive electrode of the operational amplifier U2, the overcurrent protection conditions of different power ranges can be set. max When it is greater than Ref, it is determined that overcurrent occurs. The output terminal of the operational amplifier U2 outputs a low-level alarm signal, and the system receives the alarm signal to stop the operation of the entire system to protect the power devices.

[0021] Diodes D1, D2, and D3 form a half-wave rectifier circuit. When the current flows out of the lower bridge arm power device through the power device Q2, Q4, or Q6 from GND to the motor U, V, or W, Figure 2 In the direction of Q2 current, the current will also flow through the sampling resistors R1, R2 or R3, generating a sampling voltage at both ends of the sampling resistors. Due to half-wave rectification, the common anode terminal voltage of the diodes D1, D2, and D3 is the maximum value V- of the sampling voltage generated by the three sampling resistors R1, R2 or R3. max . V- max The inverted output is sent to the operational amplifier U3. In this way, the sampled voltage value on the negative electrode of the operational amplifier U3 is the maximum current value flowing through the power devices Q2, Q4, and Q6 converted by the sampling resistor. At the same time, by setting the corresponding overcurrent threshold Ref on the positive electrode of the operational amplifier U3, the overcurrent protection conditions of different power ranges can be set. maxWhen it is greater than Ref, it is determined that overcurrent occurs. The output terminal of the operational amplifier U3 outputs a low-level alarm signal, and the system receives the alarm signal to stop the operation of the entire system to protect the power devices.

[0022] See also Figure 3 , the above circuit is simulated and calculated by simulation tools. When the motor current flows into the lower bridge arm power device and a forward overcurrent occurs, the overcurrent value is set to 90A, V+ max When it is greater than Ref, the system outputs an over-current alarm signal 3.3V and is pulled down, indicating that the circuit is working as designed.

[0023] See also Figure 4 When the current flows from the lower bridge arm power device into the motor current and a negative overcurrent occurs, the overcurrent value is set to -90A. The inverted V- max If the voltage is greater than Ref, the system outputs an over-current alarm signal 3.3V which is pulled down. This indicates that the circuit is working as designed. At the same time, it takes about 2us from the occurrence of over-current to the actual alarm signal being pulled down.

[0024] It can be seen that by adopting the circuit of the present invention and the corresponding overcurrent protection method, bidirectional overcurrent protection of power devices can be effectively provided, and the reaction is sensitive and the response is timely, so that it is convenient to give an alarm in time and take effective measures to deal with it.

[0025] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A robot joint module power device overcurrent protection circuit, comprising a first circuit (1), a second circuit (2) and a third circuit (3) connected in parallel, the first circuit (1) is connected with a power device Q1 and a power device Q2 in sequence, the second circuit (2) is connected with a power device Q3 and a power device Q4 in sequence, the third circuit (3) is connected with a power device Q5 and a power device Q6 in sequence, the circuit between the power device Q1 and the power device Q2 is connected to a motor U via a branch 1 (4), the circuit between the power device Q3 and the power device Q4 is connected to a motor V via a branch 2 (5), and the circuit between the power device Q5 and the power device Q6 is connected to a motor W via a branch 3 (6), characterized in that: The ends of the first circuit (1) are respectively connected to two parallel branches, a fourth branch (7) and a fifth branch (8); the ends of the second circuit (2) are respectively connected to two parallel branches, a sixth branch (9) and a seventh branch (10); and the ends of the third circuit (3) are respectively connected to two parallel branches, an eighth branch (11) and a ninth branch (12); The branch 4 (7) is connected to a sampling resistor R1, the branch 6 (9) is connected to a sampling resistor R2, the branch 8 (11) is connected to a sampling resistor R3, and the branch 4 (7), the branch 6 (9) and the branch 8 (11) are all connected to GND; The end of branch five (8) is connected in parallel with two circuits, namely branch one (13) and branch two (14); the end of branch seven (10) is connected in parallel with two circuits, namely branch three (15) and branch four (16); the end of branch nine (12) is connected in parallel with two circuits, namely branch five (17) and branch six (18); Branch 2 (14), branch 4 (16) and branch 6 (18) are respectively connected to the anode terminals of diodes D4, D5 and D6, and the common cathode terminals of the three diodes are connected to the cathode of the operational amplifier U2 through the terminal circuit (19). An overcurrent threshold Ref is provided on the anode of the operational amplifier U2.

2. The robot joint module power device overcurrent protection circuit according to claim 1, characterized in that: The branch path 1 (13), the branch path 3 (15) and the branch path 5 (17) are respectively connected to the cathode terminals of the diode D1, the diode D2 and the diode D3, and the common anode terminal of the three diodes is connected to the negative electrode of the operational amplifier U3 through an inverting circuit (20), and an overcurrent threshold Ref is provided on the positive electrode of the operational amplifier U3.

3. The robot joint module power device overcurrent protection circuit according to claim 2, characterized in that: The inverting circuit (20) comprises an operational amplifier U1, the cathode of the operational amplifier U1 is connected to a resistor R4 and a resistor R5 connected in parallel, the other end of the resistor R4 is connected to the common anode end of the diode D1, the diode D2 and the diode D3, the other end of the resistor R5 is connected to the output end of the operational amplifier U1 through a circuit, and the anode of the operational amplifier U1 is grounded.

4. The robot joint module power device overcurrent protection circuit according to any one of claims 1 to 3, characterized in that: The terminal circuit (19) is connected to a resistor R6, and its branch circuit is connected to a resistor R7.

5. The robot joint module power device overcurrent protection circuit according to claim 2 or 3, characterized in that: The output ends of the operational amplifier U2 and the operational amplifier U3 are both connected to the power supply voltage Vcc end, and the input ends of the first circuit (1), the second circuit (2) and the third circuit (3) are all connected to the power supply voltage Vdd end.

6. A method for overcurrent protection of power devices of a robot joint module as claimed in claim 3, characterized in that: Step 1: When the current flows from the motor U, V, W to the lower bridge arm power device through the power device Q2, Q4 or Q6 to GND, the current will also flow through the sampling resistor R1, R2 or R3, and generate a sampling voltage across the corresponding sampling resistor; Step 2: Diodes D4, D5, and D6 form a half-wave rectifier circuit. Due to half-wave rectification, the common cathode terminal voltage of diodes D4, D5, and D6 is the maximum value V+ of the sampling voltage generated by the three sampling resistors R1, R2, or R3. max ; Step 3: The sampled voltage value on the negative electrode of the operational amplifier U2 is the maximum current value flowing through the power devices Q2, Q4, and Q6 converted by the sampling resistors R1, R2, and R3; Step 4: Set the corresponding overcurrent threshold Ref on the positive electrode of the operational amplifier U2 to set the overcurrent protection conditions for different power ranges. max When it is greater than Ref, it is determined that overcurrent occurs, and the output terminal of the operational amplifier U2 outputs a low-level alarm signal. The system receives the alarm signal and stops the operation of the entire system to protect the power devices.

7. The method for overcurrent protection of power devices of a robot joint module according to claim 6, characterized in that: In step 1, when the current flows out of the lower bridge arm power device from GND through the power device Q2, Q4 or Q6 and continues to flow to the motors U, V, W, the current will also flow through the sampling resistor R1, R2 or R3 and generate a sampling voltage across the corresponding sampling resistor.

8. The method for overcurrent protection of power devices of a robot joint module according to claim 7, characterized in that: In the step 2, diodes D1, D2, and D3 form a half-wave rectifier circuit. Due to the half-wave rectification, the common anode terminal voltage of diodes D1, D2, and D3 is the maximum value V-1 of the sampling voltage generated by the three sampling resistors R1, R2, or R3. max .

9. The method for overcurrent protection of power devices of a robot joint module according to claim 8, characterized in that: In step 3, the operational amplifier U1 inverts the V- max The inverted output is given to the operational amplifier U3, so that the sampled voltage value on the negative electrode of the operational amplifier U3 is the maximum current value flowing through the power devices Q2, Q4, and Q6 converted by the sampling resistor.

10. The method for overcurrent protection of power devices of a robot joint module according to claim 9, characterized in that: In the step 4, the corresponding overcurrent threshold Ref is set on the positive electrode of the operational amplifier U3 to set the overcurrent protection conditions of different power sections, and when V- max When it is greater than Ref, it is determined that overcurrent occurs, and the output terminal of the operational amplifier U3 outputs a low-level alarm signal. The system receives the alarm signal and stops the operation of the entire system to protect the power devices.

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