Disturbance voltage filter circuit of DC brush motor

Abstract

The invention relates to the technical field of direct-current brush motors, and discloses a disturbance voltage filter circuit of a direct-current brush motor, which comprises a wiring terminal J1 connected to a live wire, a wiring terminal J2 connected to a zero wire and a rectifier bridge BR1, and a filter circuit is also connected between the rectifier bridge BR1 and the direct-current brush motor; differential-mode noise is suppressed through the added differential-mode inductor, the amplitude and frequency of the noise are effectively reduced, the electromagnetic compatibility of the circuit is improved, the filtering effect can be further improved through the design that the resistor is connected to the differential-mode inductor in parallel, a damping network can be formed through the addition of the resistor, residual energy in the inductor can be absorbed and dissipated, the resonance phenomenon is reduced, and the filtering effect is improved. The two same differential mode inductors are added, and the resistors are connected to the differential mode inductors in parallel, so that the configuration of the filter circuit is more flexible, the values of the differential mode inductors and the resistors can be adjusted according to actual needs, and the optimal filtering effect is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of brushed DC motors, in particular to a disturbance voltage filtering circuit of a brushed DC motor. Background Art

[0002] A brushed DC motor is a rotating motor with a built-in brush device. Its main function is to convert DC electrical energy into mechanical energy (DC motor) or to convert mechanical energy into DC electrical energy (DC generator).

[0003] After searching, the patent with application number CN201810934274.6 discloses a DC brush motor, including a housing, a stator, a rotor and a plastic end cap, the plastic end cap is provided with a brush holder, the carbon brush is installed in the brush holder, and the rotor is provided with a commutator, wherein the DC brush motor has a multi-stage EMC filter circuit capable of filtering noise in multiple frequency bands, the electronic components forming the multi-stage EMC filter circuit are installed on a circuit board with a conductive material layer, and the circuit board is connected to the motor housing through copper foil. In this invention, the EMC level of the DC brush motor is improved by providing a multi-stage EMC filter circuit, a circuit board with a conductive material layer, and copper foil provided between the circuit board and the motor housing.

[0004] The interference voltage (150K-30M GB4343.1-2018) of the existing brushed DC motor (ZYT46S220VDC power 2W-20W) exceeds the standard in many frequency bands. To improve this situation, an inductor will be added to the drive circuit of the brushed DC motor for filtering. After processing, the interference voltage will be improved in several frequency bands, but the margin is not much. Therefore, we need to propose a interference voltage filter circuit for brushed DC motors. Summary of the invention

[0005] The purpose of the present invention is to provide a disturbance voltage filter circuit for a brushed DC motor, which suppresses differential mode noise by increasing differential mode inductance, effectively reduces the amplitude and frequency of noise, and improves the electromagnetic compatibility of the circuit. The filtering effect can be further improved by designing a resistor in parallel with the differential mode inductor. The addition of resistors can form a damping network, which helps to absorb and dissipate residual energy in the inductor, reduce resonance, and improve the stability of the circuit. By adding two identical differential mode inductors and connecting resistors in parallel thereto, the configuration of the filter circuit is more flexible, and the values ​​of the differential mode inductor and the resistor can be adjusted according to actual needs to achieve the best filtering effect, so as to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a disturbance voltage filter circuit of a brushed DC motor, comprising a terminal J1 connected to a live wire, a terminal J2 connected to a neutral wire, a rectifier bridge BR1, a positive terminal J6 of the brushed DC motor, and a negative terminal J5 of the brushed DC motor, wherein the terminal J1 and the terminal J2 are both connected to the rectifier bridge, and a filter circuit is further connected between the rectifier bridge BR1 and the brushed DC motor;

[0007] The filtering circuit includes a differential mode inductor L3 and a resistor R5 arranged in parallel, and a differential mode inductor L4 and a resistor R6 arranged in parallel. One terminal of the differential mode inductor L3 and the resistor R5 is connected to pin 2 of the rectifier bridge BR1, and one terminal of the differential mode inductor L4 and the resistor R6 is connected to pin 4 of the rectifier bridge BR1.

[0008] Preferably, the connection terminal J1 is connected to a fuse F1 and a varistor ZE1 which are arranged in series, and the varistor ZE1 is connected to the connection terminal J2.

[0009] Preferably, the connection terminals of the fuse F1 and the varistor ZE1 are connected to pin 3 of the rectifier bridge BR1, a bidirectional thyristor Q1 is connected between the connection terminal J2 and pin 1 of the rectifier bridge BR1, and a resistor R3 is connected to pin 3 of the bidirectional thyristor Q1.

[0010] Preferably, pin 1 of the bidirectional thyristor Q1 is connected to pin 1 of the rectifier bridge BR1, pin 2 of the bidirectional thyristor Q1 is connected to the wiring terminal J2, and pin 1 of the rectifier bridge BR1 is connected to the working voltage.

[0011] Preferably, the filter circuit also includes a capacitor CX2 and a resistor R7 arranged in parallel, one terminal of the capacitor CX2 and the resistor R7 is connected to the positive terminal J6 of the DC brush motor, and the other terminal of the capacitor CX2 and the resistor R7 is connected to the negative terminal J5 of the DC brush motor.

[0012] Preferably, the other terminal of the differential mode inductor L3 and the resistor R5 is connected to the positive terminal J6 of the DC brush motor, and the other terminal of the differential mode inductor L4 and the resistor R6 is connected to the negative terminal J5 of the DC brush motor.

[0013] Preferably, the differential mode inductor L3 and the differential mode inductor L4 are set to be the same differential mode inductor, the inductance values ​​of the differential mode inductor L3 and the differential mode inductor L4 are both 68uH, and the resistance values ​​of the resistor R5 and the resistor R6 are both 2K.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention suppresses differential mode noise by increasing differential mode inductance, effectively reduces the amplitude and frequency of noise, and improves the electromagnetic compatibility of the circuit. The design of connecting resistors in parallel to the differential mode inductors can further improve the filtering effect. The addition of resistors can form a damping network, which helps to absorb and dissipate residual energy in the inductor, reduce resonance, and improve the stability of the circuit.

[0016] 2. The present invention makes the configuration of the filter circuit more flexible by adding two identical differential mode inductors and connecting resistors in parallel thereto, and the values ​​of the differential mode inductors and resistors can be adjusted according to actual needs to achieve the best filtering effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A circuit diagram of the present invention;

[0018] Figure 2 A schematic diagram of the disturbance voltage of the DC brush motor driving circuit of the present invention;

[0019] Figure 3 It is a circuit diagram of a DC brushed motor drive circuit in the prior art;

[0020] Figure 4 The circuit diagram of the prior art DC brushed motor drive circuit with capacitor and resistor filtering;

[0021] Figure 5 A circuit diagram of a DC brush motor drive circuit in which a differential mode inductor is connected to the negative pole of the DC brush motor in the prior art;

[0022] Figure 6 A circuit diagram of a DC brush motor drive circuit in which a differential mode inductor is connected to the positive pole of the DC brush motor in the prior art;

[0023] Figure 7 for Figure 3 Schematic diagram of the interference voltage in a brushed DC motor drive circuit. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] See also Figure 1-2The present invention provides a technical solution: a disturbance voltage filter circuit of a brushed DC motor, comprising a terminal J1 connected to a live wire, a terminal J2 connected to a neutral wire, a rectifier bridge BR1, a positive terminal J6 of the brushed DC motor, and a negative terminal J5 of the brushed DC motor, wherein the terminal J1 and the terminal J2 are both connected to the rectifier bridge, and a filter circuit is further connected between the rectifier bridge BR1 and the brushed DC motor; the model of the rectifier bridge BR1 is ABS10.

[0026] The filtering circuit includes a differential mode inductor L3 and a resistor R5 arranged in parallel, and a differential mode inductor L4 and a resistor R6 arranged in parallel. One terminal of the differential mode inductor L3 and the resistor R5 is connected to pin 2 of the rectifier bridge BR1, and one terminal of the differential mode inductor L4 and the resistor R6 is connected to pin 4 of the rectifier bridge BR1.

[0027] The two differential mode inductors (L3, L4) are mainly used to suppress differential mode noise, that is, the noise between the power line and the ground line. In a brushed DC motor, high-frequency differential mode noise is generated due to the contact and separation of the brush and the commutator. Increasing the differential mode inductor can effectively reduce the amplitude and frequency of these noises, thereby improving the electromagnetic compatibility (EMC) of the entire circuit.

[0028] Connecting resistors in parallel with differential mode inductors can further improve the filtering effect. The addition of resistors can form a damping network, which helps to absorb and dissipate the residual energy in the inductor, reduce the occurrence of resonance, and thus improve the stability and reliability of the filter.

[0029] In the filter circuit, components such as inductors and capacitors may form a resonant loop, resulting in enhanced noise at certain frequency points. By connecting a resistor in parallel with the differential mode inductor, this resonant condition can be destroyed, suppressing the occurrence of the resonance phenomenon, thereby improving the stability of the system.

[0030] The parallel resistor can also reduce the impedance of the system at certain frequency points, making the noise signal easier to be absorbed and dissipated by the filter, further improving the filtering effect.

[0031] In actual applications, the load of the brushed DC motor may change. By adjusting the resistance of the parallel resistor, the filter circuit can better adapt to the noise suppression requirements under different load conditions.

[0032] Adding two identical differential mode inductors and connecting resistors in parallel makes the configuration of the filter circuit more flexible. The values ​​of the inductor and resistor can be adjusted according to actual needs to achieve the best filtering effect.

[0033] In addition, during long-term operation, the differential mode inductor may saturate due to excessive current, resulting in a decrease in filtering effect. By connecting a resistor in parallel to the differential mode inductor, the current passing through the inductor can be limited to prevent the occurrence of differential mode inductor saturation, thereby improving the safety of the circuit.

[0034] The wiring terminal J1 is connected to a fuse F1 and a varistor ZE1 which are arranged in series. The varistor ZE1 is connected to the wiring terminal J2. The fuse F1 and the varistor ZE1 play a protective role on the circuit.

[0035] The varistor ZE1 is a resistor device with nonlinear characteristics. Its resistance value is very high under normal operating voltage, but when the voltage exceeds its set threshold, the resistance value drops sharply, allowing large current to pass. In this way, the varistor ZE1 can absorb the overvoltage energy in the circuit and prevent the overvoltage from causing damage to subsequent circuits or equipment.

[0036] The varistor ZE1 also has a transient voltage suppression function, which can quickly respond to transient overvoltages in the circuit, such as electrostatic discharge, surge, etc., to protect sensitive components in the circuit.

[0037] Fuse F1 is a component that will automatically blow when the current exceeds the rated value, and is used to detect and cut off overcurrent faults in the circuit. When a short circuit or overload occurs in the circuit, the current will increase sharply, and fuse F1 will quickly blow, thereby cutting off the circuit and preventing the fault from expanding.

[0038] After fuse F1 blows, an open circuit state is formed, isolating the faulty part from the rest of the circuit, ensuring the safety and stability of the circuit.

[0039] In summary, under normal working conditions, both fuse F1 and varistor ZE1 are in a high-resistance state and have almost no effect on the circuit. However, when overvoltage or overcurrent occurs in the circuit, varistor ZE1 will respond first, absorbing overvoltage energy or limiting overcurrent; if the fault persists, fuse F1 will blow and cut off the circuit.

[0040] The connection terminals of the fuse F1 and the varistor ZE1 are connected to the 3rd pin of the rectifier bridge BR1, the bidirectional thyristor Q1 is connected between the connection terminal J2 and the 1st pin of the rectifier bridge BR1, and the resistor R3 is connected to the 3rd pin of the bidirectional thyristor Q1. The model of the bidirectional thyristor Q1 is BT131, and the resistance value of the resistor R3 is 330R.

[0041] Pin 1 of the bidirectional thyristor Q1 is connected to pin 1 of the rectifier bridge BR1 , pin 2 of the bidirectional thyristor Q1 is connected to the wiring terminal J2 , and pin 1 of the rectifier bridge BR1 is connected to the working voltage.

[0042] The filter circuit also includes a capacitor CX2 and a resistor R7 arranged in parallel, one terminal of the capacitor CX2 and the resistor R7 is connected to the positive terminal J6 of the DC brush motor, and the other terminal of the capacitor CX2 and the resistor R7 is connected to the negative terminal J5 of the DC brush motor.

[0043] The other terminal of the differential mode inductor L3 and the resistor R5 is connected to the positive terminal J6 of the DC brush motor, and the other terminal of the differential mode inductor L4 and the resistor R6 is connected to the negative terminal J5 of the DC brush motor. The filtered voltage can be directly transmitted to the DC brush motor.

[0044] The differential mode inductor L3 and the differential mode inductor L4 are set to be the same differential mode inductor, the inductance values ​​of the differential mode inductor L3 and the differential mode inductor L4 are both 68uH, and the resistance values ​​of the resistor R5 and the resistor R6 are both 2K.

[0045] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. The disturbance voltage filter circuit of the brushed DC motor is characterized by: It includes a terminal J1 connected to the live wire, a terminal J2 connected to the neutral wire, a rectifier bridge BR1, a positive terminal J6 of the DC brush motor, and a negative terminal J5 of the DC brush motor. The terminal J1 and the terminal J2 are both connected to the rectifier bridge, and a filter circuit is also connected between the rectifier bridge BR1 and the DC brush motor. The filtering circuit includes a differential mode inductor L3 and a resistor R5 arranged in parallel, and a differential mode inductor L4 and a resistor R6 arranged in parallel. One terminal of the differential mode inductor L3 and the resistor R5 is connected to pin 2 of the rectifier bridge BR1, and one terminal of the differential mode inductor L4 and the resistor R6 is connected to pin 4 of the rectifier bridge BR1.

2. The disturbance voltage filter circuit of a brushed DC motor according to claim 1, characterized in that: The connection terminal J1 is connected to a fuse F1 and a varistor ZE1 which are arranged in series, and the varistor ZE1 is connected to the connection terminal J2.

3. The disturbance voltage filter circuit of a brushed DC motor according to claim 2, characterized in that: The connection terminals of the fuse F1 and the varistor ZE1 are connected to the 3rd pin of the rectifier bridge BR1, the bidirectional thyristor Q1 is connected between the connection terminal J2 and the 1st pin of the rectifier bridge BR1, and the 3rd pin of the bidirectional thyristor Q1 is connected to the resistor R3.

4. The disturbance voltage filter circuit of a brushed DC motor according to claim 3, characterized in that: Pin 1 of the bidirectional thyristor Q1 is connected to pin 1 of the rectifier bridge BR1 , pin 2 of the bidirectional thyristor Q1 is connected to the wiring terminal J2 , and pin 1 of the rectifier bridge BR1 is connected to the working voltage.

5. The disturbance voltage filter circuit of a brushed DC motor according to claim 1, characterized in that: The filter circuit also includes a capacitor CX2 and a resistor R7 arranged in parallel, one terminal of the capacitor CX2 and the resistor R7 is connected to the positive terminal J6 of the DC brush motor, and the other terminal of the capacitor CX2 and the resistor R7 is connected to the negative terminal J5 of the DC brush motor.

6. The disturbance voltage filter circuit of a brushed DC motor according to claim 1, characterized in that: The other terminal of the differential mode inductor L3 and the resistor R5 is connected to the positive terminal J6 of the DC brush motor, and the other terminal of the differential mode inductor L4 and the resistor R6 is connected to the negative terminal J5 of the DC brush motor.

7. The disturbance voltage filter circuit of a brushed DC motor according to claim 1, characterized in that: The differential mode inductor L3 and the differential mode inductor L4 are set to be the same differential mode inductor, the inductance values ​​of the differential mode inductor L3 and the differential mode inductor L4 are both 68uH, and the resistance values ​​of the resistor R5 and the resistor R6 are both 2K.

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