Motor driver and use method thereof

Abstract

The embodiment of the invention provides a motor driver and a use method thereof. The motor driver comprises a motor driver main body with a control unit, wherein the motor driver main body is electrically connected with a power supply system; the grounding circuit is communicated with the cathode of the direct-current bus of the motor driver main body and is provided with a sampling resistor; the sampling circuit is used for collecting the voltage on the sampling resistor and providing the collected voltage on the sampling resistor to the control unit; the control unit is used for determining the type of the power supply system and the grounding type of the power supply system according to the voltage on the sampling resistor. According to the technical scheme, the grounding type of the power supply system can be identified.

Description

Technical Field

[0001] The present application relates to the field of industrial technology, and in particular to a motor driver and a method for using the same.

[0002] Application Background

[0003] There are certain restrictions when the motor drive is used in different power supply systems. For example, when the motor drive is used in an IT (here, "I" means that the power phase conductor is insulated from the ground, and "T" means that the conductive shell of the electrical equipment is grounded) power grid, the internal grounded Y capacitor needs to be removed. When used in a triangle grounded power grid, the grid voltage must be lower than the voltage of a triangle ungrounded power grid, otherwise it may cause insulation failure. Current motor drives cannot identify the grounding type of the power supply system.

[0004] Therefore, those skilled in the art are still working on finding other motor driver implementation solutions.

[0005] Application Contents

[0006] In view of this, in an embodiment of the present application, on one hand, a motor driver is provided, and on the other hand, a method for using the motor driver is provided to identify the grounding type of a power supply system.

[0007] To solve the above technical problems, the technical solution of this application is implemented as follows:

[0008] A motor driver comprises: a motor driver body having a control unit, which is electrically connected to a power supply system; further comprising: a grounding circuit, which is connected to the negative pole of a DC bus of the motor driver body and has a sampling resistor; and a sampling circuit, which is used to collect a voltage on the sampling resistor and provide the collected voltage on the sampling resistor to the control unit; the control unit is used to determine the grounding type of the power supply system according to the voltage on the sampling resistor.

[0009] A method for using a motor driver comprises: after the motor driver body is powered on and before the drive motor is running, connecting the grounding circuit; a sampling circuit collects the voltage on the sampling resistor and provides the collected voltage on the sampling resistor to the control unit; the control unit determines the grounding type of the power supply system according to the voltage on the sampling resistor.

[0010] It can be seen from the above technical solution that in the embodiment of the present application, before the motor runs, the negative pole DCN of the DC bus of the motor driver is grounded through a grounding circuit with a sampling resistor. After the sampling circuit collects the voltage on the sampling resistor, it is sent to the control unit of the motor driver. The control unit can determine the type of the power supply system as a grounded power supply system or an ungrounded or high-impedance grounded power supply system based on the size of the average value of the voltage. For a power supply system that needs to be grounded, the grounding type of the power supply system can be determined based on the frequency of the AC component in the voltage, thereby realizing the identification of the grounding type of the power supply system.

[0011] In addition, after identifying the grounding type, it further determines whether the motor driver matches the grounding type and issues an alarm when it does not match, thereby improving the safety and reliability of the product.

[0012] In addition, after identifying that the power supply system is a corner-grounded triangle grid, the average voltage on the DC bus can be compared with a set allowable voltage threshold to determine whether the voltage of the power supply system exceeds the allowable voltage, and an alarm will be issued when it exceeds the limit, further improving the safety and reliability of the product.

[0013] In addition, when the power supply system is identified as an ungrounded or high-impedance grounded IT power grid, the ground loop resistance of the IT power grid is calculated and compared with a set resistance threshold to determine whether the IT power grid meets the requirements, further improving the safety and reliability of the product.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to better understand the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can better understand the above and other features and advantages of the present application. In the accompanying drawings:

[0016] Figure 1 Schematic diagram of the motor driver in the embodiment of the present application.

[0017] Figure 2 A schematic diagram of a typical voltage across a sampling resistor in an example of this application.

[0018] Figure 3 In the embodiment of this application Figure 1 An exemplary flow chart of a method of using the motor driver is shown.

[0019] The reference numerals are as follows:

[0020]

[0021]

[0022] Methods of implementing this application

[0023] In an embodiment of the present application, in order to identify the grounding type of the power supply system, it is considered that before the motor is running, the negative pole DCN of the DC bus is grounded through a sampling resistor and other components such as a voltage divider resistor and a control switch. After the sampling circuit collects the voltage on the sampling resistor, it is sent to the control unit of the motor driver. After the control unit processes the collected voltage in a certain way, the grounding type of the power grid and the grounding loop resistance can be determined.

[0024] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the technical solution of the present application is described in detail below with reference to the accompanying drawings and examples.

[0025] Figure 1 FIG. 1 is an exemplary structural diagram of a motor driver in an embodiment of the present application. Figure 1 As shown, the motor driver may include: a motor driver body 1 having a control unit CU, a sampling circuit AD, and a grounding circuit GC.

[0026] Among them, one end of the motor driver body 1 is electrically connected to the power supply system 2, and the other end is electrically connected to the drive motor M, which is used to control the rotation angle and running speed of the drive motor M; the motor driver body 1 has a DC bus positive pole DCP and a DC bus negative pole DCN. The power supply system 2 has a ground loop resistor Rg.

[0027] The grounding circuit GC is connected to the negative pole DCN of the DC bus of the motor driver body 1 and has a sampling resistor R1. In this embodiment, the grounding circuit GC may also include a control switch K1 and a voltage dividing resistor R2. Of course, in other embodiments, the grounding circuit GC may also have other implementations, which are not listed here one by one.

[0028] The sampling resistor R1, the control switch K1, and the voltage dividing resistor R2 are connected in series in sequence, the non-series connection end of the sampling resistor R1 is connected to the negative DC bus DCN of the motor driver body 1, and the non-series connection end of the voltage dividing resistor R2 is grounded.

[0029] The control switch K1 is used to close after the motor driver body 1 is powered on and before the drive motor M runs. At this time, the sampling resistor R1, the voltage divider resistor R2 and the grounding loop resistor Rg jointly share the voltage between the negative pole DCN of the DC bus and the grounding point of the power supply system 2.

[0030] The sampling circuit AD has two collection terminals and an output terminal, the two collection terminals are electrically connected to the two ends of the sampling resistor R1, and are used to collect the voltage on the sampling resistor R1; the output terminal is electrically connected to the control unit CU of the motor driver body 1, and is used to provide the collected voltage on the sampling resistor R1 to the control unit CU.

[0031] The control unit CU is used to determine the type of the power supply system 2 and its grounding type according to the voltage on the sampling resistor R1 collected by the sampling circuit AD.

[0032] Figure 2 FIG. 1 is a schematic diagram showing a typical voltage of a sampling resistor R1 in an example of the present application. Figure 2 As shown, under the condition of the same grounding loop resistance Rg, the amplitude and frequency of the AC component superimposed on the DC component in the voltage on the sampling resistor R1 corresponding to different grounding types are different. For example, when the grounding loop resistance Rg is 4 ohms, the amplitude of the AC component of the voltage 3 on the sampling resistor R1 corresponding to the midpoint grounding of the Y-type power grid is small, and the frequency is high, for example, usually three times the fundamental frequency of the power grid. That is, for a power grid with a fundamental frequency of 50Hz, its frequency is 150Hz; for a power grid with a fundamental frequency of 60Hz, its frequency is 180Hz. The amplitude of the AC component of the voltage 4 on the sampling resistor R1 corresponding to the corner grounding of the triangle power grid is large, and the frequency is low, for example, usually the fundamental frequency of the power grid. That is, for a power grid with a fundamental frequency of 50Hz, its frequency is 50Hz; for a power grid with a fundamental frequency of 60Hz, its frequency is 60Hz.

[0033] In addition, when the ground loop resistance Rg is large enough, that is, when the power supply system is not grounded or is grounded with high impedance, the voltage on the sampling resistor R1 will become small enough. Figure 2 As shown in , when the ground loop resistance Rg is 1M ohm, the voltage 5 on the sampling resistor R1 corresponding to the midpoint grounding of the Y-type grid and the voltage 6 on the sampling resistor R1 corresponding to the corner grounding of the triangle grid are both very small.

[0034] Based on this, in this embodiment, when the control unit CU determines the type of the power supply system 2 and its grounding type according to the voltage on the sampling resistor R1, the control unit CU may specifically include:

[0035] The control unit CU may calculate an average voltage on the sampling resistor R1 according to the voltage on the sampling resistor R1 , and compare the average voltage on the sampling resistor R1 with a preset first voltage threshold.

[0036] When the average voltage on the sampling resistor R1 is greater than the first voltage threshold, the control unit CU may determine that the power supply system 2 is a grounded power grid, and then determine the frequency of the AC component superimposed on the DC component in the voltage on the sampling resistor R1, and determine the grounding type of the power supply system 2 according to the frequency of the AC component. For example, if the frequency of the AC component is the grid fundamental frequency, the grounding type of the power supply system 2 is determined to be a triangle grid angle grounding, and if the frequency of the AC component is three times the grid fundamental frequency, that is, the AC component is the third harmonic of the grid fundamental, the grounding type of the power supply system 2 is determined to be a Y-type grid midpoint grounding.

[0037] Furthermore, after identifying the grounding type of the power supply system, the control unit CU can also determine whether the motor driver matches the grounding type. If not, an alarm signal can be issued in time to improve the safety and reliability of the product.

[0038] In addition, after identifying that the grounding type of the power supply system 2 is a triangle grid angle grounding, the control unit CU can determine whether the voltage of the power supply system 2 exceeds the allowable voltage by comparing the average voltage on the DC bus with a set allowable voltage threshold. If the average voltage on the DC bus exceeds the allowable voltage threshold, it is determined that the voltage of the power supply system exceeds the allowable voltage. Further, an alarm signal can be issued in time.

[0039] If the average voltage on the sampling resistor R1 is not greater than the first voltage threshold, the control unit CU may compare the average voltage on the sampling resistor R1 with a preset second voltage threshold, and the first voltage threshold is greater than the second voltage threshold. When the average voltage on the sampling resistor R1 is less than the second voltage threshold, it is determined that the power supply system 2 is an IT power grid, and its grounding type is ungrounded or high-impedance grounding.

[0040] Further, the control unit CU can calculate the ground loop resistance Rg according to the average voltage on the DC bus, the average voltage of the sampling resistor R1, and the resistance in the ground circuit GC. For example, in this embodiment, the ground loop resistance Rg can be calculated according to the following formula (1):

[0041]

[0042] Among them, U avg_dc is the average voltage on the DC bus, U avg_R1 is the average voltage of the sampling resistor R1, R1 is the sampling resistor, and R2 is the voltage dividing resistor.

[0043] The control unit CU may compare the ground loop resistance Rg calculated in the above formula (1) with a preset resistance threshold value. If the ground loop resistance Rg is greater than the resistance threshold value, it is determined that the IT power grid is not grounded or is grounded with high impedance. Otherwise, it is determined that the IT power grid has a grounding abnormality, and an alarm signal may be issued at this time.

[0044] If the average voltage on the sampling resistor R1 is between the first voltage threshold and the second voltage threshold, the control unit CU can determine that the power supply system has a grounding anomaly, and an alarm signal can be issued at this time. The grounding loop resistance Rg includes the resistance of the entire grounding loop, such as the grounding wire resistance and the contact resistance, etc., mainly to be able to identify that if the grounding wire is broken, the driver will determine that the grounding is abnormal.

[0045] The motor driver in the embodiment of the present application is described in detail above. The method for using the motor driver in the embodiment of the present application is described in detail below.

[0046] Figure 3 In the embodiment of this application Figure 1 An exemplary flow chart of a method for using a motor driver is shown in FIG. Figure 1 The motor driver shown in . Figure 3 As shown, the method may include the following steps:

[0047] Step 31, after the motor driver body 1 is powered on and before the drive motor M is running, the ground circuit GC is connected.

[0048] against Figure 1 In the case where the grounding circuit GC shown includes a control switch K1, the grounding circuit GC can be connected by closing the control switch K1.

[0049] Step 32 : The sampling circuit AD collects the voltage on the sampling resistor R1 , and provides the collected voltage on the sampling resistor R1 to the control unit CU.

[0050] Step 33 : The control unit CU determines the type of the power supply system 2 and its grounding type according to the voltage on the sampling resistor R1 collected by the sampling circuit AD.

[0051] In specific implementation, step 33 may further include:

[0052] Step 331 : The control unit CU calculates the average voltage on the sampling resistor R1 according to the voltage on the sampling resistor R1 .

[0053] Step 332 , comparing the average voltage on the sampling resistor R1 with a preset first voltage threshold. If the average voltage on the sampling resistor R1 is greater than the first voltage threshold, executing step 333 ; otherwise, executing step 335 .

[0054] Step 333 , determining the frequency of the AC component superimposed on the DC component in the voltage across the sampling resistor R1 .

[0055] Step 334: Determine the grounding type of the power supply system 2 according to the frequency of the AC component.

[0056] For example, if the frequency of the AC component is the grid fundamental frequency, the grounding type of the power supply system 2 is determined to be triangular grid angle grounding. If the frequency of the AC component is three times the grid fundamental frequency, that is, the AC component is the third harmonic of the grid fundamental, the grounding type of the power supply system 2 is determined to be Y-type grid midpoint grounding.

[0057] Furthermore, after identifying the grounding type of the power supply system, the control unit CU can also determine whether the motor driver matches the grounding type. If not, an alarm signal can be issued in time to improve the safety and reliability of the product.

[0058] In addition, after identifying that the power supply system is a triangle grid corner grounded, the average voltage on the DC bus can be further compared with a set allowable voltage threshold. If the average voltage on the DC bus is greater than the set allowable voltage threshold, it is determined that the voltage of the power supply system exceeds the allowable voltage. At this time, an alarm signal and an input switch opening signal can be issued in time.

[0059] Step 335, compare the average voltage on the sampling resistor R1 with a preset second voltage threshold, if the average voltage on the sampling resistor R1 is less than the second voltage threshold, execute step 336, otherwise execute step 337. The first voltage threshold is greater than the second voltage threshold.

[0060] Step 336: determine that the power supply system 2 is an IT power grid, and its grounding type is ungrounded or high-impedance grounded.

[0061] Furthermore, the control unit CU may calculate the ground loop resistance Rg according to the average voltage on the DC bus, the average voltage of the sampling resistor R1, and the resistance in the ground circuit GC, and compare the calculated ground loop resistance Rg with a preset resistance threshold. If the ground loop resistance Rg is greater than the resistance threshold, it is determined that the IT power grid is not grounded or is grounded with high impedance. Otherwise, it may be determined that the IT power grid has a grounding abnormality, and an alarm signal may be issued at this time.

[0062] Step 337: The control unit CU determines that there is a grounding anomaly in the power supply system 2, and an alarm signal may be issued.

[0063] It can be seen from the above technical solution that in the embodiment of the present application, before the motor runs, the negative pole DCN of the DC bus of the motor driver is grounded through a grounding circuit with a sampling resistor. After the sampling circuit collects the voltage on the sampling resistor, it is sent to the control unit of the motor driver. The control unit can determine the type of the power supply system as a grounded power supply system or an ungrounded or high-impedance grounded power supply system based on the average size of the voltage. For a power supply system that needs to be grounded, the grounding type of the power supply system can be determined based on the frequency of the AC component in the voltage, thereby realizing the identification of the grounding type of the power supply system.

[0064] In addition, after identifying the grounding type, it further determines whether the motor driver matches the grounding type and issues an alarm when it does not match, thereby improving the safety and reliability of the product.

[0065] In addition, after identifying that the power supply system is a corner-grounded triangle grid, the average voltage on the DC bus can be compared with a set allowable voltage threshold to determine whether the voltage of the power supply system exceeds the allowable voltage. If it exceeds the limit, an alarm will be issued and a switch trip signal will be input, further improving the safety and reliability of the product.

[0066] In addition, when the power supply system is identified as an ungrounded or high-impedance grounded IT power grid, the ground loop resistance of the IT power grid is calculated and compared with a set resistance threshold to determine whether the IT power grid meets the requirements, further improving the safety and reliability of the product.

[0067] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A motor driver, comprising: A motor driver body (1) having a control unit (CU), which is electrically connected to a power supply system (2); characterized in that it also includes: A grounding circuit (GC) which is electrically connected to the negative pole (DCN) of the DC bus of the motor driver body (1) and has a sampling resistor (R1); and A sampling circuit (AD) for collecting the voltage on the sampling resistor (R1) and providing the collected voltage on the sampling resistor (R1) to the control unit (CU); The control unit (CU) is used to determine the grounding type of the power supply system (2) according to the voltage on the sampling resistor (R1).

2. The motor driver according to claim 1, characterized in that: The control unit (CU) calculates an average voltage on the sampling resistor (R1) based on the voltage on the sampling resistor (R1), compares the average voltage on the sampling resistor (R1) with a preset first voltage threshold, and determines that the power supply system (2) is a grounded power grid when the average voltage on the sampling resistor (R1) is greater than the first voltage threshold, and determines the grounding type of the power supply system (2) based on the frequency of the AC component superimposed on the DC component in the voltage on the sampling resistor (R1).

3. The motor driver according to claim 2, characterized in that: The control unit (CU) determines that the grounding type of the power supply system (2) is triangular grid angle grounding when the frequency of the AC component is the grid fundamental frequency, and determines that the grounding type of the power supply system (2) is Y-type grid midpoint grounding when the frequency of the AC component is three times the grid fundamental frequency.

4. The motor driver according to claim 3, characterized in that: When the control unit (CU) determines that the grounding type of the power supply system (2) is triangle grid angle grounding, it further compares the average voltage on the DC bus with a set allowable voltage threshold, and when the average voltage on the DC bus is greater than the allowable voltage threshold, it is determined that the voltage of the power supply system exceeds the allowable voltage.

5. The motor driver according to claim 3, characterized in that: After determining the grounding type of the power supply system (2), the control unit (CU) further determines whether the motor driver matches the grounding type, and issues an alarm if it does not match.

6. The motor driver according to claim 2, characterized in that: When the average voltage on the sampling resistor (R1) is not greater than the first voltage threshold, the average voltage on the sampling resistor (R1) is compared with a preset second voltage threshold, and when the average voltage on the sampling resistor (R1) is less than the second voltage threshold, it is determined that the power supply system (2) is an IT power grid and is not grounded or is high-impedance grounded.

7. The motor driver according to claim 6, characterized in that: The power supply system (2) has a grounding loop resistor; the control unit (CU) further calculates the grounding loop resistor (Rg) based on the average voltage on the DC bus, the average voltage of the sampling resistor (R1), and the resistance in the grounding circuit; The calculated ground loop resistance (Rg) is compared with a preset resistance threshold. If the ground loop resistance Rg is greater than the resistance threshold, it is determined that the IT power grid is not grounded or is grounded with high impedance. Otherwise, it is determined that the IT power grid has grounding abnormality.

8. The motor driver according to any one of claims 1 to 7, characterized in that: The grounding circuit also includes: a control switch (K1) and a voltage dividing resistor (R2); The control switch (K1) and the voltage dividing resistor (R2) are connected in series with the sampling resistor (R1).

9. A method for using the motor driver according to any one of claims 1 to 8, characterized in that: include: After the motor driver body (1) is powered on and before the drive motor (M) is running, the grounding circuit (GC) is connected; A sampling circuit (AD) collects the voltage on the sampling resistor (R1), and provides the collected voltage on the sampling resistor (R1) to the control unit (CU); The control unit (CU) determines the grounding type of the power supply system (2) according to the voltage on the sampling resistor (R1).

10. The method for using the motor driver according to claim 9, characterized in that: The control unit (CU) determines the type of the power supply system (2) and its grounding type according to the voltage on the sampling resistor (R1), including: The control unit (CU) calculates the average voltage on the sampling resistor (R1) according to the voltage on the sampling resistor (R1); The average voltage on the sampling resistor (R1) is compared with a preset first voltage threshold, and when the average voltage on the sampling resistor (R1) is greater than the first voltage threshold, the grounding type of the power supply system (2) is determined based on the frequency of the AC component superimposed on the DC component in the voltage on the sampling resistor (R1).

11. The method for using the motor driver according to claim 10, characterized in that: The control unit (CU) determines the type of the power supply system (2) and its grounding type according to the voltage on the sampling resistor (R1), further comprising: when the average voltage on the sampling resistor (R1) is not greater than the first voltage threshold, comparing the average voltage on the sampling resistor (R1) with a preset second voltage threshold, and when the average voltage on the sampling resistor (R1) is less than the second voltage threshold, determining that the power supply system (2) is an IT power grid and is not grounded or is grounded with high impedance.

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