Brushless direct current motor driving circuit

Abstract

The utility model discloses a brushless direct current motor drive circuit, which comprises a three-phase bridge arm circuit with six MOS (Metal Oxide Semiconductor) tubes, the grid electrode of each MOS tube is connected with a compensation capacitor and charge discharge resistance module and a capacitor charge and discharge resistance module, and a switching pulse absorption RC (Resistance-Capacitance) module is connected between the source electrode and the drain electrode of each MOS tube; the compensation capacitor and charge bleeder resistor module comprises a compensation capacitor and a charge bleeder resistor connected in parallel with the compensation capacitor; the capacitor charge-discharge resistor module comprises a first charge-discharge resistor, a second charge-discharge resistor and a diode, and the second charge-discharge resistor is connected with the diode in series and then connected with the first charge-discharge resistor in parallel. According to the circuit design, the risk of current leakage between the upper arm and the lower arm of the three-phase bridge arm circuit can be prevented, and the probability of ringing effect of the MOS tubes can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of brushless DC motors, and more specifically to a brushless DC motor driving circuit. Background Art

[0002] Research on brushless DC motors is now a trend. With their lack of a mechanical steering gear, brushless DC motors offer advantages in lifespan and speed. Consequently, their share of motor applications is gradually increasing. In particular, brushless DC motors have become a dominant force in new energy vehicles and aircraft.

[0003] The requirements for brushless DC motor control circuits are gradually increasing. The mainstream brushless motor control circuit adopts a three-phase bridge arm (6MOS) structure, but different design manufacturers have adopted different motor control modes, such as 6-step square wave and magnetic field vector control. The goal is to achieve high-efficiency control at a low cost. At the same time, higher requirements are also placed on electrical compatibility and electrical performance.

[0004] Innovation in brushless DC motor control circuits is a key driver of market competitiveness. The increasing popularity of new energy electric vehicles, coupled with the widespread use of brushless DC motors, has led to intense competition in the auto parts industry. Consequently, innovation in brushless DC motor control designs is a key driver of market competitiveness. Summary of the Invention

[0005] The utility model overcomes the shortcomings of the prior art and provides a brushless DC motor drive circuit. The circuit design can prevent the risk of leakage current between the upper and lower arms of the three-phase bridge arm circuit and reduce the probability of ringing effect of the MOS tube.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] A brushless DC motor drive circuit includes a three-phase bridge arm circuit with six MOS tubes. The gate of each MOS tube is connected to a compensation capacitor and charge discharge resistor module and a capacitor charge and discharge resistor module. A switching pulse absorption RC module is connected between the source and drain of each MOS tube.

[0008] Preferably, the compensation capacitor and charge discharge resistor module includes a compensation capacitor and a charge discharge resistor connected in parallel with the compensation capacitor.

[0009] Preferably, the capacitor charge and discharge resistor module includes a first charge and discharge resistor, a second charge and discharge resistor, and a diode. The second charge and discharge resistor and the diode are connected in series and then in parallel with the first charge and discharge resistor.

[0010] Preferably, the switch pulse absorption RC module includes a pulse absorption resistor and a pulse absorption capacitor connected in parallel between the source and drain of the MOS tube, and the pulse absorption resistor and the pulse absorption capacitor are connected in series.

[0011] Preferably, both ends of each phase winding of the brushless DC motor are connected in parallel with a correction capacitor.

[0012] Preferably, it further includes a port capacitor with one end connected to the winding and the other end grounded.

[0013] Preferably, a reverse voltage acquisition module is further included, and the reverse voltage acquisition module includes a first acquisition resistor connected to the winding, a second acquisition resistor and a acquisition capacitor, and the acquisition capacitor is connected in parallel with the second acquisition resistor.

[0014] Beneficial effects of the utility model:

[0015] The circuit design of the utility model can prevent the risk of leakage current between the upper and lower arms of the three-phase bridge arm circuit, and can reduce the probability of ringing effect of the MOS tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic structural diagram of a brushless DC motor drive circuit according to a specific embodiment of the present invention.

[0017] In the figure: 1. MOS tube; 2. Compensation capacitor and charge discharge resistor module; 3. Capacitor charge and discharge resistor module; 4. Switch pulse absorption RC module; 5. Correction capacitor; 6. Port capacitor; 7. Reverse voltage acquisition module. DETAILED DESCRIPTION

[0018] 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 embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0019] like Figure 1As shown, a brushless DC motor drive circuit includes a three-phase bridge arm circuit with six MOS transistors 1. The gate of each MOS transistor 1 is connected to a compensation capacitor and charge discharge resistor module 2 and a capacitor charging and discharging resistor module 3. A switching pulse absorption RC module 4 is connected between the source and drain of each MOS transistor 1. The compensation capacitor and charge discharge resistor module 2 includes a compensation capacitor and a charge discharge resistor connected in parallel with the compensation capacitor. The capacitor charging and discharging resistor module 3 includes a first charging and discharging resistor, a second charging and discharging resistor, and a diode. The second charging and discharging resistor and the diode are connected in series and then in parallel with the first charging and discharging resistor. The switching pulse absorption RC module 4 includes a pulse absorption resistor and a pulse absorption capacitor connected in parallel between the source and drain of the MOS transistor 1. The pulse absorption resistor and the pulse absorption capacitor are connected in series. A correction capacitor 5 is connected in parallel to both ends of each phase winding of the brushless DC motor. A terminal capacitor 6 is also included, one end of which is connected to the winding and the other end is grounded. A reverse voltage acquisition module 7 is also included. The reverse voltage acquisition module 7 includes a first acquisition resistor, a second acquisition resistor, and an acquisition capacitor connected to the winding. The acquisition capacitor is connected in parallel with the second acquisition resistor.

[0020] In this invention, due to the presence of MOS inter-electrode capacitance and the effects of internal bias fields, there is a certain delay in both the MOS turning on and off. For example, in the driver circuit, each half-bridge has two MOS electrodes, one on the top and one on the bottom. When the gates are driven by the same circuit, there is a crossover time between the upper and lower MOS electrodes. This creates the risk of leakage current between the upper and lower arms. Therefore, different charge and discharge resistors are used to adjust the turn-on and turn-off times for the gate capacitance.

[0021] During the MOS turn-on process, DS transitions from cutoff to saturated conduction, and the capacitor between GD acts as a parallel resistor to GS. This causes the voltage at the G terminal to rise slowly for a short period. This process can cause MOS heating and other issues. Therefore, gate compensation capacitors are used to mitigate this. Furthermore, considering the risk of gate capacitance not being able to discharge if the driver circuit is shut down due to special circumstances, and also for stability considerations, a pull-down bleeder resistor is connected in parallel.

[0022] Furthermore, when the MOS is in periodic switching, harmonic components are generated at both ends. While the motor's operating current consists of primary and secondary currents, the remaining harmonics act on the drive circuit and react with the circuit's RLC parameters. When 2R < √(L / C), the harmonics exhibit oscillatory attenuation, a phenomenon known as ringing. Therefore, connecting an RC resistor in parallel between the MOS's Ds can appropriately slow the MOS switching waveform gradient, compressing the harmonic spectrum bandwidth and reducing the likelihood of harmonic ringing.

[0023] Furthermore, the motor's winding coils have significant inductance and inherent internal resistance. When the motor is connected to the drive circuit, the three-phase bridge generates an alternating voltage to drive the motor. This alternating voltage generates a sinusoidal current (main wave current) in the coil windings. Due to the inductance, there is a phase difference between the driving voltage and current, which increases the reactive power component. Therefore, capacitors are connected in parallel across the windings to correct the impedance angle and reduce the proportion of reactive power.

[0024] The above is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited to this. Any technician familiar with the technical field within the technical scope disclosed by the present invention can make equivalent replacements or changes based on the technical solution and utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A brushless DC motor drive circuit, comprising a three-phase bridge arm circuit having six MOS tubes (1), characterized in that: The gate of each MOS tube (1) is connected to a compensation capacitor and charge discharge resistor module (2) and a capacitor charge and discharge resistor module (3), and a switch pulse absorption RC module (4) is connected between the source and drain of each MOS tube (1).

2. The brushless DC motor drive circuit according to claim 1, characterized in that: The compensation capacitor and charge discharge resistor module (2) comprises a compensation capacitor and a charge discharge resistor connected in parallel with the compensation capacitor.

3. The brushless DC motor drive circuit according to claim 2, wherein: The capacitor charge-discharge resistor module (3) comprises a first charge-discharge resistor, a second charge-discharge resistor and a diode, wherein the second charge-discharge resistor and the diode are connected in series and then in parallel with the first charge-discharge resistor.

4. The brushless DC motor drive circuit according to claim 3, characterized in that: The switch pulse absorption RC module (4) comprises a pulse absorption resistor and a pulse absorption capacitor connected in parallel between the source and drain of the MOS tube (1), and the pulse absorption resistor and the pulse absorption capacitor are connected in series.

5. A brushless DC motor drive circuit according to claim 1, 2, 3 or 4, characterized in that: A correction capacitor (5) is connected in parallel to both ends of each phase winding of the brushless DC motor.

6. The brushless DC motor drive circuit according to claim 5, characterized in that: It also includes a terminal capacitor (6) with one end connected to the winding and the other end grounded.

7. The brushless DC motor drive circuit according to claim 6, characterized in that: It also includes a reverse voltage acquisition module (7), which includes a first acquisition resistor, a second acquisition resistor, and an acquisition capacitor connected to the winding, wherein the acquisition capacitor is connected in parallel with the second acquisition resistor.

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