Sensorless accurate commutation method and device of brushless DC motor

A brushless DC motor and sensor technology is applied in the field of sensorless precise commutation of brushless DC motors, which can solve the problems of misjudging the commutation signal by a single chip, reducing the operating efficiency and control performance of the system, and achieving stable operation and improving operation. Efficiency and stability, the effect of high system accuracy

Inactive Publication Date: 2018-09-28
张懿
1 Cites 4 Cited by

AI-Extracted Technical Summary

Problems solved by technology

In the actual commutation process, there is inductive energy storage on the switched-off phase to generate freewheeling, so that a completely opposite electromotive force is generated on the winding of this phase. After the inductive energy storage of this phase is consumed, the phase The electromotive force on the circuit is completely only generated by the winding cutting the ...
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Method used

In summary, the present invention is simple, fast and effective in operation, by introducing the interrupt service concept, effectively avoiding the interference of degaussing events, accurately judging the commutation moment, ...
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Abstract

The invention discloses a sensorless accurate commutation method and device of a brushless DC motor. The sensorless accurate commutation method comprises the steps of respectively connecting an A-phase voltage line, a B-phase voltage line and a C-phase voltage line of the brushless DC motor to corresponding voltage acquisition devices, triggering commutation service interrupt by jump edges of induction voltage waveforms of three phases A, B and C; entering commutation service interrupt if the jump edges are descending edges, and changing states of corresponding MOS tubes and IGBTs to achieve commutation after delaying by 30 electrical angels; performing triggering by ascending edges if the jump edges are ascending edges, starting to count in a circulation way from 0, entering commutation service interrupt when a counting value is 2, changing the states of the corresponding MOS tubes and IGBTs to achieve commutation after delaying by 30 electrical angels, and resetting the counter. Thecommutation method has the advantages of high interrupt service trigger and good reliability, a commutation misjudgment accident of the brushless DC motor is prevented under the interference of a demagnetization accident, and the commutation moment is scientifically and simply judged.

Application Domain

Commutation monitoringElectronic commutators

Technology Topic

Three-phaseDC motor

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  • Sensorless accurate commutation method and device of brushless DC motor
  • Sensorless accurate commutation method and device of brushless DC motor

Examples

  • Experimental program(1)

Example Embodiment

[0024] The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings.
[0025] The invention provides a sensorless accurate commutation device of a brushless DC motor, which is used to accurately determine the commutation time of a brushless DC motor, and is used to accurately determine the commutation time of a brushless DC motor. The device includes a DC power supply, Three-phase bridge inverter, new windings, three voltage acquisition devices and single-chip microcomputers. Among them, the DC power supply is connected in parallel with the three-phase bridge inverter, and the three output terminals of the three-phase bridge inverter are connected to the brushless DC The A-phase, B-phase, and C-phase ports of the new winding of the motor are connected correspondingly; the input ends of the three voltage acquisition devices are connected to the A-phase, B-phase, and C-phase ports of the new winding of the brushless DC motor, and the output ends are respectively connected Single-chip microcomputer; the 9 output terminals of the single-chip microcomputer are respectively connected to the 6 MOS tubes of the three-phase bridge inverter and the input terminals of the 3 IGBTs in the new winding, so as to control the on or off of the corresponding power tubes.
[0026] Wherein, the A-phase novel winding is formed by the first winding 1 and the first IGBT1 in series, the collector of the first IGBT1 is connected to one end of the first winding 1, and the emitter of the first IGBT1 is connected to the neutral point of the novel winding; The B-phase new winding is formed by the second winding 2 and the second IGBT2 in series, the emitter of the second IGBT2 is connected to one end of the second winding 2, and the collector of the second IGBT2 is connected to the neutral point of the new winding; the C-phase new winding It is formed by the third winding 3 and the third IGBT3 in series, the collector of the third IGBT3 is connected to one end of the third winding 3, and the emitter of the third IGBT3 is connected to the neutral point of the new winding; one end of the resistor R leads to three branches , Are respectively connected to the collector of the first IGBT1, the emitter of the second IGBT2, and the collector of the third IGBT3, and the other end of the resistor R is connected to the neutral point of the novel winding.
[0027] The single-chip microcomputer includes an AD acquisition unit and a PWM output unit. The input terminals of the AD acquisition unit are respectively connected to the output terminals of three voltage acquisition devices, and the 9 output terminals of the PWM output unit are respectively connected to 6 three-phase bridge inverters. The input terminals of the 3 IGBTs in the MOS tube and the new winding. The voltage acquisition device is composed of an amplifying circuit, which is used to convert the high voltage of the three-phase new winding port of the brushless DC motor into a low voltage to protect the single-chip microcomputer; the new winding is used to speed up the consumption of motor windings by self-inductance The electrical energy generated by the phenomenon shortens the time for voltage pulses to appear when each phase is turned off. The three-phase bridge inverter includes three parallel branches, each branch includes an upper MOS tube and a lower MOS tube connected in series, and the upper and lower MOS tubes serve as a three-phase bridge inverter. The output terminal of the device, and each upper and lower MOS transistors are connected in reverse parallel with a diode.
[0028] Such as figure 1 As shown, the DC power supply is connected in parallel with the three-phase bridge inverter, and the three output terminals of the three-phase bridge inverter are connected to the three-phase winding of the brushless DC motor. For ease of description, a three-phase bridge inverter is set The three output terminals of the inverter are numbered 21, 22, and 23, corresponding to the A-phase, B-phase and C-phase ports of the new winding of the brushless DC motor; the input terminals of the three voltage acquisition devices are respectively connected to the three-phase brushless DC motor The winding ports are connected. The input ends of three voltage acquisition devices 51, 52, and 53 are respectively connected to the A-phase, B-phase and C-phase ports of the new winding of the brushless DC motor, and the output ends of the three voltage acquisition devices are respectively connected to the microcontroller The 9 output terminals of the single-chip microcomputer are respectively connected to the input terminals of IGBT1, IGBT2, IGBT3, VT1, VT2, VT3, VT4, VT5 and VT6, thereby controlling the on or off of the corresponding power tube.
[0029] Based on the above device, cooperate figure 2 As shown, the present invention also provides a sensorless accurate commutation method of a brushless DC motor, which includes the following steps:
[0030] Step 1: Connect the A, B, and C phase voltage lines of the brushless DC motor to the input terminals of the voltage acquisition devices 51, 52, and 3 respectively, and define the initial value of the counter as 0;
[0031] Step 2: Use the rising and falling edges of the A, B, and C three-phase induced voltage waveforms as triggers to enter the interrupt. When the falling edge of the induced voltage waveform of the three phases A, B, and C is detected, the interruption is immediately entered, and the state of the corresponding MOS tube in the three-phase bridge inverter and the corresponding IGBT in the new winding is changed after a delay of 30 electrical degrees. Realize the required commutation; when the rising edge of the induced voltage waveform of the three phases A, B, C is detected, the rising edge is used as the trigger, and the counting starts from 0. When the count value is not 2, the system continues to wait for A, B, C three-phase induced voltage transition edge, when the count reaches 2, the count value is cleared to 0, and the state of the corresponding MOS tube in the three-phase bridge inverter and the corresponding IGBT in the new winding is changed after a delay of 30 electrical degrees. Realize the required commutation;
[0032] Step 3: The system continues to wait for the A, B, and C three-phase induced voltage transition edges, and then continues to step 2 after receiving the trigger signal.
[0033] In summary, the present invention is simple, fast and effective to operate. By introducing the concept of interrupt service, the interference of demagnetization events can be effectively avoided, the commutation time can be accurately judged, and the influence of commutation misjudgment events on the correct commutation of the brushless DC motor can be suppressed. Stable operation of the brushed DC motor, high system precision and good reliability.
[0034] In this embodiment, when the PWM output unit of the controller outputs a high level, the IGBT1, IGBT2, IGBT3, VT1, VT2, VT3, VT4, VT5, and VT6 are turned on, and when the PWM output unit of the controller outputs a low level, The IGBT1, IGBT2, IGBT3, VT1, VT2, VT3, VT4, VT5 and VT6 are turned off.
[0035] The above embodiments are only to illustrate the technical ideas of the present invention, and cannot be used to limit the scope of protection of the present invention. Any changes made on the basis of the technical solutions based on the technical ideas proposed by the present invention fall into the protection scope of the present invention. Inside.

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