DC link overcurrent detection method, medium, motor controller and driving system

Abstract

The invention relates to an overcurrent detection method for a direct-current link, the direct-current link is connected between a power supply and a power level circuit for driving a motor, a diode is connected in series on the direct-current link and is used for providing power supply polarity anti-reverse connection protection, and the method comprises the following steps: S1, when the power supply is switched on, the diode is connected in series on the direct-current link; a forward conduction voltage on the diode is collected; s2, inputting the forward break-over voltage on the diode into a predetermined lookup table to determine a forward current flowing through the diode; and S3, comparing the forward current flowing through the diode with an upper limit value to determine whether an overcurrent fault occurs on the DC link. The invention also relates to a computer readable storage medium for implementing the overcurrent detection method, a motor controller comprising the computer readable storage medium, and a motor driving system comprising the motor controller.

Description

Technical Field

[0001] The present invention relates to the field of overcurrent detection, and more specifically, to an overcurrent detection method for a DC link, a computer-readable storage medium for implementing the overcurrent detection method, a motor controller including the computer-readable storage medium, and a motor drive system including the motor controller. Background Art

[0002] In electronic and electrical systems, DC-link (DC-Link) overcurrent detection is a crucial component, crucial for protecting electrical components within the power system from damage. Traditional DC-Link overcurrent detection methods typically rely on adding additional sampling resistors and peripheral circuitry to the DC-Link. These components measure the DC-Link current and convert it into a signal suitable for processing by a microcontroller (MCU). While this approach provides highly accurate current measurement, it also presents a number of challenges. First, the additional hardware components increase circuit complexity, occupying valuable PCB space and potentially increasing design and manufacturing costs. Second, the integration and debugging of these components can increase development cycles and delay time to market.

[0003] Furthermore, with the rapid development of electric vehicles and renewable energy systems, the demand for DC-Link overcurrent detection is growing. In the electric vehicle sector, DC-Link overcurrent detection is particularly important because motor drive systems may encounter various abnormal conditions during operation, such as short circuits, overloads, and battery failures, all of which can cause a sharp increase in DC link current. If not detected and addressed promptly, these abnormal conditions can cause serious damage to the motor, inverter, and the entire motor drive system.

[0004] Therefore, there is an urgent need to provide a solution that can implement overcurrent detection of a DC-Link in an efficient and economical manner. Summary of the Invention

[0005] As electric vehicles continue to increase their requirements for system energy efficiency and cost-effectiveness, traditional overcurrent detection solutions are unable to meet market demand. Based on this background, the present invention proposes an innovative DC-Link overcurrent detection solution. This method utilizes the characteristics of the existing reverse polarity protection diode on the DC-Link and combines it with software control logic to achieve overcurrent detection on the DC-Link. This solution does not require the installation of additional hardware components. Specifically, the DC-Link overcurrent detection method according to the present invention can effectively estimate the current flowing through the diode by accurately measuring the forward conduction voltage and junction temperature of the diode, combined with a pre-calibrated lookup table, thereby achieving real-time monitoring of the overcurrent status on the DC-Link.

[0006] A first aspect of the present invention provides a method for overcurrent detection in a DC link, wherein the DC link is connected between a power supply and a power stage circuit for driving a motor, and a diode is connected in series with the DC link to provide protection against reverse polarity of the power supply. The method comprises the following steps:

[0007] Step S1: When the power supply is turned on, the forward conduction voltage of the diode is collected;

[0008] Step S2: inputting the forward conduction voltage of the diode into a predetermined lookup table to determine the forward current flowing through the diode; and

[0009] Step S3: Compare the forward current flowing through the diode with an upper limit value to determine whether an overcurrent fault occurs on the DC link.

[0010] According to an optional embodiment, the method further comprises the following steps:

[0011] Step S4: Measure the temperature value T on the PCB board where the diode is provided. pcb ;

[0012] Step S5: Based on the temperature value T on the PCB board pcb Calculate the junction temperature T of the diode j ;as well as

[0013] Step S6: Based on the calculated junction temperature T of the diode j The forward current determined in step S2 is corrected.

[0014] According to an optional embodiment, a thermistor is provided on the PCB near the diode, and the temperature value T of the PCB is determined by monitoring the resistance change of the thermistor. pcb .

[0015] According to an optional embodiment, the thermistor is a negative temperature coefficient thermistor.

[0016] According to an optional embodiment, a relay is provided on the DC link, and the method further includes: when the forward current flowing through the diode is higher than the upper limit value, opening the relay to cut off the current flow on the DC link.

[0017] According to an optional embodiment, the DC link, the diode, and the power stage circuit are arranged on the same PCB board.

[0018] According to an optional embodiment, the method further includes, after collecting the forward conduction voltage on the diode, performing a signal amplification operation on the collected result.

[0019] A second aspect of the present invention further provides a computer-readable storage medium having a computer program stored thereon. The computer program includes program instructions, and when the program instructions are executed by a processor, the steps of the method described above are implemented.

[0020] A third aspect of the present invention further provides a motor controller, the motor controller comprising:

[0021] processor; and

[0022] A memory comprising the computer-readable storage medium as described above.

[0023] A fourth aspect of the present invention further provides a motor drive system, the motor drive system comprising:

[0024] a power supply, the power supply being used to supply power to the motor;

[0025] A power stage circuit, wherein the power stage circuit is used to drive the motor;

[0026] a DC link connected between a power source and the power stage circuit; and

[0027] Motor controller as described above.

[0028] The DC-link overcurrent detection method according to the present invention not only simplifies circuit design and reduces costs, but also improves the reliability and flexibility of the overall motor drive system. Furthermore, this overcurrent detection method is applicable not only to electric vehicles but also to all other applications requiring DC-link overcurrent protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] By incorporation into this document of the accompanying drawings and Figure 1 Other features and advantages of the method of the present invention will become clear or be described in more detail with reference to the specific embodiments that are used to illustrate certain principles of the present invention.

[0030] Figure 1 A schematic diagram showing a conventional overcurrent detection scheme used in a motor drive system.

[0031] Figure 2 A schematic diagram of a DC link overcurrent detection solution according to an exemplary embodiment of the present invention is shown.

[0032] Figure 3 A flow chart of a method for detecting overcurrent in a DC link according to an exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION

[0033] The following describes an overcurrent detection method for a DC link according to the present invention by way of example, with reference to the accompanying drawings. In the following description, numerous specific details are set forth to provide those skilled in the art with a more comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be implemented without some of these specific details. Rather, the present invention may be implemented using any combination of the following features and elements, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments, and advantages are provided for illustrative purposes only and should not be construed as elements or limitations of the claims.

[0034] Figure 1 Figure 2 shows the schematic diagram of a traditional overcurrent detection scheme used in motor drive systems. Figure 1 As can be seen in the previous section, traditional overcurrent protection methods in motor drive systems typically require a shunt resistor (SHUNT) to be connected in series with the DC-Link. The voltage across the SHUNT resistor is acquired using the ADC sampling port of the controller MCU to calculate the DC-Link current. However, this solution has the disadvantage that the SHUNT resistor introduces additional losses, affecting the overall energy efficiency of the electric drive system. Furthermore, additional peripheral circuitry and precise determination of the SHUNT resistance value are required to ensure accurate measurement results.

[0035] As electric vehicles continue to demand ever-increasing system energy efficiency and cost-effectiveness, traditional overcurrent detection solutions are struggling to meet market demands. Against this backdrop, this paper proposes an innovative DC-Link overcurrent detection solution. This solution leverages the characteristics of the existing reverse polarity protection diode on the DC-Link and combines it with software-controlled logic to implement DC-Link overcurrent detection without requiring additional hardware components. This approach not only simplifies circuit design and reduces costs, but also improves the overall reliability and flexibility of the motor drive system.

[0036] Specifically, the DC-link overcurrent detection method according to the present invention accurately measures the forward voltage and junction temperature of a diode. Combined with a pre-calibrated lookup table, it effectively estimates the current flowing through the diode, enabling real-time monitoring of overcurrent conditions on the DC-Link. This overcurrent detection method is applicable not only to electric vehicles but also to all other applications requiring DC-Link overcurrent protection.

[0037] Figure 2The schematic diagram shows a DC link overcurrent detection scheme according to an exemplary embodiment of the present invention. Assuming the overcurrent detection scheme is applied to a vehicle's motor drive system, the DC link DC-Link can be connected between a power source Vbat and a power stage circuit H1 for driving a motor M (e.g., a three-phase motor). In this case, the power source Vbat can specifically be a battery pack for powering the motor, and the power stage circuit can be a three-phase inverter bridge circuit.

[0038] like Figure 2 As shown in Figure 1, a diode D1, also known as a "polarity reverse protection diode," is typically connected in series with the DC-Link. This diode is a protective element that prevents reverse polarity connection of the power supply, thereby protecting the motor controller and other sensitive electronic equipment downstream from damage caused by reverse shock waves.

[0039] In practical applications of motor drive systems, reverse polarity protection diodes are crucial components for ensuring stable system operation. They are typically integrated between the power module and the motor controller (especially the power stage circuit). If, in certain circumstances, such as when replacing a battery pack, the positive and negative polarity of the power supply are reversed, current can flow in the wrong direction, potentially causing serious damage to the motor controller or even leading to a safety incident. Reverse polarity protection diodes protect the circuit by allowing current to flow in the normal direction but automatically blocking it when the power supply polarity is reversed.

[0040] The overcurrent detection solution of the present invention utilizes the characteristics of the existing reverse polarity protection diode D1 on the DC link and combines it with software control logic to implement overcurrent detection on the DC-Link. This solution does not require the provision of additional hardware components.

[0041] Figure 3 FIG. 1 shows a flow chart of a method for detecting an overcurrent in a DC link according to an exemplary embodiment of the present invention. Figure 3 The working process of this method is introduced in detail.

[0042] First, in step S1, when the motor's power supply Vbat is connected, the forward voltage across the reverse polarity protection diode D1 is collected. Optionally, after collecting the forward voltage across the diode, a signal amplification operation is performed on the collected result to facilitate subsequent processing by the MCU. Subsequently, in step S2, the forward voltage across diode D1 is input into a predetermined lookup table to determine the forward current flowing through the diode. Finally, in step S3, the forward current flowing through the diode can be compared with an upper limit value to determine whether an overcurrent fault has occurred in the DC link. This is a simplified operation of the overcurrent detection method.

[0043] Optionally, the method may further include a step of correcting the current calculation result based on temperature. Referring to steps S4-S5, for example, in step S4, the temperature value T on the PCB board provided with the diode may be further measured. pcb ; At temperature T pcb For example, it can be the surface temperature of the PCB board. After determining the temperature value, in step S5, it can be further based on the temperature value T pcb Calculate the diode junction temperature T j Finally, in step S6, the junction temperature T of the diode can be calculated based on the j The forward current determined in step S2 is corrected.

[0044] That is to say, when determining the forward current flowing through the diode, not only the forward conduction voltage on the diode D1 is considered, but also the temperature value T on the PCB board. pcb , and then consider the junction temperature T of the diode j , thereby ensuring the accuracy of the current detection results.

[0045] The temperature of a PCB can be determined using a temperature sensor. The core component of this temperature sensor is a thermistor. For example, a thermistor, particularly a negative temperature coefficient thermistor (NTC), can be installed near the diode on the PCB. When the PCB circuit is powered, the resistance of the thermistor changes with the ambient temperature. Therefore, the temperature of the PCB can be determined by monitoring the change in the resistance of the thermistor. pcb .

[0046] Alternatively, a relay can be provided on the DC link. When the forward current flowing through the reverse polarity protection diode D1 is detected to be higher than a predetermined upper limit, the controller can disconnect the relay to cut off the current flow in the DC link, thereby protecting the subsequent power stage circuitry from damage caused by reverse current surges. In the motor drive system, the DC link, diode, and power stage circuitry can be provided on the same PCB.

[0047] According to the DC link (DC-Link) overcurrent detection method of the present invention, the method realizes overcurrent detection of the DC-Link by utilizing the characteristics of the existing polarity reverse protection diode on the DC-Link and combining it with software control logic. This solution does not require the provision of additional hardware components. Specifically, the DC link overcurrent detection method of the present invention can effectively estimate the current flowing through the diode by accurately measuring the forward conduction voltage and junction temperature of the diode, combined with a pre-calibrated lookup table, thereby realizing real-time monitoring of the overcurrent state on the DC-Link. The DC link overcurrent detection method of the present invention not only simplifies the circuit design and reduces the cost, but also improves the overall reliability and flexibility of the motor drive system. In addition, the overcurrent detection method is not only applicable to the field of electric vehicles, but also to all other application fields that require DC-Link overcurrent protection.

[0048] In an exemplary embodiment of the present invention, a computer-readable storage medium is further provided, on which a computer program is stored. The program includes executable program instructions. When the executable program instructions are executed by, for example, a processor, they can implement the various steps of the DC link overcurrent detection method described in any embodiment of this document.

[0049] In another exemplary embodiment of the present invention, a motor controller is provided. The motor controller includes: a processor; and a memory, wherein the memory includes the computer-readable storage medium described above.

[0050] In another exemplary embodiment of the present invention, a motor drive system is also provided, which includes: a power supply, the power supply is used to supply power to the motor; a power stage circuit, the power stage circuit is used to drive the motor; a DC link, the DC link is connected between the power supply and the power stage circuit; and the motor controller described above.

[0051] Those skilled in the art will appreciate that the exemplary embodiments herein can be implemented via software or by combining software with necessary hardware. Therefore, the technical solutions according to the embodiments of the present invention can be embodied in the form of a software product, which can be stored in a non-volatile storage medium or on a network and includes several instructions for enabling a computing device (such as a personal computer, server, or network device) to execute the DC link overcurrent detection method described in various embodiments of the present invention.

[0052] Although the present invention has been disclosed above with reference to preferred embodiments, the present invention is not limited thereto. Any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A method for detecting overcurrent in a DC link, wherein the DC link is connected between a power supply and a power stage circuit for driving a motor, and a diode is connected in series with the DC link to provide protection against reverse polarity of the power supply, characterized in that: The method comprises the following steps: Step S1: When the power supply is turned on, the forward conduction voltage of the diode is collected; Step S2: inputting the forward conduction voltage of the diode into a predetermined lookup table to determine the forward current flowing through the diode; and Step S3: Compare the forward current flowing through the diode with an upper limit value to determine whether an overcurrent fault occurs on the DC link.

2. The overcurrent detection method according to claim 1, wherein: The method further comprises the following steps: Step S4: Measure the temperature value T on the PCB board where the diode is provided. pcb ; Step S5: Based on the temperature value T on the PCB board pcb Calculate the junction temperature T of the diode j ;as well as Step S6: Based on the calculated junction temperature T of the diode j The forward current determined in step S2 is corrected.

3. The overcurrent detection method according to claim 2, wherein: A thermistor is provided on the PCB near the diode, and the temperature value T of the PCB is determined by monitoring the resistance change of the thermistor. pcb .

4. The overcurrent detection method according to claim 3, wherein: The thermistor is a negative temperature coefficient thermistor.

5. The overcurrent detection method according to any one of claims 1 to 4, characterized in that: A relay is provided on the DC link, and the method further includes: when the forward current flowing through the diode is higher than the upper limit value, opening the relay to cut off the current flow on the DC link.

6. The overcurrent detection method according to any one of claims 1 to 4, characterized in that: The DC link, the diode, and the power stage circuit are arranged on the same PCB board.

7. The overcurrent detection method according to any one of claims 1 to 4, characterized in that: The method further includes performing a signal amplification operation on the collected result after collecting the forward conduction voltage on the diode.

8. A computer-readable storage medium having a computer program stored thereon, the computer program comprising program instructions, characterized in that: When the program instructions are executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

9. A motor controller, characterized in that: The motor controller includes: processor; and A memory comprising the computer-readable storage medium according to claim 8.

10. A motor drive system, characterized in that: The motor drive system includes: a power supply, the power supply being used to supply power to the motor; A power stage circuit, wherein the power stage circuit is used to drive the motor; a DC link connected between a power source and the power stage circuit; and The motor controller according to claim 9.

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