Driving system

Abstract

The invention discloses a driving system. The driving system comprises a driving circuit, a switch module, a motor and at least two resistors, the driving circuit is electrically connected with a three-phase input shaft of the motor through the switch module; the driving circuit comprises a terminal electrically connected with a grounding end; the switch module comprises three control switches; the resistors are connected in parallel to the two ends of the control switches. According to the technical scheme, the use safety of the driving system can be improved.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more particularly to a drive system. Background Technology

[0002] With the rapid development of next-generation wide-bandgap semiconductor technology and the new energy vehicle industry, third-generation wide-bandgap semiconductor switching devices have been widely used in motor drive systems. Their higher switching frequencies have led to more severe electromagnetic interference (EMI) in these systems. EMI includes common-mode EMI and differential-mode EMI, which can affect the normal operation of electronic equipment and hinder the development of power electronic circuits towards higher frequencies.

[0003] In modern rail transit, electric vehicles, and other fields, permanent magnet synchronous motors are widely used as traction motors due to their high power and high efficiency. There is an unavoidable parasitic capacitance between the windings and the motor housing of a permanent magnet motor. When the motor operates at high speeds with high switching frequencies, the high-frequency PWM voltage on the windings will couple through this parasitic capacitance, inducing a high voltage to ground (i.e., common-mode voltage) on the motor housing. Under normal traction or braking conditions, the contactor connected to the motor in the drive circuit is in a closed state. The motor windings can form an effective discharge path through the inverter and converter, thus the induced charge on the housing can be discharged in time, preventing high voltage residue on the motor.

[0004] However, under specific operating conditions, such as "shaft isolation" or "trailer operation," the contactor is in the open state. Although the motor rotates at high speed due to mechanical drive, its electrical circuit is completely isolated from the converter. The charge accumulated by the parasitic capacitance between the motor windings and the casing loses its discharge path, causing a voltage of hundreds or even thousands of volts to be maintained between the motor casing and the three-phase terminals for an extended period. When maintenance personnel touch the three-phase terminals of the motor, the accumulated charge will discharge instantaneously through the human body, posing a serious risk of electric shock. Summary of the Invention

[0005] This invention provides a drive system to improve the safety of drive system use.

[0006] This invention provides a drive system, comprising: a drive circuit, a switching module, a motor, and at least two resistors;

[0007] The drive circuit is electrically connected to the three-phase input shaft of the motor through the switch module; the drive circuit includes a terminal electrically connected to the ground terminal.

[0008] The switching module includes three control switches; each resistor is connected in parallel across the two ends of each control switch.

[0009] Optionally, the resistance value of the resistor is R;

[0010] Among them, 500KΩ≤R≤80MΩ.

[0011] Optionally, when the switching module is turned on, the rated power of the resistor is P;

[0012] Where 0W < P ≤ 5W.

[0013] Optionally, the drive system may also include:

[0014] The three resistors are connected in parallel across the two ends of the control switch.

[0015] Optionally, within the safe time t during which the switching module switches from the on state to the off state, the voltage of the three-phase input shaft drops to a safe voltage;

[0016] Where t≤40s.

[0017] Optionally, the drive circuit includes: a converter and an inverter;

[0018] The converter is electrically connected to the switching module via the inverter; the converter includes terminals electrically connected to the ground terminal.

[0019] Optionally, the resistor is located in the switching module.

[0020] Optionally, the resistor is located in the cabinet where the drive circuit is located.

[0021] Optionally, the control switch includes a contactor.

[0022] Optionally, the motor may include a permanent magnet synchronous motor.

[0023] The technical solution provided by this invention, based on a drive system including a drive circuit, a switching module, and a motor, further includes at least two resistors. The drive circuit is electrically connected to the three-phase input shaft of the motor through the switching module, and the drive circuit includes terminals electrically connected to a ground terminal. The switching module includes three control switches; each resistor is connected in parallel across the two ends of each control switch. Thus, when the switching module switches from a conducting state to an open state, the induced charge on the parasitic capacitance in the motor can be discharged to the ground terminal of the drive circuit through the resistors connected in parallel with the control switches. This prevents damage to maintenance personnel when they come into contact with the three-phase input shaft or the housing, improving the safety of the drive system. Attached Figure Description

[0024] Figure 1 A schematic diagram of a drive system provided in an embodiment of the present invention;

[0025] Figure 2This is a schematic diagram of another drive system provided in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of another driving system provided in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of another driving system provided in an embodiment of the present invention;

[0028] Figure 5 A voltage variation diagram of a three-phase input shaft in a drive system without resistors, provided as an embodiment of the present invention;

[0029] Figure 6 A voltage variation diagram of the three-phase input shaft in a drive system with a set resistor, provided as an embodiment of the present invention. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0031] Figure 1 A schematic diagram of a drive system provided in an embodiment of the present invention is shown below. Figure 1 As shown, the drive system 100 includes a drive circuit 10, a switching module 20, and a motor 30.

[0032] The drive circuit 10 includes devices such as switching transistors, resistors, and capacitors; the switching module 20 includes switching devices such as contactors or relays; and the motor 30 includes permanent magnet motors, etc. These can be configured according to actual needs, and no specific limitations are made here.

[0033] Specifically, the motor 30 includes windings and a housing 15. Since both the windings and the housing 15 are conductors, there is an insulator between them, such as insulating varnish, slot insulating paper, or air. The ends of the windings, i.e., the shafts, are used to connect to the drive circuit 10 and receive drive electrical signals from the drive circuit 10. The ends of the windings are suspended in the internal space of the motor 30, forming a parasitic capacitance between them and the grounded housing 15. When the drive system 100 is in high-speed operation, the high-frequency voltage on the windings will pass through the parasitic capacitance and induce a high voltage to ground on the housing 15. When the drive system 100 is in traction or braking conditions, the switching module 20 is in the conducting state, and the induced charge on the parasitic capacitance can be discharged to the drive circuit 10 through the switching module 20. Alternatively, common-mode interference generated by parasitic capacitance is usually suppressed through the main insulation design of the motor, grounding protection, or suppression of conducted electromagnetic interference. However, these designs are all strategies for dealing with the situation when the switching module 20 is in the conducting state, and do not take into account the safety issues when the switching module 20 is in the disconnected state.

[0034] When a faulty shaft exists in motor 30, the fault needs to be isolated. This, along with the disconnection of switch module 20, prevents the induced charge in the parasitic capacitor from dissipating in a timely manner. This poses a safety hazard if maintenance personnel come into contact with the three-phase input shaft or housing. Similarly, if a fault occurs in the vehicle or other components of the drive system 100, causing switch module 20 to disconnect, the induced charge in the parasitic capacitor will also fail to dissipate in a timely manner.

[0035] Therefore, the technical solution provided by the present invention involves setting at least two resistors 40; the drive circuit 10 is electrically connected to the three-phase input shaft of the motor 30 through the switch module 20; the switch module 20 includes three control switches K; and each resistor 40 is connected in parallel across the two ends of each control switch K.

[0036] Among them, resistor 40 is a high-resistance resistor, and the specific resistance value can be set according to actual needs. The switch module 20 includes a first control switch K1, a second control switch K2, and a third control switch K3. The first control switch K1 is electrically connected to the drive circuit 10 and the A-phase input shaft, the second control switch K2 is electrically connected to the drive circuit 10 and the B-phase input shaft, and the third control switch K3 is electrically connected to the drive circuit 10 and the C-phase input shaft.

[0037] Specifically, the three-phase input shaft includes an A-phase input shaft, a B-phase input shaft, and a C-phase input shaft. The parasitic capacitance between the A-phase input shaft and the housing 15 is the first parasitic capacitance Cs1, the parasitic capacitance between the B-phase input shaft and the housing 15 is the second parasitic capacitance Cs2, and the parasitic capacitance between the C-phase input shaft and the housing 15 is the third parasitic capacitance Cs3. Terminal G0 in the drive circuit 10 is electrically connected to the ground terminal GND. When the switching module 20 is in the ON state, the induced charge on the first parasitic capacitance Cs1, the second parasitic capacitance Cs2, and the third parasitic capacitance Cs3 can be transferred to the ground terminal GND of the drive circuit 10 through the switching module 20. When the switch module 20 switches from the on state to the off state, the induced charge on the first parasitic capacitor Cs1, the second parasitic capacitor Cs2, and the third parasitic capacitor Cs3 can be discharged to the ground terminal GND of the drive circuit 10 through the first resistor 41 and the third resistor 44. This prevents damage to maintenance personnel when they come into contact with the three-phase input shaft or the housing 15, thus improving the safety of the drive system 100.

[0038] The technical solution provided by this invention, based on a drive system including a drive circuit, a switching module, and a motor, further includes at least two resistors. The drive circuit is electrically connected to the three-phase input shaft of the motor through the switching module, and the drive circuit includes terminals electrically connected to a ground terminal. The switching module includes three control switches; each resistor is connected in parallel across each control switch. Thus, when the switching module switches from a conducting state to an open state, the induced charge on the parasitic capacitance in the motor can be discharged to the ground terminal of the drive circuit through the resistors connected in parallel with the control switches. This prevents damage to maintenance personnel when they come into contact with the three-phase input shaft or the housing, improving the safety of the drive system.

[0039] It should be noted that, Figure 1 The diagram only shows the drive system 100 including two resistors 40, namely a first resistor 41 and a third resistor 43. The first resistor 41 is connected in parallel across the two ends of the first control switch K1, and the third resistor 43 is connected in parallel across the two ends of the third control switch K3. Based on this, the drive system 100 may also include three or more resistors 40. In an optional embodiment, two or more resistors 40 may be connected in parallel across the two ends of the first control switch K1, or two or more resistors 40 may be connected in parallel across the two ends of the third control switch K3, depending on actual needs. Furthermore, the resistance values ​​of the resistors 40 connected in parallel across each control switch K may be equal or different, depending on actual needs.

[0040] In an optional embodiment, only one resistor 40 is connected in parallel across each control switch K, and the resistance of resistor 40 is R; wherein, 500KΩ≤R≤80MΩ.

[0041] Specifically, when the resistance R of resistor 40 is less than 500KΩ, the resistance of resistor 40 is relatively small. When the switching module 20 is in the conducting state, the drive signal provided by the drive circuit 10 can flow through resistor 40, resulting in inaccurate drive signals transmitted to motor 30 and unreliable operation of motor 30. When the resistance R of resistor 40 is greater than 80MΩ, resistor 40 occupies a large space, resulting in a larger overall size of drive system 100 and affecting handling. Therefore, by setting the resistance R of resistor 40 within the range of 500KΩ to 80MΩ, the induced charge of parasitic capacitance can be discharged while ensuring the operational reliability of drive system 100 in driving motor 30, avoiding abnormal operation of motor 30, and improving the drive system's reliability and stability.

[0042] Optionally, when the switch module 20 is turned on, the rated power of the resistor 40 is P. Wherein, 0W < P ≤ 5W.

[0043] Wherein, the rated power P of resistor 40 represents the effective power that resistor 40 can continuously output.

[0044] Specifically, when the switch module 20 is turned on, a small portion of the drive signal provided by the drive circuit 10 inevitably flows through the resistor 40. By limiting the rated power P of the resistor 40 to less than or equal to 5W, the loss of the drive signal in the resistor 40 is reduced, which will not affect the operation of the motor 30 and improve the drive reliability of the drive system 100.

[0045] It should be noted that, Figure 1 The diagram only shows a structure where the drive system 100 includes two resistors 40; the drive system 100 may also include three resistors 40. In an optional embodiment, Figure 2 A schematic diagram of another drive system provided in an embodiment of the present invention is shown below. Figure 2 As shown, the drive system 100 also includes three resistors 40, each of which is connected in parallel across the two ends of each control switch K.

[0046] Specifically, by setting the drive system 100 to include three resistors 40, namely a first resistor 41, a second resistor 42 and a third resistor 43, the first resistor 41 is connected in parallel to the two ends of the first control switch K1, the second resistor 42 is connected in parallel to the two ends of the second control switch K2, and the third resistor 43 is connected in parallel to the two ends of the third control switch K3, so that the induced charge of the parasitic capacitor can be discharged simultaneously through the first resistor 41, the second resistor 42 and the third resistor 43, thereby improving the discharge efficiency.

[0047] Optionally, within the safe time t during which the switch module 20 switches from the on state to the off state, the voltage of the three-phase input shaft drops to a safe voltage; where t≤40s.

[0048] The safety voltage can be 80V or 60V, which can be set according to actual needs; no specific limitation is made here.

[0049] Specifically, by setting the safety time t to be less than or equal to 40s, the voltage of the three-phase input shaft can drop to a safe voltage within 40s after the switch module 20 switches from the on state to the off state, so that the voltage of the three-phase input shaft can be released quickly, thereby improving the safety of the motor 30.

[0050] It is understood that the safety time t is related to the resistance value R of resistor 40 and the size of parasitic capacitance. In an optional embodiment, the safety time t = -τ × ln(U1 / U0), τ = R × C, where C is parasitic capacitance, U1 is safety voltage, and U0 is the voltage value on the three-phase input shaft at the instant when the switch module 20 switches from the on state to the off state.

[0051] Optional, Figure 3 This is a schematic diagram of another driving system provided in an embodiment of the present invention, such as... Figure 3 As shown, the drive circuit 10 includes a converter 11 and an inverter 12; the converter 11 is electrically connected to the switching module 20 through the inverter 12; the converter 11 includes a terminal electrically connected to the ground terminal.

[0052] The converter 11 includes devices such as transformers, resistors, capacitors or switching transistors, and the inverter 12 includes devices such as switching transistors. The specific structure of the converter 11 or the inverter 12 can be set according to actual needs, and no specific limitation is made here.

[0053] Specifically, the input terminal of the converter 11 can receive AC signals from the grid side. The converter 11 may include a rectifier, which converts the input AC signals into DC signals and transmits them to the inverter 12. The inverter 12 further converts the input DC signals into AC signals of the required frequency and outputs them to the motor 30 to adjust and control the operating frequency of the motor 30, thereby improving the frequency adjustability of the drive system.

[0054] It should be noted that the specific location of resistor 40 in the drive system 100 can be set according to actual needs. In an optional embodiment, refer to... Figure 3 The resistor 40 is located in the switch module 20.

[0055] Specifically, since resistor 40 is connected in parallel with control switch K in switch module 20, resistor 40 is placed in switch module 20 and integrally manufactured with switch module 20. This can shorten the length of the connection harness between resistor 40 and control switch K, reduce the transmission path of induced charge, and improve discharge efficiency.

[0056] In another alternative embodiment, Figure 4 A schematic diagram of another driving system provided in an embodiment of the present invention is shown below. Figure 4 As shown, resistor 40 is located in the cabinet where drive circuit 10 is located.

[0057] Specifically, resistor 40 is placed in the cabinet where drive circuit 10 is located. The two ends of resistor 40 are electrically connected to the two ends of control switch K through wires. The cabinet can protect resistor 40 and prevent it from being corroded.

[0058] Optionally, the control switch K may include a contactor KM.

[0059] Specifically, a contactor KM is an automatic electromagnetic switch that uses electromagnetic principles to frequently connect and disconnect the main circuit by controlling the energization and de-energization of a control coil. By incorporating a control switch K including a contactor KM, operators can control high-power equipment from locations away from high-current hazards (such as control rooms) using low-current signals from buttons, PLCs, etc. The contactor KM can also be automatically controlled based on sensors, timers, or program instructions. During equipment maintenance, the contactor KM can reliably disconnect the main circuit, providing a clear electrical isolation point and ensuring personal safety. Thus, by incorporating a control switch K including a contactor KM, remote control, automatic control, and safety isolation can be achieved.

[0060] Optionally, motor 30 may include a permanent magnet synchronous motor.

[0061] Specifically, the rotor excitation of a permanent magnet synchronous motor (PMSM) is provided by permanent magnets, requiring no direct current, thus eliminating the rotor winding current losses found in induction motors. The powerful permanent magnets (especially neodymium iron boron) in a PMSM can generate a strong magnetic field within a small volume, allowing for greater power and torque output than induction motors with the same volume and weight. Through vector control technology, PMSMs can achieve independent and precise control of torque and magnetic field, resulting in fast response and excellent dynamic performance.

[0062] Figure 5 A voltage variation diagram of the three-phase input shaft in a drive system without resistors, provided as an embodiment of the present invention, is shown below. Figure 5 As shown, when no resistor is connected in parallel with the control switch in the drive system, the voltage of the three-phase input shaft is 630V when the switch module switches from the on state to the off state. After 10 minutes, the voltage of the three-phase input shaft is 253.8V. The voltage cannot be discharged in time. If maintenance personnel touch the three-phase input shaft at this time, it will cause a safety accident. Figure 6 A voltage variation diagram of the three-phase input shaft in a drive system with set resistors, provided as an embodiment of the present invention, and Figure 6As shown, when a resistor connected in parallel with the control switch is set in the drive system, the voltage of the three-phase input shaft is 590.6V when the switch module switches from the on state to the off state. After 38 minutes, the voltage of the three-phase input shaft is 78.7V, which is reduced to a safe voltage. At this time, when maintenance personnel come into contact with the three-phase input shaft, it will not cause damage to the maintenance personnel, thus ensuring the safety of the drive system.

[0063] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A drive system, characterized in that, include: Drive circuit, switching module, motor, and at least two resistors; The drive circuit is electrically connected to the three-phase input shaft of the motor through the switch module; the drive circuit includes a terminal electrically connected to the ground terminal. The switching module includes three control switches; each resistor is connected in parallel across the two ends of each control switch.

2. The drive system according to claim 1, characterized in that, The resistance value of the resistor is R; Among them, 500KΩ≤R≤80MΩ.

3. The drive system according to claim 1, characterized in that, When the switching module is turned on, the rated power of the resistor is P; Where 0W < P ≤ 5W.

4. The drive system according to claim 1, characterized in that, Also includes: The three resistors are connected in parallel across the two ends of the control switch.

5. The drive system according to claim 1, characterized in that, Within the safe time t during which the switching module switches from the on state to the off state, the voltage of the three-phase input shaft drops to a safe voltage; Where t≤40s.

6. The drive system according to claim 1, characterized in that, The drive circuit includes: a converter and an inverter; The converter is electrically connected to the switching module via the inverter; the converter includes terminals electrically connected to the ground terminal.

7. The drive system according to claim 1, characterized in that, The resistor is located in the switching module.

8. The drive system according to claim 1, characterized in that, The resistor is located in the cabinet where the drive circuit is located.

9. The drive system according to claim 1, characterized in that, The control switch includes a contactor.

10. The drive system according to claim 1, characterized in that, The motor includes a permanent magnet synchronous motor.

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