Direct-current brushless motor brake protection device based on ideal diode

Abstract

An ideal diode equivalent circuit comprises a comparator and a metal oxide semiconductor (MOS) tube, under the condition of normal forward current in a working range, the MOS tube has on-resistance, voltage drop exists from a source electrode to a drain electrode of the MOS tube, the drain electrode voltage is lower than the source electrode voltage, and therefore the direct current brushless motor brake protection device can be used for protecting the direct current brushless motor. The comparator detects the voltage drop from the source electrode to the drain electrode of the MOS tube; when the inductive load is in a braking state, counter electromotive force is generated, so that kinetic energy of the motor is converted into electric energy, the power supply voltage rises instantly, the current is reversed, the voltage of the drain electrode of the MOS tube is higher than the voltage of the source electrode of the MOS tube, the comparator outputs low level after detecting, the MOS tube is turned off, the load is disconnected, and the input end circuit and the input power supply are protected. According to the utility model, through intelligent management of an ideal diode circuit, rising of power supply voltage in a braking process is effectively inhibited, and safe operation of an external power supply circuit and other circuits of the driving board is ensured.

Description

Technical Field

[0001] This utility model belongs to the field of motor protection technology, and in particular relates to a DC brushless motor braking protection device based on an ideal diode. Background Technology

[0002] DC brushless motors are known for their high efficiency, low noise, and long lifespan. However, during braking, the conversion of the motor's kinetic energy into electrical energy often causes a momentary surge in the power supply voltage. This can not only impact the power supply system but also damage the drive board and its external circuitry.

[0003] A brushless DC motor generates reverse current during braking. Reverse current refers to the inductive load (in this case, the motor) attempting to draw current back to the power supply. This phenomenon can occur when the power supply voltage suddenly drops or disappears, or when the power supply is connected, decoupling at the load end, bypass capacitors, or the battery can also cause reverse current. Furthermore, the load voltage may exceed the power supply voltage, which can also lead to reverse current, such as reverse voltage caused by the inductive load or voltage leakage from a failed battery charging circuit. Utility Model Content

[0004] To solve the above problems, the technical solution of this utility model includes a reverse connection protection circuit and an ideal diode equivalent circuit, wherein,

[0005] The reverse connection protection circuit input is connected to the power input terminal, the reverse connection protection circuit output is connected to the ideal diode equivalent circuit, and the ideal diode equivalent circuit output is connected to the inductive load.

[0006] The ideal diode equivalent circuit includes a comparator and a MOSFET. The source of the MOSFET is connected to the input terminal of the comparator, and the drain of the MOSFET is connected to the output terminal of the comparator. Under normal forward current conditions within the operating range, the MOSFET has on-resistance, resulting in a voltage drop from the source to the drain, causing the drain voltage to be lower than the source voltage. The comparator detects this voltage drop. When the inductive load is in braking mode, a back electromotive force is generated, converting the motor's kinetic energy into electrical energy. This instantaneous increase in the power supply voltage causes the current to reverse, resulting in the drain voltage of the MOSFET being higher than the source voltage. Upon detecting this, the comparator outputs a low level, turning off the MOSFET, disconnecting the load, and protecting the input circuit and the input power supply.

[0007] Preferably, the MOS transistor is an NCEP023N10LL model chip.

[0008] Preferably, the comparator is an MX1617D100 chip.

[0009] Preferably, pin 1 of the comparator, the voltage detection pin, is connected to the source pin of the MOSFET; pin 2, the power supply pin (VS), is the auxiliary power supply pin for all internal biases and the internal gate drive charge pump, and is connected to VOUT or VIN; pin 3, the OFF pin, has a logic high level that pulls the GATE pin low and turns off the MOSFET, and can be left empty or connected to ground; pin 4, the GND pin, is the ground loop of the comparator; pins 5 and 8 are left empty; pin 6, the output pin, is the voltage detection output connected to the drain of the MOSFET; and pin 7, the gate pin, is connected to the gate of the MOSFET.

[0010] Preferably, it also includes a braking controller connected to the equivalent circuit of an ideal diode, which controls the braking process of the inductive load when a braking command is received, and works in conjunction with the equivalent circuit of the ideal diode to suppress the power supply voltage and protect the drive board.

[0011] Compared with the prior art, the present invention has at least the following beneficial effects:

[0012] 1. Effectively suppresses the rise in power supply voltage during the braking process of the brushless DC motor, protecting the stability and safety of the power supply system;

[0013] 2. The intelligent management of the ideal diode circuit reduces the impact of feedback current on the power supply system, extending the service life of the power supply and motor;

[0014] 3. Improved the reliability of the driver board and its external circuits, and reduced the failure rate caused by overvoltage and overcurrent;

[0015] 4. Suitable for various DC brushless motor applications that require frequent braking or high power supply stability. Attached Figure Description

[0016] Figure 1 This is a structural block diagram of a DC brushless motor braking protection device based on an ideal diode, according to a specific embodiment of the present invention.

[0017] Figure 2 This is a circuit diagram of a DC brushless motor braking protection device based on an ideal diode, according to a specific embodiment of this utility model.

[0018] Figure 3 The diagram shows the equivalent circuit diagram of an ideal diode-based DC brushless motor braking protection device according to a specific embodiment of this utility model. Detailed Implementation

[0019] The technical solution provided by this utility model will be further described below with reference to the accompanying drawings.

[0020] See Figure 1The diagram shows a block diagram of the DC brushless motor braking protection device based on an ideal diode, comprising a reverse connection protection circuit 10 and an ideal diode equivalent circuit 20, wherein...

[0021] The reverse connection protection circuit 10 is connected to the power input terminal, and its output is connected to the ideal diode equivalent circuit 20. The output of the ideal diode equivalent circuit 20 is connected to the inductive load 30. The reverse connection protection circuit 10 is designed to prevent the positive and negative terminals of the input terminals from being reversed, which could damage the circuit.

[0022] The ideal diode equivalent circuit 20 includes a comparator and a MOSFET, suppressing the rise in power supply voltage during braking and protecting the external power supply circuit and other circuits of the driver board. The source of the MOSFET is connected to the input terminal of the comparator, and the drain of the MOSFET is connected to the output terminal of the comparator. Under normal forward current conditions within the operating range, the MOSFET has on-resistance, and there will be a voltage drop from the source to the drain of the MOSFET, causing the drain ( Figure 3 The voltage at point 2 is lower than that at the source ( Figure 3 The voltage at point 1 is used by the comparator to detect the voltage drop from the source to the drain of the MOSFET (i.e., ...). Figure 3 (Voltage drop between points 1 and 2) When the inductive load 30 is in braking state, it generates back electromotive force, which converts the kinetic energy of the motor into electrical energy. The power supply voltage rises instantaneously, the current reverses, and the voltage at the drain of the MOSFET is higher than the voltage at the source of the MOSFET. After the comparator detects this, it outputs a low level, which turns off the MOSFET, disconnects the load 30, and protects the input circuit and the input power supply.

[0023] This invention introduces an ideal diode equivalent circuit 20 between the drive board and the power supply system. This circuit has the characteristics of low on-state voltage, fast response and reverse blocking. It can intelligently manage the feedback current when the motor is braking, prevent it from directly impacting the power supply system, and thus effectively suppress the rise of the power supply voltage.

[0024] Reverse current suppression mechanism: When the inductive load 30 (which may be a motor in a specific embodiment) is in a braking state, the ideal diode equivalent circuit 20 can respond quickly and guide the feedback current to an appropriate path to prevent it from directly flowing back into the power system, thereby protecting the stability and safety of the power supply.

[0025] Driver board protection: The ideal diode equivalent circuit 20 not only suppresses the rise of the power supply voltage, but also acts as a protective barrier to isolate the overvoltage and overcurrent that may be generated during braking, protecting the external power supply circuit and other key circuit components of the driver board, and improving the reliability and stability of the entire system.

[0026] See Figure 2 , Figure 3The MOSFETs Q2 and Q14 are NCEP023N10LL chips. These transistors utilize Super Trench II technology, providing the most efficient high-frequency switching performance. Due to the extremely low combination of RDS(ON) and Qg, both conduction and switching losses are minimized. They are ideal for high-frequency switching and synchronous rectification.

[0027] General characteristics: VDS = 100V, ID = 300A, RDS(ON) = 1.7mΩ, typical @ VGS = 10V; excellent gate charge xRDS(on) product (FOM); extremely low on-resistance RDS(on); 175 °C operating temperature; lead-free plating, 100% UIS tested; 100% ΔVds tested; Turn-off characteristics: drain-source breakdown voltage BVDSS, VGS=0V, ID=250μA, 100-V; zero gate voltage leakage current IDSS VDS=100V, VGS=0V - -1uA; gate leakage current IGSS VGS=±20V, VDS=0V - - ±100 nA; Turn-on characteristics: gate threshold voltage VGS(th) VDS=VGS, ID=250μA 2.0 3.0 4.0 V, drain-source on-resistance RDS(ON) VGS=10V, ID=150A - 1.7 2.3 mΩ; Gate resistance RG F=1.0MHz - 2.0 - Ω; Switching characteristics: On-delay time td(on) - 34 – nS; On-rise time tr -27 – nS; Off-delay time td(off) - 78 – nS; Off-fall time tf VDD=50V,ID=150A VGS=10V,RG=1.6Ω - 30 – nS.

[0028] Comparator U10 is an MX1617D100 chip.

[0029] Pin 1 of comparator U10, the voltage detection pin, is connected to the source pin of the MOSFET; pin 2, the power supply pin (VS), is the auxiliary power supply pin for all internal biases and the internal gate drive charge pump, connected to VOUT or VIN; pin 3, the OFF pin, has a logic high level that pulls the GATE pin low and turns off the MOSFET, left empty or connected to ground; pin 4, the GND pin, is the comparator's ground loop; pins 5 and 8 are left empty; pin 6, the output pin, is the voltage detection output connected to the drain of the MOSFET; pin 7, the gate pin, is connected to the gate of the MOSFET. The comparator controls the MOSFET to simulate a low forward voltage diode.

[0030] It also includes a braking controller, which is connected to the ideal diode equivalent circuit 20. When a braking command is received, it controls the braking process of the inductive load 30 and works in conjunction with the ideal diode equivalent circuit 20 to suppress the power supply voltage and protect the drive board.

[0031] This invention effectively suppresses the rise in power supply voltage during braking through the intelligent management of the ideal diode equivalent circuit 20, while ensuring the safe operation of the external power supply circuit and other circuits of the drive board. Optimization and adjustment of the hardware circuit contribute to the smooth, safe, and reliable operation of the inductive load 30, demonstrating broad application prospects and significant practical value in the field of brushless motors.

[0032] The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

[0033] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A braking protection device for a brushless DC motor based on an ideal diode, characterized in that, This includes a reverse connection protection circuit and an ideal diode equivalent circuit, among which, The reverse connection protection circuit input is connected to the power input terminal, the reverse connection protection circuit output is connected to the ideal diode equivalent circuit, and the ideal diode equivalent circuit output is connected to the inductive load. The ideal diode equivalent circuit includes a comparator and a MOSFET. The source of the MOSFET is connected to the input terminal of the comparator, and the drain of the MOSFET is connected to the output terminal of the comparator. Under normal forward current conditions within the operating range, the MOSFET has on-resistance, resulting in a voltage drop from the source to the drain, causing the drain voltage to be lower than the source voltage. The comparator detects this voltage drop. When the inductive load is in braking mode, a back electromotive force is generated, converting the motor's kinetic energy into electrical energy. This instantaneous increase in the power supply voltage causes the current to reverse, resulting in the drain voltage of the MOSFET being higher than the source voltage. Upon detecting this, the comparator outputs a low level, turning off the MOSFET, disconnecting the load, and protecting the input circuit and the input power supply.

2. The DC brushless motor braking protection device based on an ideal diode according to claim 1, characterized in that, The MOSFET is an NCEP023N10LL model chip.

3. The DC brushless motor braking protection device based on an ideal diode according to claim 2, characterized in that, The comparator is an MX1617D100 chip.

4. The DC brushless motor braking protection device based on an ideal diode according to claim 3, characterized in that, The comparator's pin 1, the voltage detection pin, is connected to the source pin of the MOSFET; pin 2, the power supply pin (VS), is the auxiliary power supply pin for all internal biases and the internal gate drive charge pump, and is connected to VOUT or VIN; pin 3, the OFF pin, has a logic high level that pulls the GATE pin low and turns off the MOSFET, and can be left empty or connected to ground; pin 4, the GND pin, is the comparator's ground loop; pins 5 and 8 are left empty; pin 6, the output pin, is the voltage detection output and is connected to the drain of the MOSFET. The gate of pin 7 is connected to the gate of the MOSFET.

5. The DC brushless motor braking protection device based on an ideal diode according to claim 1, characterized in that, It also includes a braking controller, which is connected to the equivalent circuit of an ideal diode. When a braking command is received, it controls the braking process of the inductive load and works in conjunction with the equivalent circuit of the ideal diode to suppress the power supply voltage and protect the drive board.

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