201111785 六、發明說明： 【發明所屬之技術領域】 本發明係有關於-種馬達的轉速㈣模組與轉速摘測方 法’且特別係有關於可精確地仙】馬達轉速的轉速賴模組與 轉速偵測方法。 【先前技術】 目别，馬達已成為—種常見的驅動裝置，以直流無刷馬達 (ess Dc Mot°r，BLDC)為例，由於直流無刷馬達具有高 效率、轉速穩定、高扭力、耐用、容易保養等特性，因而廣泛 地應用於各種產品，例如：硬碟機、光碟機或電動車。 -般對於馬達的速㈣測方式，可利用磁感元件或光感元 件對於磁或光的遮斷來為價測。然而’此债測方式需加裝债測 70件於馬達上，且容易受元件的特性（磁、光）影響，進行影響 偵測效果和準確率。另一㈣測方式是使用編碼器（encoder)， 其:馬達的轉速，並具有高響應速度和高精度，然而編碼器的 元件成本較高。 【發明内容】 ::發明之一方面係在於提供—種轉速偵測模組與轉 速伯測方法，藉以符合高精度及低成本的轉速_要求。 =本㈣之實_，本㈣之馬達㈣ ==號合成單元及計算單元。相移單元係用以將馬: 的換相信號相移-相位，而產生相㈣^ 一 以將換相信號與相移信號合成為合成信號。；算；元: 據合成信號來計算得到一轉速^ '' 201111785 又’根據本發明之實施例，本發明之馬達的轉速偵測模組 包含第一相移單元、第一信號合成單元、第二相移單元第二 仏號合成單元及計算單元。第一相移單元係用以將馬達的換相 信號相移—相位，而產生第一相移信號。第一信號合成單元係 用以將換相信號與第一相移信號合成為第一合成信號。第二相 移單元係用以將第一合成信號相移另一相位，而產生第二相移 “號。第二信號合成單元係用以將第一合成信號與第二相移信 號合成為第二合成信號。計算單元係用以根據第二合成信號來 計算得到一轉速。 又’根據本發明之實施例，本發明之馬達的轉速偵測方法 包含以下步驟：取得馬達的換相信號；將換相信號相移一相 位’以產生相移信號；將換相信號與相移信號合成一合成信 號；以及根據合成信號來計算得到一轉速。 又’根據本發明之實施例’本發明之馬達的轉速偵測方法 包含以下步驟：取得馬達的換相信號；將換相信號相移一相 位’以產生第一相移信號；將換相信號與第一相移信號合成第 一合成信號；將第一合成信號相移另一相位，以產生第二相移 信號；將第一合成信號與第二相移信號合成第二合成信號；以 及根據第二合成信號來計算得到一轉速。 又，根據本發明之實施例’上述馬達與轉速偵測模組可應 用於電子裝置中 因此’本發明之轉速偵測模組與轉速偵測方法可更精確地 偵測馬達的轉速，且可符合高可靠性、高精度及低成本的轉速 偵測要求* 【實施方式】 201111785 為讓本發明之上述和其他目的、特徵、優點與實施例能更 ^顯易1’本說明書將特舉出—系列實施例來加以說明。但值 付，主思的係’此些實施例只係用以說明本發明之實施方式，而 非用以限定本發明。 請參照圖1，其繪示依照本發明之第一實施例之轉速偵測 模組的系統方塊示意圖。本實施例的轉速偵測模組與轉速 摘測方法可用以摘測馬達200的轉速，藉以進行馬達的轉 速控制，其中此馬達200可例如為直流馬達、交流馬達、無刷 _馬達有刷馬達、二相馬達或單相馬達。本實施例的轉速偵測 模組1〇〇可例如為積體電路、微處理器、可程式控制器（PLC)、 多重處理單元、數位訊號處理器、具有處理路線的處理器、中 央處理器或其他類似模組，轉速偵測模組100可包含感測單元 11〇、相移單元120、信號合成單元130及計算單元14〇，其中 相移單元12〇與信號合成單元13〇可整合為邏輯電路。 請參照圖1和圖2，圖2繪示依照本發明之第一實施例之 轉速偵測模組的信號波形圖。本實施例之轉速偵測模組1〇〇的 • 感測單元U0可感測馬達200的磁極位置、操作電流及/或轉 速以產生感測訊號，其中此感測訊號即為馬達2〇〇的換相信 號。在本實施例中，感測單元110可包含霍爾元件或光感元件 (未繪示），此霍爾元件可用以感測馬達2〇〇的磁極位置，以產 生換相信號，並輸出至相移單元12〇與信號合成單元13〇。舉 例說明，如圖2所示，此時，感測單元110可輪出三個換相信 號a、b、c,其為各自延遲一預設電氣角度（例如6〇度電氣角） 的信號。 請參照圖2和圖3，圖3繪示依照本發明之第一實施例之 轉速偵測模組的結構示意圖。本實施例之轉速偵測模組1〇〇的 201111785 相移單TO 120可電性連接於感測單元m與信號合成單元㈣ 之間’用以接收換相信號A、B、C，並分別將換相信號A、B、 C相移相位’例如〇~18〇度電氣角而產生相移信號八，、b，、 C ’並輸出至信號合成單元130。以相移90度為例，如圖2 所不此時，相移單元120可分別相移此些換相信號a、b、C 成相移信號A’、B，、ς;，。 如圖2和圖3所示’本實施例之轉速偵測模組100的信號 &成早元130可電性連接於感測單元ι1〇與相移單元12〇，用 以接收換相信號A、B、c與相移信號Α，、Β，、c，，並可將換 相^號A、B、C與相移信號A，、B，、C，合成為-合成信號S， 而輸出至計算單元14〇。由於合成信號s係由換相信號A、B、 C及其所相移後之相移信號A，、B，、c，所合成，因而可具有更 精細的電氣角度變化。以圖2的信號變化為例，相較於原本換 相信號A、B、C之60度的電氣角度變化，合成信號s可用以 感知30度的電氣角度變化。 如圖2和圖3所示’本實施例之轉速偵測模組100的計算 單元可電性連接於信號合成單元130，用以接收合成信號 S，並根據合成信號S來計算得到馬達200的轉速。以圖2的 合成信號S為例’計算單元ι4〇可根據合成信號s的％度的 電氣角度變化，來計算馬達2〇〇每移動1/12對極的時間，因而 可叶算得到馬達200的瞬時轉速。 因此’本實施例之轉速偵測模組1〇〇可利用換相信號A、 B、C及其相移後之相移信號A，、B’、c’來合成一合成信號s， 藉以计舁馬達2〇〇的轉速’因而可更精確地偵測馬達2〇〇的轉 速。再者，相較於使用編碼器來偵測馬達轉速，轉速偵測模組 100可具有較低的元件成本’以符合高精度低成本的需求。 201111785 β月參照圖4,其繪示依照本發明之第一實施例之轉速偵測 方法的方法流程圖。當進行本實施例之轉速偵測方法時，首 先，取得馬達200的換相信號（步驟S301)，在本實施例中，馬 達200的換相信號係利用感測單元i 1〇來取得。接著，利用相 移單το 120將換相信號相移一相位（步驟S3〇2),以產生相移信 號。接著，利用信號合成單元13〇將換相信號與相移信號合成 為一合成信號（步驟S303)。接著，利用計算單元14〇來根據合 成k號來汁异得到馬達2〇〇的轉速（步驟S3〇4)。 凊參照圖5，其繪示依照本發明之第二實施例之轉速偵測 模組的系統方塊示意圖。第二實施例的轉速偵測模組4〇〇可包 含相移單元420、信號合成單元43〇及計算單元44〇，其中信 號合成單元430係電性連接於相移單元42〇與計算單元44〇之 間在第一實施例中，相移單元420所接收的換相信號係利用 馬達200之端電壓及反電動勢的變化來形成，亦即利用馬達2〇〇 的反電動勢k號來作為換相信號^相移單元42〇可接收馬達 的換相仏號，並分別將換相信號相移一相位，例如〇〜1度電 氣=，而產生相移信號，並輸出至信號合成單元43〇。信號合 成單元430可接收馬達2〇〇的換相信號與相移單元的相移 信號’並可將換相信號與相移信號合成為—合成信號，而輸出 至7算單元440。計算單元44〇可接收合成信號，並根據此合 成信號來計算得到馬達·的轉速。因此，第二實施例的轉速 偵測模組400可更精確地偵測馬達2〇〇的轉速，且符合高精度 低成本的需求。 ”月參照圖6，其繪示依照本發明之第三實施例之轉速偵測 模組的結構示意圖°第三實施例的轉速仙模組5GG可包含感 測單元510、第一相移單元520、第一信號合成單元53〇、計算f201111785 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to a rotational speed (four) module and a method for measuring a rotational speed of a motor, and particularly relates to a rotational speed module of a motor speed that can accurately Speed detection method. [Prior Art] As far as the motor is concerned, the motor has become a common driving device. For example, the DC brushless motor (ess Dc Mot°r, BLDC) has high efficiency, stable speed, high torque and durability. It is easy to maintain and so on, so it is widely used in various products, such as hard disk drives, CD players or electric vehicles. Generally, for the speed (four) measurement method of the motor, it is possible to use a magneto-sensitive element or a light-sensing element to block magnetic or light. However, this debt measurement method requires 70 pieces of debt to be attached to the motor, and is easily affected by the characteristics of the components (magnetic, optical), affecting the detection effect and accuracy. The other (four) measurement method is to use an encoder, which has a high rotational speed and high precision, but the component cost of the encoder is high. SUMMARY OF THE INVENTION One aspect of the invention is to provide a speed detecting module and a speed measuring method to meet the requirements of high precision and low cost. = (4) The actual _, the motor of this (4) (4) == number synthesis unit and calculation unit. The phase shifting unit is configured to phase-shift the phase-shifting signal of the horse: phase to produce a phase (four)^ to synthesize the phase-shifted signal and the phase-shifted signal into a composite signal. Calculating a unit according to the embodiment of the present invention, the speed detecting module of the motor of the present invention comprises a first phase shifting unit, a first signal synthesizing unit, and a first The second phase shifting unit is a second compositing unit and a calculating unit. The first phase shifting unit is configured to phase shift the phase of the commutating signal of the motor to produce a first phase shifting signal. The first signal synthesizing unit is configured to synthesize the commutation signal and the first phase shift signal into a first composite signal. The second phase shifting unit is configured to phase shift the first composite signal to another phase to generate a second phase shift “number. The second signal synthesizing unit is configured to synthesize the first synthesized signal and the second phase shifted signal into a first The second synthesis signal is used to calculate a rotation speed according to the second composite signal. Further, according to an embodiment of the present invention, the rotation speed detection method of the motor of the present invention comprises the steps of: obtaining a commutation signal of the motor; The commutation signal is phase shifted by one phase ' to generate a phase shift signal; the commutation signal and the phase shift signal are combined into a composite signal; and a rotational speed is calculated based on the composite signal. Further, the motor of the present invention according to an embodiment of the present invention The rotation speed detecting method comprises the steps of: obtaining a commutation signal of the motor; phase shifting the phase-shifted signal by one phase to generate a first phase-shift signal; synthesizing the commutation signal and the first phase-shifting signal into the first composite signal; The first composite signal is phase shifted by another phase to generate a second phase shifted signal; the first composite signal and the second phase shifted signal are combined into a second composite signal; and In addition, according to the embodiment of the present invention, the motor and the rotation speed detecting module can be applied to an electronic device, so that the speed detecting module and the speed detecting method of the present invention can detect more accurately. The rotational speed of the motor and the high-reliability, high-precision and low-cost rotational speed detection requirements* [Embodiment] 201111785 The above and other objects, features, advantages and embodiments of the present invention can be made easier. The present specification will be described with reference to a series of embodiments. However, the present embodiments are merely illustrative of the embodiments of the present invention and are not intended to limit the present invention. The system block diagram of the speed detecting module according to the first embodiment of the present invention is shown. The speed detecting module and the speed picking method of the embodiment can be used to extract the rotating speed of the motor 200, thereby performing motor The rotation speed control, wherein the motor 200 can be, for example, a DC motor, an AC motor, a brushless motor brush motor, a two-phase motor, or a single-phase motor. The rotation speed detecting module 1 of this embodiment can be, for example, The integrated circuit, the microprocessor, the programmable controller (PLC), the multi-processing unit, the digital signal processor, the processor with the processing route, the central processing unit or the like, the rotational speed detecting module 100 can include a sense The measuring unit 11〇, the phase shifting unit 120, the signal synthesizing unit 130 and the calculating unit 14〇, wherein the phase shifting unit 12〇 and the signal synthesizing unit 13〇 can be integrated into a logic circuit. Referring to FIG. 1 and FIG. 2, FIG. The signal waveform diagram of the rotation speed detecting module according to the first embodiment of the present invention. The sensing unit U0 of the rotation speed detecting module 1 of the embodiment can sense the magnetic pole position, operating current and/or of the motor 200. Or a rotational speed to generate a sensing signal, wherein the sensing signal is a commutation signal of the motor 2〇〇. In this embodiment, the sensing unit 110 may include a Hall element or a light sensing element (not shown). The Hall element can be used to sense the magnetic pole position of the motor 2〇〇 to generate a commutation signal and output to the phase shift unit 12 and the signal synthesizing unit 13A. For example, as shown in FIG. 2, at this time, the sensing unit 110 can rotate three conversion signals a, b, and c, which are signals each delayed by a predetermined electrical angle (for example, an electrical angle of 6 degrees). Referring to FIG. 2 and FIG. 3, FIG. 3 is a schematic structural diagram of a rotation speed detecting module according to a first embodiment of the present invention. The 201111785 phase shift single TO 120 of the speed detecting module 1 of the embodiment can be electrically connected between the sensing unit m and the signal synthesizing unit (4) to receive the commutation signals A, B, and C, respectively. The phase-shifted signals A, B, and C are phase-shifted by, for example, 〇~18〇 electrical angles to generate phase-shifted signals VIII, b, C' and output to the signal synthesizing unit 130. Taking the phase shift of 90 degrees as an example, as shown in Fig. 2, the phase shifting unit 120 can phase shift the commutation signals a, b, and C into phase shift signals A', B, and ς; As shown in FIG. 2 and FIG. 3, the signal & early 130 of the rotation detecting module 100 of the present embodiment is electrically connected to the sensing unit ι1 〇 and the phase shifting unit 12 〇 for receiving the commutation signal. A, B, c and the phase shift signals Α, Β, c, and can synthesize the commutative numbers A, B, C and the phase shift signals A, B, and C into a composite signal S, and Output to the computing unit 14A. Since the composite signal s is synthesized by the phase-shifted signals A, B, C and their phase-shifted phase-shifted signals A, B, and c, it is possible to have a finer electrical angle change. Taking the signal change of Fig. 2 as an example, the composite signal s can be used to sense an electrical angle change of 30 degrees compared to the electrical angle change of 60 degrees of the original commutation signals A, B, and C. As shown in FIG. 2 and FIG. 3, the calculation unit of the rotation speed detecting module 100 of the present embodiment can be electrically connected to the signal synthesizing unit 130 for receiving the composite signal S, and calculating the motor 200 according to the composite signal S. Rotating speed. Taking the composite signal S of FIG. 2 as an example, the calculation unit ι4〇 can calculate the time of each movement of the motor 2〇〇 by 1/12 of the pole according to the electrical angle change of the % of the composite signal s, so that the motor 200 can be calculated. Instantaneous speed. Therefore, the rotation speed detecting module 1 of the present embodiment can synthesize a composite signal s by using the phase-shifted signals A, B, C and their phase-shifted phase-shifted signals A, B', and c'. The rotation speed of the motor 2〇〇 can thus more accurately detect the rotational speed of the motor 2〇〇. Moreover, the rotational speed detecting module 100 can have a lower component cost than the use of an encoder to detect the motor speed to meet the high precision and low cost requirements. 201111785 β month Referring to FIG. 4, a flow chart of a method for detecting a rotation speed according to a first embodiment of the present invention is shown. When the rotation speed detecting method of the present embodiment is performed, first, the commutation signal of the motor 200 is obtained (step S301). In the present embodiment, the commutation signal of the motor 200 is obtained by the sensing unit i1〇. Next, the phase-shifted signal is phase-shifted by one phase using the phase shift το 120 (step S3 〇 2) to generate a phase shift signal. Next, the phase change signal and the phase shift signal are combined into a composite signal by the signal synthesizing unit 13 (step S303). Next, the rotation speed of the motor 2〇〇 is obtained by the calculation unit 14〇 according to the synthesis k number (step S3〇4). Referring to FIG. 5, a block diagram of a system of a rotation speed detecting module according to a second embodiment of the present invention is shown. The rotation speed detecting module 4 of the second embodiment may include a phase shifting unit 420, a signal synthesizing unit 43A, and a calculating unit 44A, wherein the signal synthesizing unit 430 is electrically connected to the phase shifting unit 42A and the calculating unit 44. In the first embodiment, the commutation signal received by the phase shifting unit 420 is formed by the change of the terminal voltage and the back electromotive force of the motor 200, that is, by using the back electromotive force k of the motor 2〇〇 as a change. The phase signal phase shifting unit 42〇 can receive the commutation apostrophe of the motor, and phase shift the phase-change signal by one phase, for example, 〇~1 degree electrical=, to generate a phase-shifted signal, and output to the signal synthesizing unit 43〇. . The signal synthesizing unit 430 can receive the phase-shifted signal of the commutation signal of the motor 2〇〇 and the phase shift unit and can synthesize the commutation signal and the phase-shifted signal into a composite signal, and output to the arithmetic unit 440. The calculation unit 44A can receive the composite signal and calculate the rotational speed of the motor based on the synthesis signal. Therefore, the rotational speed detecting module 400 of the second embodiment can more accurately detect the rotational speed of the motor 2〇〇 and meet the requirements of high precision and low cost. Referring to FIG. 6 , a schematic diagram of a structure of a rotation speed detecting module according to a third embodiment of the present invention is shown. The rotation speed module 5GG of the third embodiment may include a sensing unit 510 and a first phase shifting unit 520. , the first signal synthesizing unit 53 〇, calculate f
I V « 201111785 單元540、第二相移單元550及第二信號合成單元56〇β其中 第二相移單元550及第二信號合成單元56〇係電性連接於第一 信號合成單元530與計算單元540之間。感測單元510可感測 馬達200的磁極位置、操作電流及/或轉速，以產生馬達2〇〇的 換相信號。第一相移單元520可接收換相信號，並分別將換相 信號相移一相位，以產生第一相移信號。第一信號合成單元53〇 可接收換相信號與第一相移信號，並可將換相信號與第一相移 信號合成為第一合成信號，而輸出至第二相移單元55〇。第二 相移單元550可接收第一合成彳§號，並將第一合成信號再相移 另一相位，以產生第二相移信號，並輸出至第二信號合成單元 560。第二信號合成單元560可接收第一合成信號與第二相移 信號，並可將第一合成信號與第二相移信號合成為第二合成信 號，而輸出至計算單元540。由於第二合成信號係由第一合成 信號及其所相移後之第二相移信號所合成，因此，相較於第一 實施例的合成信號S，第三實施例的第二合成信號可具有更精 細的電氣角度變化。計算單元54〇可接收第二合成信號，並根 據第二合成彳§號來計算得到馬達2〇〇的轉速。因此，相較於第 一實施例，第二實施例的轉速偵測模組5〇〇可更精確地偵測馬 達200的轉速。 在第三實施例中，轉速偵測模組5〇〇包含第一相移單元 520、第一信號合成單元53〇、第二相移單元55〇及第二信號合 成單元560。然不限於此，在其他實施中，轉速偵測模組亦可 包含更多的相移單元與信號合成單元，以進一步進行相移及合 成信號’而可進行更精確的轉速偵測。 請參照圖7’其綠示具有根據本發明之馬達與轉速摘測模 組的電子裝置。本發明之轉速偵測模組】〇〇、4〇〇或5〇〇及馬 201111785 達200可應用於電子裝置600。此電子裝置6〇〇包括根據本發 明之轉速偵測模組1〇〇、4〇〇或500、馬達2〇〇以及電源供應 601，電源供應601係電性連接於馬達2〇〇，用以供應電源至馬 達200。此電子裝置600可為電動車、電動工具機、電動風扇、 硬碟機或光碟機。 由上述本發明的實施例可知，本發明之轉速偵測模組與轉 速偵測方法可精確地偵測馬達的轉速，且可符合高可靠性、高 精度及低成本的轉速偵測要求。 • 综上所述，雖然本發明已用較佳實施例揭露如上，然其並 非用以限定本發明，本發明所屬技術領域中具有通常知識者， 在不脫離本發明之精神和範圍内，當可作各種之更動與潤飾， 因此本發明之保護範圍當視後附之申請專利範圍所界定者為 準。 【圖式簡單說明】 為讓本發明之上述和其他目的、特徵、優點與實施例能更 φ 明顯易懂’所附圖式之詳細說明如下： 圖1繪示依照本發明之第一實施例之轉速偵測模組的系統 方塊不意圖。 圖2繪示依照本發明之第一實施例之轉速偵測模組的信號 波形圖 圖3繪示依照本發明之第一實施例之轉速偵測模組的鈇 示意圖。 13 圖4繪示依照本發明之第一實施例之轉速偵測方法的方法 流程圖。 圖5繪不依照本發明之第二實施例之轉速偵測模組的系筚 201111785 方塊不意圖。 圖6繪示依照本發明之第三實施例之轉速偵測模組的結構 示意圖。 圖7繪示具有根據本發明之馬達與轉速偵測模組的電子裝 置 【主要元件符號說明】 130、430 :信號合成單元 200 :馬達 530 :第一信號合成單元 560 :第二信號合成單元 601 :電源供應 100、400、500 :轉速偵測模組輛 110、510 :感測單元 120、420 :相移單元 140、440、540 :計算單元 520 :第一相移單元 550 :第二相移單元 600 :電子裝置 S301 :取得換相信號 S302:將換相信號相移一相位 5303 :將換相信號與相移信號合成為一合成信號 5304 :根據合成信號來計算得到馬達的轉速IV _ 201111785 unit 540, second phase shifting unit 550 and second signal synthesizing unit 56 〇β, wherein the second phase shifting unit 550 and the second signal synthesizing unit 56 are electrically connected to the first signal synthesizing unit 530 and the computing unit Between 540. Sensing unit 510 can sense the magnetic pole position, operating current, and/or rotational speed of motor 200 to produce a commutation signal for motor 2〇〇. The first phase shifting unit 520 can receive the commutation signals and phase shift the phase-converted signals by one phase to generate a first phase-shifted signal. The first signal synthesizing unit 53A can receive the commutation signal and the first phase shift signal, and can synthesize the commutation signal and the first phase shift signal into a first composite signal and output to the second phase shift unit 55A. The second phase shifting unit 550 can receive the first synthesized 彳§ number and phase shift the first synthesized signal to another phase to generate a second phase shifted signal, and output to the second signal synthesizing unit 560. The second signal synthesizing unit 560 can receive the first synthesized signal and the second phase shifted signal, and can synthesize the first synthesized signal and the second phase shifted signal into a second synthesized signal and output to the calculating unit 540. Since the second synthesized signal is synthesized by the first synthesized signal and the phase-shifted second phase-shifted signal, the second synthesized signal of the third embodiment can be compared to the synthesized signal S of the first embodiment. Has a finer electrical angle change. The calculation unit 54A can receive the second composite signal and calculate the rotational speed of the motor 2〇〇 based on the second synthetic 彳§. Therefore, compared with the first embodiment, the rotation speed detecting module 5 of the second embodiment can detect the rotation speed of the motor 200 more accurately. In the third embodiment, the rotation speed detecting module 5A includes a first phase shifting unit 520, a first signal synthesizing unit 53A, a second phase shifting unit 55A, and a second signal synthesizing unit 560. However, in other implementations, the speed detection module may also include more phase shifting units and signal synthesizing units to further perform phase shifting and synthesizing signals' for more accurate speed detection. Referring to Fig. 7', the electronic device having the motor and the rotational speed picking module according to the present invention is shown in green. The rotation speed detecting module of the present invention, 〇〇, 4〇〇 or 5〇〇, and the horse 201111785 up to 200 can be applied to the electronic device 600. The electronic device 6A includes a rotation detecting module 1〇〇, 4〇〇 or 500, a motor 2〇〇, and a power supply 601 according to the present invention. The power supply 601 is electrically connected to the motor 2〇〇. Power is supplied to the motor 200. The electronic device 600 can be an electric vehicle, a power tool, an electric fan, a hard disk drive, or a CD player. It can be seen from the above embodiments of the present invention that the rotation speed detecting module and the speed detecting method of the present invention can accurately detect the rotation speed of the motor, and can meet the requirements of high reliability, high precision and low speed rotation detection. In the above, although the present invention has been disclosed in the above preferred embodiments, the present invention is not intended to limit the invention, and the present invention is not limited to the spirit and scope of the present invention. Various changes and modifications may be made, and the scope of the invention is defined by the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, advantages and embodiments of the present invention are <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; The system block of the speed detection module is not intended. 2 is a signal waveform diagram of a rotation speed detecting module according to a first embodiment of the present invention. FIG. 3 is a schematic diagram of a rotation speed detecting module according to a first embodiment of the present invention. FIG. 4 is a flow chart showing a method of the rotation speed detecting method according to the first embodiment of the present invention. FIG. 5 depicts a system of a speed detecting module that is not in accordance with a second embodiment of the present invention. 6 is a schematic structural view of a rotation speed detecting module according to a third embodiment of the present invention. 7 shows an electronic device having a motor and a rotation speed detecting module according to the present invention. [Main component symbol description] 130, 430: Signal synthesizing unit 200: Motor 530: First signal synthesizing unit 560: Second signal synthesizing unit 601 Power supply 100, 400, 500: speed detecting module 110, 510: sensing unit 120, 420: phase shifting unit 140, 440, 540: computing unit 520: first phase shifting unit 550: second phase shift The unit 600: the electronic device S301: obtains the commutation signal S302: phase shifts the commutation signal by one phase 5303: synthesizes the commutation signal and the phase shift signal into a composite signal 5304: calculates the rotational speed of the motor according to the synthesized signal