A contactor sticking detection processing device and method

Abstract

The application discloses a kind of contactor sticking detection processing device and method, including contactor, key switch, battery, power supply bus, power supply control module, pre-charge circuit, discharge circuit, motor controller and current sampling module;Wherein, pre-charge circuit includes pre-charge resistance and bus capacitor;Battery, contactor, power supply bus, bus capacitor and discharge circuit are sequentially connected in series, pre-charge resistance and key switch are connected in series and are connected in parallel with contactor, current sampling module is connected in parallel at the two ends of pre-charge resistance, for detecting the current flowing through pre-charge resistance when contactor sticking detection is carried out, power supply control module is connected in parallel at the two ends of pre-charge resistance, and the output end of power supply control module is connected with motor controller, and power supply control module is used to power supply motor controller.The application can reduce detection period, improve response speed, eliminate the problem of power supply control module being always worked after power-off caused by battery fluctuation.

Description

Technical Field

[0001] This invention belongs to the field of vehicle battery technology, and in particular relates to a contactor adhesion detection and processing device and method. Background Technology

[0002] Currently, in electric forklifts, the contactor, as a power component switch, is located outside the motor controller. One end is connected to the battery, and the other end is connected to the motor controller's bus. The motor controller provides the contactor with coil power supply circuits and bus pre-charge and discharge circuits. Contactor sticking is a common contactor fault, manifested as the main contacts failing to open normally after the contactor coil is de-energized, resulting in continuous circuit energization. The invention patent application with application number CN201811643726.1, entitled "Contactor Adhesion Detection Circuit and Contactor Adhesion Detection Method," describes a contactor adhesion detection circuit comprising a motor controller, a detection circuit, a first sampling circuit, multiple second sampling circuits, a first controllable switch, and a second controllable switch. When the first and second controllable switches are open, the detection circuit cannot receive the adhesion detection signal and is in a non-operating state, reducing the power consumption of the detection circuit.

[0003] The existing technology described above detects adhesion by measuring the voltage difference between two contacts. However, for motor controllers, a live conductor is only introduced when the control components are operating, and detection is only performed on the bus-side contacts, not the battery-side contacts. Single-point detection can only determine adhesion by observing the monotonically decreasing change in bus voltage after the contactor coil is de-energized. However, voltage changes depend on the applied load, and for motor controllers, this is only due to leakage current losses in the components on the bus link. Under load, voltage changes are slow, resulting in a long detection cycle and slow response. Changes in the battery also cause changes in the bus voltage. During detection, the battery waveform shows monotonically decaying, which can lead to missed adhesion detections. In addition, motor controllers have a rapid bus discharge function, which quickly discharges the bus voltage after shutdown. Furthermore, if adhesion is detected, the current motor controller can only perform an alarm. After shutdown, the discharge circuit continues to operate, leading to prolonged battery depletion. Summary of the Invention

[0004] The purpose of this invention is to provide a contactor adhesion detection and processing device and method, which can solve the problems of missed detection of adhesion caused by changes in the battery and the discharge circuit continuing to work after shutdown.

[0005] The present invention adopts the following technical solution: A contactor adhesion detection and processing device includes a contactor, a key switch, a battery, a power supply bus, a power supply control module, a pre-charging circuit, a discharging circuit, a motor controller, and a current sampling module; wherein the pre-charging circuit includes a pre-charging resistor and a bus capacitor; The battery, contactor, power supply bus, bus capacitor, and discharge circuit are connected in series. The pre-charge resistor and key switch are connected in series and then in parallel with the contactor. The current sampling module is connected in parallel across the pre-charge resistor to detect the current flowing through the pre-charge resistor when performing contactor sticking detection. The power supply control module is connected in parallel across the pre-charge resistor. The output of the power supply control module is connected to the motor controller, and the power supply control module is used to supply power to the motor controller.

[0006] Furthermore, the power supply control module includes: a first power supply switch, a second power supply switch, and an auxiliary power supply; the first power supply switch is normally closed, and the second power supply switch is normally open; the auxiliary power supply is used to supply power to the motor controller with the electrical energy stored after the key switch is turned off and charged by the bus capacitor.

[0007] Furthermore, the discharge circuit is represented by a discharge resistor, and the first power supply switch Q1 and the second power supply switch Q2 are MOSFETs and / or relays.

[0008] A contactor adhesion detection and processing method, applicable to the above-mentioned device, comprising: S1: Close the key switch KSI, the pre-charging circuit starts working, and at the same time the power supply control module is powered on to perform the power-on pre-charging test; S2: After the pre-charge test is completed, the motor controller issues the first control command, and the adhesion detection device performs contactor adhesion detection. When the contactor sticks together, the motor controller triggers the fault protection mechanism, controlling the discharge circuit to stop working. When the contactor does not stick, the discharge circuit starts to perform the discharge operation of the bus capacitor; S3: If the contactor sticks, when the key switch KSI is turned off, the power supply control module supplies power to the motor controller through the pre-charging circuit, and continuously controls the discharge circuit to not work.

[0009] Furthermore, in S1, the size of the pre-charging resistor must be such that the start-up time of the motor controller is less than the time required for the bus pre-charging to be completed.

[0010] Furthermore, the power supply control module mentioned in S1 includes: a first power supply switch Q1, a second power supply switch Q2, and an auxiliary power supply.

[0011] Furthermore, the pre-charge detection in S1 is as follows: the pre-charge circuit starts working, the electrical energy of the battery positive terminal is input to the bus capacitor through the pre-charge resistor, the bus voltage rises, and when the bus capacitor voltage is greater than or equal to the charging voltage threshold, the contactor contacts close, indicating that the bus pre-charge is complete.

[0012] Furthermore, in S2, the first control command refers to controlling the contactor and the first power supply switch Q1 to disconnect via the motor controller, while simultaneously controlling the second power supply switch Q2 to close; the process of adhesion detection is as follows: The current value of the pre-charge resistor is detected by the current sampling module. If the current sampling module detects that the current value of the pre-charge resistor is greater than the set current threshold, it indicates that the contactor has not stuck. If the current sampling module detects that the current value of the pre-charge resistor is less than or equal to the set current threshold, it indicates that the contactor has stuck.

[0013] Furthermore, in S2, when the contactor does not stick, the enable terminal of the motor controller that controls the discharge circuit is at a low level, and the discharge circuit performs the discharge operation of the bus capacitor.

[0014] Furthermore, the fault protection mechanism in S2 refers to the motor controller issuing an alarm command and a second control command after detecting contactor sticking. The second control command is used to set the enable terminal of the motor controller that controls the operation of the discharge circuit to a high level. When the enable terminal of the motor controller that controls the operation of the discharge circuit is at a high level, the discharge circuit does not work, and the bus capacitor does not discharge.

[0015] This invention provides a method for determining contactor sticking by detecting the current flowing through the pre-charge resistor, reducing the detection cycle and improving the response speed; the current signal does not change with battery voltage fluctuations, eliminating missed detections caused by battery fluctuations; it increases the motor controller's ability to handle sticking faults, avoids the problem of the discharge circuit continuing to work after shutdown, and the discharge circuit latching function can prevent the discharge circuit from continuing to work after shutdown, preventing battery over-discharge and extending battery life; after the key switch is turned off, the motor controller can still maintain key protection functions, solving the problem of loss of control after shutdown in traditional solutions. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 A connection diagram of a first embodiment of the contactor adhesion detection and processing device provided by the present invention; Figure 2 This is a connection diagram of Embodiment 2 of the contactor adhesion detection and processing device provided by the present invention; Figure 3 This is a schematic diagram of the connection of the motor controller in the device provided by the present invention; Figure 4 This is a flowchart of the contactor adhesion detection and processing method provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments described herein clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments described herein, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are within the scope of protection of this document. It should be noted that, unless otherwise specified, the embodiments and features described herein can be arbitrarily combined with each other.

[0019] The following is in conjunction with the appendix Figures 1 to 3 The present invention will be described in detail with reference to the embodiments: Contactor sticking is a common fault in contactors, which manifests as the main contacts failing to open properly after the contactor coil is de-energized, resulting in continuous power supply to the circuit.

[0020] A contactor adhesion detection and processing device includes a contactor, a key switch, a battery, a power supply bus, a power supply control module, a pre-charging circuit, a discharging circuit, a motor controller, and a current sampling module; wherein the pre-charging circuit includes a pre-charging resistor and a bus capacitor; The battery, contactor, power supply bus, bus capacitor, and discharge circuit are connected in series. The pre-charge resistor and key switch are connected in series and then in parallel with the contactor. The current sampling module is connected in parallel across the pre-charge resistor to detect the current flowing through the pre-charge resistor when performing contactor sticking detection. The power supply control module is connected in parallel across the pre-charge resistor. The output of the power supply control module is connected to the motor controller, and the power supply control module is used to supply power to the motor controller.

[0021] A current sampling module is connected in parallel across the pre-charging resistor to detect the current flowing through it during adhesion detection. The power supply control module is connected in parallel with the pre-charging resistor in the pre-charging circuit and supplies power to the motor controller. The motor controller sends a command to disconnect the contactor and the first power supply switch while simultaneously closing the second power supply switch to detect contactor adhesion. Once contactor adhesion is detected and the key switch is disconnected, the power supply control module receives power through the bus capacitor to continuously supply power to the motor controller. The motor controller outputs a control signal to disable the discharge circuit.

[0022] like Figure 2As shown, the present invention also provides another embodiment, wherein the power supply control module includes a first power supply switch Q1, a second power supply switch Q2, and an auxiliary power supply; the first power supply switch Q1 is a normally closed switch, and the second power supply switch Q2 is a normally open switch; the input terminal of the first power supply switch Q1 is connected to the input terminal of the pre-charge resistor; the output terminal of the first power supply switch Q1 is connected to the auxiliary power supply; the input terminal of the second power supply switch Q2 is connected to the power supply bus; the output terminal of the second power supply switch Q2 is connected to the auxiliary power supply; both the first power supply switch Q1 and the second power supply switch Q2 are used to control the power on and power off of the auxiliary power supply; the auxiliary power supply is used to supply power to the motor controller with the electrical energy stored after being charged by the bus capacitor after the key switch is turned off.

[0023] In this embodiment, the discharge circuit is represented by a discharge resistor. Obviously, the discharge circuit can also be composed of other discharge devices. Therefore, the composition of the discharge circuit is not limited in this invention.

[0024] In this invention, the contactor contacts are initially in an open state. In this context, "closing the contactor" means closing the main contacts, "opening the contactor" means opening the main contacts, and "contaminant sticking" means the main contacts of the contactor sticking together. The pre-charging circuit charges the bus capacitor through a pre-charging resistor. When the motor controller detects that the voltage of the bus capacitor reaches a preset voltage threshold, it indicates that the pre-charging circuit is complete, and the motor controller controls the contactor to close. If no pre-charging is performed and the contactor is closed directly, due to the characteristic that the voltage of a capacitor cannot change abruptly, the bus capacitor will experience an equivalent short circuit. In high-voltage systems, the capacity of the bus capacitor is usually large, and in this case, a surge current may be generated, potentially burning out the contactor contacts and damaging the capacitor. An equivalent short circuit in the bus capacitor refers to the situation where, when the capacitor is in an uncharged state with a voltage of 0V, if it is directly connected to a high-voltage power source (such as a battery BAT+), the capacitor will exhibit a momentary resistance of 0.

[0025] In this invention, the presence of current flowing through the pre-charge resistor is detected by the motor controller to determine whether the contactor is stuck, thereby achieving contactor sticking detection.

[0026] As attached Figure 3 The diagram shows the connection of the motor controller in Embodiment 2 of the contactor adhesion detection and processing device provided by the present invention. The motor controller receives the current information from the current sampling module, and determines whether current flows through the pre-charging resistor by comparing the received current value with the set current value, thereby determining whether the contactor is stuck. The motor controller collects the voltage value of the bus capacitor and determines whether the bus pre-charging is completed by combining it with the preset charging voltage threshold. The motor controller outputs control signals to the contactor, the first power supply switch Q1, the second power supply switch Q2 and the discharge circuit.

[0027] In this embodiment, the auxiliary power supply provides voltage to the motor controller. The battery positive terminal—contactor—bus capacitor—discharge circuit serves as the power harness, which transmits high voltage and high current power. The key switch KSI—first power supply switch Q1—auxiliary power supply serves as the control harness. The auxiliary power input is separate from the power harness on the vehicle wiring harness. That is, the control harness and the power harness are completely independent in physical wiring and do not share cables. The high voltage and high current of the power harness circuit will not interfere with the signal of the control harness circuit, and it also avoids the safety of the power harness circuit being affected by the failure of the control harness circuit.

[0028] A contactor adhesion detection and processing method, applicable to the aforementioned contactor adhesion detection and processing device. S1: Close the key switch KSI, the pre-charging circuit starts working, and at the same time the power supply control module is powered on to perform the power-on pre-charging test; In this invention, closing the key switch KSI powers on the electric forklift. The first power supply switch Q1 is normally closed, and the second power supply switch Q2 is normally open. At this time, the auxiliary power supply is powered on to provide power to the motor controller. After power-on, the bus pre-charge is performed. The bus pre-charge and the motor controller start-up are performed in parallel.

[0029] In this invention, to achieve pre-charge detection upon startup, the motor controller startup time must be less than the bus pre-charge completion time. Pre-charge requires a certain amount of time for the bus capacitor voltage to rise to the charging voltage threshold, and the motor controller startup requires initialization and power stabilization processes. Only when the motor controller starts up first can it issue timely commands during pre-charge (such as controlling the contactor to engage upon confirmation of pre-charge completion). Simultaneously, it can promptly disconnect the pre-charge circuit in case of a pre-charge fault, avoiding risks such as overheating of the pre-charge resistor and abnormal bus voltage.

[0030] In the pre-charge detection process, timely disconnection of the pre-charge circuit to avoid risks when a pre-charge fault is detected is a conventional technique in the field and is not the main issue discussed in this invention, so it will not be elaborated here.

[0031] If the pre-charge resistor is set too small, the pre-charge process may have already ended and the contactor may have already engaged before the motor controller starts up. This makes it impossible to monitor the voltage / current changes during pre-charge or determine whether the pre-charge is normal, leading to the failure of the pre-charge detection upon startup. In the event of a pre-charge failure, the contactor may be accidentally engaged, causing a surge impact.

[0032] In this invention, when the key switch KSI is closed, the pre-charge detection process is as follows: the pre-charge circuit starts working and charges the bus capacitor; when the pre-charge circuit is turned on, the electrical energy of the battery positive terminal BAT+ flows slowly into the bus capacitor through the pre-charge resistor, and the bus voltage gradually rises. When the bus capacitor voltage is greater than or equal to the charging voltage threshold, the contactor contacts close, indicating that the bus pre-charge is complete.

[0033] In this embodiment, the charging voltage threshold is set to 90% of the battery voltage. The charging progress is determined by detecting the voltage input to the bus capacitor. When the bus capacitor voltage rises above 90% of the battery voltage, it indicates that the bus capacitor is fully charged, and power-on is complete. At this time, the motor controller controls the contactor to engage, the pre-charging circuit is disconnected, and the power supply bus is connected to the battery through the contactor, and the high-voltage system enters normal power supply mode. The bus capacitor is slowly charged by the electrical energy input from the positive terminal (BAT+) of the battery to avoid large current surges. After pre-charging is complete, the main contactor will close.

[0034] S2: After the pre-charge test is completed, the motor controller issues the first control command, and the adhesion detection device performs contactor adhesion detection. When the contactor sticks together, the motor controller triggers the fault protection mechanism, controlling the discharge circuit to stop working. When the contactor does not stick, the discharge circuit starts to perform the discharge operation of the bus capacitor.

[0035] The first control command is used to control the contactor and the first power supply switch Q1 to open while simultaneously closing the second power supply switch Q2 via the motor controller.

[0036] The process of performing adhesion detection is as follows: The current value of the pre-charge resistor is detected by the current sampling module. If the current sampling module detects that the current value of the pre-charge resistor is greater than the set current threshold, it means that current is flowing through the two ends of the pre-charge resistor, that is, the contactor is disconnected well and no sticking has occurred. If the current sampling module detects that the current value of the pre-charging resistor is less than or equal to the set current threshold, it means that no current flows through the pre-charging resistor, i.e., the contactor is stuck.

[0037] In this embodiment, when the contactor is disconnected, the path of the pre-charge resistor is key switch KSI → pre-charge resistor → bus capacitor. The key switch KSI terminal is the battery voltage, and the bus side is the capacitor voltage. At this time, there is a voltage difference across the pre-charge resistor, and current will flow through the pre-charge resistor. At this time, the current value detected by the current sampling module will be greater than the set current threshold.

[0038] When contactor sticking occurs, meaning the contactor fails to disconnect, the upper (BAT+) and lower (busbar side) terminals of the contactor are connected, and the voltages across them are equal. The two ends of the pre-charging resistor are short-circuited, resulting in no voltage difference across the resistor and no current flow. The current value detected by the current sampling module will be less than or equal to the set current threshold. Therefore, the presence of contactor sticking can be determined by detecting the current value of the pre-charging resistor using the current sampling module.

[0039] The fault protection mechanism refers to the motor controller issuing an alarm command and a second control command after detecting contactor sticking. The second control command is used to set the enable terminal of the motor controller that controls the discharge circuit to a high level.

[0040] When the enable terminal of the motor controller that controls the discharge circuit is at a high level, the discharge circuit does not work, and the bus capacitor does not discharge. When the enable terminal of the motor controller that controls the operation of the discharge circuit is at a low level, the discharge circuit starts to perform the discharge operation of the bus capacitor.

[0041] S3: When the key switch KSI is turned off, the power supply control module supplies power to the motor controller through the pre-charging circuit and continuously controls the discharge circuit to not work.

[0042] When the second power supply switch Q2 is closed, the auxiliary power supply is powered after discharging through the bus capacitor in the pre-charging circuit. The enable terminal of the motor controller that maintains the operation of the discharge circuit is at a high level, and the discharge circuit is not operated.

[0043] When the contactor is not stuck, the power-off procedure for the KSI electric forklift after disconnecting the key switch is as follows: When the enable terminal of the motor controller that controls the operation of the discharge circuit is turned low, a discharge trigger signal is output, the discharge circuit is activated, and the discharge circuit (internal resistor) is connected in parallel with the bus capacitor. The high voltage residual charge stored in the bus capacitor is quickly consumed through the discharge resistor, and the bus voltage drops to a safe voltage within a few seconds, completing the rapid discharge. After the discharge is completed, the discharge circuit will automatically stop working.

[0044] When the contactor sticks together, it fails to disconnect when it should, and the battery remains connected to the bus. If the discharge circuit is activated at this time, it will continuously discharge to the bus. However, because the contactor is stuck together, the battery will continue to supply power to the bus. The discharge circuit is essentially discharging on one side while the battery is charging on the other. The discharge circuit will continue to run (without automatically stopping), and over time, it will deplete the battery.

[0045] In this embodiment, since the discharge circuit is not working, the motor controller is in a safe state, so the battery will not be depleted due to the contactor sticking together.

[0046] This invention provides a method for determining contactor sticking by detecting the current flowing through the pre-charge resistor, reducing the detection cycle and improving the response speed; the current signal does not change with battery voltage fluctuations, eliminating missed detections caused by battery fluctuations; it increases the motor controller's ability to handle sticking faults, avoids the problem of the discharge circuit continuing to work after shutdown, and the discharge circuit latching function can prevent the discharge circuit from continuing to work after shutdown, preventing battery over-discharge and extending battery life; after the key switch KSI is turned off, the motor controller can still maintain key protection functions, solving the problem of loss of control after shutdown in traditional solutions.

[0047] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A contactor adhesion detection and processing device, characterized in that: It includes a contactor, key switch, battery, power supply bus, power supply control module, pre-charge circuit, discharge circuit, motor controller and current sampling module; wherein, the pre-charge circuit includes a pre-charge resistor and a bus capacitor; The battery, contactor, power supply bus, bus capacitor, and discharge circuit are connected in series. The pre-charge resistor and key switch are connected in series and then in parallel with the contactor. The current sampling module is connected in parallel across the pre-charge resistor to detect the current flowing through the pre-charge resistor when performing contactor sticking detection. The power supply control module is connected in parallel across the pre-charge resistor. The output of the power supply control module is connected to the motor controller, and the power supply control module is used to supply power to the motor controller.

2. The contactor adhesion detection and processing device according to claim 1, characterized in that: The power supply control module includes: a first power supply switch, a second power supply switch, and an auxiliary power supply; the first power supply switch is normally closed, and the second power supply switch is normally open; the auxiliary power supply is used to supply power to the motor controller with the electrical energy stored after the key switch is turned off and charged by the bus capacitor.

3. The contactor adhesion detection and processing device according to claim 2, characterized in that: The discharge circuit is represented by a discharge resistor, and the first power supply switch and the second power supply switch are MOSFETs and / or relays.

4. A contactor adhesion detection and processing method, applicable to the contactor adhesion detection and processing device according to any one of claims 1 to 3, characterized in that, include: S1: Close the key switch KSI, the pre-charging circuit starts working, and at the same time the power supply control module is powered on to perform the power-on pre-charging test; S2: After the pre-charge test is completed, the motor controller issues the first control command, and the adhesion detection device performs contactor adhesion detection. When the contactor sticks together, the motor controller triggers the fault protection mechanism, controlling the discharge circuit to stop working. When the contactor does not stick, the discharge circuit starts to perform the discharge operation of the bus capacitor; S3: If the contactor sticks, when the key switch KSI is turned off, the power supply control module supplies power to the motor controller through the pre-charging circuit, and continuously controls the discharge circuit to not work.

5. The contactor adhesion detection and processing method according to claim 4, characterized in that: In S1, the size of the pre-charge resistor must be such that the start-up time of the motor controller is less than the time it takes for the bus pre-charge to complete.

6. The contactor adhesion detection and processing method according to claim 5, characterized in that: The power supply control module mentioned in S1 includes: a first power supply switch, a second power supply switch, and an auxiliary power supply.

7. The contactor adhesion detection and processing method according to claim 6, characterized in that: The pre-charge detection in S1 is as follows: the pre-charge circuit starts working, the electrical energy of the battery positive terminal is input to the bus capacitor through the pre-charge resistor, the bus voltage rises, and when the bus capacitor voltage is greater than or equal to the charging voltage threshold, the contactor contacts close, indicating that the bus pre-charge is complete.

8. The contactor adhesion detection and processing method according to claim 7, characterized in that, S2, the first control command, refers to controlling the contactor and the first power supply switch to disconnect via the motor controller, while simultaneously controlling the second power supply switch to close; the adhesion detection process is as follows: The current value of the pre-charge resistor is detected by the current sampling module. If the current sampling module detects that the current value of the pre-charge resistor is greater than the set current threshold, it indicates that the contactor has not stuck. If the current sampling module detects that the current value of the pre-charge resistor is less than or equal to the set current threshold, it indicates that the contactor has stuck.

9. The contactor adhesion detection and processing method according to claim 8, characterized in that: In S2, when the contactor does not stick, the enable terminal of the motor controller that controls the discharge circuit is at a low level, and the discharge circuit performs the discharge operation of the bus capacitor.

10. The contactor adhesion detection and processing method according to claim 8, characterized in that: The fault protection mechanism in S2 refers to the motor controller issuing an alarm command and a second control command after detecting contactor sticking. The second control command is used to set the enable terminal of the motor controller that controls the discharge circuit to a high level. When the enable terminal of the motor controller that controls the discharge circuit is at a high level, the discharge circuit does not work, and the bus capacitor does not discharge.

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