Over-temperature protection circuit for direct current motor and electric device

Abstract

The application provides an over-temperature protection circuit of a direct current motor and an electric device. The circuit comprises a temperature detection unit, a voltage reduction protection unit and a power-off protection unit. The temperature detection unit is used for detecting the temperature of the direct current motor. The voltage reduction protection unit is used for reducing the voltage provided by a first power supply to the direct current motor when the temperature detection unit detects that the temperature of the direct current motor is greater than a first preset temperature. The power-off protection unit is used for controlling the first power supply to stop supplying power to the direct current motor when the temperature detection unit detects that the temperature of the direct current motor is greater than a second preset temperature after the voltage reduction protection unit reduces the voltage provided by the first power supply to the direct current motor, and the first preset temperature is less than the second preset temperature. The over-temperature protection circuit of the direct current motor and the electric device are beneficial to protecting the direct current motor during over-temperature protection and improving the service life of the direct current motor.

Description

Technical Field

[0001] This application relates to the field of over-temperature protection technology, and in particular to an over-temperature protection circuit and electric device for a DC motor. Background Technology

[0002] DC motors are widely used in various fields due to their simple structure, mature technology, easy control, and simple speed adjustment. For example, they are used in massage chairs and massage beds in the medical field, as well as electric vehicles and height-adjustable tables in daily life. According to the working characteristics of DC motors, the current of the power supply that drives them changes greatly during their start-up and operation. They also need to be started and stopped frequently during use, which can easily cause the power supply to heat up, thus placing higher demands on the reliability of the power supply.

[0003] The common method in existing technology is to directly shut off the power when the temperature reaches a certain value to prevent overheating. However, if the existing protection method is used during high-speed operation, it will cause the motor to stop working immediately, which can easily damage the motor and reduce its service life. Utility Model Content

[0004] This application provides an over-temperature protection circuit and electric device for a DC motor, which helps to solve the problem that over-temperature protection achieved by directly stopping the motor when it is in high-speed operation can easily damage the motor and reduce its service life.

[0005] In a first aspect, embodiments of this application provide an over-temperature protection circuit for a DC motor. The over-temperature protection circuit includes: a temperature detection unit, a voltage reduction protection unit, and a power-off protection unit; a first port of the temperature detection unit is connected to a first port of the voltage reduction protection unit; a second port of the temperature detection unit is connected to a first port of the power-off protection unit, wherein: the temperature detection unit is used to detect the temperature of the DC motor; the voltage reduction protection unit is used to reduce the voltage supplied by the first power supply to the DC motor when the temperature detection unit detects that the temperature of the DC motor is greater than a first preset temperature; and the power-off protection unit is used to control the first power supply to stop supplying power to the DC motor when the temperature detection unit detects that the temperature of the DC motor is greater than a second preset temperature after the voltage reduction protection unit reduces the voltage supplied by the first power supply to the DC motor, wherein the first preset temperature is less than the second preset temperature.

[0006] As can be seen, the architecture of the temperature detection unit, the voltage reduction protection unit, and the power failure protection unit realizes the phased protection of DC motor over-temperature protection. When the temperature decreases, the voltage reduction over-temperature protection is first implemented, which alleviates the high temperature of the motor and also reduces the motor's operating speed. If the temperature continues to rise, the power failure protection unit implements the power-off over-temperature protection. Since the motor's operating speed is reduced before the power is directly cut off, damage to the motor is reduced and the motor's service life is improved.

[0007] In conjunction with the first aspect, in one possible embodiment, the temperature detection unit includes a first resistor, a thermistor, a second resistor, and a third resistor; a first port of the first resistor is connected to the first power supply; a second port of the first resistor is connected to the first port of the thermistor; a second port of the thermistor is connected to the first port of the second resistor; a second port of the second resistor is connected to the first port of the third resistor; a second port of the third resistor is grounded; the second port of the thermistor and the first port of the second resistor are the first ports of the temperature detection unit; the second port of the second resistor and the first port of the third resistor are the second ports of the temperature detection unit; wherein: the thermistor is used to decrease its resistance when the temperature of the DC motor increases and increase its resistance when the temperature of the DC motor decreases.

[0008] In conjunction with the first aspect, in one possible embodiment, the resistance value of the second resistor is adjustable.

[0009] As can be seen, by indicating the voltage values ​​at different locations in the temperature detection unit, the step-down protection unit and the power-off protection unit are triggered sequentially, which can reduce the motor's operating speed before directly shutting off the power, thereby reducing damage to the motor and extending its service life. Furthermore, the triggering time interval between the step-down protection mechanism and the power-off protection mechanism of the over-temperature protection circuit can be adjusted based on actual conditions, improving the practicality of the over-temperature protection circuit.

[0010] In conjunction with the first aspect, in one possible embodiment, the step-down protection unit includes: a fourth resistor, a fifth resistor, a first voltage comparator, a first capacitor, a step-down element, a sixth resistor, a seventh resistor, and an eighth resistor; the first port of the fourth resistor is connected to the first power supply; the second port of the fourth resistor is connected to the second port of the first voltage comparator and the first port of the first capacitor; the first port of the fifth resistor is the first port of the step-down protection unit; the second port of the fifth resistor is connected to the first port of the first voltage comparator; the third port of the first voltage comparator is grounded; the second port of the first capacitor is grounded; the first port of the step-down element is connected to the second port of the fourth resistor, the second port of the first voltage comparator, and the first port of the first capacitor. Connections are made as follows: the first port of the sixth resistor is connected to the first power supply; the second port of the sixth resistor is connected to the second port of the step-down element and the first port of the seventh resistor; the second port of the seventh resistor is connected to the third port of the step-down element and the first port of the eighth resistor; the eighth resistor is connected to the DC motor, wherein: the second and third ports of the first voltage comparator are turned on when the voltage between the second port of the thermistor and the first port of the second resistor is greater than a preset voltage; the step-down element is turned off when the second and third ports of the step-down element are turned on, stopping the short circuit of the seventh resistor, so as to reduce the voltage supplied by the first power supply to the DC motor.

[0011] As can be seen from the embodiments of this application, the first voltage comparator and the step-down element can activate the step-down protection function when the DC motor reaches the first temperature, thereby reducing the power supply voltage of the DC motor, protecting the power supply safety of the DC motor, and improving stability.

[0012] In conjunction with the first aspect, in one possible embodiment, the step-down element is an N-MOS transistor, with the gate of the N-MOS transistor serving as the first port of the step-down element, the drain of the N-MOS transistor serving as the second port of the step-down element, and the source of the N-MOS transistor serving as the third port of the step-down element. The N-MOS transistor is used to stop shorting the seventh resistor when the second and third ports of the first voltage comparator are turned on, thereby reducing the voltage supplied by the first power supply to the DC motor.

[0013] In conjunction with the first aspect, in one possible embodiment, the over-temperature protection circuit further includes a step-down circuit, wherein a first port of the step-down circuit is connected to a first power supply; a second port of the step-down circuit is connected to a fourth resistor; the voltage at the first port of the step-down circuit is a first voltage, and the voltage at the second port of the step-down circuit is a second voltage; the first voltage is greater than the second voltage.

[0014] In conjunction with the first aspect, in one possible embodiment, the step-down circuit includes a ninth resistor, a tenth resistor, a Zener diode, an NPN transistor, and a second capacitor; the first ports of the ninth resistor and the tenth resistor are the first ports of the step-down circuit; the second port of the ninth resistor is connected to the base of the NPN transistor and the first port of the Zener diode; the second port of the tenth resistor is connected to the collector of the NPN transistor; and the emitter of the NPN transistor is connected to the first port of the second capacitor and the first port of the fourth resistor.

[0015] As can be seen, in this embodiment of the application, by reducing the voltage of the first power supply through the step-down circuit, the over-temperature protection circuit can operate on the same power supply as the DC motor, without the need to configure an independent power supply for the over-temperature protection circuit, thereby reducing the energy consumption of the over-temperature protection circuit and ensuring the safe operation of the DC motor.

[0016] In conjunction with the first aspect, in one possible embodiment, the power failure protection unit includes: an eleventh resistor, a twelfth resistor, a shutdown element, and a second voltage comparator; the first port of the eleventh resistor is connected to the first power supply; the second port of the eleventh resistor is connected to the first port of the twelfth resistor and the first port of the shutdown element; the second port of the twelfth resistor is connected to the second port of the second voltage comparator; the second port of the shutdown element is connected to the second port of the second voltage comparator; the first port of the second voltage comparator is the first port of the power failure protection unit; the third port of the second voltage comparator is grounded, wherein: the second voltage comparator is used to turn on the second port and the third port of the second voltage comparator when the voltage between the second port of the second resistor and the first port of the third resistor is greater than a preset voltage; the shutdown element is used to control the first power supply to stop supplying power to the DC motor when the second port and the third port of the second voltage comparator are turned on.

[0017] As can be seen, in this embodiment of the application, by using the shutdown element and the second voltage comparator, the temperature of the DC motor continues to be collected after the voltage reduction protection measures are implemented, thereby realizing the timely shutdown of the power supply to the DC motor when the temperature of the DC motor continues to rise; thus, while ensuring the safe operation of the DC motor, the operating speed of the motor is reduced before the power supply to the DC motor is shut off, reducing damage to the motor and improving the service life of the motor.

[0018] In conjunction with the first aspect, in one possible embodiment, the shutdown element is an optocoupler; the optocoupler is used to generate a power-off signal when the second voltage comparator is turned on, so that the PWM controller in the power supply circuit controls the first power supply to stop supplying power to the DC motor according to the power-off signal, and the power supply circuit is used to generate the first power supply.

[0019] Secondly, embodiments of this application also provide an electric device that includes part or all of the over-temperature protection circuit as described in the first aspect.

[0020] It is understood that the beneficial effects of the second aspect's embodiments can be referred to in the beneficial effects of the circuit in the first aspect, and will not be repeated here. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of an over-temperature protection circuit for a DC motor provided in an embodiment of this application;

[0023] Figure 2 A circuit diagram of an over-temperature protection circuit provided in an embodiment of this application;

[0024] Figure 3 A circuit diagram of another over-temperature protection circuit provided in an embodiment of this application;

[0025] Figure 4 This application provides a schematic diagram of the connection between a power supply circuit and an over-temperature protection circuit in an embodiment.

[0026] Figure 5 A circuit diagram of an over-temperature protection circuit including a step-down circuit provided for an embodiment of this application;

[0027] Figure 6 This is a schematic diagram of the structure of an electric device provided in an embodiment of this application.

[0028] Figure reference numerals: 100: Over-temperature protection circuit; 101: Temperature detection unit; 102: Voltage reduction protection unit; 103: Power failure protection unit; V1: First power supply; R1: First resistor; RT1: Thermistor; R2: Second resistor; R3: Third resistor; R4: Fourth resistor; R5: Fifth resistor; U1: First voltage comparator; C1: First capacitor; Q1: Voltage reduction element; R6: Sixth resistor; R7: Seventh resistor; R8: Eighth resistor; R9: Ninth resistor; R10: Tenth resistor; ZD1: Zener diode; Q2: NPN transistor; C2: Second capacitor; R11: Eleventh resistor; R12: Twelfth resistor; U1A: Shutdown element; U2: Second voltage comparator; 600: Electrical equipment; 601: Power supply circuit; 602: DC motor; 603: Protection circuit. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0030] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps is not limited to the steps listed, but may optionally include steps not listed, or may optionally include other steps inherent to these processes, methods, products, or apparatuses.

[0031] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0032] Example 1:

[0033] Please see Figure 1 , Figure 1 The figure shows a schematic diagram of an over-temperature protection circuit for a DC motor according to an embodiment of this application. As shown, the over-temperature protection circuit 100 includes a temperature detection unit 101, a voltage reduction protection unit 102, and a power failure protection unit 103. The first port of the temperature detection unit 101 is connected to the first port of the voltage reduction protection unit 102; the second port of the temperature detection unit 101 is connected to the first port of the power failure protection unit 103.

[0034] The temperature detection unit 101 can be a temperature detection device, a thermistor, etc. The temperature detection unit 101 collects the temperature of the DC motor and generates a corresponding electrical signal (such as a voltage signal or a resistance signal) to detect the temperature of the DC motor.

[0035] The step-down protection unit 102 is mainly used to reduce the supply voltage of the first power supply to the DC motor, thereby reducing the heat generated by the DC motor and enabling the DC motor to pass the overheat protection.

[0036] Specifically, the step-down protection unit 102 can reduce the supply voltage from the first power source to the DC motor by activating the step-down module (such as a step-down converter) in the power supply circuit of the DC motor, or by changing the resistance of the power supply circuit in the DC motor.

[0037] Specifically, the step-down protection unit 102 reduces the supply voltage of the DC motor to 50% or 30% of the normal operating voltage. For example, if the normal operating voltage of the DC motor is 36V, after the step-down protection unit 102 performs step-down protection, the supply voltage of the first power supply drops to 27V.

[0038] In addition, the voltage reduction protection of the step-down protection unit 102 can be completed in multiple steps. For example, if the temperature detection unit 101 detects that the temperature of the DC motor is greater than the first preset temperature, the supply voltage of the first power supply is immediately reduced to 30V. If the temperature detection unit 101 does not detect that the temperature of the DC motor is not greater than the first preset temperature after a preset period of time, the supply voltage of the first power supply is further reduced to 27V.

[0039] If the temperature of the DC motor is still not effectively controlled after the step-down protection unit 102 performs the step-down measures, further over-temperature protection measures need to be performed by the power-off protection unit 103.

[0040] The power failure protection unit 103 is used to control the first power supply to stop supplying power to the DC motor when the temperature detection unit detects that the temperature of the DC motor is greater than the second preset temperature (the first preset temperature is less than the second preset temperature) after the voltage reduction protection unit 102 reduces the voltage supplied by the first power supply to the DC motor.

[0041] The power failure protection unit 103 specifically controls the first power supply to stop supplying power to the DC motor by cutting off the power supply or turning off the power supply, which is over-temperature protection (OTP).

[0042] It should also be noted that the term "unit" as used in this specification specifically refers to a circuit, integrated circuit, or component based on the same principle.

[0043] As can be seen, the architecture of the temperature detection unit, the voltage reduction protection unit, and the power failure protection unit realizes the phased protection of DC motor over-temperature protection. When the temperature decreases, the voltage reduction over-temperature protection is first implemented, which alleviates the high temperature of the motor and also reduces the motor's operating speed. If the temperature continues to rise, the power failure protection unit implements the power-off over-temperature protection. Since the motor's operating speed is reduced before the power is directly cut off, damage to the motor is reduced and the motor's service life is improved.

[0044] Optionally, the temperature detection unit includes a first resistor, a thermistor, a second resistor, and a third resistor; the first port of the first resistor is connected to the first power supply; the second port of the first resistor is connected to the first port of the thermistor; the second port of the thermistor is connected to the first port of the second resistor; the second port of the second resistor is connected to the first port of the third resistor; the second port of the third resistor is grounded; the second port of the thermistor and the first port of the second resistor are the first ports of the temperature detection unit; the second port of the second resistor and the first port of the third resistor are the second ports of the temperature detection unit; wherein: the thermistor is used to decrease the resistance value when the temperature of the DC motor rises and increase the resistance value when the temperature of the DC motor falls.

[0045] Specifically, in the embodiments of this application, the temperature detection function of the temperature detection unit is mainly realized through a thermistor. The temperature of the DC motor is detected by the voltage values ​​at different locations in the temperature detection unit. The detection function of the temperature detection unit will be described in detail below with reference to a more detailed circuit diagram.

[0046] Please see Figure 2 , Figure 2 The circuit diagram provided in this application embodiment is an over-temperature protection circuit; wherein, the over-temperature protection circuit includes a temperature detection unit 101 (not shown in the figure), a voltage reduction protection unit 102 and a power failure protection unit 103, and the temperature detection unit 101 is connected to a first resistor R1, a thermistor RT1, a second resistor R2 and a third resistor R3.

[0047] remove Figure 2 In addition to the connection relationship of the internal components of the temperature detection unit 101 shown, it should be noted that the first port of the first resistor R1 is connected to the first power supply V1, and the second port of the thermistor RT1 and the first port of the second resistor R2 are the first ports of the temperature detection unit 101 (i.e., Figure 2 Point A (as shown) means that the step-down protection unit 102 is connected to the temperature detection unit 101 through point A. Furthermore, the first port of the first resistor R1 is connected to the first power supply, and the second port of the third resistor is grounded.

[0048] The second port of the second resistor R2 and the first port of the third resistor R3 are the second ports of the temperature detection unit 101 (i.e., Figure 2 Point B (as shown), that is to say, the power failure protection unit 103 is connected to the temperature detection unit 101 through point B.

[0049] The thermistor RT1 is used to sample the temperature of the DC motor. As the temperature sampled by the thermistor RT1 increases, its resistance decreases (and vice versa), which causes the voltage at points A and B to increase.

[0050] Based on this, the voltage U at point A A =V0×(r2+r3) / (r1+rt1+r2+r3), while the voltage U at point B is... B =V0×r3 / (r1+rt1+r2+r3). Where V0 is the voltage of the first power supply, r1 is the resistance of the first resistor R1, r2 is the resistance of the second resistor R2, r3 is the resistance of the third resistor R3, and rt1 is the current resistance of the thermistor.

[0051] Due to the presence of the second resistor R2, at the same temperature, the voltage at point A will be higher than the voltage at point B. That is to say, if the voltage at point A is the preset voltage, the temperature of the DC motor sampled by the thermistor RT1 is the first temperature; if the voltage at point B is the preset voltage, the temperature of the DC motor sampled by the thermistor RT1 is the second temperature, which is higher than the first temperature.

[0052] As the resistance of the thermistor RT1 changes, the voltages at points A and B will also change accordingly. However, due to the characteristics of the circuit structure, the voltage at point A is always higher than the voltage at point B. This voltage difference can be used by subsequent circuits to determine the temperature change trend. Under the same triggering conditions (such as when a preset voltage is acquired), the voltage reduction protection unit 102 and the power failure protection unit 103 will trigger the protection mechanism sequentially.

[0053] Optionally, in one possible embodiment, the resistance value of the second resistor is adjustable.

[0054] Specifically, the resistance value of the second resistor is adjustable. This is to adjust the triggering interval between the voltage reduction protection unit 102 and the power failure protection unit 103. Specifically, under the premise of constant heating rate, the higher the resistance value of the second resistor R2, the shorter the triggering interval between the voltage reduction protection unit 102 and the power failure protection unit 103. The lower the resistance value of the second resistor R2, the longer the triggering interval between the voltage reduction protection unit 102 and the power failure protection unit 103.

[0055] Therefore, the resistance value of the second resistor can be adjusted based on parameters such as the type of motor, operating status, and degree of damage, thereby setting a more suitable trigger time interval for the voltage reduction protection mechanism and power failure protection mechanism of the over-temperature protection circuit.

[0056] As can be seen, by indicating the voltage values ​​at different locations in the temperature detection unit, the step-down protection unit and the power-off protection unit are triggered sequentially, which can reduce the motor's operating speed before directly shutting off the power, thereby reducing damage to the motor and extending its service life. Furthermore, the triggering time interval between the step-down protection mechanism and the power-off protection mechanism of the over-temperature protection circuit can be adjusted based on actual conditions, improving the practicality of the over-temperature protection circuit.

[0057] Example 2:

[0058] The above embodiments provide an over-temperature protection circuit based on a thermistor. Based on this, and on the premise that the voltage reduction protection unit and the power failure protection unit are triggered by a voltage comparator, the embodiments of this application also provide a more detailed over-temperature protection circuit.

[0059] Please see Figure 3 , Figure 3 This is a circuit diagram of another over-temperature protection circuit provided in an embodiment of this application. The step-down protection unit 102 (not shown in the figure) includes a fourth resistor R4, a fifth resistor R5, a first voltage comparator U1, a first capacitor C1, a step-down element Q1, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8.

[0060] The power failure protection unit 103 (not shown in the figure) includes an eleventh resistor R11, a twelfth resistor R12, a shutdown element U1A, and a second voltage comparator U2. It should be noted that, except for... Figure 3 In addition to the internal component connections shown, the first port of the fourth resistor R4 is connected to the first power supply V1. The first port of the eleventh resistor R11 is also connected to the first power supply V1.

[0061] First, for the step-down protection unit 102, when the voltage at point A is not greater than the preset voltage (2.5V in this example), the first voltage comparator U1 is not turned on and is in the off state. At this time, the first port of the step-down element Q1 (i.e., point C in the figure) is at a high level. Then, the second and third ports of the step-down element Q1 are turned on, and R7 is short-circuited. The output voltage is [(r6 / r8)+1]×2.5V=36V (36V is taken as an example in this example. The actual value is determined based on the voltage of r6, r8 and the first power supply). Among them, r6 is the resistance value of the sixth resistor R6 and r8 is the resistance value of the eighth resistor R8.

[0062] When the temperature of the DC motor sampled by the thermistor RT1 rises, the resistance of RT1 decreases. When the voltage at point A is greater than the preset voltage, the first voltage comparator U1 will turn on. At this time, the level at point C will be pulled low, and the second and third ports of the step-down component Q1 will also turn off. The output voltage will then drop to [(r6 / (r7+r8))+1]×2.5V=27V (27V is taken as an example in this example), where r7 is the resistance of the seventh resistor R7.

[0063] It should be noted that the step-down component Q1 can also be an N-MOS transistor, a P-MOS transistor, a triode, or other types of switching transistors.

[0064] Optionally, the step-down element is an N-MOS transistor, with the gate of the N-MOS transistor being the first port of the step-down element, the drain of the N-MOS transistor being the second port of the step-down element, and the source of the N-MOS transistor being the third port of the step-down element. The N-MOS transistor is used to stop shorting the seventh resistor when the second and third ports of the first voltage comparator are turned on, so as to reduce the voltage supplied by the first power supply to the DC motor.

[0065] Specifically, in the embodiments of this application and in Figure 3 In the example shown, the step-down element Q1 is an N-MOS transistor. Therefore, the drain of the N-MOS transistor is the second port of the step-down element, and the source of the N-MOS transistor is the third port of the step-down element. It should be noted that the step-down element Q1 can also be a P-MOS transistor, a bipolar transistor, or other types of components capable of achieving the above functions. Depending on the type of step-down element Q1, the connection relationship of Q1 in this over-temperature protection circuit will also differ, which will not be elaborated here.

[0066] As can be seen from the embodiments of this application, the first voltage comparator and the step-down element can activate the step-down protection function when the DC motor reaches the first temperature, thereby reducing the power supply voltage of the DC motor, protecting the power supply safety of the DC motor, and improving stability.

[0067] For power failure protection unit 103, Figure 3 When the voltage at point B shown is not greater than the preset voltage, the second and third ports of the second voltage comparator U2 are not conducting and are in the off state. At this time, the first power supply V1 cannot supply power to the shutdown element U1A, and the shutdown element U1A is in the sleep state.

[0068] When the voltage at point B is greater than the preset voltage, the second and third ports of the second voltage comparator U2 are turned on, causing the first power supply V1 to supply power to the shutdown element U1A, thereby activating the shutdown element U1A, and then controlling the first power supply to stop supplying power to the DC motor through the shutdown element U1A.

[0069] Optionally, the shutdown element is an optocoupler; the optocoupler is used to generate a power-off signal when the second voltage comparator is turned on, so that the PWM controller controls the first power supply to stop supplying power to the DC motor according to the power-off signal.

[0070] It should be noted that the first power source here refers to the DC motor's power supply circuit, which is generated based on the second power source. Please refer to [link / reference]. Figure 4 , Figure 4The diagram shows the connection between a power supply circuit and an over-temperature protection circuit provided in this application embodiment. It can be seen that the second power supply is specifically 90V~264V AC power. After rectification and filtering by the input power supply circuit (not shown in the figure), it is supplied to the switching transistor and transformer. After being controlled by the PWM controller, chopped by the switching transistor, and transformed by the transformer, AC-DC conversion is realized. After being rectified, filtered and regulated by the output, a stable 36V DC safety voltage (i.e., the first power supply) is output to supply a stable operating voltage for the DC motor.

[0071] The over-temperature protection circuit achieves voltage reduction protection and power failure protection by connecting to the PWM controller and output rectifier filter module in the power supply circuit.

[0072] In this embodiment of the application, the shut-off element is an optocoupler (i.e., Figure 3 When the second voltage comparator is turned on, the shutdown element U1A shown generates a power-off signal, which in turn generates an optical signal to activate the photodetector (not shown) connected to the PWM controller (not shown in the figure). The photodetector then generates a power-off signal and sends it to the PWM controller so that the PWM controller controls the first power supply to stop supplying power to the DC motor according to the power-off signal.

[0073] For further details regarding the temperature detection unit 101, please refer to the relevant content in Embodiment 1, which will not be repeated here.

[0074] As can be seen, in this embodiment of the application, by using the shutdown element and the second voltage comparator, the temperature of the DC motor continues to be collected after the voltage reduction protection measures are implemented, thereby realizing the timely shutdown of the power supply to the DC motor when the temperature of the DC motor continues to rise; thus, while ensuring the safe operation of the DC motor, the operating speed of the motor is reduced before the power supply to the DC motor is shut off, reducing damage to the motor and improving the service life of the motor.

[0075] Example 3:

[0076] The above-described embodiments of the application describe an over-temperature protection circuit based on an N-MOS transistor. Based on this, the embodiments of the application also provide a more detailed over-temperature protection circuit, while including a step-down circuit.

[0077] In this embodiment, since the step-down element is an N-MOS transistor, if the maximum withstand voltage between the gate and source of the N-MOS transistor is greater than the voltage of the first power supply, then the first power supply and the N-MOS transistor in the step-down protection element need to be connected through a step-down circuit.

[0078] By using a step-down circuit, the voltage of the first power supply can be reduced to a second voltage (below 20V) when the voltage at the first port of the step-down circuit is a first voltage (i.e., 36V), thereby providing a stable and safe voltage for the temperature sensing element, the step-down protection element, and the power failure protection element.

[0079] Optionally, the step-down circuit includes a ninth resistor, a tenth resistor, a Zener diode, an NPN transistor, and a second capacitor; the first ports of the ninth resistor and the tenth resistor are the first ports of the step-down circuit; the second port of the ninth resistor is connected to the base of the NPN transistor and the first port of the Zener diode; the second port of the tenth resistor is connected to the collector of the NPN transistor; and the emitter of the NPN transistor is connected to the first port of the second capacitor and the first port of the fourth resistor.

[0080] Specifically, please see Figure 5 , Figure 5 This application provides a circuit diagram of an over-temperature protection circuit including a step-down circuit, wherein the step-down circuit (not marked in the figure) includes a ninth resistor R9, a tenth resistor R10, a Zener diode ZD1, an NPN transistor Q2, and a second capacitor C2. It should be noted that the first ports of the ninth and tenth resistors are the first ports of the step-down circuit, meaning that the first ports of the ninth and tenth resistors are connected to a first power supply.

[0081] For further details regarding the temperature detection unit 101, the voltage reduction protection unit 102, and the power failure protection unit 103, please refer to the relevant content in Embodiment 1 and Embodiment 2, which will not be repeated here.

[0082] As can be seen, in this embodiment of the application, by reducing the voltage of the first power supply through the step-down circuit, the over-temperature protection circuit can operate on the same power supply as the DC motor, without the need to configure an independent power supply for the over-temperature protection circuit, thereby reducing the energy consumption of the over-temperature protection circuit and ensuring the safe operation of the DC motor.

[0083] As can be seen from the over-temperature protection circuit in the above-described embodiments, the architecture of the temperature detection unit, the voltage reduction protection unit, and the power-off protection unit achieves phased over-temperature protection for the DC motor. Before directly shutting off the power, it reduces the motor's operating speed, thereby reducing damage to the motor and extending its service life. The triggering time intervals of the voltage reduction protection mechanism and the power-off protection mechanism of the over-temperature protection circuit can be adjusted based on actual conditions, improving the practicality of the over-temperature protection circuit. By reducing the voltage of the first power supply through the voltage reduction circuit, the over-temperature protection circuit can operate on the same power supply as the DC motor, eliminating the need for a separate power supply for the over-temperature protection circuit, reducing its energy consumption, and ensuring the safe operation of the DC motor.

[0084] Furthermore, embodiments of this application also provide an electric device that includes part or all of the over-temperature protection circuit described in any of the above embodiments.

[0085] Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of an electric device provided in an embodiment of this application. The electric device 600 includes a power supply circuit 601, a DC motor 602, and a protection circuit 603. The protection circuit 603 includes part or all of the over-temperature protection circuit described in any of the above embodiments. Specifically, the electric device 600 can be a massage chair, massage bed, height-adjustable table, or other device that operates via a motor.

[0086] In the embodiments provided in this application, it should be understood that the disclosed circuits or devices can be implemented in other ways. For example, the embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between devices or units, and may be electrical or other forms.

[0087] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0088] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0089] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An over-temperature protection circuit for a DC motor, characterized in that, The over-temperature protection circuit includes: a temperature detection unit, a voltage reduction protection unit, and a power failure protection unit; the first port of the temperature detection unit is connected to the first port of the voltage reduction protection unit; the second port of the temperature detection unit is connected to the first port of the power failure protection unit, wherein: The temperature detection unit is used to detect the temperature of the DC motor; The voltage reduction protection unit is used to reduce the voltage supplied by the first power supply to the DC motor when the temperature detection unit detects that the temperature of the DC motor is greater than the first preset temperature. The power failure protection unit is used to control the first power supply to stop supplying power to the DC motor when the temperature detection unit detects that the temperature of the DC motor is greater than the second preset temperature after the voltage reduction protection unit reduces the voltage supplied by the first power supply to the DC motor. The first preset temperature is less than the second preset temperature.

2. The over-temperature protection circuit according to claim 1, characterized in that, The temperature detection unit includes a first resistor, a thermistor, a second resistor, and a third resistor; the first port of the first resistor is connected to the first power supply; the second port of the first resistor is connected to the first port of the thermistor; the second port of the thermistor is connected to the first port of the second resistor; the second port of the second resistor is connected to the first port of the third resistor; the second port of the third resistor is grounded; the second port of the thermistor and the first port of the second resistor are the first ports of the temperature detection unit; the second port of the second resistor and the first port of the third resistor are the second ports of the temperature detection unit; wherein: The thermistor is used to decrease its resistance when the temperature of the DC motor increases and increase its resistance when the temperature of the DC motor decreases.

3. The over-temperature protection circuit according to claim 2, characterized in that, The resistance value of the second resistor is adjustable.

4. The over-temperature protection circuit according to claim 2, characterized in that, The step-down protection unit includes: a fourth resistor, a fifth resistor, a first voltage comparator, a first capacitor, a step-down element, a sixth resistor, a seventh resistor, and an eighth resistor; the first port of the fourth resistor is connected to the first power supply; the second port of the fourth resistor is connected to the second port of the first voltage comparator and the first port of the first capacitor; the first port of the fifth resistor is the first port of the step-down protection unit; the second port of the fifth resistor is connected to the first port of the first voltage comparator; the third port of the first voltage comparator is grounded; the second port of the first capacitor is grounded; the first port of the step-down element is connected to the second port of the fourth resistor, the second port of the first voltage comparator, and the first port of the first capacitor; the first port of the sixth resistor is connected to the first power supply; the second port of the sixth resistor is connected to the second port of the step-down element and the first port of the seventh resistor; the second port of the seventh resistor is connected to the third port of the step-down element and the first port of the eighth resistor; the eighth resistor is connected to the DC motor, wherein: The first voltage comparator is configured to turn on its second and third ports when the voltage between the second port of the thermistor and the first port of the second resistor is greater than a preset voltage. The step-down element is used to stop shorting the seventh resistor when the second and third ports of the first voltage comparator are turned on, so as to reduce the voltage supplied by the first power supply to the DC motor.

5. The over-temperature protection circuit according to claim 4, characterized in that, The step-down device is an N-MOS transistor, the gate of the N-MOS transistor is the first port of the step-down device, the drain of the N-MOS transistor is the second port of the step-down device, and the source of the N-MOS transistor is the third port of the step-down device. The N-MOS transistor is used to stop shorting the seventh resistor when the second and third ports of the first voltage comparator are turned on, thereby reducing the voltage supplied by the first power supply to the DC motor.

6. The over-temperature protection circuit according to claim 5, characterized in that, The over-temperature protection circuit further includes a step-down circuit, wherein the first port of the step-down circuit is connected to the first power supply; the second port of the step-down circuit is connected to the fourth resistor; the voltage at the first port of the step-down circuit is a first voltage, and the voltage at the second port of the step-down circuit is a second voltage; the first voltage is greater than the second voltage.

7. The over-temperature protection circuit according to claim 6, characterized in that, The step-down circuit includes a ninth resistor, a tenth resistor, a Zener diode, an NPN transistor, and a second capacitor; the first ports of the ninth resistor and the tenth resistor are the first ports of the step-down circuit; the second port of the ninth resistor is connected to the base of the NPN transistor and the first port of the Zener diode; the second port of the tenth resistor is connected to the collector of the NPN transistor; the emitter of the NPN transistor is connected to the first port of the second capacitor and the first port of the fourth resistor.

8. The over-temperature protection circuit according to any one of claims 2-7, characterized in that, The power failure protection unit includes: an eleventh resistor, a twelfth resistor, a shutdown element, and a second voltage comparator; the first port of the eleventh resistor is connected to the first power supply; the second port of the eleventh resistor is connected to the first port of the twelfth resistor and the first port of the shutdown element; the second port of the twelfth resistor is connected to the second port of the second voltage comparator; the second port of the shutdown element is connected to the second port of the second voltage comparator; the first port of the second voltage comparator is the first port of the power failure protection unit; the third port of the second voltage comparator is grounded, wherein: The second voltage comparator is configured to turn on its second and third ports when the voltage between the second port of the second resistor and the first port of the third resistor is greater than a preset voltage. The shutdown element is used to control the first power supply to stop supplying power to the DC motor when the second and third ports of the second voltage comparator are turned on.

9. The over-temperature protection circuit according to claim 8, characterized in that, The shutdown element is an optocoupler; The optocoupler is used to generate a power-off signal when the second voltage comparator is turned on, so that the PWM controller in the power supply circuit controls the first power supply to stop supplying power to the DC motor according to the power-off signal, and the power supply circuit is used to generate the first power supply.

10. An electric device, characterized in that, Includes the over-temperature protection circuit as described in any one of claims 1-9.

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