Direct current motor reverse electromotive force absorption circuit

Abstract

The utility model discloses a direct current motor reverse electromotive force absorption circuit, and belongs to the technical field of circuit design. Comprising a power supply input end, a first resistor R5, a second resistor R8, a first component R6, a first voltage stabilizing diode D2, a comparator, a third resistor R4, a fourth resistor R7, an MOS tube Q1, a second component R3, a third component R1, a second voltage stabilizing diode D1, a capacitor C1, a load anode, a load cathode 48V-12V power supply. A preceding-stage power supply is protected, and motor driving is also protected; the switch is long in service life and high in reliability, and cannot be damaged due to frequent switching.

Description

Technical Field

[0001] The utility model discloses a reverse electromotive force absorption circuit for a DC motor, belonging to the technical field of circuit design. Background Art

[0002] Brushless DC motors (BLDC) are widely used in many applications due to their high efficiency, long life and low maintenance requirements. Compared with traditional brushed DC motors, the control of brushless motors is more complex and usually requires an electronic controller to manage their speed and direction. When an inductive load (such as a motor, relay coil, etc.) is suddenly powered off, according to Lenz's law, the load will try to keep the current unchanged, thereby generating a very high voltage in the disconnected circuit, namely the reverse electromotive force. If not controlled, this high voltage may damage sensitive components in the circuit. In the control process of this motor, the problem of reverse electromotive force is also encountered, especially when the motor suddenly stops or changes direction. The existing technical solutions generally use series diodes and TVS diodes to absorb reverse voltage circuits. The series diode uses the unidirectional conductivity of the diode to isolate the reverse voltage. As long as the diode is connected in series at the power supply end. However, the disadvantages are also obvious. Mainly because the internal resistance of the diode is large, when it is applied to high-power scenarios, it is necessary to design the heat dissipation of the diode in a targeted manner, which is difficult to accomplish in actual situations. Moreover, the essence of this solution is to isolate energy, and the problem of reverse voltage is thrown to the motor drive, which will also affect the life of the motor drive. The principle of the TVS diode reverse voltage absorption circuit is to connect a TVS (transient voltage suppression) diode in parallel at both ends of the motor drive. The TVS diode can respond to voltage spikes in a very short time and provide effective protection. Its advantage is that the TVS reacts very quickly and has a good absorption effect within the tolerance range of the TVS tube. However, once the reverse voltage spike pulses appear frequently, the life of the TVS tube will be greatly reduced, which in turn reduces the life and reliability of the system. Utility Model Content

[0003] The utility model aims to provide a reverse electromotive force absorption circuit for a DC motor, so as to solve the problem in the prior art that the reverse voltage of a brushless motor is difficult to absorb.

[0004] A DC motor reverse electromotive force absorption circuit includes a power input terminal, a first resistor R5, a second resistor R8, a first component R6, a first voltage regulator diode D2, a comparator, a third resistor R4, a fourth resistor R7, a MOS tube Q1, a second component R3, a third component R1, a second voltage regulator diode D1, a capacitor C1, a load positive electrode, a load negative electrode 48V-, and a 12V power supply;

[0005] R5, R8, D2, and R6 form a loop in sequence, the power input terminal is connected between R5 and R6, a first branch is provided between R5 and R8 to connect to the non-inverting input terminal of the comparator, a second branch is provided between R8 and D2 to connect to the source s of Q1, and the second branch has two branches respectively connected to the 4th port and the 1st port of the comparator;

[0006] R3, R1, and D1 form a loop in sequence, the drain d of Q1 is connected between R3 and D1, the positive pole of the load is connected between R3 and R1, and the second branch is provided with a third branch, which starts from the source s of Q1 and connects C1 and R1 in sequence, and the third branch is provided with a branch connected to 48V- before connecting to C1.

[0007] The resistance value of R5 is 160K.

[0008] The resistance value of R8 is 47K.

[0009] The resistance value of R6 is 10K.

[0010] The comparator includes 8 ports, port 2 is the non-inverting input port, port 3 is the inverting input port, port 5 is normally open, port 6 is normally open, port 7 is connected to one end of R4, one end of R7 and gate g of Q1 at the same time, and ports 3 and 8 are both connected to a 12V power supply.

[0011] The other end of R4 and port 8 are connected to a 12V power supply.

[0012] The other end of R7 is connected to port 2.

[0013] The resistance value of R4 is 4.7K.

[0014] The resistance value of R7 is 1K.

[0015] The resistance value of R1 is 10K.

[0016] Compared with the prior art, the utility model has the following beneficial effects: Compared with the solution of series diodes, the utility model has two advantages. First, there is no need to consider its heat dissipation problem, because the switch of this circuit is not always open. The circuit only works when there is a reverse voltage. In this case, there is basically no device with serious heat generation; second, this circuit is an absorption circuit, which absorbs excess energy and is a self-digestion problem. It not only protects the power supply of the previous stage, but also protects the motor drive. Compared with the TVS diode reverse voltage absorption circuit, the advantages of the utility model are mainly long life and high reliability, and it will not be damaged due to frequent switching times. Moreover, under high-power and high-voltage fields, there are almost no suitable TVS tube models, which is also a major advantage of the utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1It is a circuit structure diagram of the utility model.

[0018] The reference numerals include: 1-power input terminal, 2-first resistor, 3-second resistor, 4-first component, 5-first voltage regulator diode, 6-comparator, 7-third resistor, 8-fourth resistor, 9-MOS tube, 10-second component, 11-third component, 12-second voltage regulator diode, 13-capacitor, 14-load positive electrode, 15-load negative electrode. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the utility model, but not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0020] DC motor reverse electromotive force absorption circuit, such as Figure 1 , including a power input terminal 1, a first resistor 2, a second resistor 3, a first component 4, a first voltage zener diode 5, a comparator 6, a third resistor 7, a fourth resistor 8, a MOS tube 9, a second component 10, a third component 11, a second voltage zener diode 12, a capacitor 13, a load positive electrode 14, a load negative electrode 15, and a 12V power supply;

[0021] The first resistor 2, the second resistor 3, the first voltage stabilizing diode 5, and the first component 4 sequentially form a loop, the power input end is connected between the second resistor 3 and the first component 4, a first branch is provided between the first resistor 2 and the second resistor 3 to connect to the non-inverting input end of the comparator, a second branch is provided between the second resistor 3 and the first voltage stabilizing diode 5 to connect to the source s of the MOS tube 9, and the second branch has two branches respectively connected to the 4 port and the 1 port of the comparator;

[0022] The second component 10, the third component 11, and the second zener diode 12 form a loop in sequence, the drain d of the MOS tube 9 is connected between the second component 10 and the second zener diode 12, the load positive electrode 14 is connected between the second component 10 and the third component 11, the second branch is provided with a third branch, the third branch starts from the source s of the MOS tube 9 and is connected to the capacitor 13 and the third component 11 in sequence, and the third branch is provided with a branch connected to the load negative electrode 15 before being connected to the capacitor 13.

[0023] The resistance value of the first resistor 2 is 160K, the resistance value of the second resistor 3 is 47K, the resistance value of the first component 4 is 10K, the resistance value of the third resistor 7 is 4.7K, the resistance value of the fourth resistor 8 is 1K, and the resistance value of the third component 11 is 10K.

[0024] The comparator includes 8 ports, port 2 is the non-phase input port, port 3 is the inverting input port, port 5 is normally open, port 6 is normally open, port 7 is simultaneously connected to one end of the third resistor 7, one end of the fourth resistor 8 and the gate g of Q1, port 3 and port 8 are both connected to a 12V power supply, the other end of the third resistor 7 and port 8 are commonly connected to the 12V power supply, and the other end of the fourth resistor 8 is connected to port 2.

[0025] The core device of the utility model is the comparator 6 of LM393, the MOS tube 9 performs the switching action, and the second component 10 absorbs the energy of the reverse voltage. Its working process is that the inverting input end of the comparator 6 is a fixed 12V power supply, and the positive input end is a power supply resistor voltage divider. By default, the voltage of the positive input end is lower than 12V. At this time, the MOS tube 9 is turned off, and the circuit from the second component 10 to the MOS tube 9 is broken. Once there is a reverse voltage, the voltage at the positive input end of the comparator will be greater than 12V. At this moment, the MOS tube 9 is turned on, and the power input end 1 is connected from the second component 10 to the MOS tube 9. The second component 10 absorbs the main reverse voltage energy, and the power input end 1 is protected.

[0026] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A DC motor reverse electromotive force absorption circuit, characterized in that: It includes a power input terminal, a first resistor R5, a second resistor R8, a first component R6, a first voltage stabilizing diode D2, a comparator, a third resistor R4, a fourth resistor R7, a MOS tube Q1, a second component R3, a third component R1, a second voltage stabilizing diode D1, a capacitor C1, a load positive electrode, a load negative electrode 48V-, and a 12V power supply; R5, R8, D2, and R6 form a loop in sequence, the power input terminal is connected between R5 and R6, a first branch is provided between R5 and R8 to connect to the non-inverting input terminal of the comparator, a second branch is provided between R8 and D2 to connect to the source s of Q1, and the second branch has two branches respectively connected to the 4th port and the 1st port of the comparator; R3, R1, and D1 form a loop in sequence, the drain d of Q1 is connected between R3 and D1, the positive pole of the load is connected between R3 and R1, and the second branch is provided with a third branch, which starts from the source s of Q1 and connects C1 and R1 in sequence, and the third branch is provided with a branch connected to 48V- before connecting to C1.

2. The DC motor reverse electromotive force absorption circuit according to claim 1, characterized in that: The resistance value of R5 is 160K.

3. The DC motor reverse electromotive force absorption circuit according to claim 1, characterized in that: The resistance value of R8 is 47K.

4. The DC motor reverse electromotive force absorption circuit according to claim 1, characterized in that: The resistance value of R6 is 10K.

5. The DC motor reverse electromotive force absorption circuit according to claim 1, characterized in that: The comparator includes 8 ports, port 2 is the non-inverting input port, port 3 is the inverting input port, port 5 is normally open, port 6 is normally open, port 7 is connected to one end of R4, one end of R7 and gate g of Q1 at the same time, and ports 3 and 8 are both connected to a 12V power supply.

6. The DC motor reverse electromotive force absorption circuit according to claim 5, characterized in that: The other end of R4 and port 8 are connected to a 12V power supply.

7. The DC motor reverse electromotive force absorption circuit according to claim 5, characterized in that: The other end of R7 is connected to port 2.

8. The DC motor reverse electromotive force absorption circuit according to claim 1, characterized in that: The resistance value of R4 is 4.7K.

9. The DC motor reverse electromotive force absorption circuit according to claim 1, characterized in that: The resistance value of R7 is 1K.

10. The DC motor reverse electromotive force absorption circuit according to claim 1, characterized in that: The resistance value of R1 is 10K.

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