無刷馬達無位置感測器驅動技術之研究

Research on the Position Sensorless Control Technology of the Brushless DC Motor

何祖盛(Zu-Sheng Ho)

指導教授 ： 汪啟茂

義守大學/電機資訊學院/電子工程學系/博士(2015年)

https://doi.org/10.6343/ISU.2015.00096

摘要

無刷直流馬達需要依靠轉子位置感測器提供轉子位置資訊來做為驅動換相的依據，若轉子位置的安置不是在最佳的位置就有可能會造成驅動相位落後或超前。無刷直流馬達還可以採用無感測器驅動法來偵測轉子的位置資訊，如此一來無感測器驅動就不會有轉子位置感測器安裝的問題，且更適合在高溫或高濕等惡劣的環境中運行。但是，在無感測器驅動中最困擾的就是啟動以及無感測器偵測轉子位置的方法對於運轉的影響。本文提出一種全域型無感測驅動電路，利用了換相訊號的PWM來濾除相電壓中因PWM切換所造成的雜訊，使得容易啟動且在高轉速下不會產生相位偏移的問題，更達到了高、低壓系統共用的目的。
無刷直流馬達運行時會因為電感的特性而造成電流落後的問題。為了改善這個問題，本文提出了二種校正方法：一種為未導通相校正法，是由一個電氣周期內所存在的二個浮接相電流續流效應來檢測當前相位的偏差，再藉由相位控制達到正確的相位校正; 另一種為最小轉矩漣波校正法，是根據驅動直流母線電流所反應出來的特性來判斷相位偏差，最終也是使用相位控制來達到最小轉矩漣波的校正以改善驅動時扭矩波動的問題。這二種校正方法除了對於無感測器驅動提供了一個正確的相位資訊外，同時也可以套用在有感測器驅動來改善轉子位置感測器安置偏差的問題。
本文綜合了所提的反電動勢電路、正相位驅動和最小漣波驅動建立了一套轉子位置感測器校正平台。轉子位置感測器通常是固定在電路板上或是嵌入於機構中。但是在加工或操作員在組裝的過程中容易造成位置偏移。目前校正轉子位置感測器的方法都是透過拖動的方式使轉子旋轉藉由反電動勢與轉子位置感測器的關係來校正。我們的轉子位置感測器校正平台是利用無感測驅動在正相位或最小漣波相位中，藉由換相狀態與轉子位置感測器的關係來判斷誤差角度再藉由控制器的顯示器或電腦來顯示。最後經由實驗驗證本文所提的反電動勢電路、正相位校正、最小漣波校正和轉子位置感測器校正平台是非常穩定的技術並達成了理論實用化的目的。

關鍵字

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並列摘要

The brushless DC motor rotor position sensors are needed to provide rotor position information for commutation. If the rotor is not placed in the best position, it might cause a phase-lag or phase-lead during commutation. The brushless DC motor can adopt a sensorless drive method to detect the rotor position and replace the rotor position sensors. This can remove the placement problems of rotor position sensors and enable the motor to run better in environments of high temperatures or humidity and other harsh conditions. However, the most troublesome aspects of the sensorless drive are the starting process and the impact that the sensorless method to detect the rotor position has on the operation. This dissertation presents a full speed range sensorless circuit that uses the PWM of commutation signals to filter out noise caused by PWM switching in the phase voltages. This makes the motor easy to start, does not produce phase shifting problems at high speed, and even achieves the purposes of high and low voltage systems.
When the brushless DC motor is running, it will cause the problem of a current lag because of the characteristics of the inductor. To improve this problem, this dissertation proposes two correction methods: One is unexcited phase correction method. The method detects deviations from the current phase by using the two unexcited phase freewheeling current effects that exist within an electric cycle and then achieves phase correction through the phase control. The other way is the minimum torque ripple correction method, which uses the characteristics of the DC bus current driving produced in response to determine the phase deviation. Ultimately, the method uses the phase control to achieve the correction of minimum torque ripple to improve the problem of torque fluctuation when driving. In addition to providing the correct phase information for the sensorless drive, these two correction methods can also be applied to the sensor drive to improve the placement of the rotor position sensor offset problems.
This dissertation integrates the proposed back electromotive force (BEMF) circuit, positive phase drive, and the minimum torque ripple drive to establish a platform for rotor position sensor calibration. The rotor position sensor is usually fixed on the PCB or embedded into mechanical structure. However, during the processing or assembly by operators, position deviation can easily occur. Currently, the rotor position sensor calibration methods make the rotor rotate by the method of dragging and make corrections through the relationship between the back electromotive force and the rotor position sensor. The proposed rotor position sensor calibration platform uses the sensorless drive in the correct phase or minimum ripple phase, determines the deviated angle by the relationship between the commutation state and the rotor position sensor, and then displays the error angle on the LCD or computer. Finally, the experiments verified that the sensorless circuit, correct phase correction, minimum ripple correction, and rotor position sensor calibration platform proposed by this dissertation are correct, and stably achieved the practical purposes of the theory.

並列關鍵字

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參考文獻

[1] K. Iizuka, H. Uzuhashi, M. Kano, T. Endo and K. Mohri, "Microcomputer control for sensorless brushless motor," IEEE Transactions Industry Appl., vol. IA-21, no. 4, pp. 595-601, 1985.

[2] T. M. Jahns, R. C. Becerra and M. Ehsani, "Integrated current regulation for a brushless ECM drive," IEEE Transactions Power Electron., vol. 6, pp. 118-126, Jan. 1991.

[3] Application Note 43: Using the ML4425/ML4426 BLDC motor controller, Micro Linear Co., June, 1996.

[4] ML4425 Sensorless BLDC PWM Motor Controller, MicroLinear Co., May, 1997.

[5] ML4425 Sensorless BLDC Motor Controller, Micro Linear Co., July, 2000.