“M285850 八、新型說明： 【新型所屬之技術領域】 本創作係關於一種無刷直流馬達風扇驅動電路，尤指 一種能有效改善無刷直流馬達的驅動電路。 【先前技術】 無刷直流馬達常見的有單相全波及雙相半波兩種驅動 型態，目前為了使無刷直流馬達具有溫控或容易調整馬達 轉速的功能，其驅動I c主要採用脈寬調變驅動器，請配 •合參閱第:四圖所示，即為目前一種採用脈寬調變控制轉速 的無刷直流馬達驅動電路方塊圖，其包含有·· 一脈寬調變驅動器（5〇)，其包含有一霍爾信號輸 入端、一 PWM輸入端、一低轉速設定端、一頻率產生輸出 立而及重置端，其時序信號輸入端係連接一振盪電路（5 〇1)(約輸出幾十K的振盪頻率）； 一 史社斯觸發電路（5 3 )，其輸出端係連接至該脈 寬調變驅動器（5 0 )的霍爾信號輸入端，其輸入端則供 •霍爾感知器（圖中未示）連接； 一鎖住偵測及自動啟動電路（5 4 )，係連接於該史 ㈣觸發電路（53)、該振盪電路（5〇1)及該脈實 調變駆動器（5 〇 )的重置端；及 一全橋電路（5 1 )，係連接於該脈寬調變驅動器（5 〇 )的輸出端與單線圈（5 2 )之間。 上述馬達驅動電路係主要藉由史密斯觸發電路（5 3 )將隹爾感知器的弦波輸出信號轉換為脈波信號，再輸 3 M285850 入至該脈寬調變驅動器（5 〇 ) @霍爾信號輸入端1财 寬調變驅動器（5 0)依照簡信號及低轉速設定端^ 電壓，判斷控制轉速為高或低，#剛㈣大於低轉速設 定端電壓，則代表控制馬達呈高轉速運轉，則該脈寬調變 驅動器會依照霍爾方波信號，控制對全橋電路（5 1 )輸 出南脈寬的PWM驅動信號，令輸入單線圈（5 2 )電漭增 加提咼轉速，反之，則調低輸出至全橋電路的pwM驅動信 號，以降低轉速。 σ 請配合參閱第五圖A、Β、c所示，為脈寬調變驅動 器（5 0 )輸出至全橋電路（5丄）的pWM驅動信號及線 圈電流（IL)的波形圖，由圖中可所示可知，由於採用ρ· 驅動信號驅動單線圈（5 3 )，故會導致線圈電流（匕） 波形為一大斜率的鋸齒波形，且鏈波現象相當嚴重，使得 馬達運轉時容易產生電子噪音，並且會降低無刷直流馬達 可靠性。 由於使用上述PWM驅動信號作為全橋電路的驅動信號 容易控制馬達轉速，但卻也產生了負面效果，因此，一種 輸出梯形脈寬驅動信號的驅動電路被提出，以改良pwM驅 動信號的缺點。請參閱第六圖A所示，由於PWM驅動信號 為一脈波波形，會使得線圈電流（II )波形的斜率很大， 再如第六圖B所示，若將PWM驅動信號調整為梯形驅動信 號，則可使得線圈電流（Il)信號的波形斜率減緩，降低 鏈波現象。惟，此一設計仍有其負面效果，即若要改變方 波信號呈一梯形信號，則其信號頻率無法太高，惟，上述 M285850 驅動電路的振i電路的頻率約在幾十κ(m，無 y成有放的梯形驅動信號，因此，若此一梯形驅動信號 要達到與PWM脈波驅動信號一樣的轉速，則需加大其電流。 又來兒右要達到4000轉的轉速，上述驅動電路只需 、勺30 0毫安的電流，而此一驅動電路則要至少3 5 〇毫安的 電w相較之下即更為耗電，且運轉效率也比較差。 由上述兩種採脈波調變控制轉速的驅動電路設計看 來，均有其缺點待改善。 ^ 【新型内容】 為此’本創作的主要新型目的係提供一種無刷直流馬 達風扇驅動電路’同樣採用脈寬調變的驅動信號，但卻可 .使線圈電路信號較為平滑，減緩漣波現象，降低馬達運轉 時的電子噪音，提高無刷直流馬達的可靠度。 右欠達上述目的所使用的主要技術手段係令該無刷直流 馬達風扇驅動電路，其包含有： φ 霍爾脈寬調變信號產生電路，係供霍爾感知器連 接，將霍爾弦波信號轉換為一脈寬調變信號，令該脈寬調 變信號的脈寬隨該霍爾弦波信號的振幅調變； 一轉速到斷信號產生電路，係連接至該霍爾脈寬調變 #號產生電路的輸出端，以與pwM輸入信號進行比對，以 輸出包含有控制轉速的脈寬調變信號； 一脈寬調變驅動器，其包含有一霍爾信號輸入端、一 SPWM (Sinusoidal puise width m〇dulati〇n)信號輸入 端、一重置端及一頻率產生輸出端，又該脈寬調變驅動器 5 -M285850 係可再包含有一除頻輸入端，其中該SPWM信號輸入端係 連接至該轉速判斷信號產生電路的輸出端，藉由該轉速判 斷信號產生電路輸出的脈寬調變信號調整輸出脈寬驅動信 號；及 一全橋電路，係連接至該脈寬調變驅動器的輸出端， 並與一單單線圈連接； 上述驅動電路仍保有脈寬調變控制風扇轉速的設計，"M285850 VIII. New Description: [New Technology Field] This paper is about a brushless DC motor fan drive circuit, especially a drive circuit that can effectively improve the brushless DC motor. [Prior Art] Brushless DC Motor Common There are two-phase full-wave and two-phase and half-wave drive types. At present, in order to make the brushless DC motor have temperature control or easy to adjust the motor speed, the drive I c mainly uses pulse width modulation driver. Referring to Fig. 4, it is a block diagram of a brushless DC motor drive circuit using pulse width modulation control speed, which includes a pulse width modulation driver (5〇), which includes a Hall. The signal input end, a PWM input end, a low speed set end, a frequency generating output and a reset end, and the timing signal input end is connected to an oscillating circuit (5 〇 1) (about an output oscillation frequency of several tens of K) a history trigger circuit (5 3 ) whose output is connected to the Hall signal input of the pulse width modulation driver (50), and the input terminal is provided with a Hall sensor (in the figure) Connected to the detection and auto-start circuit (5 4 ), connected to the history (4) trigger circuit (53), the oscillation circuit (5〇1) and the pulse modulation actuator (5 〇) a reset terminal; and a full bridge circuit (5 1 ) connected between the output of the pulse width modulation driver (5 〇) and the single coil (52). The motor drive circuit is mainly by Smith The trigger circuit (5 3 ) converts the sine wave output signal of the Muir sensor into a pulse wave signal, and then inputs 3 M285850 into the pulse width modulation driver (5 〇) @ Hall signal input terminal 1 Cai width modulation driver (5 0) According to the simple signal and low speed setting terminal voltage, determine whether the control speed is high or low, #刚(四) is greater than the low speed setting terminal voltage, it means that the control motor is running at high speed, then the pulse width modulation driver will According to the Hall square wave signal, the PWM drive signal for outputting the south pulse width of the full bridge circuit (5 1 ) is controlled, so that the input single coil (52) is increased to increase the speed, and vice versa, the output is turned to the full bridge circuit. The pwM drive signal to reduce the speed. σ Please refer to Figure 5A, Β c shows the waveform of the pWM drive signal and coil current (IL) output to the full-bridge circuit (5丄) of the pulse width modulation driver (5 0 ). As can be seen from the figure, the ρ· drive is used. The signal drives a single coil (5 3 ), which causes the coil current (匕) waveform to be a sawtooth waveform with a large slope, and the chain wave phenomenon is quite serious, which makes the motor easy to generate electronic noise during operation and reduces the reliability of the brushless DC motor. Since the above PWM driving signal is used as the driving signal of the full bridge circuit, it is easy to control the motor rotation speed, but it also has a negative effect. Therefore, a driving circuit for outputting a trapezoidal pulse width driving signal is proposed to improve the disadvantage of the pwM driving signal. . Please refer to Figure 6A. Since the PWM drive signal is a pulse waveform, the slope of the coil current (II) waveform will be large. If the PWM drive signal is adjusted to a ladder drive as shown in Figure 6B. The signal can slow down the waveform of the coil current (Il) signal and reduce the chain wave phenomenon. However, this design still has its negative effect. If the square wave signal is changed to a trapezoidal signal, the signal frequency cannot be too high. However, the frequency of the oscillation circuit of the M285850 driving circuit is about several tens (k). , no y into the trapezoidal drive signal, so if this trapezoidal drive signal to achieve the same speed as the PWM pulse drive signal, you need to increase its current. Again, the right to reach 4000 rpm, the above The driving circuit only needs to scoop 30 mA current, and this driving circuit needs at least 3 5 〇 mAh, which is more power-consuming than the power w, and the operating efficiency is also poor. The design of the drive circuit for the pulse-controlled modulation speed seems to have its shortcomings to be improved. ^ [New content] For this purpose, the main new purpose of this creation is to provide a brushless DC motor fan drive circuit that also uses pulse width. Modulated drive signal, but can make the coil circuit signal smoother, slow down the chopping phenomenon, reduce the electronic noise during motor operation, and improve the reliability of the brushless DC motor. The technical means is the brushless DC motor fan driving circuit, which comprises: φ Hall pulse width modulation signal generating circuit, which is connected by the Hall sensor to convert the Hall string signal into a pulse width modulation signal. , the pulse width of the pulse width modulation signal is modulated with the amplitude of the Hall sine wave signal; a rotation speed to off signal generation circuit is connected to the output end of the Hall pulse width modulation # number generation circuit, Comparing with the pwM input signal to output a pulse width modulation signal including a control speed; a pulse width modulation driver including a Hall signal input terminal and an SPWM (Sinusoidal puise width m〇dulati〇n) signal The input end, the reset end and a frequency generating output end, and the pulse width modulation driver 5-M285850 further includes a frequency dividing input end, wherein the SPWM signal input end is connected to the rotation speed determining signal generating circuit The output end adjusts the output pulse width driving signal by the pulse width modulation signal outputted by the rotation speed determining signal generating circuit; and a full bridge circuit is connected to the output end of the pulse width modulation driver, and Coil connection only; the drive circuit still retains the PWM control design of the fan speed,
惟為改善因為脈寬調變驅動信號造成線圈電流具有明顯的 漣波現象’本創作係主要將霍爾弦波信號轉換為一個隨著 霍爾弦波信號改變而變動脈寬調變信號，再將該脈寬調變 k號與外部轉速控制信號進行比對，以產生一個包含轉速 控制信號的脈寬调變信號，如此，該脈寬調變驅動器在一 特定轉速下即對全橋電路輸出脈寬變動之脈寬調變驅動信 號，使線圈電流“號的漣波現象減緩，呈一近弦波的較平 滑電流波形信號，有效改善無刷直流馬達運轉時的電子噪 音。 【實施方式】 首先請蒼閱弟一圖所示，将兔士名丨 知、為本創作無刷直流馬達驅 動電路的/較佳實施例的電路方塊圖，其主要包含有·· 一霍爾脈寬調變信號產生電路（丄〇 )，係供霍爾感 知器（圖中未示）連接，將霍爾弦波信號（Han".!-) 轉換為一脈寬調變信號，令該脈^ 脈見调變信號的脈寬隨該霍 爾弦波信號的振幅調變； 係連接至該霍爾However, in order to improve the coil current, the coil current has obvious chopping phenomenon because of the pulse width modulation drive signal. The author mainly converts the Hall sine wave signal into a variable amplitude modulation signal as the Hall sine wave signal changes. Comparing the pulse width modulation k number with an external rotation speed control signal to generate a pulse width modulation signal including a rotation speed control signal, so that the pulse width modulation driver outputs the full bridge circuit at a specific rotation speed The pulse width variation of the pulse width changes the driving signal, so that the chopping phenomenon of the coil current "number" is slowed down, and a smoother current waveform signal of a near-sine wave is used to effectively improve the electronic noise during the operation of the brushless DC motor. First of all, please read the picture of the rabbit, as shown in the figure, and the circuit block diagram of the preferred embodiment of the brushless DC motor drive circuit, which mainly includes a Hall pulse width modulation. The signal generating circuit (丄〇) is connected to the Hall sensor (not shown) to convert the Hall sine wave signal (Han".!-) into a pulse width modulation signal, so that the pulse is seen Modulated signal The Hall with wide amplitude modulated sinusoidal signal; lines connected to the Hall
一轉速判斷信號產生電路（2 Q •M285850 以與外部控制 以輸出包含有 脈寬調變信號產生電路（1 〇)的輪出端 轉速用的PWM信號（PWM Ι/P)進行比對 控制轉速的脈寬調變信號（SPWM ); 一胍：C調變驅動器I d J ，其包含右一言取 ^ 隹_信號輪 入端、一 SPWM信號輸入端、一重置端及一頻牽 夕只午產生輪出 端，又該脈寬調變驅動器（3 0 )係可苒白八女 幵匕a有一除頻輸 入端，其中該SPWM信號輸入端係連接至呤鉍$丄， <很主邊轉速判斷信號A rotation speed judging signal generating circuit (2 Q • M285850 for comparison with an external control to output a PWM signal (PWM Ι/P) including a wheel-end rotation speed of a pulse width modulation signal generating circuit (1 〇) Pulse width modulation signal (SPWM); one: C modulation driver I d J , which includes the right word ^ _ signal wheel input terminal, an SPWM signal input terminal, a reset terminal and a frequency Only the round-out end is generated, and the pulse width modulation driver (30) can have a frequency-receiving input terminal, wherein the SPWM signal input terminal is connected to 呤铋$丄, < Side speed judgment signal
產生電路（2 〇 )的輸出端’藉由該轉速判斷信號產生_ 路（2 〇 )輸出的脈寬調變信號（SPWM)調整輸出脈宽L 動信號；又，該脈寬調變驅動器（3 〇 )係包含有一… 電路（圖中未示），其信號輸入端係透過一史密斯觸：： 路（3 3 )連接至該霍爾脈寬調變信號產生電路（工^ 的放大電路（1 〇 )輸出端，其除頻倍數選擇端係為一陕 頻選擇端，供設定不同電壓準位設定除頻電路的除頻= 數而重置^則供一鎖住彳貞測及自動啟動電路（3 4 ) 其中該鎖住偵測及自動啟動電路（3 4 )輸入端分別連 史密斯觸發電路（3 3)及振盪電路（1 2 1 )的輪出端， 以判斷目前馬達運轉是否鎖纟’若是’則重置： 驅動器（3 〇 Ο ;及 文 全橋電路（3 1 )，係連接至該脈寬調變驅動器（3 〇)的輸出端，並與一單單線圈（3 2)連接。 上述霍爾脈寬調變信號產生電路（1 0 )係主要包含 有·· 放大電路（1 1 ) ’係連接霍爾感知器的輪出端 7 M285850 (Hall+/Hall-)，以蔣雪磁并、山 )以將隹爾弦波信號予以放大後輸出· 及 ， -第-比較電路（12) ’其—輸入端係與放大電路 (1 1 )連接，另一輸入端則連接至一振盪電4 ( η 的輸出端’使第一比較電路（12)冑放大的霍爾弦波信 號與該固定頻率的振湯作辨μμ卜 盈就比較，輸出一個隨著霍爾弦波 信號振幅改變的脈寬調變信號。由於第一比較電路（丄2) 制以將霍^波信號㈣為—脈波信號，故可使用由運 放大裔組成的比較器。 而上述轉速判斷信號產生電路（2〇)則主要包含有： ^一第二比較電路（2 i )，其中—輸人端連接至第一 :匕敉電路（1 2 )#輸出端，而其輸出端則連接至該脈寬 调變驅動器（3 〇 )的SPWM信號輸入端；及 一第三比較電路（2 2 )’其輸人端分別連接振盪電 路（1 2 1 )的輸出端、一控制轉速用pwM信號（pwM I/p) 及低轉速設定信號（Low Speed Set )連接，以決定控 制轉速用PWM信號高於或低於低轉速設定信號，又，該第 从：車乂電路（2 2 )的輸出端連接至第二比較器（2 1 ) 微:侧八,，以與第一比較電路（1 2 )輸出的脈寬調 =L嬈進行比較，以決定最後控制轉速spwM信號，再將 “輸入至忒脈波寬度調變驅動器（3 〇 )的”而信號輸 入端。 h由於第一比較電路（1 2 )及第三比較電路（2 2 ) :輪出脈波信號，故該第二比較電路（2工）係為一 N娜 •M285850 沾輯電路’而其中第二比較電路（2 2 )是用以判斷爾 信號與低轉速設定信號，而該低轉速設定信號通常為一電 壓準位，請配合參閱第二圖所示’此一第三比較電路（2 2 )係包含有： 一積分電路（2 2 1 )，係將PWM脈寬信號轉換為直 流電壓準位； 一選擇放大電路（2 2 2 )，其輸入端分別連接該積 刀電路（2 2 1 )及低轉速設定信號連接，以判斷兩者之 間準位高者放大後輸出；及 一比較器（2 2 3 )，其輸入端分別連接該選擇放大 電路（2 2 2)的輸出端及振盪電路（1 2丄）的輸出端， 將選擇放大電路（2 2 2 )選擇輸出的直流準位轉換為PWM 4吕號，再輸入至第二比較電路（2；!)。 前揭示霍爾脈寬調變信號產生電路（1 〇 )、轉速判 斷#號產生電路（2 0 )、脈寬調變驅動器（3 〇 )、全 φ 橋電路（3 1 )及鎖住偵測及自動啟動電路（3 4 )係可 整合為一積體電路元件。 請蒼閱第三圖A〜C所示，係分別本創作電路各點波 形圖，由圖中可知，本創作主要先將霍爾弦波信號與振盪 電路的二角波信號進行比較，獲得一脈寬調變信號（由於 二角波信號振幅及頻率皆為固定，故其脈隨著霍爾弦波信 號改變而變動），再將該脈寬調變信號與外部轉速控制pWM 信號進行比對，以產生一個包含轉速控制信號的脈寬調變 信號，如第三圖B所示，當該脈寬調變驅動器適當控制輸 9 M285850 出端輸出如第三圖c驅動信號波形時，線圈電流㈠。波 形，會呈現一近弦波的較為平滑波形，若外部轉速控制作 號的脈寬加大時（增加轉速），則電流波形會更接近弦^ ㈣’使得漣波現象有效獲得改善，意即，本創作於運轉 時因為電流信號較為平滑，故能有效滅少電子噪音，而為 一低’音的無刷直流馬達驅動電路。 由上述說明可知，本創作同樣採用脈寬調變方式控制 _無刷直流馬達的轉速，但本創作藉由加入脈寬調變霍爾信 =，使得單線圈電流波形獲得改善，而有效減緩漣波現象： 令馬達具有低噪音運轉功效。 【圖式簡單說明】 ' 第一圖··係本創作一較佳實施例的電路方塊圖。 第二圖：係本創作第三比較電路之一較佳實施例電路 方塊圖。 第三圖A、B、C :係本創作各點信號波形圖。 _ 弟四圖：係既有無刷直流馬達的一驅動電路。 第五圖A、B、C ··係第四圖驅動電路在不同脈寬調 變驅動信號下的線圈電流波形圖。 第六圖A、B :係既有無刷直流馬達的信號波形圖。 【主要元件符號說明】 (1 0 )霍爾脈寬調變信號產生電路 (1 1 )放大電路 (1 2 )第一比較電路 (121)振盈電路 10 M285850 (2 Ο )轉速判斷信號產生電路 (2 1 )第二比較電路 (2 2 )第三比較電路 (2 2 1 )積分電路 (222)選擇放大電路 (2 2 3 )比較器 (3 0 )脈寬調變驅動器 (3 1 )全橋電路 (3 2 )單線圈 (3 3)史密斯觸發電路 (3 4 )鎖住偵測及自動啟動電路 (5 0 )脈寬調變驅動器 (5 0 1 )振盪電路 (5 1 )全橋電路 (5 2 )單線圈 (5 3 )史密斯觸發電路 (5 4 )鎖住偵測及自動啟動電路 11The output end of the generating circuit (2 〇) adjusts the output pulse width L motion signal by the pulse width modulation signal (SPWM) of the θ circuit (2 〇) output; and the pulse width modulation driver ( 3 〇) contains a circuit (not shown) whose signal input is transmitted through a Smith touch:: (3 3 ) is connected to the Hall pulse width modulation signal generating circuit (amplifier circuit of 1 〇) output terminal, its frequency selection multiple selection terminal is a Shaanxi frequency selection terminal, which is used to set different voltage levels to set the frequency division circuit to eliminate the frequency = number and reset ^ for a lock detection and automatic start The circuit (3 4 ) wherein the input of the lock detection and auto-start circuit (3 4 ) is respectively connected to the wheel of the Smith trigger circuit (3 3) and the oscillation circuit (1 2 1) to determine whether the current motor is locked or not.纟 'If yes' then reset: the driver (3 〇Ο ; and the full bridge circuit (3 1 ), is connected to the output of the pulse width modulation driver (3 〇), and with a single coil (3 2) The above-mentioned Hall pulse width modulation signal generating circuit (10) mainly includes ·· Road (1 1 ) ' is connected to the wheel of the Hall sensor 7 M285850 (Hall+/Hall-), with Jiang Xue magnetic and mountain) to amplify the sine wave signal and output ·, - - The comparison circuit (12) 'the input terminal is connected to the amplifying circuit (1 1 ), and the other input terminal is connected to an oscillating electric 4 (the output end of η 'the first comparison circuit (12) 胄 amplified Hall The sine wave signal is compared with the vibration of the fixed frequency, and a pulse width modulation signal which changes with the amplitude of the Hall sine wave signal is output. Since the first comparison circuit (丄2) is made, The wave signal (4) is a pulse wave signal, so a comparator composed of augmented persons can be used. The above-mentioned rotational speed judgment signal generating circuit (2〇) mainly includes: ^ a second comparison circuit (2 i ), wherein - The input end is connected to the first: 匕敉 circuit (1 2 ) # output terminal, and the output end thereof is connected to the SPWM signal input end of the pulse width modulation driver (3 〇); and a third comparison circuit (2) 2) 'The input end is connected to the output of the oscillating circuit (1 2 1 ), and the control speed is pwM signal (pwM) I/p) and low speed setting signal (Low Speed Set) are connected to determine the control speed. The PWM signal is higher or lower than the low speed setting signal. In addition, the output of the second slave: 乂 circuit (2 2 ) is connected. To the second comparator (2 1 ) micro: side eight, compared with the pulse width modulation = L 输出 outputted by the first comparison circuit (1 2 ) to determine the final control speed spwM signal, and then "input to 忒The pulse width modulation driver (3 〇) of the signal input terminal. h The first comparison circuit (1 2 ) and the third comparison circuit (2 2 ): the pulse signal is rotated, so the second comparison circuit ( 2) is a N Na•M285850 dip circuit' and the second comparison circuit (2 2 ) is used to judge the signal and the low speed setting signal, and the low speed setting signal is usually a voltage level, please Referring to the second figure, the third comparison circuit (2 2 ) includes: an integration circuit (2 2 1 ) for converting the PWM pulse width signal into a DC voltage level; and a selection amplification circuit (2) 2 2), the input end is connected to the integrated knife circuit (2 2 1 ) and the low speed setting signal Connected to determine the highest level of amplification between the two outputs; and a comparator (2 2 3), the input end of which is connected to the output of the selective amplifier circuit (2 2 2) and the oscillation circuit (1 2丄The output terminal converts the DC level of the selected amplifier circuit (2 2 2 ) to the PWM 4 Lu number, and then inputs it to the second comparison circuit (2; !). The front reveals the Hall pulse width modulation signal generation circuit (1 〇), the rotation speed judgment # number generation circuit (2 0 ), the pulse width modulation driver (3 〇), the full φ bridge circuit (3 1 ), and the lock detection. And the automatic start circuit (3 4 ) can be integrated into an integrated circuit component. Please read the third figure A~C, which is the waveform diagram of each point of the creation circuit. It can be seen from the figure that this creation mainly compares the Hall sine wave signal with the octave wave signal of the oscillating circuit to obtain a Pulse width modulation signal (because the amplitude and frequency of the binary wave signal are fixed, the pulse changes with the change of the Hall sine wave signal), and then the pulse width modulation signal is compared with the external rotation speed control pWM signal. To generate a pulse width modulation signal including a speed control signal, as shown in FIG. 3B, when the pulse width modulation driver appropriately controls the output of the output of the M M85850, such as the driving signal waveform of the third figure c, the coil current (1). The waveform will present a smoother waveform of a near-sine wave. If the pulse width of the external speed control number is increased (increasing the speed), the current waveform will be closer to the string ^ (4)', so that the chopping phenomenon is effectively improved, that is, Because the current signal is smoother during operation, it can effectively eliminate electronic noise, and is a low-sound brushless DC motor drive circuit. It can be seen from the above description that the creation also uses the pulse width modulation method to control the rotational speed of the brushless DC motor. However, by adding the pulse width modulation Hall letter =, the single coil current waveform is improved, and the efficiency is effectively slowed down. Wave phenomenon: The motor has low noise operation. [Simple Description of the Drawings] 'The first figure is a circuit block diagram of a preferred embodiment of the present invention. The second figure is a circuit block diagram of a preferred embodiment of a third comparison circuit of the present invention. The third figure A, B, C: is the signal waveform diagram of each point of the creation. _ brother four map: is a drive circuit that has both brushless DC motor. Fig. 5, A, B, and C are the coil current waveform diagrams of the driving circuit of the fourth figure under different pulse width modulation driving signals. Figure 6A, B: Signal waveform diagram of a brushless DC motor. [Main component symbol description] (1 0) Hall pulse width modulation signal generation circuit (1 1 ) Amplification circuit (1 2 ) First comparison circuit (121) Vibration circuit 10 M285850 (2 Ο ) Speed determination signal generation circuit (2 1 ) second comparison circuit (2 2 ) third comparison circuit (2 2 1 ) integration circuit (222) selection amplification circuit (2 2 3 ) comparator (30) pulse width modulation driver (3 1 ) Bridge circuit (3 2 ) single coil (3 3) Smith trigger circuit (3 4) lock detection and automatic start circuit (50) pulse width modulation driver (5 0 1) oscillation circuit (5 1) full bridge circuit (5 2 ) Single coil (5 3 ) Smith trigger circuit (5 4 ) lock detection and auto start circuit 11