Motor thermal protection device and operation method thereof

Abstract

Disclosed are a motor thermal protection device and an operation method thereof. The motor thermal protection device is powered by a power supply of a motor, and comprises: a capacitor timing circuit for timing after the motor is powered off; a power-off time determination unit for performing a reading operation of the output voltage of the capacitor timing circuit after the motor is powered on, and determining the power-off time from when the motor is powered off to when the motor is powered on according to the output voltage; and a heat accumulation calculation unit for calculating the remaining heat accumulation when the motor is powered on according to the power-off time and the heat accumulation when the motor is powered off.

Description

Technical Field

[0001] The present disclosure relates to a motor thermal protection device and an operating method of the motor thermal protection device. Background Art

[0002] In industrial processes, electromechanical equipment often needs to be operated continuously. Accidents caused by motor overheating or temperature control failure often occur. The use of motor thermal protection devices can automatically cut off the power when the motor overheats to protect the motor and the electromechanical equipment in the circuit. Current motor thermal protection devices cannot accurately track and monitor the accumulated heat of the motor in real time and judge the thermal state of the motor because they cannot know the residual heat when the motor is powered on. If the judgment is based on the experience of the staff, it may cause unnecessary accidents due to low accuracy; if the motor is used after waiting for a period of time sufficient for the motor heat to completely cool down (generally speaking, at least 50 minutes), it may not be allowed. Summary of the invention

[0003] The present disclosure relates to a motor thermal protection device capable of determining residual heat accumulation when the motor is powered on and an operation method thereof.

[0004] According to one aspect of the present disclosure, there is provided a motor thermal protection device, which is powered by a power supply of a motor and includes: a capacitor timing circuit, which is used to perform timing after the motor is powered off; a power-off time determination unit, which is used to perform a reading operation of the output voltage of the capacitor timing circuit after the motor is powered on, and determine the power-off time from when the motor is powered off to when the motor is powered on according to the output voltage; and a heat accumulation calculation unit, which is used to calculate the remaining accumulated heat when the motor is powered on according to the power-off time and the accumulated heat when the motor is powered off.

[0005] According to another aspect of the present disclosure, there is provided an operating method for a motor thermal protection device, wherein the motor thermal protection device is powered by a power supply of a motor, and the motor thermal protection device comprises a capacitor timing unit, a power-off time determination unit and a heat accumulation calculation unit, wherein the method comprises: the capacitor timing circuit performs timing after the motor is powered off; the power-off time determination unit performs a reading operation of an output voltage of the capacitor timing circuit after the motor is powered on, and determines the power-off time from when the motor is powered off to when the motor is powered on according to the output voltage; and the heat accumulation calculation unit calculates the remaining heat accumulation when the motor is powered on according to the power-off time and the heat accumulation when the motor is powered off.

[0006] According to an embodiment of the present disclosure, the motor thermal protection device can obtain the cooling time from when the motor is powered off to when the motor is powered on, thereby obtaining the residual heat accumulation when the motor is powered on, and can optionally calculate the cumulative heat accumulation of the motor in real time during the motor power-on period, thereby protecting the motor and other electromechanical equipment in the circuit from damage due to motor overheating. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The aspects, features and advantages of the present disclosure will become clearer and easier to understand through the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0008] Figure 1 is a schematic circuit module diagram of a motor thermal protection device according to an embodiment of the present disclosure;

[0009] Figure 2 is a schematic circuit diagram of a capacitor timing circuit in a motor thermal protection device according to an embodiment of the present disclosure;

[0010] Figure 3 is a schematic circuit diagram of a capacitor timing circuit in a motor thermal protection device according to an embodiment of the present disclosure;

[0011] Figure 4 is a flow chart of an operating method of a motor thermal protection device according to an embodiment of the present disclosure;

[0012] Figure 5 is a schematic circuit diagram of a capacitor timing circuit in a motor thermal protection device according to another embodiment of the present disclosure;

[0013] Figure 6 is a flow chart of a diagnostic operation of a motor thermal protection device according to another embodiment of the present disclosure; and

[0014] Figure 7 is a flow chart of a calibration operation of a motor thermal protection device according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0015] The present disclosure will be described in detail below with reference to exemplary embodiments of the present disclosure. However, the present disclosure is not limited to the embodiments described herein, and it can be implemented in many different forms. The described embodiments are only used to make the present disclosure thorough and complete, and to fully convey the concept of the present disclosure to those skilled in the art. The features of the various embodiments described can be combined or replaced with each other, unless explicitly excluded or should be excluded according to the context.

[0016] For motor thermal protection, the industry often uses thermal overload relays that are easy to install and low-cost. However, when the motor is powered on, the traditional thermal overload relay cannot know the power-off time from the last power-off to the power-on time of the motor, and therefore cannot obtain the residual heat accumulation when the motor is powered on, and thus cannot accurately calculate the accumulated heat of the motor over time in real time. Such thermal overload relays are not enough to ensure the safe use of motors and electromechanical equipment in circuits.

[0017] The present disclosure proposes a motor thermal protection device, which is used to obtain the residual heat accumulation when the motor is powered on and can calculate the accumulated heat accumulation of the motor over time in real time. The motor thermal protection device includes a capacitor timing circuit, which uses the capacitor charging and discharging principle to obtain the discharge time of the capacitor, thereby obtaining the power-off time of the motor from power off to power on. The motor thermal protection device can calculate the heat dissipation of the motor from power off to power on based on the power-off time and the heat dissipation principle, thereby obtaining the residual heat accumulation when the motor is powered on, and then can calculate the accumulated heat accumulation of the motor over time in real time, and then can protect the motor according to the real-time heat accumulation, for example, when the motor is judged to be overheated, the motor is powered off. According to an embodiment of the present disclosure, the capacitor timing circuit can perform timing when the motor is powered off, thereby causing the motor thermal protection device to also be powered off, which solves the problem that timing cannot be performed after the motor is powered off in the prior art.

[0018] According to an embodiment of the present disclosure, the motor thermal protection device can also perform diagnostic operations and calibration operations. The diagnostic operation is usually performed as needed during the daily use of the motor thermal protection device by the user, and it can diagnose whether the motor thermal protection device is faulty to prevent the motor from being powered off in time when the motor is overheated. The calibration operation is usually performed by the manufacturer when the motor thermal protection device leaves the factory, and is used to calibrate the capacitance value of the capacitor included therein, and then the user performs relevant calculations based on the calibrated capacitance value, so that the obtained residual heat accumulation and cumulative heat accumulation of the motor are more accurate.

[0019] Figure 1 1 is a schematic circuit module diagram of a motor thermal protection device 100 according to an embodiment of the present disclosure. The motor thermal protection device 100 is powered by the power supply of the motor, so when the motor is powered off, the various components of the motor thermal protection device also lose power. For example, the motor thermal protection device 100 receives an input voltage provided by the power supply of the motor via an input power line, and the input voltage is provided to various circuit units after necessary conversion.

[0020] The motor thermal protection device 100 includes a capacitor timing circuit 101. The capacitor timing circuit 101 is used to time the motor after the motor is powered off. Specifically, the capacitor timing circuit 101 can be configured to charge and discharge capacitors (e.g. Figure 2 The capacitor C) and the discharge resistor (e.g. Figure 2 For example, during the period when the motor is powered on, the capacitor C in the capacitor timing circuit 100 can be charged to the maximum capacitor voltage, and during the period when the motor is powered off, the capacitor C can be discharged. If the motor is powered on again after a certain period of time (i.e., the discharge time), the output voltage V output from the capacitor timing circuit 101 indicating the voltage remaining at both ends of the capacitor after the discharge time has passed. thermal It can be used to calculate the power-off time T from when the motor is powered off to when the motor is powered on again off.

[0021] The motor thermal protection device 100 further includes a power-off time determination unit 102. The power-off time determination unit 102 is used to read the output voltage V of the capacitor timing circuit 101 after the motor is powered on. thermal The read operation and the output voltage V thermal Determine the power-off time T from when the motor is powered off to when the motor is powered on off .

[0022] The motor thermal protection device 100 further includes a heat accumulation calculation unit 103. The heat accumulation calculation unit 103 calculates the power-off time T determined by the power-off time determination unit 102. off and heat accumulation THS when the motor is powered off last Calculate the residual heat accumulation THS(0) when the motor is powered on. Calculate the residual heat accumulation THS when the motor is powered off last It may be a value stored in a memory (not shown) of the motor thermal protection device 100, which represents the accumulated heat closest to the motor power-off time calculated and stored by the motor thermal protection device 100 during the last power-on of the motor. The memory may be a memory provided inside the motor thermal protection device 100 or provided outside the motor thermal protection device 100 and from which data can be read and written by the motor thermal protection device 100.

[0023] According to the above-mentioned embodiment of the present disclosure, by using the output voltage V after the discharge time of the capacitor timing circuit 101 thermal By calculating the power-off time from when the motor is powered off to when the motor is powered on, the residual heat accumulation THS(0) when the motor is powered on can be obtained, and the accumulated heat accumulated over time during the power-on period can be calculated in real time. At the same time, it can be judged whether the accumulated heat meets the conditions for tripping the motor according to the preset motor tripping criteria. When the accumulated heat meets the conditions for tripping the motor, corresponding actions are taken to trip the motor and cut off the power, thereby preventing the motor and the electromechanical equipment in the circuit from being damaged due to overheating of the motor.

[0024] The various units of the motor thermal protection device 100 of the present disclosure can be implemented by various specific circuits. For example, the power-off time determination unit 102 and the heat accumulation calculation unit 103 can be implemented by the same microcontroller unit (MCU), and the MCU can also implement other calculation or control functions of the present disclosure, such as determining whether the accumulated heat meets the motor tripping condition and controlling the motor tripping. Figure 2 1 is a schematic circuit diagram of a capacitor timing circuit 101 in a motor thermal protection device 100 according to an embodiment of the present disclosure. It should be noted that: Figure 2 The specific structure of the capacitor timing circuit 101 in FIG. 1 may be replaced by other suitable structures.

[0025] refer to Figure 2 The capacitor timing circuit 101 includes a power supply unit 201, a capacitor C, a first resistor R1, a semiconductor switch module 202, a charging end, and an output end.

[0026] When the motor is powered on, the power supply unit 201 receives an input voltage V provided by the power supply of the motor. in , and outputs a voltage V applied to the control terminal 3 of the semiconductor switch module 202 out (For example, 10V). The semiconductor switch module 202 includes a first terminal 1, a second terminal 2, and a control terminal 3. In the configuration of this embodiment, V out The first terminal 1 and the second terminal 2 of the semiconductor switch module 202 are controlled to be conductive, and at this time, the capacitor C can be charged by the capacitor charging voltage V provided by the power-off time determination unit 102. charge In this embodiment, the power-off time determination unit 102 can provide the capacitor charging voltage V to the capacitor timing circuit 101 through a digital-to-analog converter (DAC). charge , and the capacitor C can be charged to the maximum capacitor voltage E within a few milliseconds.

[0027] When the motor is powered off, the motor's power supply stops providing input voltage V in , the power supply unit 201 stops outputting the control voltage V applied to the control terminal 3 of the semiconductor switch module 202 out , the first terminal 1 and the second terminal 2 of the semiconductor switch module 202 are disconnected. At this time, the capacitor C and the first resistor R1 form a discharge loop, and the capacitor C is discharged through the first resistor R1. The capacitor C can be charged to and maintained at the maximum capacitor voltage E when the motor is powered on, so the initial voltage across the capacitor C at the beginning of discharge can be the maximum capacitor voltage E. According to the capacitor charging and discharging principle, after the discharge time t has passed since the motor was powered off, the remaining voltage across the capacitor C (i.e., the output voltage of the capacitor timing circuit 101) V thermal The voltage across the capacitor C and the discharge time t when the motor is powered off satisfy the following equation (1):

[0028]

[0029] Where E is the voltage across the capacitor C when the motor is powered off, for example, the maximum capacitor voltage; t is the discharge time; V thermal is the residual voltage across the capacitor C after the discharge time t; Tau1 is a time constant, which is equal to the product of the capacitance of the capacitor C and the resistance of the first resistor R1.

[0030] When the motor is powered off for a period of time T offWhen the power is turned on again, the power supply unit 201 can output the control voltage V applied to the control terminal 3 of the semiconductor switch module 202. out At this time, V out By controlling the first terminal 1 and the second terminal 2 of the semiconductor switch module 202 to be conductive, the power-off time determination unit 102 can perform a reading operation to read the output voltage V from the output terminal of the capacitor timing circuit 101. thermal , which is used to calculate the residual heat accumulation of the motor. In addition, when performing the reading operation, in order to prevent the output voltage V read from the output terminal from being discharged from the charging terminal of the capacitor C, thermal The value of is not accurate enough, the power-off time determination unit 102 can set the charging terminal to a high-impedance input state (for example, leaving the charging terminal suspended) before performing the reading operation to ensure that the output voltage V read from the capacitor timing circuit 101 is thermal In addition, after the reading operation is completed, the charging terminal can be reset from the high impedance input state to the charging voltage input state, that is, the capacitor charging voltage V is provided through the digital-to-analog converter (DAC) as described above. charge , so that the capacitor C is charged, so that the voltage across it is maintained at the maximum capacitor voltage E. In this way, if the motor is powered off again, the capacitor C will start to discharge with the maximum capacitor voltage E as the initial voltage.

[0031] As mentioned above, the discharge time t of the capacitor C may correspond to the power-off time T from when the motor is powered off to when the motor is powered on. off , therefore, is used to calculate the power-off time T off Equation (2) can be a transformation of equation (1):

[0032]

[0033] Reference Figure 1 The power-off time determination unit 102 reads the output voltage V from the capacitor timing circuit 101. thermal , calculate the power-off time T using equation (2) off .

[0034] Thereafter, the heat accumulation calculation unit 103 obtains the power-off time T from the power-off time unit 102. of f , and according to the power-off time T off The residual heat accumulation THS(0) when the motor is powered on can be calculated by using equation (3):

[0035] THS(0)=THS last ·eT off / Tau2 (3)

[0036] Wherein, THS(0) is the residual heat when the motor is powered on; THS last is the accumulated heat when the motor is powered off, which can be directly read from the memory (not shown) of the motor thermal protection device 100; Tau2 is a time constant, which is proportional to the thermal overload level of the motor, which is determined by the heat dissipation capacity of the motor and can be determined through experiments.

[0037] Calculating the residual heat accumulation THS(0) when the motor is powered on can track and monitor the accumulated heat accumulation of the motor in real time. Therefore, the accumulated heat calculation unit 103 can calculate the accumulated heat accumulated over time t during the motor power-on period according to equation (4) based on the residual heat accumulation THS(0) calculated by equation (3):

[0038]

[0039] Wherein, t is the time elapsed from the motor power-on; THS(t) is the accumulated heat of the motor after time t has passed since the motor power-on; THS(0) is the residual heat when the motor is powered on calculated by equation (3); I is the motor current; Tau2 is the time constant, which is proportional to the thermal overload level of the motor.

[0040] In some embodiments, the accumulated heat of the motor can be calculated once every time period, and the time interval for calculating the accumulated heat can be set to 100 milliseconds, 150 milliseconds, etc. as needed, and the calculated value is stored in the memory of the thermal protection device 100. A new accumulated heat value is calculated at each time interval as an updated value to overwrite the accumulated heat value calculated at the previous time interval stored in the memory, so that the latest accumulated heat value is always stored in the memory. Optionally, in some cases, considering that frequently reading data from the memory or writing data to the memory will damage the life of the memory, the current accumulated heat value can also be stored in the memory before it is detected that the motor is about to lose power or before the thermal trip. In addition, the new accumulated heat value calculated at each time interval is used to determine whether the value meets the condition of the motor tripping according to the preset motor tripping criteria. There may be multiple preset motor tripping criteria, such as comparing the new accumulated heat value calculated at each time interval with a preset accumulated heat threshold, and when the new accumulated heat value exceeds the preset accumulated heat threshold, determining that the motor tripping condition is met; another example is appropriately transforming the new accumulated heat value calculated at each time interval and then comparing it with the preset accumulated heat threshold, and when the new accumulated heat value exceeds the preset accumulated heat threshold, determining that the motor tripping condition is met, such as transforming the new accumulated heat value into the thermal capacity of the motor, and when the thermal capacity>=1, determining that the motor tripping condition is met. The present disclosure does not impose any restrictions on this, and the preset motor tripping criteria may also be any other suitable criteria.

[0041] The embodiments of the present disclosure described above can obtain the power-off time from when the motor is powered off to when the motor is powered on by means of the capacitor charging and discharging principle, and thereby obtain the residual heat accumulation when the motor is powered on, and then use the residual heat accumulation as the initial value to calculate and track the accumulated heat accumulation of the motor in real time, and when it is determined that the accumulated heat accumulation value meets the motor tripping condition according to the preset motor tripping criteria, it is determined that the motor should be powered off. In this case, the power-off operation allowed by the user can be automatically executed to power off the motor (for example, controlled by the MCU), or an alarm message can be sent to the user (for example, turning on the alarm light, sounding an alarm, etc.) to allow the user to manually perform the power-off operation. In this way, the accumulated heat accumulation of the motor can be tracked and monitored in real time to prevent the motor and other electromechanical equipment from being damaged due to overheating of the motor.

[0042] As an embodiment of the present disclosure, the semiconductor switch module 202 in the capacitance timing circuit 101 may have a variety of structures, and the capacitance timing circuit 101 may further include some auxiliary elements. Figure 3 FIG. 4 is a schematic circuit diagram of a capacitor timing circuit 101 in a motor thermal protection device 100 according to an embodiment of the present disclosure.

[0043] As an example, refer to Figure 3 The semiconductor switch module 202 may include at least one MOS transistor connected in series, for example, T1 and T2, each of the at least one MOS transistor includes a control terminal, a first terminal, and a second terminal, and the control terminal of each MOS transistor receives a voltage V output by the power supply unit. out When the first and second ends of the MOS transistors are connected, the first end of the first MOS transistor in the series connection is connected to the first end of the capacitor C as the first end of the semiconductor switch module 202, and the second end of the last MOS transistor in the series connection is connected to the charging end and the reading end as the second end of the semiconductor switch module 202. In the configuration of this example, the power supply unit 201 can control whether to output the voltage V applied to the control ends of T1 and T2. out , so T1 and T2 are turned on or off at the same time, thereby controlling the charge and discharge of the capacitor C. The present disclosure is not limited to the specific structure of the semiconductor switch module 202. For example, the present disclosure is not limited to the number of MOS transistors, which may include one MOS transistor or two or more MOS transistors. There is no limitation on the type of MOS transistors, which may include only NMOS transistors, only PMOS transistors, or both, and the type of MOS transistors may also include ordinary MOS transistors, MOS transistors with parasitic diodes, etc., as long as the relevant functions described above can be achieved.

[0044] As an example, refer to Figure 3 The capacitor timing circuit 101 may further include some auxiliary components, such as a second resistor R2, a third resistor R3 and a fourth resistor R4. The second resistor R2 protects the semiconductor switch module 202. For example, during the motor power-off period, the power supply unit does not output the voltage V applied to the control terminal of the semiconductor switch module 202. out In the case of a power failure, the presence of the second resistor R2 can prevent the control terminal of the semiconductor switch module 202 from floating. When the power failure time determination unit 102 charges the capacitor C through the charging terminal, the presence of the third resistor R3 can protect the capacitor C from being damaged due to excessive charging current. The presence of the fourth resistor R4 can speed up the discharge speed of the capacitor C. For example, the resistance value of the fourth resistor R4 can be set to be relatively small so that the capacitor C has a relatively obvious and observable discharge amount in a relatively short discharge time, which is used for capacitance value calibration, as shown in the following combination Figure 5 and Figure 7 as described.

[0045] Figure 4 1 is a flow chart of an operation method of a motor thermal protection device according to an embodiment of the present disclosure. The operation method can be applied to a motor thermal protection device 100 (such as a motor thermal protection device 100) including a capacitor timing circuit 101, a power-off time determination unit 102 and a heat accumulation timing unit 103. Figure 1-Figure 3 The operation method comprises steps S401-S403. In step S401, the capacitor timing circuit 101 performs timing after the motor is powered off; in step S402, the power-off time determination unit 102 reads the output voltage V of the capacitor timing circuit 101 after the motor is powered on. thermal The read operation and the output voltage V thermal Determine the power-off time T from when the motor is powered off to when the motor is powered on off In step S403, after the reading operation is completed, the heat accumulation calculation unit calculates the remaining heat accumulation THS(0) when the motor is powered on based on the power-off time and the heat accumulation when the motor is powered off.

[0046] The above embodiment describes that after the motor is powered off, the capacitor C in the capacitor timing circuit 101 is discharged through the discharge resistor R1 to realize the timing after power failure. In some scenarios, it is desired to diagnose whether the motor thermal protection device, especially the capacitor timing circuit 101, is faulty during the normal operation of the motor without powering off the motor, which is helpful to avoid the situation where the motor or the electromechanical equipment in the circuit is damaged due to the failure of the motor thermal protection device 100 and the failure of timely protection measures.

[0047] Another embodiment of the present disclosure is described below, which can diagnose whether a motor thermal protection device fails by controlling the charging and discharging of the capacitor C during motor power-on, without powering off the motor. Figure 5 1 is a schematic circuit diagram of a capacitor timing circuit 101 in a motor thermal protection device 100 according to another embodiment of the present disclosure. It should be noted that: Figure 5 The specific structure of the capacitor timing circuit 101 in FIG. 1 may be replaced by other suitable structures.

[0048] refer to Figure 5 ,and Figure 2 and Figure 3 The power supply unit 201 in FIG. 1 is different in that: Figure 5 The power supply unit 201 in the embodiment further includes an enable terminal, the voltage of which can be provided by a control unit (not shown) of the motor thermal protection device 100, the control unit can be implemented by an MCU, for example, the same MCU can be shared with the power-off time determination unit 102 and the heat accumulation calculation unit 103. The enable terminal is used to control whether the power supply unit 201 can output a voltage V applied to the control terminal 3 of the semiconductor switch module 202. out That is to say, even if the motor power supply supplies power to the motor thermal protection device 100, the capacitor timing circuit 100 can be powered off due to the control of the enable terminal. It should be noted that the power supply of other units such as the power-off time determination unit 102 and the heat accumulation calculation unit 103 is not affected by the power supply unit 201, and these units are still powered as long as the motor power supply is not powered off.

[0049] In this embodiment, for example, the following can be used: Figure 5 The circuit of the power supply unit 201 shown in FIG. 201 includes an enable terminal, an NMOS transistor T3 and a PMOS transistor T4, and resistors R5 and R6. For example, it can be set that when the enable terminal is set to a high level voltage (for example, 3V), the power supply unit 201 can apply a voltage V to the control terminal 3 of the semiconductor switch module 202 via the PMOS transistor T4. out , the first terminal 1 and the second terminal 2 of the semiconductor switch module 202 are connected. In this embodiment, V in It is the voltage provided by the motor power supply after necessary conversion, V out Can be equal to or not equal to V in , this disclosure does not impose any restrictions on this, as long as V out The size of is sufficient to drive the control terminal of the semiconductor switch module 202 without damaging it. On the other hand, it can be set that when the enable terminal is set to a low level voltage (for example, 0V), the control power supply unit 201 does not output the voltage V applied to the control terminal 3 of the semiconductor switch module 202. out , the first end 1 and the second end 2 of the semiconductor switch module 202 are disconnected.

[0050] As described above, during the motor power-on period, without powering off the motor, the conduction or disconnection between the first terminal 1 and the second terminal 2 of the semiconductor switch module 202 can also be controlled by means of the enable terminal.

[0051] Figure 6 FIG. 1 is a flow chart of a diagnostic operation of a motor thermal protection device 100 according to another embodiment of the present disclosure. The diagnostic operation may be performed as follows: Figure 5 The motor protection device 100 is shown to be in operation during the motor power-up period. Figure 6 The diagnostic operation includes steps S601-S606. In step S601, the enable terminal is set to turn on the semiconductor switch module 202, and the power-off time determination unit 102 performs a charging operation to charge the capacitor C to the maximum capacitance voltage E. For example, the control unit of the motor thermal protection device 100 sets the enable terminal to a high level voltage (for example, 3V), thereby applying the output voltage V of the power supply unit 201 to the control terminal of the semiconductor switch module 202. out , the first terminal 1 and the second terminal 2 are connected, and the power-off time determination unit 102 can perform a charging operation to charge the capacitor C to the maximum capacitance voltage E; in step S602, the enabling terminal is set to make the semiconductor switch module 202 disconnected, so that the capacitor C is discharged for a predetermined discharge time t pre For example, the control unit of the motor thermal protection device 100 sets the enable terminal to a low voltage level (e.g., 0V), thereby disconnecting the first terminal 1 and the second terminal 2 of the semiconductor switch module 202, and the capacitor C discharges through the first resistor R1 for a predetermined discharge time t pre It can be set to 1 second to 2 seconds to avoid the motor being discharged before reaching the preset discharge time t pre In step S603, the enable terminal is set to turn on the semiconductor switch module 202, and the power-off time determination unit 102 performs a reading operation. For example, similar to the above, the control unit of the motor thermal protection device 100 sets the enable terminal to a high level voltage (for example, 3V), thereby connecting the first terminal 1 and the second terminal 2 of the semiconductor module 202, and the power-off time determination unit 102 can read the predetermined discharge time t pre Then the output voltage V of the capacitor timing circuit 101 thermal In step S604, the power-off time determination unit 102 may determine the maximum capacitor voltage E and the predetermined discharge time t according to equation (1). pre Calculate the capacitor C after a predetermined discharge time t pre The theoretical output voltage after (i.e. the theoretical value of the output voltage) V theory In step S605, the power-off time determination unit 102 sets the theoretical output voltage V theoryand the output voltage V obtained through the read operation thermal There are many ways to compare. For example, the theoretical output voltage V theory and output voltage V therma The difference between the theoretical output voltage V theory In step S606, it is determined whether the motor thermal protection device has a fault according to the comparison in step S605. For example, it can be determined whether the motor thermal protection module 100 has a fault according to a preset fault diagnosis criterion. There can be multiple preset fault diagnosis criteria, for example, when the output voltage V thermal With the theoretical output voltage V theory When the difference between the values ​​exceeds a certain proportional range (eg, ±5%) of the theoretical output voltage, it is determined that the motor thermal protection module 100 is faulty. The present disclosure is not limited to this, and any other suitable diagnostic criteria may also be used.

[0052] In addition to diagnosing whether the motor thermal protection device is faulty during motor power-on, the present embodiment can also implement a calibration operation on the capacitor C in the capacitor timing circuit 101. For example, when the motor thermal protection device 100 leaves the factory, the manufacturer can calibrate the capacitance value of the capacitor C in the capacitor timing circuit 101 to obtain a calibrated capacitance value, so that various related calculations as described above can be performed based on the calibrated capacitance value during the use process after leaving the factory, for example, the calibrated capacitance value is used in the calculation process of the power-off time from motor power-off to motor power-on as described above. Still referring to Figure 5 , when the motor thermal protection device is connected to the motor and the motor is powered on, or when the motor thermal protection device is not connected to the motor and the motor thermal protection device is powered by an external power supply, the first end 1 and the second end 2 of the semiconductor switch module 202 are controlled to be conductive by means of the enable end, and while the first section 1 and the second end 2 of the semiconductor switch module 202 are kept conductive, the capacitor C is charged by placing the charging end in a charging voltage input state, and the capacitor C is discharged through the first resistor R1 and the fourth resistor R4 by placing the charging end in a high-impedance input state. Optionally, the resistance value of the fourth resistor R4 can be set to be much smaller than the resistance value of the first resistor R1, so that the capacitor C is mainly discharged from the fourth resistor R4, thereby having a more obvious and easy-to-observe discharge amount in a shorter discharge time. In this case, since the resistance value of R1 is much larger than the resistance value of the fourth resistor R4, the discharge amount through R1 can be ignored. In this way, when the thermal protection device is connected to the motor and the motor is powered on, or when the thermal protection device is not connected to the motor and is powered by an external power supply, the charging and discharging of the capacitor C in the capacitor timing circuit 101 can be controlled by controlling the state of the enable terminal and the charging terminal, thereby calibrating the capacitance value of the capacitor C.

[0053] Figure 7 FIG. 1 is a flow chart of a calibration operation of a motor thermal protection device 100 according to another embodiment of the present disclosure. The calibration operation may be performed as follows: Figure 5 The motor protection device 100 shown is connected to the motor and the motor is powered on or is not connected to the motor and is powered by an external power supply. In step S701, similar to step S601, the enable terminal is set to turn on the semiconductor switch module 202, and the power-off time determination unit 102 performs a charging operation to charge the capacitor C to the maximum capacitor voltage E; in step S702, the charging terminal is set to a high-impedance input state so that the capacitor C is discharged for a predetermined discharge time t pre , the predetermined discharge time t pre It can be set to, for example, 1 second, 2 seconds, etc. as required, but cannot exceed the time required for the capacitor C to be discharged to zero. Optionally, the predetermined discharge time t pre is set to the theoretical discharge time when the capacitor C is discharged to half of the maximum capacitor voltage E to improve the calibration accuracy; in step S703, the electrical appliance C is discharged for a predetermined discharge time t pre Afterwards, the power-off time determination unit 102 performs a reading operation to read the time after the predetermined discharge time t pre The output voltage V of the post-capacitor timing circuit 101 thermal In step S704, the power-off time determination unit 102 may determine the power-off time according to the following equation (5) which is a variation of equation (1), based on the voltage across the capacitor C when the semiconductor switch module is disconnected, such as the maximum capacitor voltage E, the predetermined discharge time t pre , output voltage V thermal And the parallel resistance value of the first resistor R1 and the fourth resistor R4 is used to determine the calibrated capacitance value of the capacitor C:

[0054]

[0055] Among them, R is the parallel resistance value of R1 and R4. When R4 is much smaller than R1, R is approximately equal to R4.

[0056] When the motor thermal protection device leaves the factory, the calibrated capacitance value of the capacitor C is obtained by executing steps S701 to S704. Using this calibrated capacitance value as the basis for calculating the power-off time of the capacitor will be beneficial for more accurate real-time monitoring of the accumulated heat of the motor.

[0057] It should be noted that the embodiments of the present disclosure have different resistance values ​​for the resistors R1-R6, the capacitance value for the capacitor C, and the voltage V in 、V out 、V chargeThere is no specific limitation on the voltage value and the models of the MOS transistors T1-T4, as long as the functions described in the embodiments of the present disclosure can be realized. Any suitable values ​​can be used without departing from the protection scope of the present disclosure.

[0058] In addition, in order to reduce leakage current, the capacitor C included in the capacitance timing circuit of the present disclosure can use tantalum capacitors, electrolytic capacitors, and other capacitors with smaller leakage current.

[0059] According to the motor thermal protection device and its operation method of the embodiment of the present disclosure, the power-off time of the motor from power-off to power-on is obtained according to the capacitor charging and discharging principle, and the residual heat accumulation when the motor is powered on is obtained by using the motor thermal model, so that the accumulated heat accumulation of the motor over time can be tracked and monitored in real time, and the motor is powered off when the accumulated heat accumulation meets the preset criteria, thereby protecting the motor and the electromechanical equipment in the circuit from being damaged due to motor overheating. At the same time, according to the embodiment of the present disclosure, a diagnostic operation can be performed on the motor thermal protection device during the motor power-on period to determine whether the motor thermal protection device is faulty, and a calibration operation can be performed on the capacitor in the motor thermal protection device to calibrate the capacitance value of the capacitor included therein at the factory.

[0060] The hardware computing device described in the present disclosure may be implemented in its entirety or in parts thereof through various suitable hardware means, including but not limited to FPGA, ASIC, SoC, discrete gate or transistor logic, discrete hardware components, or any combination thereof.

[0061] The block diagrams of circuits, devices, apparatuses, equipment, and systems involved in the present disclosure are only illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these circuits, devices, apparatuses, equipment, and systems may be connected, arranged, or configured in any manner as long as the desired purpose can be achieved.

[0062] Those skilled in the art should understand that the above-mentioned specific embodiments are merely examples and not limitations, and various modifications, combinations, partial combinations and replacements may be made to the embodiments of the present disclosure according to design requirements and other factors. As long as they are within the scope of the attached claims or their equivalents, they belong to the scope of rights to be protected by the present disclosure.

Claims

1. A motor thermal protection device, which is powered by a power supply of the motor, comprising: A capacitor timing circuit, used for timing after the motor is powered off; a power-off time determining unit, configured to perform a reading operation of reading an output voltage of the capacitor timing circuit after the motor is powered on, and determine a power-off time from when the motor is powered off to when the motor is powered on according to the output voltage; as well as A heat accumulation calculation unit is used to calculate the remaining heat accumulation when the motor is powered on according to the power-off time and the heat accumulation when the motor is powered off, in: The capacitance timing circuit comprises a power supply unit, a capacitor, a first resistor, a semiconductor switch module, a charging terminal and an output terminal; The power supply unit is powered by the power supply of the motor and outputs a voltage applied to the control end of the semiconductor switch module. After the motor is powered off, the power supply unit stops outputting the output voltage applied to the control end of the semiconductor switch module. The semiconductor switch module comprises a first end, a second end and the control end. When the control end of the semiconductor switch module receives the voltage output by the power supply unit, the first end of the semiconductor switch module and the second end of the semiconductor switch module are controlled to be turned on. The first end of the semiconductor switch module is connected to the first end of the capacitor, and the second end of the semiconductor switch module is connected to the charging end and the output end. The second terminal of the capacitor is grounded; A first end of the first resistor is connected to a first end of the capacitor, and a second end of the first resistor is grounded; and The power-off time determination unit is connected to the charging end and the output end. The power-off time determination unit performs the reading operation through the output end after the motor is powered on, and performs the charging operation of providing a capacitor charging voltage to the capacitor timing circuit through the charging end after the reading operation is completed.

2. The motor thermal protection device according to claim 1, wherein The reading operation of the power-off time determination unit includes reading the output voltage of the capacitor timing circuit from the output terminal when the charging terminal is set to a high-impedance input state, and The charging operation of the power-off time determination unit includes providing the capacitor charging voltage to the charging terminal when the charging terminal is placed in a charging voltage input state.

3. The motor thermal protection device according to claim 2, wherein The power supply unit includes an enable terminal, and the enable terminal controls whether the power supply unit can output a voltage applied to a control terminal of the semiconductor switch module.

4. The motor thermal protection device according to claim 3, wherein The capacitive timing circuit also includes a second resistor; A first end of the second resistor is connected to a control end of the semiconductor switch module, and a second end of the second resistor is grounded.

5. The motor thermal protection device according to claim 3, wherein The capacitive timing circuit also includes a third resistor; A first end of the third resistor is connected to a second end of the semiconductor switch module, and a second end of the third resistor is connected to the charging end.

6. The motor thermal protection device according to claim 3, wherein The capacitive timing circuit also includes a fourth resistor; A first end of the fourth resistor is connected to a second end of the semiconductor switch module, and a second end of the fourth resistor is grounded.

7. The motor thermal protection device according to any one of claims 3 to 6, wherein during power-on of the motor, the motor thermal protection device is further configured to perform the following operations: The enabling terminal is set to turn on the semiconductor switch module, and the power-off time determination unit performs the charging operation to charge the capacitor to a maximum capacitance voltage; The enabling terminal is set to disconnect the semiconductor switch module so that the capacitor is discharged for a predetermined discharge time; The enabling terminal is set to turn on the semiconductor switch module, and the power-off time determination unit performs the reading operation; The power-off time determination unit determines the theoretical output voltage of the capacitor after the capacitor is discharged for the predetermined discharge time according to the maximum capacitor voltage and the predetermined discharge time. The power-off time determination unit compares the theoretical output voltage with the output voltage obtained through the reading operation; A determination is made based on the comparison whether the motor thermal protection device is faulty.

8. The motor thermal protection device according to claim 6, wherein During the motor power-on period, the motor thermal protection device is also used to perform the following operations: The enabling terminal is set to turn on the semiconductor switch module, and the power-off time determination unit performs the charging operation to charge the capacitor to a maximum capacitance voltage; placing the charging terminal in a high impedance input state so that the capacitor discharges for a predetermined discharge time; After the capacitor is discharged for a predetermined discharge time, the power-off time determination unit performs the reading operation; The power-off time determination unit determines a capacitance value of the capacitor according to the maximum capacitance voltage, the predetermined discharge time, an output voltage obtained through the read operation, and resistance values ​​of the first resistor and a fourth resistor.

9. The motor thermal protection device according to claim 1, wherein The semiconductor switch module comprises at least one MOS transistor connected in series, Each of the at least one MOS transistor comprises a control terminal, a first terminal, and a second terminal; The control end of each MOS transistor of the at least one MOS transistor controls the first end and the second end thereof to be turned on when receiving the voltage output by the power supply unit; The control end of each MOS transistor in the at least one MOS transistor is connected together as the control end of the semiconductor switch module; The first end of the first MOS transistor among the at least one MOS transistor connected in series is connected to the first end of the capacitor as the first end of the semiconductor switch module, and the second end of the last MOS transistor among the at least one MOS transistor connected in series is connected to the charging end and the output end as the second end of the first-end semiconductor switch module.

10. The motor thermal protection device according to claim 1, wherein The heat accumulation calculation unit further calculates the accumulated heat of the motor at predetermined time intervals based on the remaining accumulated heat, and de-energizes the motor when the accumulated heat exceeds a threshold value of the accumulated heat.

11. An operating method of a motor thermal protection device, wherein the motor thermal protection device is powered by a power supply of a motor, the motor thermal protection device comprises a capacitor timing circuit, a power-off time determination unit and a heat accumulation calculation unit, the method comprising: The capacitor timing circuit performs timing after the motor is powered off; The power-off time determination unit performs a reading operation of reading the output voltage of the capacitor timing circuit after the motor is powered on, and determines the power-off time from when the motor is powered off to when the motor is powered on according to the output voltage; as well as The heat accumulation calculation unit calculates the remaining heat accumulation when the motor is powered on according to the power-off time and the heat accumulation when the motor is powered off, in: The capacitor timing circuit includes a power supply unit, a capacitor, a first resistor, a semiconductor switch module, a charging end and an output end, and the power-off time determination unit is connected to the charging end and the output end of the capacitor timing circuit. The power supply unit is powered by the power supply of the motor and outputs a voltage applied to the control end of the semiconductor switch module. After the motor is powered off, the power supply unit stops outputting the output voltage applied to the control end of the semiconductor switch module. The semiconductor switch module comprises a first end, a second end and the control end. When the control end of the semiconductor switch module receives the voltage output by the power supply unit, the first end of the semiconductor switch module and the second end of the semiconductor switch module are controlled to be turned on. The first end of the semiconductor switch module is connected to the first end of the capacitor, and the second end of the semiconductor switch module is connected to the charging end and the output end. The second terminal of the capacitor is grounded; A first end of the first resistor is connected to a first end of the capacitor, and a second end of the first resistor is grounded; The power-off time determination unit is connected to the charging terminal and the output terminal, and the power-off time determination unit performs the reading operation through the output terminal; The method further includes: after the reading operation is completed, the power-off time determination unit performs a charging operation to provide a capacitor charging voltage to the capacitor timing circuit through the charging terminal; The reading operation includes reading the output voltage of the capacitor timing circuit from the output terminal when the charging terminal is set to a high impedance input state; and The charging operation includes providing the capacitor charging voltage to the charging terminal when the charging terminal is placed in a charging voltage input state.

12. The operating method according to claim 11, wherein the power supply unit comprises an enable terminal for controlling whether the power supply unit can output a voltage applied to the control terminal of the semiconductor switch module, and the method further comprises: During the power-up of the motor, The enabling terminal is set to turn on the semiconductor switch module, and the power-off time determination unit performs the charging operation to charge the capacitor to a maximum capacitance voltage; Setting the enabling terminal to disconnect the semiconductor switch module so that the capacitor discharges for a predetermined discharge time; Setting the enable terminal to turn on the semiconductor switch module, and the power-off time determination unit performing the reading operation; The power-off time determining unit determines a theoretical output voltage of the capacitor after the capacitor is discharged for the predetermined discharge time according to the maximum capacitor voltage and the predetermined discharge time; comparing the theoretical output voltage with the output voltage obtained through the reading operation; A determination is made based on the comparison whether the motor thermal protection device is faulty.

13. The operating method according to claim 11, wherein the power supply unit comprises an enable terminal for controlling whether the power supply unit can output a voltage applied to the control terminal of the semiconductor switch module, the capacitor timing circuit further comprises a fourth resistor; a first terminal of the fourth resistor is connected to the second terminal of the semiconductor switch module, and a second terminal of the fourth resistor is grounded, and the method further comprises: During the power-up of the motor, The enabling terminal is set to turn on the semiconductor switch module, and the power-off time determination unit performs the charging operation to charge the capacitor to a maximum capacitance voltage; placing the charging terminal in a high impedance input state so that the capacitor discharges for a predetermined discharge time; After the capacitor is discharged for a predetermined discharge time, the power-off time determination unit performs the reading operation; The power-off time determination unit determines a capacitance value of the capacitor according to the maximum capacitance voltage, the predetermined discharge time, an output voltage obtained through the read operation, and resistance values ​​of the first resistor and a fourth resistor.

14. The operating method according to claim 11, further comprising: The accumulated heat calculation unit calculates the accumulated heat of the motor at predetermined time intervals based on the remaining accumulated heat, and when the accumulated heat exceeds a threshold value of the accumulated heat, the motor is de-energized.

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