A real-time power limiting circuit

Abstract

The utility model relates to a kind of real-time power limiting circuit, including direct current detection circuit and closed loop output voltage regulating circuit.Direct current detection circuit detects motor current in real time and exports corresponding voltage signal, the signal is connected after being isolated by a diode feedback node or reference voltage node of closed loop output voltage regulating circuit.When motor overload or blocked rotation leads to current increase, current detection signal voltage rises, and feedback node potential is pulled up or reference node potential is pulled down by diode, force closed loop output voltage regulating circuit to reduce its output voltage, to realize motor input power automatic, real-time limit.The utility model circuit is simple, response speed is fast, can maintain motor operation while protecting motor and circuit, and reliability is high.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, and in particular to a real-time power limiting circuit. Background Technology

[0002] When a DC motor experiences a sudden increase in load (overload) or becomes completely stalled (locked rotor), the armature current rises sharply. According to the power formula P = V * I, with the supply voltage V remaining constant, a sharp increase in current I will lead to a sharp increase in the motor's input power. This can not only damage the motor itself due to overheating, but may also cause its power supply line or drive circuit to trigger protection and stop working due to overcurrent, or even burn out power devices, affecting the normal operation and reliability of the entire system.

[0003] Traditional overcurrent protection often employs a shutdown-type overcurrent protection circuit, which completely cuts off the power supply when the current exceeds a set threshold. This method causes the motor to stop, interrupts system operation, and requires manual intervention to reset. For applications where sudden shutdown is not permissible, or where the motor needs to automatically maintain a certain torque output after overload, this protection method is not ideal. Therefore, a circuit is needed that can monitor the motor current in real time and automatically reduce the output voltage to limit power when the current is too high, allowing the motor to continue operating at lower power without stopping or being damaged. Utility Model Content

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a real-time power limiting circuit. This circuit can detect the operating current of a DC motor in real time and automatically and quickly reduce the motor's supply voltage when the current is too high, thereby limiting the motor's input power to a safe range. This ensures that the motor can continue to operate without burning out under overload or stall conditions, improving the reliability and safety of the system.

[0005] The above-mentioned utility model objective is achieved through the following technical solution:

[0006] A real-time power limiting circuit is applied to a DC motor control system, comprising: a DC current detection circuit and a closed-loop output voltage regulation circuit;

[0007] The input terminal of the DC current detection circuit is connected to the motor drive circuit to detect the output current flowing through the motor in real time and convert it into a current detection signal.

[0008] The output terminal of the DC current detection circuit is isolated by a diode and then connected to the feedback node or reference voltage node of the closed-loop output voltage regulation circuit.

[0009] As a further technical solution of this utility model: the DC current detection circuit is configured such that when the output current increases, the voltage of its output current detection signal increases accordingly, thereby lowering the potential of the feedback node or reference voltage node of the closed-loop output voltage regulation circuit, thereby reducing its output voltage and realizing automatic limitation of the motor output power.

[0010] As a further technical solution of this utility model: the DC current detection circuit includes a current sampling element and an operational amplifier; the current sampling element is connected in series in the motor drive circuit; the operational amplifier is connected as a non-inverting proportional amplifier circuit or a differential amplifier circuit, and its input terminal is connected to both ends of the current sampling element to obtain the sampling voltage, and amplifies the sampling voltage to output the current detection signal.

[0011] As a further technical solution of this utility model: the current sampling element is a low-resistance precision sampling resistor.

[0012] As a further technical solution of this utility model: the amplification factor of the operational amplifier is set by its peripheral resistor network, and the power supply voltage value of the operational amplifier is used to limit the maximum amplitude of the current detection signal voltage.

[0013] As a further technical solution of this utility model: by setting the power supply voltage value of the operational amplifier and the amplification factor, the maximum power limit point of the real-time power limiting circuit is jointly set.

[0014] As a further technical solution of this utility model: the closed-loop output voltage regulation circuit is a DC-DC conversion circuit based on a switching regulator or a linear regulator, and its output voltage is adjusted after being compared with an internal reference voltage through a feedback network.

[0015] As a further technical solution of this utility model: the diode is a silicon diode or a Schottky diode, its anode is connected to the output terminal of the DC current detection circuit, and its cathode is connected to the feedback node or reference voltage node of the closed-loop output voltage regulation circuit.

[0016] As a further technical solution of this utility model: the DC current detection circuit is alternatively constructed using a Hall current sensor or a current transformer.

[0017] In summary, compared with the prior art, the present invention has at least one of the following beneficial technical effects:

[0018] 1. Automatic real-time limiting: It has a fast response speed and can start to act the moment the current increases, automatically limiting the power within a safe range without the need for microprocessor intervention.

[0019] 2. Keep the motor running: Unlike simple shutdown protection, this circuit reduces the voltage rather than cuts off the power supply, allowing the motor to continue running at low speed or maintain torque under power-limited conditions. It is suitable for occasions where stopping is not allowed.

[0020] 3. Simple and reliable circuit: It is implemented using analog circuits, which are simple in structure, low in cost, stable and reliable in operation, and have strong anti-interference ability.

[0021] 4. Easy to set: The maximum power limit can be easily set by adjusting the operational amplifier's gain and the supply voltage.

[0022] 5. Comprehensive protection: It protects both the motor from overheating and burnout, and the drive circuit from overcurrent damage. Attached Figure Description

[0023] Figure 1 This is a block diagram of the overall structure of this utility model.

[0024] Figure 2 This is a schematic diagram of the structure of this utility model.

[0025] Figure 3 This is the circuit diagram of this utility model. Detailed Implementation

[0026] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0027] In the description of this application, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0029] Example 1:

[0030] Reference Figures 1-3 This utility model discloses a real-time power limiting circuit applied to a DC motor control system, comprising: a DC current detection circuit and a closed-loop output voltage regulation circuit; the input terminal of the DC current detection circuit is connected to the motor drive circuit for real-time detection of the output current flowing through the motor and converting it into a current detection signal; the output terminal of the DC current detection circuit is isolated by a diode and then connected to the feedback node or reference voltage node of the closed-loop output voltage regulation circuit.

[0031] The DC current detection circuit is configured such that when the output current increases, the voltage of its output current detection signal increases accordingly, thereby lowering the potential of the feedback node or reference voltage node of the closed-loop output voltage regulation circuit, and thus reducing its output voltage, thereby achieving automatic limitation of the motor output power.

[0032] The DC current detection circuit includes a current sampling element and an operational amplifier. The current sampling element is connected in series in the motor drive circuit. The operational amplifier is connected as a non-inverting proportional amplifier circuit or a differential amplifier circuit. Its input terminal is connected to both ends of the current sampling element to obtain the sampling voltage, and the sampling voltage is amplified to output the current detection signal.

[0033] The current sampling element is a low-resistance precision sampling resistor. The amplification factor of the operational amplifier is set by its external resistor network, and the supply voltage of the operational amplifier is used to limit the maximum amplitude of the current detection signal voltage.

[0034] The maximum power limit point of the real-time power limiting circuit is set by configuring the supply voltage and amplification factor of the operational amplifier. The closed-loop output voltage regulation circuit is a DC-DC converter circuit based on a switching regulator or linear regulator. Its output voltage is adjusted by comparing it with an internal reference voltage through a feedback network.

[0035] The diode is a silicon diode or a Schottky diode, with its anode connected to the output terminal of the DC current detection circuit and its cathode connected to the feedback node or reference voltage node of the closed-loop output voltage regulation circuit. The DC current detection circuit can alternatively be constructed using a Hall current sensor or a current transformer.

[0036] The core idea of ​​this invention is to control the motor supply voltage by detecting the motor current, thereby achieving closed-loop automatic power limiting. The circuit mainly consists of two parts: a DC current detection circuit and a closed-loop output voltage regulation circuit.

[0037] A DC current detection circuit is used to acquire the current signal in the motor circuit in real time. It typically consists of a current sampling element (such as a precision sampling resistor) connected in series in the motor power supply circuit and a signal conditioning circuit (such as a non-inverting amplifier circuit composed of operational amplifiers). The operational amplifier amplifies the small voltage difference signal across the sampling resistor to obtain a voltage signal that accurately reflects the real-time current magnitude (i.e., the current detection signal).

[0038] The closed-loop output voltage regulation circuit is the power supply for the motor. It is usually a DC-DC converter (such as a Buck converter). It stabilizes the output voltage by comparing the feedback voltage with the reference voltage through an internal error amplifier.

[0039] The key connection of this invention lies in connecting the output terminal of the DC current detection circuit to the feedback node or reference voltage node of the closed-loop output voltage regulation circuit via a diode. The diode serves as an isolation element, preventing the voltage of the regulation circuit from affecting the current detection circuit during normal operation.

[0040] The working principle of this utility model is as follows:

[0041] When the motor is working normally, the current is small, the voltage signal output by the current detection circuit is low, the diode is in reverse bias cutoff state, which does not affect the normal operation of the closed-loop output voltage regulation circuit, and the motor obtains the full voltage.

[0042] When the motor is overloaded or stalled, the current increases sharply. The voltage signal output by the current detection circuit rises accordingly. When this voltage exceeds the voltage of the feedback node / reference node of the closed-loop output voltage regulation circuit plus the forward voltage drop of the diode, the diode conducts.

[0043] The conducting diode "injects" or "superimposes" this increased voltage signal onto the feedback / reference node. This is equivalent to increasing the feedback voltage or decreasing the reference voltage, causing the error amplifier in the closed-loop output voltage regulation circuit to consider the output voltage "too high," thereby driving the power switch to adjust its duty cycle and ultimately reduce the output voltage.

[0044] The reduction in output voltage suppresses the tendency for current to increase under the same load, or forces the current to decrease under high load, ultimately limiting the power P = V*I to near a set maximum value. The entire process is continuous, automatic, and real-time, forming a stable power closed-loop control.

[0045] The implementation principle of this utility model is as follows: This utility model discloses a real-time power limiting circuit, including a DC current detection circuit and a closed-loop output voltage regulation circuit. The DC current detection circuit detects the motor current in real time and outputs a corresponding voltage signal. This signal is isolated by a diode and then connected to the feedback node or reference voltage node of the closed-loop output voltage regulation circuit. When the motor is overloaded or stalled, causing the current to increase, the current detection signal voltage rises. This raises the potential of the feedback node or lowers the potential of the reference node through the diode, forcing the closed-loop output voltage regulation circuit to reduce its output voltage, thereby achieving automatic and real-time limiting of the motor input power. This utility model has a simple circuit, fast response speed, and can maintain motor operation while protecting the motor and circuit, with high reliability.

[0046] The embodiments described herein are preferred embodiments of this utility model and are not intended to limit the scope of protection of this utility model. Therefore, all equivalent changes made to the structure, shape, and principle of this utility model should be included within the scope of protection of this utility model.

Claims

1. A real-time power limiting circuit, applied to a DC motor control system, characterized in that, include: DC current detection circuit and closed-loop output voltage regulation circuit; The input terminal of the DC current detection circuit is connected to the motor drive circuit to detect the output current flowing through the motor in real time and convert it into a current detection signal. The output terminal of the DC current detection circuit is isolated by a diode and then connected to the feedback node or reference voltage node of the closed-loop output voltage regulation circuit.

2. The real-time power limiting circuit according to claim 1, characterized in that, The DC current detection circuit is configured such that when the output current increases, the voltage of its output current detection signal increases accordingly, thereby lowering the potential of the feedback node or reference voltage node of the closed-loop output voltage regulation circuit, and thus reducing its output voltage, thereby achieving automatic limitation of the motor output power.

3. The real-time power limiting circuit according to claim 1, characterized in that, The DC current detection circuit includes a current sampling element and an operational amplifier; the current sampling element is connected in series in the motor drive circuit; the operational amplifier is connected as a non-inverting proportional amplifier circuit or a differential amplifier circuit, and its input terminal is connected to both ends of the current sampling element to obtain the sampling voltage, and amplifies the sampling voltage to output the current detection signal.

4. The real-time power limiting circuit according to claim 3, characterized in that, The current sampling element is a low-resistance precision sampling resistor.

5. A real-time power limiting circuit according to claim 3, characterized in that, The amplification factor of the operational amplifier is set by its surrounding resistor network, and the supply voltage value of the operational amplifier is used to limit the maximum amplitude of the current detection signal voltage.

6. A real-time power limiting circuit according to claim 5, characterized in that, The maximum power limit point of the real-time power limiting circuit is set by setting the supply voltage value of the operational amplifier and the amplification factor.

7. A real-time power limiting circuit according to claim 1, characterized in that, The closed-loop output voltage regulation circuit is a DC-DC converter circuit based on a switching regulator or a linear regulator. Its output voltage is adjusted by comparing it with an internal reference voltage through a feedback network.

8. A real-time power limiting circuit according to claim 1, characterized in that, The diode is a silicon diode or a Schottky diode, with its anode connected to the output terminal of the DC current detection circuit and its cathode connected to the feedback node or reference voltage node of the closed-loop output voltage regulation circuit.

9. A real-time power limiting circuit according to claim 1, characterized in that, The DC current detection circuit is alternatively constructed using a Hall current sensor or a current transformer.

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