Motor overvoltage protection device and motor control system

Abstract

The utility model provides a motor overvoltage protection device comprising a software crash prevention unit, an input end of which is connected with a control unit and is used for detecting abnormal information of the control unit and generating control information; and the input end of the back electromotive force protection unit is connected with the software crash prevention unit, the output end of the back electromotive force protection unit is connected with the motor driving unit, and the back electromotive force protection unit is closed according to the control information, so that a lower bridge arm MOS tube of an inverter circuit in the motor driving unit is conducted, and back electromotive force electric energy in the motor is consumed. When the software crash prevention unit detects abnormity, control information is generated, so that the back electromotive force protection unit is closed, and then the back electromotive force protection unit can convert back electromotive force electric energy into heat energy to be consumed by driving a lower bridge arm MOS tube of the inverter circuit to be conducted, so that energy accumulation is avoided; the protection function in the motor overvoltage protection device is completely realized by a hardware circuit, and the motor overvoltage protection device can still work independently even when software fails or is powered down, so that the system reliability is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of motor protection technology, specifically to a motor overvoltage protection device and a motor control system. Background Technology

[0002] In motor control systems, when the motor suddenly loses power or experiences a software malfunction (such as a system crash or runaway), the motor coils generate a high-amplitude back electromotive force (EMF). If this energy is not released in time, the back EMF will flow back into the controller through the inverter circuit, causing device breakdown and damage. Existing technologies mostly rely on software monitoring and control for back EMF protection, but when the controller loses power or the software fails, the protection mechanism cannot be triggered, posing a risk of hardware damage.

[0003] To address the aforementioned shortcomings, the following solutions are commonly used in existing technologies: 1. Software monitoring method: Real-time monitoring of the motor status via software triggers energy recovery or discharge circuits. This method is highly dependent on software; if the software crashes or power fails, the protection function fails, and the system loses its protection capability. 2. Hardware RC absorption circuit: An RC buffer circuit is connected in parallel in the inverter circuit to passively absorb some of the back electromotive force energy. This method has insufficient response speed, low passive absorption efficiency of the RC circuit, and cannot quickly discharge the large back electromotive force, and its reliability is low. Summary of the Invention

[0004] To overcome the above-mentioned technical defects, the present invention provides a motor overvoltage protection device and a motor control system, which can consume the back electromotive force energy inside the motor.

[0005] To solve the above problems, the present invention is implemented according to the following technical solution:

[0006] An overvoltage protection device for a motor, comprising:

[0007] The anti-software crash unit has its input end connected to the control unit and is used to detect abnormal information from the control unit and generate control information.

[0008] The back electromotive force protection unit has its input end connected to the anti-software crash unit and its output end connected to the motor drive unit. It is used to close according to the control information so that the lower bridge arm MOS transistor in the inverter circuit of the motor drive unit is turned on, consuming the back electromotive force energy inside the motor.

[0009] As a further improvement of this utility model, the anti-software crash unit includes:

[0010] Current limiting circuit, with its input terminal connected to the control unit;

[0011] The voltage multiplier circuit has its input terminal connected to the current limiting circuit and its output terminal connected to the back electromotive force protection unit.

[0012] As a further improvement of this utility model, the current limiting circuit includes: a first resistor;

[0013] The control unit is connected to the voltage multiplier circuit through the first resistor.

[0014] As a further improvement of this utility model, the voltage multiplier circuit is a double voltage multiplier circuit.

[0015] As a further improvement of this utility model, the voltage multiplier circuit includes: a first capacitor, a second capacitor, a first diode, and a second diode;

[0016] The current limiting circuit is connected to the back EMF protection unit through the first capacitor and the first diode.

[0017] The current limiting circuit is grounded through the first capacitor and the second diode;

[0018] The first diode is grounded through the second capacitor.

[0019] As a further improvement of this utility model, the back EMF protection unit includes: an inverter and a switching circuit;

[0020] The input terminal of the inverter is connected to the output terminal of the anti-software crash unit, and the output terminal of the inverter is sequentially connected to the switching circuit and the motor drive unit.

[0021] As a further improvement of this utility model, this utility model also includes: a fourth resistor: the inverter includes: a first transistor, a second resistor, and a third resistor;

[0022] The output terminal of the anti-software crash unit is connected to the base of the first transistor through the second resistor;

[0023] The base of the first transistor is grounded through the fourth resistor, the collector of the first transistor is connected to the power supply through the third resistor, the collector of the first transistor is connected to the switching circuit, and the emitter of the first transistor is grounded.

[0024] As a further improvement of this utility model, the switching circuit includes: a fifth resistor, a sixth resistor, a second transistor, a third diode, and a fourth diode;

[0025] The base of the second transistor is connected to the collector of the first transistor. The second transistor is connected to the power supply through the sixth resistor. The emitter of the second transistor is grounded through the fourth diode. The emitter of the second transistor is connected to the motor drive unit through the fifth resistor and the third diode.

[0026] As a further improvement of this utility model, both the first transistor and the second transistor are NPN transistors.

[0027] In addition, this utility model also provides a motor control system, including the above-mentioned motor overvoltage protection device, and further including: a motor drive unit and a control unit;

[0028] The control unit is connected to the anti-software crash unit, and the motor drive unit is connected to the back EMF protection unit and the motor.

[0029] Compared with the prior art, the beneficial effects of this utility model are as follows: By using the anti-software crash unit to detect abnormal information of the control unit in real time, such as whether the control unit has lost power or crashed, it does not rely on software operation. When an abnormality is detected, control information is generated, causing the back EMF protection unit to close. In turn, the back EMF protection unit can drive the lower bridge arm MOS transistor of the inverter circuit to conduct, converting the back EMF energy into heat energy for consumption, avoiding energy accumulation. The protection function in the motor overvoltage protection device is completely implemented by hardware circuit. Even if the software fails or the power is lost, it can still work independently, significantly improving the system reliability. Attached Figure Description

[0030] Figure 1 This is a framework diagram of the motor overvoltage protection system described in this invention;

[0031] Explanation of reference numerals in the attached diagram: 1. Anti-software crash unit; 11. Current limiting circuit; 12. Voltage multiplier circuit; 2. Back EMF protection unit; 21. Inverter; 22. Switching circuit; 100. Motor drive unit; 200. Control unit; 300. Motor. Detailed Implementation

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

[0033] Example 1

[0034] This embodiment provides a motor overvoltage protection device, such as... Figure 1 As shown, it includes: an anti-software crash unit 1 and a back EMF protection unit 2; wherein, the input terminal of the anti-software crash unit 1 is connected to the control unit 200, and is used to detect abnormal information of the control unit 200 and generate control information; the input terminal of the back EMF protection unit 2 is connected to the anti-software crash unit 1, and the output terminal is connected to the motor drive unit 100, and is used to close according to the control information, so that the lower bridge arm MOS transistor of the inverter circuit in the motor drive unit 100 is turned on, consuming the back EMF energy inside the motor 300.

[0035] Abnormal information includes information generated when the controller loses power or the software crashes. The back EMF protection module uses the back EMF to drive the inverter circuit control branch. If the motor 300 has a back EMF, the back EMF protection module will conduct the three control branches of the lower bridge arm of the inverter circuit to consume the back EMF energy inside the motor 300.

[0036] The anti-software crash unit 1 includes: a current limiting circuit 11 and a voltage multiplier circuit 12. The input terminal of the current limiting circuit 11 is connected to the control unit 200; the input terminal of the voltage multiplier circuit 12 is connected to the current limiting circuit 11, and the output terminal is connected to the back electromotive force protection unit 2.

[0037] The current limiting circuit 11 includes: a first resistor R1; the control unit 200 is connected to the voltage multiplier circuit 12 through the first resistor.

[0038] Preferably, the voltage multiplier circuit 12 is a double voltage multiplier circuit.

[0039] The voltage multiplier circuit 12 includes: a first capacitor C1, a second capacitor C2, a first diode D1, and a second diode D2; the current limiting circuit 11 is connected to the back EMF protection unit 2 through the first capacitor C1 and the forward-conducting first diode D1; the current limiting circuit 11 is grounded through the first capacitor C1 and the reverse-conducting second diode D2; the cathode of the first diode D1 is grounded through the second capacitor C2.

[0040] The first resistor R1 is connected to the I / O port of the control unit 200, which serves to limit current and protect the subsequent circuit from damage caused by charging surges.

[0041] The back EMF protection unit 2 includes an inverter 21 and a switching circuit 22; the input terminal of the inverter 21 is connected to the output terminal of the anti-software crash unit 1, and the output terminal of the inverter 21 is sequentially connected to the switching circuit 22 and the motor drive unit 100.

[0042] Furthermore, this embodiment also includes: a fourth resistor R4; the inverter 21 includes: a first transistor Q1, a second resistor R2, and a third resistor R3; the output terminal of the anti-software crash unit 1 is connected to the base of the first transistor Q1 through the second resistor R2; the base of the first transistor Q1 is grounded through the fourth resistor R4, the collector of the first transistor Q1 is connected to the positive power supply VM through the third resistor R3, the collector of the first transistor Q1 is connected to the switching circuit 22, and the emitter of the first transistor Q1 is grounded.

[0043] The second resistor R2 limits the current. The first transistor Q1 is an NPN transistor. The fourth resistor R4 enhances the anti-static capability, improves the shutdown speed, and prevents malfunctions. At the same time, it provides a fixed voltage level to the first transistor Q1 in the event of a power failure or software malfunction.

[0044] The switching circuit 22 includes: a fifth resistor R5, a sixth resistor R6, a second transistor Q2, a third diode D3, and a fourth diode D4; the base of the second transistor Q2 is connected to the collector of the first transistor Q1, the second transistor Q2 is connected to the positive power supply VM through the sixth resistor R6, the emitter of the second transistor Q2 is grounded through the fourth diode D4, and the emitter of the second transistor Q2 is connected to the motor drive unit 100 through the fifth resistor R5 and the third diode D3.

[0045] Inverter 21 outputs a control signal to the second transistor Q2 to control the on / off state of the second transistor Q2. When the anti-software crash module outputs a low level signal, the first transistor Q1 is cut off, and inverter 21 outputs a high level signal to control the second transistor Q2 to turn on; conversely, when the anti-software crash module outputs a high level signal, inverter 21 outputs a low level signal to control the second transistor Q2 to turn off.

[0046] In the circuit described above, the third resistor R3 shares the power flowing through the first transistor Q1 and provides the driving power to the base of the second transistor Q2. The sixth resistor R6 is connected to the positive terminal VM of the power supply and the collector of the second transistor Q2, respectively, and serves as a current limiter. The second transistor Q2 is an NPN transistor. When the inverter 21 outputs a low level and there is a back electromotive force at the positive terminal VM of the power supply, the second transistor Q2 turns on, and the back electromotive force is transmitted through the sixth resistor R6, the second transistor Q2, the fifth resistor R5, and the third diode D3 to drive the MOSFET of the lower bridge arm. The fifth resistor R5 is connected to the emitter of the second transistor Q2 and the third diode D3, respectively, and serves as a current limiter. The third diode D3 is connected to the MOSFET of the lower bridge arm and the fifth resistor R5, which utilizes the unidirectional conductivity of the diode to prevent interference from the normal driving signal of the control unit 200. The fourth diode, D4, is a Zener diode. Zener diode D4 is connected to the emitter of the second transistor Q2 and ground, respectively, to prevent excessive reverse electromotive force from damaging the gate of the MOSFET.

[0047] The present invention will be further explained in conjunction with the specific implementation process, as follows:

[0048] When the control unit 200 is in normal working condition, the I / O port continuously outputs square wave signals to the voltage doubler circuit 12. After the second capacitor C2 starts storing energy, the voltage rises to a high level. When the control unit 200 is in a power-off or software crash state, the I / O port stops outputting square wave signals, and the second capacitor C2 quickly discharges to a low level. Therefore, the output signal of the anti-software crash module has two different level states. By observing the level state of this output signal, it can be determined whether the control unit 200 is in a power-off or crash state or in normal working condition.

[0049] When the control unit 200 is in normal working condition, the I / O port continuously outputs square wave signals. If the control signal output by the anti-software crash unit 1 is greater than the input threshold of the back EMF protection module, the second transistor Q2 will be cut off, and the back EMF protection unit 2 will be disabled. If a back EMF exists, the control unit 200 can implement energy recovery according to the normal function strategy. Conversely, when the control unit 200 is in a power-off or software crash state, the I / O port stops outputting square wave signals, and the second capacitor C2 quickly discharges to a level lower than the input threshold of the back EMF protection module. If a back EMF exists, the back EMF protection unit 2 will be enabled.

[0050] In summary, this utility model has the following beneficial effects:

[0051] 1. High-reliability protection:

[0052] The back EMF protection function is implemented independently through hardware circuitry, completely eliminating reliance on software operation. Even if the control unit loses power, the software crashes, or malfunctions, it can still autonomously trigger protection actions, avoiding the risk of hardware damage due to software failure.

[0053] Comparative results: Traditional software monitoring solutions have a near 100% failure rate under abnormal conditions, while this invention can achieve nearly 100% hardware-level protection coverage.

[0054] 2. Ultra-fast response capability:

[0055] Hardware circuits (such as the voltage doubler circuit of the anti-software crash unit) detect abnormal information of the control unit in real time. Combined with inverter and MOSFET drive logic, the protection action can be completed within milliseconds of detecting the abnormality, and the response speed is more than 10 times faster than the traditional RC snubber circuit.

[0056] Comparative results: Existing hardware RC circuits require passive absorption to gradually consume energy, while the active discharge mechanism of this invention can quickly cut off the risk in the early stage of back electromotive force formation.

[0057] 3. High-efficiency energy release:

[0058] By turning on the lower bridge arm MOSFET of the inverter circuit through the back EMF protection unit, the back EMF energy is directly converted into heat energy and consumed, avoiding energy feedback to the power supply or accumulation in the circuit. The protection efficiency is improved by more than 80% compared with the traditional solution.

[0059] Comparative results: In traditional solutions, energy may remain in the circuit, causing secondary impacts, while this invention can completely eliminate such potential hazards.

[0060] 4. Dynamic adaptive protection:

[0061] Based on the charging and discharging characteristics of the capacitor (such as the voltage change of the second capacitor C2), the state of the control unit is dynamically determined to ensure that the protection threshold matches the system operating conditions in real time. For example, protection can still be accurately triggered under high motor speed or heavy load scenarios.

[0062] Comparative results: Existing fixed threshold schemes are prone to false triggering or protection delays due to changes in operating conditions, while the dynamic threshold design of this invention can adapt to complex application environments.

[0063] 5. Extend device lifespan:

[0064] The Zener diode D4 and current-limiting resistors (sixth resistor R6 and fifth resistor R5) protect the gate of the MOSFET from high-voltage surges, while reducing long-term damage to the inverter circuit from back electromotive force, thus significantly extending the service life of key components.

[0065] Comparative results: In traditional solutions, the probability of MOSFET breakdown is relatively high, while the present invention can reduce the device failure rate by more than 90%.

[0066] Example 2

[0067] This embodiment provides a motor control system, including the motor overvoltage protection device described in Embodiment 1, and further including: a motor drive unit 100 and a control unit 200; the control unit 200 is connected to the anti-software crash unit 1, and the motor drive unit 100 is connected to the back EMF protection unit 2 and the motor 300.

[0068] For the structure of the control unit and the motor drive unit, please refer to the prior art. For the specific implementation of this embodiment, please refer to Implementation 1, which will not be repeated here.

[0069] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A motor overvoltage protection device, characterized in that, include: The anti-software crash unit has its input end connected to the control unit and is used to detect abnormal information from the control unit and generate control information. The back electromotive force protection unit has its input end connected to the anti-software crash unit and its output end connected to the motor drive unit. It is used to close according to the control information so that the lower bridge arm MOS transistor in the inverter circuit of the motor drive unit is turned on, consuming the back electromotive force energy inside the motor.

2. The motor overvoltage protection device according to claim 1, characterized in that, The anti-software crash unit includes: Current limiting circuit, with its input terminal connected to the control unit; The voltage multiplier circuit has its input terminal connected to the current limiting circuit and its output terminal connected to the back electromotive force protection unit.

3. The motor overvoltage protection device according to claim 2, characterized in that, The current limiting circuit includes: a first resistor; The control unit is connected to the voltage multiplier circuit through the first resistor.

4. The motor overvoltage protection device according to claim 2, characterized in that, The voltage multiplier circuit is a double voltage multiplier circuit.

5. The motor overvoltage protection device according to claim 3 or 4, characterized in that, The voltage multiplier circuit includes: a first capacitor, a second capacitor, a first diode, and a second diode; The current limiting circuit is connected to the back EMF protection unit through the first capacitor and the first diode. The current limiting circuit is grounded through the first capacitor and the second diode; The first diode is grounded through the second capacitor.

6. The motor overvoltage protection device according to claim 1, characterized in that, The back EMF protection unit includes: an inverter and a switching circuit; The input terminal of the inverter is connected to the output terminal of the anti-software crash unit, and the output terminal of the inverter is sequentially connected to the switching circuit and the motor drive unit.

7. The motor overvoltage protection device according to claim 6, characterized in that, Also includes: Fourth resistor: The inverter includes: a first transistor, a second resistor, and a third resistor; The output terminal of the anti-software crash unit is connected to the base of the first transistor through the second resistor; The base of the first transistor is grounded through the fourth resistor, the collector of the first transistor is connected to the power supply through the third resistor, the collector of the first transistor is connected to the switching circuit, and the emitter of the first transistor is grounded.

8. The motor overvoltage protection device according to claim 7, characterized in that, The switching circuit includes: a fifth resistor, a sixth resistor, a second transistor, a third diode, and a fourth diode; The base of the second transistor is connected to the collector of the first transistor. The second transistor is connected to the power supply through the sixth resistor. The emitter of the second transistor is grounded through the fourth diode. The emitter of the second transistor is connected to the motor drive unit through the fifth resistor and the third diode.

9. The motor overvoltage protection device according to claim 8, characterized in that, Both the first transistor and the second transistor are NPN transistors.

10. A motor control system, characterized in that, The device includes the motor overvoltage protection device as described in any one of claims 1 to 9, and further includes: a motor drive unit and a control unit; The control unit is connected to the anti-software crash unit, and the motor drive unit is connected to the back EMF protection unit and the motor.

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