CN110829909B

CN110829909B - Chopping control method for brushless direct current motor

Info

Publication number: CN110829909B
Application number: CN201911003362.5A
Authority: CN
Inventors: 胡小菊; 王华超; 李洋
Original assignee: Beijing Shuguang Aero Electrical Co ltd
Current assignee: Beijing Shuguang Aero Electrical Co ltd
Priority date: 2019-10-18
Filing date: 2019-10-18
Publication date: 2021-12-28
Anticipated expiration: 2039-10-18
Also published as: CN110829909A

Abstract

The invention relates to a chopping control method of a brushless direct current motor, wherein the brushless direct current motor consists of a controller, a power converter and a motor body, and the control method is based on a hardware circuit of the power converter, a DSP + CPLD digital platform is built in the controller, and double-tube alternate chopping control of connection and disconnection of 6 power tubes in the power converter is completed, so that power supply control of a three-phase winding of the brushless direct current motor is realized, and operation control of the brushless direct current motor is completed. The control technology is realized through software, the design period of the main power circuit is shortened, the design process of the active rate circuit is simplified, the safety threat of the dispersibility of hardware devices of the main power circuit to the operation of the motor is weakened, the power drive is reliably reset through alternate chopping, the power tube heats uniformly, and the technical requirements of aviation products on stability and reliability can be better met.

Description

Chopping control method for brushless direct current motor

Technical Field

The invention relates to a brushless direct current motor drive control design technology, in particular to optimization and improvement of a brushless direct current motor drive control mode.

Background

The brushless direct current motor basically comprises a controller, a power inverter and a motor body, wherein the controller is used for controlling the starting, running and protection of the motor; the power inverter converts direct current into alternating current to be input into the motor, so that the motor is rotated. The brushless direct current motor has the advantages of high operation efficiency, good speed regulation, low loss and the like, in order to realize a good control function, a double-closed-loop control strategy (rotating speed outer ring-current inner ring) is adopted under most conditions, the current inner ring in double-loop control is used as the feedback and reference of the rotating speed outer ring, higher requirements are provided for the rapidity and the accuracy of the double-closed-loop control, and the steady-state accuracy and the dynamic rapidity of the whole operation system are directly determined by the advantages and disadvantages of the configuration of the inner ring.

The brushless direct current motor is applied to a high-power low-voltage starting power generation system, the starting current is very large due to the large starting power requirement, so that the model selection of a power tube and the starting of the motor have more practical problems, and great challenges and difficulties are also provided for the design of a main power circuit and a driving circuit. Therefore, the comprehensive matching design among the driving circuit, the stability and the rapidity of the current inner loop and the power conversion circuit is a more key design idea.

Disclosure of Invention

The purpose of the invention is:

the novel chopping control method for the brushless direct current motor is provided, double-tube alternative chopping control is achieved through software programming, the design period and process of a main power circuit and a driving circuit are simplified, and the accuracy and the rapidity of a system are improved. Meanwhile, the chopping frequency of the current inner ring in double-ring control is improved, and the chopping frequency of the main power tube is only half of the current chopping frequency.

The technical scheme of the invention is as follows: a chopping control method of a brushless direct current motor comprises a controller, a power converter and a motor body, and is characterized in that a DSP + CPLD digital platform is built in the controller based on a hardware circuit of the power converter, and double-tube alternate chopping control of connection and disconnection of 6 power tubes in the power converter is completed through software programming, so that power supply control of a three-phase winding of the brushless direct current motor is realized, and operation control of the brushless direct current motor is completed.

The controller is a digital control platform consisting of a digital processing chip DSP and a programmable complex logic device CPLD, and realizes the operation control, the fault protection and the information transmission of the whole brushless DC motor.

The power converter adopts a full-bridge inverter structure and comprises a direct-current power supply, a bus current sensor, 6 power MOS (metal oxide semiconductor) tubes and 6 RDC (remote data center) absorption circuits.

The motor body is a brushless direct current motor without an electric brush mechanical reversing device, and comprises a three-phase winding and a Hall position sensor, the controller realizes the detection of the position through the Hall position sensor in the brushless direct current motor, and the phase change operation control of the three-phase winding of the brushless direct current motor is completed by means of position signals.

The chopping control is a control method for controlling the on-off of an upper tube and a lower tube which are simultaneously conducted in each state of the power converter, and is divided into three chopping modes, namely, chopping of the upper tube and the lower tube simultaneously, chopping of the upper tube and the single tube, lower tube fixing and direct connection, and chopping of the lower tube and the single tube, chopping and upper tube fixing and direct connection.

The power converter is only provided with two upper tubes and two lower tubes which are conducted at the same time, wherein the tubes 1 and 4, the

tubes

3 and 6, the

tubes

5 and 2 respectively form a bridge arm, the tubes on the different bridge arms are combined in six states which are respectively the tubes 1 and 2, the tubes 1 and 6, the

tubes

3 and 2, the

tubes

3 and 4, the

tubes

5 and 4, and the

tubes

5 and 6, and the 6 states are overlapped according to a certain sequence in an electric cycle to realize the electrification control of the three-phase winding.

The double-tube alternative chopping control is based on one of 6 states of two-phase conduction at the same time when the brushless direct current motor operates, and the upper tube and the lower tube carry out chopping replacement control by means of different states.

The alternating chopping of the two tubes is based on the conduction state of two phases of the motor AC, as shown in fig. 1, when the AC winding is conducted, the corresponding conducted tubes are the 1 tube of the upper bridge arm and the 2 tube of the lower bridge arm, and in one chopping period, as shown in fig. 2, the chopping of the upper tube 1 is controlled in the state 1, the fixed and straight-through of the lower tube 2 is controlled in the state 2, the fixed and straight-through of the upper tube 1 and the chopping of the lower tube 2 are controlled in the state 2, and the alternating circulation is performed in sequence, so that the chopping frequency of the main power device is half of the current chopping frequency.

The invention has the advantages that: the invention provides a novel double-tube alternative chopping technology by combining the requirements of large starting current and stable and quick starting current. The double-tube chopping control technology is completely realized through software programming, hardware design is not required to be changed, the design process of a power conversion circuit and a drive control circuit is simplified, the design period of the whole product is shortened, and the stable control of current is realized; the chopping control technology is a novel technology realized on the basis of a digital platform, and by matching the entering states of an upper pipe and a lower pipe, when phase commutation control is carried out, dead zone control of 5us-100us (the chopping period is 100us) can be realized without independently arranging a dead zone module, so that the condition of straight-through connection of the upper pipe and the lower pipe is reliably avoided; aiming at the problems that the upper and lower double tubes simultaneously chop, the requirement on the dispersity of the tubes is strict, the upper and lower tubes of a single tube chop are heated unevenly, the selection of the tubes is difficult and the like, the alternating chopping technology solves the problems of the dispersity of the upper and lower tubes of different bridge arms and the nonuniform heating of power tubes; the chopping frequency of each main switching device is 1/2 of the current chopping frequency, on the premise that the switching frequency is not changed, the current chopping frequency is improved, the current is stably controlled, and the precision and the reliability of the inner ring are guaranteed.

Drawings

FIG. 1 is a schematic diagram of a brushless DC motor;

FIG. 2 is a waveform of alternate chopping of the upper and lower tubes;

FIG. 3 is a flow chart of the technical solution.

Detailed Description

The present invention is described in further detail below. The two tubes in the two-tube alternating chopping technology respectively correspond to an upper tube and a lower tube which are conducted in a certain state (the upper tube and the lower tube are controlled by the same PWM) in the three-phase six states of the brushless direct current motor, such as the 1 tube and the 2 tube in the figure 1. The technical implementation process is as shown in fig. 3, a digital control platform of DSP + CPLD is adopted, the position of the motor is obtained through a capture port of the DSP, a conducting code conducted by the winding of the motor is obtained, a flag state is set according to the conducting code and the position state of the motor, PWM of the DSP is controlled according to the flag state to output two paths of square wave signals of alternate chopping, the square wave signals are output to the CPLD, and the square wave signals are output to a driving power circuit after being judged and latched by the CPLD, a driving power MOS transistor is conducted to electrify the winding of the motor, and the motor is driven to work.

The working principle of the invention is as follows: in a two-phase conduction PWM chopping mode of a brushless direct current motor, an upper tube and a lower tube are both subjected to the same PWM control chopping mode to cause obvious pump rise, so that a control strategy of a two-tube alternative chopping mode is adopted, a chopping cycle is taken as a unit for alternative alternation, the AC two-phase conduction state in figure 1 is used for analysis, when an AC winding is conducted, the correspondingly conducted tubes are 1 tube of an upper bridge arm and 2 tubes of a lower bridge arm, and according to a state mark in software, in a certain PWM cycle T, as shown in figure 2, the upper tube 1 is configured to be chopped, the lower tube 2 is configured to be fully communicated, and the state mark is changed; in the next cycle, the upper tube 1 is configured to be all-on, the lower tube 2 is configured to be chopped, and the state flag is changed; chopping is carried out in sequence and alternately and circularly.

Examples

In one embodiment of the invention, the digital processing chip DSP adopts TMS320F2812, and the programmable complex logic device CPLD adopts EPM570T 144. The invention realizes double-tube alternate chopping control by programming a digital processing core DSP chip, finishes the latch output of chopping control signals by a programmable complex logic device CPLD, realizes the chopping control of a power converter through a certain power amplifying circuit, stably controls the rotating speed and the current in the no-load, half-load and full-load tests of a certain brushless direct current motor, and tests prove that the double-tube alternate chopping control method has simple realization, reliable operation and convenient control and meets the technical requirements of the brushless direct current motor on smooth and reliable operation.

Claims

1. A chopping control method of a brushless direct current motor applied to a high-power low-voltage starting power generation system is characterized in that the brushless direct current motor is composed of a controller, a power converter and a motor body, the control method is based on a hardware circuit of the power converter, a DSP + CPLD digital platform is built in the controller, and double-tube alternate chopping control of connection and disconnection of 6 power tubes in the power converter is completed through software programming, so that power supply control of a three-phase winding of the brushless direct current motor is realized, operation control of the brushless direct current motor is completed, and the specific process is as follows:

the method comprises the steps that a DSP + CPLD digital control platform is adopted, the position of a motor is obtained through a capture port of the DSP, a conducting code conducted by a motor winding is obtained, a flag state is set according to the conducting code and the position state of the motor, PWM of the DSP is controlled according to the flag state to output two paths of square wave signals chopped alternately, the square wave signals are output to the CPLD, the square wave signals are output to a driving power circuit after being judged and latched by the CPLD, a driving power MOS tube is conducted to electrify the motor winding, and the motor is driven to work;

the power converter adopts a full-bridge inverter structure and comprises a direct-current power supply, a bus current sensor, 6 power MOS (metal oxide semiconductor) tubes and 6 RDC (remote data center) absorption circuits;

the power converter is only provided with two upper pipes and two lower pipes which are communicated with each other at the same time, wherein the upper pipe and the lower pipe of each bridge arm are 1, 4, 3 and 6, and the lower pipe and the upper pipe of each bridge arm are 5 and 2 respectively to form a bridge arm, the upper pipe and the lower pipe of each bridge arm have six state combinations which are respectively 1, 2, 1, 6, 3, 2, 3, 4, 5, 4 and 5, 6, and the 6 states are overlapped according to a certain sequence in an electric cycle to realize the electrification control of the three-phase winding;

the double-tube alternative chopping control is based on one state of 6 states of two-phase conduction at the same time when the brushless direct current motor operates, and the upper tube and the lower tube carry out chopping replacement control by means of different states;

the alternating chopping of the double-tube is based on the two-phase conduction state of the motor AC, when an AC winding is conducted, the corresponding conducted tubes are 1 tube of an upper bridge arm and 2 tubes of a lower bridge arm, in a chopping period, the chopping of the upper tube 1 tube is controlled in the state 1, the lower tube 2 tube is fixedly and directly connected, the chopping of the upper tube 1 tube and the chopping of the lower tube 2 tube are controlled in the state 2, the alternating circulation is carried out in sequence, the chopping frequency of a main power device is half of the current chopping frequency, and the controller is a digital control platform consisting of a digital processing chip DSP and a programmable complex logic device CPLD, so that the operation control, fault protection and information transmission of the whole brushless direct current motor are realized.

2. The chopper control method for a brushless dc motor according to claim 1, wherein the motor body is a brushless dc motor without a brush mechanical commutation device, and includes three-phase windings and hall position sensors, and the controller detects the position by the hall position sensors in the brushless dc motor, and performs the control of the commutation operation of the three-phase windings of the brushless dc motor by using the position signals.

3. The chopping control method for the brushless dc motor according to claim 1, wherein the chopping control is a control method for on-off control of upper and lower tubes that are simultaneously turned on in each state of the power converter, and is divided into three chopping modes, i.e., upper and lower double-tube simultaneous chopping, upper-tube single-tube chopping lower-tube fixed through, and lower-tube single-tube chopping upper-tube fixed through.