Soft commutation circuit of brushless driver

Abstract

The invention relates to a soft commutation circuit of a brushless driver. The soft commutation circuit comprises an input end input of a commutation signal IN, a monostable trigger A, a monostable trigger B, resistors R1 and R2, an exclusive-OR gate 1, an exclusive-OR gate 2, an exclusive-OR gate 3, a D trigger and capacitors C1, C2 and C3, wherein the monostable trigger A and the monostable trigger B are connected in parallel; wherein the input end input is divided into two paths, one path is connected to the monostable trigger A through the end A of the OR gate 1, and the other path is connected to the monostable trigger B through the end B of the OR gate 2; the device is reasonable in design, compact in structure and convenient to use.

Description

Technical Field

[0001] The invention relates to a soft commutation circuit of a brushless driver, belongs to the field of circuits, and particularly relates to a circuit for realizing soft commutation of a brushless driver and reducing current and voltage peaks at a power end by adjusting driver commutation and power switch timing during the working commutation process of a brushless motor. Background Art

[0002] At present, brushless drives mostly use hard commutation technology in applications, that is, directly giving commutation signals during motor operation without considering the working state of the motor at this time. Or in system applications, external software is used to control commutation and power switch timing, but this method is generally used more in high-power applications.

[0003] Brushless motors require frequent commutation during operation, which will bring large current and voltage peaks, causing impact or even damage to the circuit. Therefore, it is necessary to provide a certain buffer during the commutation process to reduce circuit impact.

[0004] Most brushless drivers in the prior art use hard commutation technology, which causes a large circuit impact and easily causes circuit damage. They use software methods to control timing, which increases the complexity of the circuit. Summary of the invention

[0005] The technical problem to be solved by the present invention is generally to provide a soft commutation circuit for a brushless driver. The present invention does not require programming, has a relatively simple circuit structure, and has good general adaptability. At the same time, it solves the problem of large voltage and current peaks during hard commutation of the brushless motor, thereby reducing the impact on the circuit.

[0006] To solve the above problems, the technical solution adopted by the present invention is:

[0007] A soft commutation circuit of a brushless driver includes an input terminal input of a commutation signal IN, a monostable trigger A and a monostable trigger B connected in parallel, resistors R1 and R2, XOR gates 1, 2 and 3, a D trigger, and capacitors C1 and C2; wherein the input terminal input is divided into two paths,

[0008] Monostable trigger A has OR gate 1,

[0009] Monostable trigger B has OR gate 2;

[0010] One way is connected to the monostable trigger A through the A terminal of OR gate 1.

[0011] One way is to connect the monostable trigger B through the B end of OR gate 2.

[0012] The Q terminals of monostable trigger A and monostable trigger B are connected to the A and B input terminals of XOR gate 1 respectively. The output terminal F of XOR gate 1 is divided into two paths, one path is connected to the B terminal of XOR gate 2, and the other path is connected to the A terminal of XOR gate 3.

[0013] The F terminal of XOR gate 2 is connected to the main circuit shutoff signal output terminal, and the F terminal of XOR gate 3 is connected to the switching signal O.

[0014] As a further improvement of the above technical solution:

[0015] The A terminal of XOR gate 2 is connected to VCC.

[0016] The B terminal of the XOR gate 3 is grounded.

[0017] For the monostable trigger A, capacitor C1 is connected between terminals T1 and T2, and terminal T2 is connected to VCC through resistor R1.

[0018] For the monostable trigger B, a capacitor C2 is connected between the T1 and T2 terminals, and the T2 terminal is connected to VCC through a resistor R2.

[0019] A of OR gate 2 is grounded, B of OR gate 1 and CD of monostable trigger A are connected to VCC.

[0020] The CD terminal of the monostable trigger B is connected to VCC.

[0021] Monostable trigger A and monostable trigger B process forward and reverse signals respectively.

[0022] In the working process, first, the commutation signal enters the monostable trigger circuit A and the monostable trigger circuit B; then, the monostable trigger circuit A and the monostable trigger circuit B process the commutation signals of different directions respectively, wherein the monostable trigger circuit A and the monostable trigger circuit B process the forward and reverse signals respectively, and generate a pulse signal of a set width at the commutation position, and the width of the pulse signal is the duration of the subsequent stage to turn off the PWM;

[0023] Secondly, the processed pulse signal enters the XOR gate 1 for signal synthesis, that is, the pulse signals in two directions are synthesized into one signal; thirdly, the synthesized signal is divided into two paths;

[0024] Among them, one path inverts the signal and enters the main control path to turn off the PWM signal;

[0025] The signal enters the D flip-flop input terminal CLOCK1 through the XOR gate 3 and sets the delay time. The PWM shutdown is completed within the delay time. The delay time is the time when the new commutation signal appears. After that, the D flip-flop generates a new commutation signal.

[0026] The input terminal CLOCK1 of the D flip-flop is grounded through the capacitor C3; the delay time is determined by the capacitor C3.

[0027] The present invention achieves the purpose of soft commutation of the brushless motor by adjusting the timing of the commutation signal and the power main circuit PWM. The scheme can effectively protect the circuit from commutation damage. The present invention has reasonable design, low cost, strong and durable, safe and reliable, simple operation, time and labor saving, money saving, compact structure and convenient use. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the circuit structure of the present invention. DETAILED DESCRIPTION

[0029] like Figure 1 As shown, the soft commutation circuit of the brushless driver of this embodiment includes an input terminal input of a commutation signal IN, a monostable trigger A and a monostable trigger B connected in parallel, resistors R1, R2, XOR gates 1, 2, 3, a D trigger, and capacitors C1, C2; wherein the input terminal input is divided into two paths,

[0030] Monostable trigger A has OR gate 1,

[0031] Monostable trigger B has OR gate 2;

[0032] One way is connected to the monostable trigger A through the A terminal of OR gate 1.

[0033] One way is to connect the monostable trigger B through the B end of OR gate 2.

[0034] The Q terminals of monostable trigger A and monostable trigger B are connected to the A and B input terminals of XOR gate 1 respectively. The output terminal F of XOR gate 1 is divided into two paths, one path is connected to the B terminal of XOR gate 2, and the other path is connected to the A terminal of XOR gate 3.

[0035] The F terminal of XOR gate 2 is connected to the main circuit shutoff signal output terminal, and the F terminal of XOR gate 3 is connected to the switching signal O. The A terminal of XOR gate 2 is connected to VCC.

[0036] The B terminal of the XOR gate 3 is grounded.

[0037] For the monostable trigger A, capacitor C1 is connected between terminals T1 and T2, and terminal T2 is connected to VCC through resistor R1.

[0038] For the monostable trigger B, capacitor C2 is connected between T1 and T2, and T2 is connected to VCC through resistor R2. A of OR gate 2 is grounded, and B of OR gate 1 and CD of monostable trigger A are connected to VCC.

[0039] The CD terminal of the monostable trigger B is connected to VCC.

[0040] Monostable trigger A and monostable trigger B process forward and reverse signals respectively.

[0041] like Figure 1 In the present invention, the commutation signal first enters the monostable trigger circuit, which mainly processes the commutation signals of different directions and generates a pulse signal of a certain width at the commutation position. The width can be adjusted as needed. The width of the pulse signal is the duration of the subsequent stage closing PWM.

[0042] The two monostable trigger circuits process the forward and reverse signals respectively. The processed signals enter the XOR gate for signal synthesis, that is, the signals in the two directions are synthesized into one signal. After synthesis, the signal is divided into two signals, one of which is inverted and enters the main control path to turn off the PWM signal; the other signal enters the D trigger. The D trigger generates a new commutation signal. The time when the new commutation signal appears can be adjusted by adjusting the capacitor.

[0043] The purpose of the design is to first turn off the main PWM square wave when the brushless driver commutation signal is sent externally, so that the circuit can suspend working first. The suspension time is 5μS (this time is adjustable). After the circuit suspends working, the commutation signal is delayed by 2μS (this time is adjustable) and then sent to the main power circuit. After 5μS, the brushless driver resumes normal operation and commutation normally.

[0044] The present invention is fully described for a clearer disclosure, and the prior art is not listed one by one.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; 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 of the technical features therein with equivalents; it is obvious for those skilled in the art to combine multiple technical solutions of the present invention. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention. The technical contents not described in detail in the present invention are all known technologies.

Claims

1. A soft commutation circuit for a brushless driver, characterized in that: It includes an input terminal input of a commutation signal IN, a monostable trigger A and a monostable trigger B connected in parallel, resistors R1 and R2, XOR gates 1, 2 and 3, a D trigger, and capacitors C1, C2 and C3; wherein the input terminal input is divided into two paths; Monostable trigger A has OR gate 1, Monostable trigger B has OR gate 2; One way is connected to the monostable trigger A through the A terminal of OR gate 1. One way is to connect the monostable trigger B through the B end of OR gate 2. The Q terminals of monostable trigger A and monostable trigger B are connected to the A and B input terminals of XOR gate 1 respectively. The output terminal F of XOR gate 1 is divided into two paths, one path is connected to the B terminal of XOR gate 2, and the other path is connected to the A terminal of XOR gate 3. The F terminal of XOR gate 2 is connected to the main circuit shutoff signal output terminal, and the F terminal of XOR gate 3 is connected to the switching signal O.

2. The soft commutation circuit of the brushless driver according to claim 1, characterized in that: The A terminal of XOR gate 2 is connected to VCC.

3. The soft commutation circuit of the brushless driver according to claim 2, characterized in that: The B terminal of the XOR gate 3 is grounded.

4. The soft commutation circuit of the brushless driver according to claim 3, characterized in that: For the monostable trigger A, capacitor C1 is connected between terminals T1 and T2, and terminal T2 is connected to VCC through resistor R1.

5. The soft commutation circuit of the brushless driver according to claim 4, characterized in that: For the monostable trigger B, a capacitor C2 is connected between the T1 and T2 terminals, and the T2 terminal is connected to VCC through a resistor R2.

6. The soft commutation circuit of the brushless driver according to claim 5, characterized in that: A of OR gate 2 is grounded, B of OR gate 1 and CD of monostable trigger A are connected to VCC.

7. The soft commutation circuit of the brushless driver according to claim 6, characterized in that: The CD terminal of the monostable trigger B is connected to VCC.

8. The soft commutation circuit of the brushless driver according to claim 7, characterized in that: Monostable trigger A and monostable trigger B process forward and reverse signals respectively.

9. The soft commutation circuit of the brushless driver according to claim 8, characterized in that: In the working process, first, the commutation signal enters the monostable trigger circuit A and the monostable trigger circuit B; then, the monostable trigger circuit A and the monostable trigger circuit B process the commutation signals of different directions respectively, wherein the monostable trigger circuit A and the monostable trigger circuit B process the forward and reverse signals respectively, and generate a pulse signal of a set width at the commutation position, and the width of the pulse signal is the duration of the subsequent stage to turn off the PWM; Secondly, the processed pulse signal enters the XOR gate 1 for signal synthesis, that is, the pulse signals in two directions are synthesized into one signal; thirdly, the synthesized signal is divided into two paths; Among them, one path inverts the signal and enters the main control path to turn off the PWM signal; The signal enters the D flip-flop input terminal CLOCK1 through the XOR gate 3 and sets the delay time. The PWM shutdown is completed within the delay time. The delay time is the time when the new commutation signal appears. After that, the D flip-flop generates a new commutation signal. The input terminal CLOCK1 of the D flip-flop is grounded through the capacitor C3; the delay time is determined by the capacitor C3.

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