CN104410341A - Low-speed torque ripple restraining device and restraining method based on direct current voltage adjustment - Google Patents

Abstract

The invention discloses a low-speed torque ripple suppression device based on DC voltage regulation, which includes a Buck converter, a voltage-type inverter and a controller, wherein the output end of the voltage-type inverter is connected to a three-phase winding of a brushless DC motor , the input end of the controller is connected to the Hall signal output end of the brushless DC motor, and the output end of the controller is respectively connected to the voltage type inverter and the Buck converter to control its working state; the Buck converter The output terminal is connected to the input terminal of the voltage source inverter. This device can suppress torque ripple by adjusting bus voltage. The invention also discloses a suppression method of the low-speed torque ripple suppression device based on DC voltage regulation.

Description

Low-speed torque ripple suppression device and suppression method based on DC voltage regulation

technical field

The invention relates to an electronic control method and a control device, in particular to a device and method for suppressing low-speed torque ripple of a brushless DC motor based on DC voltage regulation.

Background technique

Brushless DC motor has the advantages of small size, good performance, simple structure, high reliability, and large output torque. The scope of application of this type of motor. At present, most of the brushless DC motors use the principle of constant DC to realize the operation of the motor, which brings about the generation of torque ripple when the brushless DC motor is running at low speed. The size of the input voltage can play a very good role, and this case arises from it.

Contents of the invention

The purpose of the present invention is to provide a low-speed torque ripple suppression device and suppression method based on DC voltage regulation, which can suppress torque ripple by adjusting the bus voltage.

In order to achieve the above object, the solution of the present invention is:

A low-speed torque ripple suppression device based on DC voltage regulation, including a Buck converter, a voltage-type inverter and a controller, wherein the output end of the voltage-type inverter is connected to the three-phase winding of the brushless DC motor, and the controller The input end of the controller is connected to the Hall signal output end of the brushless DC motor, and the output end of the controller is respectively connected to the voltage type inverter and the Buck converter to control its working state; the output end of the Buck converter Connect to the input terminal of the voltage source inverter.

The above-mentioned Buck converter includes a DC voltage source, an inductor, an IGBT, a resistor and a diode, wherein the collector of the IGBT is connected to the anode of the DC voltage source, and the emitter of the IGBT is respectively connected to the cathode of the diode and one end of the inductor, and the other end of the inductor is connected via The resistor is connected to the anode of the diode, and the anode of the diode is also connected to the negative pole of the DC voltage source; the control electrode of the IGBT is connected to the controller, and the conduction time is adjusted under the control of the controller, thereby adjusting the on-duty ratio; and the Output voltage between the cathode and anode of the diode.

The above inductance adopts a large inductance.

The above-mentioned voltage-type inverter adopts a three-phase bridge inverter, and the three-phase bridge inverter is formed by connecting six power tubes in series and then in parallel. The input terminals of the three-phase bridge inverter are connected to The output terminal of the Buck converter, and the three output terminals of the three-phase bridge inverter are used as the output terminals of the voltage source inverter, which are respectively connected to the three-phase windings of the brushless DC motor.

A suppression method based on the aforementioned low-speed torque ripple suppression device based on DC voltage regulation, comprising the following steps:

(1) The controller collects the Hall signal of the brushless DC motor, and calculates the commutation conduction phase of the brushless DC motor according to the collected Hall signal;

(2) The controller provides signals to the Buck converter according to the commutation conduction phase in step (1), and controls the Buck converter to adjust the on-duty ratio to change the output voltage, so that the terminal voltage of the commutation conduction phase is close to 4 times the amplitude of the counter electromotive force, that is, the value floats within ±10% of the amplitude of the counter electromotive force.

In the above step (1), the controller judges the commutation and conduction phase according to the following table:

state 1-2 2-3 3-4 4-5 5-6 6-1 Hall state 110-100 100-101 101-001 001-011 011-010 010-110 Commutation conduction phase X A C B A C B

Among them, A, B, and C respectively refer to the three-phase windings of the brushless DC motor.

After adopting the above solution, the present invention uses the principle based on DC voltage regulation to reduce the magnitude of the DC voltage, thereby suppressing torque ripple, and has a simple structure.

Description of drawings

Fig. 1 is the overall structure diagram of suppression device of the present invention;

Figure 2 is a diagram of the induced potential and input current of each phase winding of the brushless DC motor;

Among them, (a), (b), and (c) represent the induced potentials of the A, B, and C three-phase windings, respectively, and (d), (e), and (f) represent the input of the A, B, and C three-phase windings, respectively. current;

Figure 3 is a flow chart of the suppression method of the present invention.

Detailed ways

The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the present invention provides a low-speed torque ripple suppression device based on DC voltage regulation, which is used to control the brushless DC motor in Figure 1, and the suppression device includes a Buck converter, a voltage-type inverter A device and a controller (in this embodiment, a single-chip microcomputer is used), wherein the output end of the voltage type inverter is connected to the three-phase winding of the brushless DC motor, and the input end of the controller is connected to the Hall signal output end of the brushless DC motor. The output terminals of the controller are respectively connected to the voltage source inverter and the Buck converter to control their working states; the output terminals of the Buck converter are connected to the input terminals of the voltage source inverter. Each component module will be introduced separately below.

The Buck converter includes a DC voltage source Ud, an inductor L, an IGBT, a resistor R and a diode VD, wherein the collector of the IGBT is connected to the positive pole of the DC voltage source Ud, and the emitter of the IGBT is connected to the cathode of the diode VD and the diode VD respectively. The other end of the inductance L is connected to the anode of the diode VD via the resistor R, and the anode of the diode VD is also connected to the negative pole of the DC voltage source Ud; the control electrode of the IGBT is connected to the controller, and the conduction is adjusted under the control of the controller. On-time, thereby adjusting the on-duty cycle. A voltage Uo is output between the cathode and the anode of the diode VD. In this embodiment, the inductance L adopts a large inductance of more than 30mh, so as to avoid the situation of current discontinuity in the Buck converter.

The voltage-type inverter adopts a three-phase bridge inverter, and the three-phase bridge inverter is formed by two groups of six power tubes MOS1-MOS6 connected in series and then in parallel, and the control terminals of each power tube are respectively connected to control The inverter is turned on or off under the control of the controller; the input end of the three-phase bridge inverter is connected to the output end of the Buck converter, and the three output ends of the three-phase bridge inverter are used as voltage-type inverters The output terminals of the voltage source inverter are correspondingly connected to the three-phase windings of the brushless DC motor.

As shown in Figure 2, it is the induction potential and input current diagram of each phase winding of the brushless DC motor. The electromotive force of the three phases is a trapezoidal wave, and the width of the flat top of the trapezoidal wave is 120° electrical angle. It is as wide as the flat top of the trapezoidal wave back electromotive force, and the current and the back electromotive force are the same positive and negative. In a certain operating state, the electromagnetic torque is proportional to the sum of the products of the induced electromotive force of each phase and the input current.

As shown in Figure 3, the present invention also provides a suppression method based on the aforementioned low-speed torque ripple suppression device based on DC voltage regulation, including the following steps:

(1) The controller collects the Hall signal of the brushless DC motor, and calculates the commutation and conduction phase X and the non-phase Y of the brushless DC motor according to the collected Hall signal; where X and Y refer to three Phase windings A, B, and C, and there are corresponding states as shown in Table 1. Here, the commutation and conduction phase X refers to the phase that turns from off to on at this time, not the one that remains on all the time. one phase;

Table 1

state 1-2 2-3 3-4 4-5 5-6 6-1 Hall state 110-100 100-101 101-001 001-011 011-010 010-110 Commutation conduction phase X A C B A C B

(2) The controller provides signals to the IGBT in the Buck converter according to the commutation and conduction of phase X in step (1), and controls the IGBT to adjust the on-duty ratio to change the output voltage Uo, so that the commutation and conduction of phase X The terminal voltage Uxo is close to 4 times of the amplitude of the back electromotive force. In this embodiment, the set value is within ±10% of the amplitude of the back electromotive force to meet the condition. At this time, the commutation torque ripples is close to 0, where U _xo is the terminal voltage of the commutation and conduction phase X, E _m is the amplitude of the back electromotive force, ω _m is the angular velocity, L is the self-inductance of each phase winding, and M is the mutual inductance between each two-phase winding , t is the time variable; among them, the calculation formula of the back electromotive force amplitude E _m is:

E _m =C _e φn

In the formula, C _e is the electromotive force coefficient of the brushless DC motor, φ is the rotor flux of the brushless DC motor, and n is the speed of the brushless DC motor.

In summary, the present invention is based on a low-speed torque ripple suppression device and suppression method based on DC voltage regulation. According to the operating state of the brushless DC motor, a single-chip microcomputer is used to control the IGBT conduction time in the Buck converter to make the commutation torque The pulsation is reduced, which meets the requirement of small torque pulsation when the brushless DC motor runs at low speed.

The above embodiments are only to illustrate the technical ideas of the present invention, and can not limit the protection scope of the present invention with this. All technical ideas proposed in accordance with the present invention, any changes made on the basis of technical solutions, all fall within the protection scope of the present invention. Inside.

Claims (6)

1. the low-speed torque ripple restraining device based on DC voltage regulation, it is characterized in that: comprise Buck converter, voltage source inverter and controller, wherein, the output of voltage source inverter connects the three-phase windings of brshless DC motor, the input of controller connects the hall signal output of brshless DC motor, and the output of described controller connects voltage source inverter and Buck converter respectively, its operating state is controlled; The output of described Buck converter connects the input of voltage source inverter.

2. as claimed in claim 1 based on the low-speed torque ripple restraining device of DC voltage regulation, it is characterized in that: described Buck converter comprises direct voltage source, inductance, IGBT, resistance and diode, wherein, the collector electrode of IGBT connects the positive pole of direct voltage source, the emitter of IGBT connects the negative electrode of diode and one end of inductance respectively, and the other end of inductance connects the anode of diode via resistance, the anode of described diode also connects the negative pole of direct voltage source; The control pole connection control device of described IGBT, regulates ON time under the control of the controller, thus duty ratio is opened in adjustment; And output voltage between the negative electrode of described diode, anode.

3. as claimed in claim 2 based on the low-speed torque ripple restraining device of DC voltage regulation, it is characterized in that: described inductance adopts the large inductance of more than 30mh.

4. as claimed in claim 1 based on the low-speed torque ripple restraining device of DC voltage regulation, it is characterized in that: described voltage source inverter adopts three-phase bridge type converter, three-phase bridge type converter is by 6 power tubes, one group of in parallel formation of first connecting again between two, the input of described three-phase bridge type converter connects the output of Buck converter, and three of three-phase bridge type converter outputs are as the output of voltage source inverter, be connected respectively the three-phase windings of brshless DC motor.

5., based on a suppressing method for the low-speed torque ripple restraining device based on DC voltage regulation as claimed in claim 1, it is characterized in that comprising the steps:

(1) controller gathers the hall signal of brshless DC motor, and calculates the commutation conducting phase of brshless DC motor according to the hall signal collected;

(2) controller is according to the commutation conducting phase in step (1), for Buck converter provides signal, control Buck converter regulates to be opened duty ratio thus changes output voltage, make the terminal voltage of commutation conducting phase close to 4 times of back electromotive force amplitude, namely numerical value float back electromotive force amplitude ± 10% within.

6., as claimed in claim 5 based on the suppressing method of the low-speed torque ripple restraining device of DC voltage regulation, it is characterized in that: in described step (1), controller judges commutation conducting phase according to following table:

State 1-2 2-3 3-4 4-5 5-6 6-1 Hall device state 110-100 100-101 101-001 001-011 011-010 010-110 Commutation conducting phase X A C B A C B

Wherein, A, B, C refer to the three-phase windings of brshless DC motor respectively.