Motor overcurrent protection device

Abstract

This utility model discloses a motor overcurrent protection device, which includes an overcurrent resistor, an amplifier, a comparator, a logic gate, and a switch. The overcurrent resistor is electrically connected to a control circuit of a motor to obtain a voltage divider signal from the control circuit. The amplifier is electrically connected to the overcurrent resistor and is used to amplify the voltage divider signal. The comparator is electrically connected to the amplifier and the control circuit and is used to compare the amplified voltage divider signal with a signal threshold stored in the control circuit to output a comparison result signal. The logic gate is electrically connected to the comparator and is used to receive the comparison result signal to output a drive signal. The switch is electrically connected to the logic gate and is used to receive the drive signal to cut off the power supply to the motor.

Description

Technical Field

[0001] This utility model relates to a motor protection device, and more particularly to a protection device for preventing motor overcurrent. Background Technology

[0002] During operation, a motor should typically maintain a stable current input to ensure smooth operation. However, when operating conditions are abnormal or the load changes suddenly, the current may momentarily exceed the normal range, resulting in overcurrent. For example, when the load on a motor-driven machine suddenly increases, the motor needs to draw additional current to maintain its operating speed. If the load exceeds the motor's design capacity, the current will surge, potentially causing the coils to overheat or even be damaged.

[0003] Furthermore, motors need to overcome initial resistance during startup, thus absorbing a large current instantaneously. If the startup process lacks proper control, the starting current may be far higher than the normal operating current, causing a short-term overcurrent. Besides load changes and starting current, abnormal motor conditions can also trigger overcurrent, such as mechanical failures, power supply voltage fluctuations, or insulation aging. In particular, when a short circuit occurs in the motor coil, the current may flow uncontrollably, directly leading to motor failure or even equipment damage.

[0004] Currently, motors typically incorporate overcurrent protection mechanisms, primarily relying on microcontroller firmware to monitor current changes and adjust pulse width modulation (PWM) to reduce current output and protect the motor. However, this approach has several limitations. First, it depends on analog-to-digital conversion to calculate current changes, resulting in a slow response time, especially during sudden, short-term overcurrent events, where it may fail to detect them in time. Second, this method can only adjust the output current and cannot directly cut off the motor's power supply. If the overcurrent persists, the motor may still burn out due to overheating.

[0005] To ensure that the power supply to the motor can be quickly cut off under abnormal current conditions, so as to avoid damage and maintain system stability, the overcurrent protection mechanism needs to be improved to provide a faster and more reliable response.

[0006] In view of the above-mentioned shortcomings, this is the direction that the creator of this utility model and related manufacturers in this industry urgently want to study and improve. Utility Model Content

[0007] The main purpose of this invention is to provide a motor overcurrent protection device that can detect whether the motor is overcurrent in real time and cut off the power supply to the motor in real time.

[0008] In addition, another objective of this invention is to provide a motor overcurrent protection device that can detect and cut off the power supply to the motor in real time during a sudden short-term overcurrent event.

[0009] To achieve the above objectives and effects, this utility model provides a motor overcurrent protection device, which includes an overcurrent resistor, an amplifier, a comparator, a logic gate, and a switch. The overcurrent resistor is electrically connected to a control circuit of a motor to obtain a voltage divider signal from the control circuit. The amplifier is electrically connected to the overcurrent resistor and amplifies the voltage divider signal. The comparator is electrically connected to the amplifier and the control circuit, and compares the amplified voltage divider signal with a signal threshold stored in the control circuit to output a comparison result signal. The logic gate is electrically connected to the comparator and receives the comparison result signal to output a drive signal. The switch is electrically connected to the logic gate and receives the drive signal to cut off the power supply to the motor.

[0010] In one embodiment of this utility model, the overcurrent resistor is disposed on the motor body.

[0011] In one embodiment of this utility model, the logic gate is an OR gate.

[0012] In one embodiment of this utility model, the logic gate is used to ensure that the overcurrent protection device is triggered only once.

[0013] In one embodiment of this invention, the switch is composed of a metal-oxide-semiconductor field-effect transistor.

[0014] To enable those skilled in the art to understand the purpose, features and effects of this utility model, the following detailed description is provided through specific embodiments and in conjunction with the accompanying drawings. Attached Figure Description

[0015] Figure 1 This utility model relates to a motor overcurrent protection device;

[0016] Figure 2A This is a partial circuit diagram of the motor control loop and overcurrent resistor.

[0017] Figure 2B Here is the circuit diagram for the comparator;

[0018] Figure 2C The circuit diagram for the logic gate; and

[0019] Figure 2D This is the circuit diagram for the switch.

[0020] Explanation of reference numerals in the attached diagram: 10-Overcurrent protection device; 20-Motor; 101-Overcurrent resistor; 102-Amplifier; 103-Comparator; 104-Logic gate; 105-Switch; 201-Control circuit; 202-Power supply; U1-Circuit; Current-Voltage divider signal; CH1-Left side of the circuit; CH2-Right side of the circuit; R58, R59-Resistors; Q12, Q13, Q14-Transistors; Y'-Signal. Detailed Implementation

[0021] The above-mentioned objectives of this utility model and its structural and functional characteristics will be described with reference to the preferred embodiments shown in the accompanying drawings.

[0022] Figure 1 This invention relates to a motor overcurrent protection device. The overcurrent protection device 10 is designed to detect the operating status of the motor 20 in real time and quickly cut off the power supply when there is an abnormal overload of current, so as to prevent the motor from burning out or affecting the stability of the system. The overcurrent protection device 10 includes an overcurrent resistor 101, an amplifier 102, a comparator 103, a logic gate 104, and a switch 105. The motor 20 includes a control circuit 201 and a power supply 202. The control circuit 201 controls the operation of the motor 20, and the power supply 202 provides power to the motor 20 and the control circuit 201.

[0023] The overcurrent resistor 101 is installed in the control circuit 201 of the motor 20 and is responsible for monitoring the current status of the motor 20 during operation. When the motor 20 is running normally, the current flowing through the overcurrent resistor 101 is within a safe range, and the resulting voltage divider signal is low. However, when the load on the motor 20 increases or an abnormality occurs, the current flowing through the overcurrent resistor 101 may suddenly increase, causing the voltage divider signal to become larger. In this case, it is necessary to determine whether to activate the overcurrent protection mechanism.

[0024] Amplifier 102 is electrically connected to overcurrent resistor 101. Its function is to amplify the voltage divider signal output by overcurrent resistor 101, making it clearer and improving the accuracy of overcurrent detection by overcurrent resistor 101. Since the voltage divider value of overcurrent resistor 101 is usually low, direct comparison may not accurately determine the overcurrent condition. Therefore, amplifier 102 amplifies the signal, making it easier for subsequent comparator 103 to identify the overcurrent condition.

[0025] Comparator 103 is electrically connected to amplifier 102 and is responsible for processing the signal from amplifier 102 and comparing it with a preset signal threshold in control loop 201. The signal threshold is the upper limit of safe current set by overcurrent protection device 10. If the amplified voltage divider signal exceeds this threshold, it means that the current of motor 20 has exceeded the safe range and may enter an overload state. Comparator 103 outputs a comparison result signal at this time, and overcurrent protection device 10 further executes protection action.

[0026] Logic gate 104 is electrically connected to comparator 103, and is used to receive the comparison result signal from comparator 103 and determine whether to activate the protection mechanism. The function of logic gate 104 is to provide additional logical judgment during control signal processing, such as ensuring signal stability, eliminating false triggers due to short-term fluctuations, and ensuring that hardware overcurrent is triggered only once. If the signal meets the set conditions, such as lasting for a period of time and being determined to be in an overcurrent state, logic gate 104 will output a drive signal to switch 105, notifying switch 105 to perform power cut-off.

[0027] The purpose of switch 105 is to quickly cut off the power supply when the overcurrent protection device 10 determines that the motor 20 has entered an overcurrent state, ensuring that the motor 20 stops running and preventing further damage. In this invention, switch 105 is preferably constructed of a metal-oxide-semiconductor field-effect transistor (MOSFET), which has high-speed switching capability and can complete the conduction or cutoff action in a very short time, ensuring the immediacy of overcurrent protection. Once switch 105 receives the drive signal output from logic gate 104, switch 105 will quickly shut off the power supply to motor 20, causing motor 20 to stop running, and restore power supply after the overcurrent condition is resolved.

[0028] The design of this motor overcurrent protection device effectively ensures the safe operation of the motor 20. Through real-time detection and hardware response mechanisms, it prevents the motor 20 from burning out or the system from malfunctioning due to overcurrent. By combining the overcurrent resistor 101, amplifier 102, comparator 103, logic gate 104, and switch 105, the overcurrent protection device 10 can complete detection and power supply management in a short time, improving the accuracy and reliability of the protection mechanism.

[0029] Figure 2A This is a partial circuit diagram of the motor control loop and overcurrent resistor. Figure 2B This is a circuit diagram of an amplifier and a comparator. (Example) Figure 2A and Figure 2B As shown, and refer to Figure 1The component labels are as follows: CH1 on the left side of circuit U1 acts as amplifier 102, primarily for signal amplification; CH2 on the right side acts as comparator 103, primarily for signal comparison. Resistors R58 and R59 provide a reference voltage for comparator 103. This reference voltage is a fixed safety threshold; if the amplified signal exceeds this threshold, it indicates that the motor 20 is experiencing excessive current. When motor 20 is running, the voltage divider signal 'current' from overcurrent resistor 101 is input to pins 2 and 3 of circuit U1 for amplification, ensuring sufficient signal strength for comparator 103 to determine the signal strength. The amplified signal is output to pin 1 of circuit U1 and then connected to pin 5. Comparator 103 compares the amplified signal with the reference voltage provided by resistors R58 and R59. When motor 20 experiences overcurrent, pin 7 of circuit U1 will output a high-level signal.

[0030] Figure 2C This is the circuit diagram for a logic gate. Figure 2D The circuit diagram for the switch, such as Figure 2C and Figure 2D As shown, the logic gate 104 of this invention is preferably an OR gate, used to process the high-level signal from the comparator 103. Pin 1 of the logic gate 104 is preset to a low-level signal, indicating that the overcurrent protection device 10 has not detected an overcurrent, and both the motor 20 and the control circuit 201 are operating normally. When pin 2 of the logic gate 104 receives the high-level signal output from pin 7 of the comparator 103, the logic gate 104 performs a logical operation and outputs a high-level signal from pin 4. This high-level signal is then transmitted to pin 7 of the logic gate 104 for an OR gate operation. Pin 4 of the logic gate 104 outputs a high-level signal to pin 1, creating a latching effect to ensure that the overcurrent protection mechanism, triggered only once, is not accidentally deactivated. The high-level signal output from pin 4 of logic gate 104 is also transmitted to switch 105. The high-level signal drives switch 105 to turn on, thereby cutting off the power supply 202 of motor 20. After the overcurrent protection device 10 is triggered, transistor Q14 will turn on, and the signal Y' output from the collector of transistor Q14 will switch to a low level, causing transistor Q13 to control the power switch of transistor Q12 to turn off, thereby achieving the purpose of turning off the power supply 202 after the overcurrent trigger.

[0031] The motor overcurrent protection device of this invention ensures that the motor stops running immediately when an overcurrent occurs, preventing damage, and shuts off the power supply 202 of the control circuit 201 to protect the system. The overcurrent resistor 101 detects current changes; the signal is processed by the amplifier 102 and then enters the comparator 103 to determine if it exceeds the safe range. When an overcurrent is detected, the logic gate 104 locks the protection state to prevent false triggering and drives the switch 105 to cut off the power supply to the control circuit 201. When the overcurrent is resolved, the system automatically restores power, allowing the motor 20 and control circuit 201 to resume operation, ensuring the safety and stability of the equipment.

[0032] The above description illustrates the implementation of this utility model through specific embodiments. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this utility model specification.

[0033] The above description is only a preferred embodiment of the present utility model and is not intended to limit the scope of the present utility model; all other equivalent changes or modifications made without departing from the spirit disclosed in the present utility model should be included in the following protection scope.

Claims

1. A motor overcurrent protection device, characterized by, Include: An overcurrent resistor is electrically connected to a control circuit of a motor to obtain a voltage divider signal from the control circuit. An amplifier, electrically connected to the overcurrent resistor, is used to amplify the voltage divider signal; A comparator, electrically connected to the amplifier and the control loop, is used to compare the amplified voltage divider signal with a signal threshold stored in the control loop, so as to output a comparison result signal; A logic gate is electrically connected to the comparator, which is used to receive the comparison result signal to output a drive signal; as well as A switch, electrically connected to the logic gate, is used to receive the drive signal to cut off the power supply to the motor.

2. The motor overcurrent protection device of claim 1, wherein, The overcurrent resistor is installed on the motor body.

3. The motor overcurrent protection device of claim 2, wherein the first and second conductive elements are formed of a conductive material. This logic gate is an OR gate.

4. The motor overcurrent protection device of claim 3, wherein the first and second conductive elements are formed of a conductive material. This logic gate ensures that the overcurrent protection device is triggered only once.

5. The motor overcurrent protection device of claim 4, wherein the first and second conductive elements are formed of a conductive material. The switch is made of a metal-oxide-semiconductor field-effect transistor.

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