TWI298972B - Motor control circuit,control method,and zero-crossing detection circuit - Google Patents

Description

1298972 IX. INSTRUCTIONS: [Technical Field] The present invention relates to a sensorless motor control circuit, and more particularly to a method for backing up an electromotive force without using any masking procedure (back electrical moti〇n) Force, bEMF) Zero-crossing sensorless motor control circuit.

[Prior Art] Fig. 1 shows a circuit diagram of a three-phase motor u and a switching circuit 12 which are not known. The motor η has three coils A, B, and c, wherein the ends of the respective coils are coupled together, as shown by the center point N of FIG. i, and the respective lines are coupled with "Pa Pb" and Pc. Switching circuit 12. The switching circuit 12 has three pairs of identical upper and lower sides _sm s SH3 and L3 for determining the ends Pa, Pb, and ρ of the two coils A, B, and C. The system is connected to the supply of the voltage source Vm, or coupled to the ground potential, or is neither coupled to the 佴. The voltage source Vm is also not coupled to the floating state of the ground potential. In the body, the switching circuit 12 operates in six phases in sequence to form a loop for the 岫邋2| Fu a, b, fish c and the right 兮 from the w drive current through the three coils And effectively driving the horse's operation. In the first phase - the upper side switch SH1 and the second lower side A end point P 4 / V j switch SL2 is turned on, so that the coil < taste point pa is coupled to the supply to the ground The potential, and the green ·, , and the end point Pb of the coil B are coupled to the % bit, and the end point of the coil C is d

If the motor is J Pc, it is in a floating state. The junction current flows from the supply voltage source Vm to the ground potential via the coil AU 4 1298972 in sequence. In the second phase, only the first upper side switch SH1 and the second lower side switch SL3 are turned on, such that the end point Pa of the coil A is coupled to the supply voltage source Vm, the end point Pb of the coil B is in a floating state, and the coil c is Point Pc is coupled to the ground potential. As a result, the motor drive current flows from the supply voltage source Vm to the ground potential via the coils A and C in order. In the third phase, only the second upper side switch SH2 and the third lower side switch SL3 are turned on 'so that the end point Pa of the coil A is in a floating state, the end point Pb of the coil b is coupled to the supply voltage source vm, and the coil C The end point pc is coupled to the ground potential. As a result, the motor drive current flows from the supply voltage source to the ground potential via the coils B and c in sequence. In the fourth phase, only the second upper side switch SH2 is electrically connected to the first lower side switch SL1 such that the point Pa of the coil A is coupled to the ground potential, the end point Pb of the coil B is coupled to the supply power, the voltage source Vm, and The end point Pc of the coil C is in a floating state. As a result, the motor drive current flows from the supply voltage source Vm to the ground potential via the coils B and A in sequence. In the fifth phase, only the third upper side switch SH3 is electrically connected to the first lower switch SL1 such that the end point pa of the coil A is coupled to the ground potential, the end point Pb of the coil B is in a floating state, and the end of the coil c is The point pc is coupled to the supply voltage, source Vm. As a result, the motor drive current flows from the supply voltage source Vm to the ground potential via the coils 0 and A in sequence. In the sixth phase, only the third upper side switch SH3 and the second lower side switch SL2 are turned on so that the end point Pa of the coil A is in a floating state, the end point pb of the coil B is coupled to the ground potential, and the end point of the coil C Pc is coupled to the supply voltage vm. As a result, the motor drive current flows from the supply voltage source to the ground potential via coils C and B in sequence. 1298972 In the sensorless motor control technology, the terminal voltage of the coil in the floating state is used as an important basis for the (4) phase change timing, because the end voltage of the coil in the floating state (four) is centered? The potential difference between iN represents the resistance of the motor to the electromotive force. Figure 2 shows a timing diagram of the voltages presented at the terminals pa, Pb, and Pc of coils A, B, and c. As is clear from the figure, the end voltage of the coil will occur at the initial stage of the floating state - a sharp change - which is caused by the inductance characteristics of the coil. For example, in the case of switching from the first phase to the first phase, since the current originally flowing through the coil B cannot be instantaneously removed, it turns on the flywheel diode of the second upper switch SH2 to flow into the supply. Voltage source Vm. Therefore, at the beginning of the second phase: the terminal Pb voltage of the coil B instantaneously jumps from the ground potential and is higher than the supply voltage source Vm by a diode-directed voltage drop. In order to avoid the drastic changes in the floating period affecting the electromotive force (4) and causing the erroneous judgment of the adverse effects of the zero-crossing event against the electromotive force, the conventional non-inductive motor control circuit usually uses a shielding circuit for Prevent drastic changes in the initial stage of floating to the input circuit. Figure 3 is a block diagram of a circuit block of the sensorless motor control circuit 30. The anti-electromotive force detecting circuit 33 is coupled to the known points P a and P b of the coils A, B, and c, and the masking circuit 34 is provided to detect the reactance of the floating coil. The occlusion is placed between the anti-electromotive force detecting circuit 33 and the comparison circuit 35 to prevent the sharp changes in the initial stage from being forwarded to the comparison circuit 35 to cause an erroneous estimator. Based on the occurrence of the zero-crossing contention measured by the comparison circuit 35, the driving port is used to control the switching circuit 1V; the circuit 36 generates the appropriate driving signal, 2 the upper side and the lower side switch, thereby correctly entering the 1129972 lamp motor. 31 commutation operation. Further, a drive signal is also supplied to the shading circuit 34 and the sagas circuit 35 to control the timing of execution of the masking program. In the prior art, the masking circuit 34 is usually preset with a fixed length and a concealing period, and it is assumed that it has fully covered the dramatic changes in the initial stage of the floating. - Fixed value, but varies depending on various factors such as the speed of the motor and the magnitude of the motor drive current. Although in some conventional techniques, the masking circuit 34 provides a masking period of variable length, even so, the modulation rate of the variable length must be preset, and when the preset modulation rate is set. When the actual situation is not met, the dramatic changes in the initial stage of floating cannot be completely obscured. SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a benefit-sensing motor control circuit that can correctly detect a zero-crossing event against an electromotive force without using any masking procedure. The motor control circuit of the invention is applied to a motor having a plurality of springs, having a "(four) circuit, a comparison circuit, a screening circuit, and a - drive circuit. A circuit to be tested is coupled to the plurality of coils for generating detection artifacts. The detection signal is associated with the terminal voltage of the coil in the state in which k is set to the i state. The comparison circuit is coupled to the debt measurement circuit for comparing the test signal with a reference voltage to generate a comparison #. The screening circuit is lightly coupled to the comparison circuit to receive the comparison signal. The screening circuit sequentially receives one of the comparison signals 1298972, the first crossover and the second crossover, and generates an indication signal in response to the second crossover. The drive circuit controls the commutation operation of the motor in response to the indication signal. The motor control method according to the present invention is applied to a motor having a plurality of coils, and includes the following steps. A detection signal is generated by detecting one of the plurality of coils to be selected as a terminal voltage of the coil in the floating state. Comparing the detection signal with a reference voltage to generate a comparison signal. The %^ signal has a first crossover and a second crossover. The second crossover is selected from the first parent and the second crossover. In response to the first person, an indication signal is generated. The commutation operation of the motor is controlled in response to the indication signal. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features and advantages of the invention will become more apparent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments in accordance with the present invention will be described in detail with reference to the drawings. Figure 4 is a block diagram showing the circuit of the sensorless motor control circuit 4 in accordance with the present invention. First, in the same manner as the prior art, the anti-electromotive force detector 43 is coupled to the terminals Pa, Pb, and p'e of the coils A, B, and C, and detects the reactance of the floating coil. However, in the present invention, the intrusion signal of the potential debt measuring circuit 43 is directly input to the comparing circuit 45, and no adjustment or correction of the conventional masking circuit 34 has been made. The ::select circuit 47 then receives the comparison signal of the comparison circuit 45 and proceeds to::: to select a zero-crossing event that can be used to control the commutation. Based on the selected zero crossing event of the filter circuit, the drive signal synthesizing circuit 46 generates an appropriate drive signal for controlling the switching circuit 42 to cause the motor 41 to perform the commutation operation. In other words, the masking circuit and method of the prior art can be regarded as belonging to a technique of "/35» pre-detecting (pre_zer〇_cr〇ssing), but the screening circuit and method according to the present invention can be regarded as belonging to a kind of "P〇st-zero-crossing" technology.

The diagram of the operation principle of the screening circuit 47 of the invention is not shown. For the sake of simplicity of explanation, only the coil turns are taken as an example in Fig. 5. Since the operation principle of the wire Α舆 and the coil c is the same as that of the coil β, the person familiar with the art can implement the invention in the three-phase motor system without difficulty after reading the example of the coil Β. In general, although the embodiments disclosed herein are three-phase horses, the screening circuit and method according to the present invention can be applied to motors of more phases, and is not limited to any particular type of motor. When the motor 4 1 is stably operated, it is shown in Fig. 5. At the end of the first to the coil, the electric system is connected to the ground potential, such as the younger brother and the sixth phase, and the ρ_ν point Pb is connected to the ground potential, so the second and fifth phases of the P_niPv+❻ temple are at the ground potential. . In the PXV, the end of the coil B is in a floating state, so the voltage system 鸲2 Pb is in the middle of the four phases P-III and p_lv. In the third and the first voltage source Vm, the voltage of the terminal Pb is only connected to the supply terminal in the second phase p: the voltage source. As mentioned above, 'the end of the month coil B pb bit jumps instantaneously and the supply voltage source V ik is also surfaced at the beginning, the end of the coil B 9 1298972 point Pb is covered by the supply voltage source vm instantaneously falling and the ground potential A lower diode is passed down the pressure drop. In the comparison circuit 45, the terminal Pb voltage of the coil B is compared with a reference voltage Vref. In the case of driving the motor in a linear manner, the reference voltage vref is implemented by directly detecting the voltage of the center point N, or simply using the supply voltage source Vm as an approximation of the N voltage of the towel. In the example of driving a motor using a pulse width modulation (QP), the reference voltage is implemented by a predetermined compensation voltage, such as the detection method disclosed in U.S. Patent No. 6,633,145. The literature is incorporated herein by reference. Looking closely at Figure 5, it can be seen that during the period in which the coil B is in the floating state, that is, the second phase Ρ_π or the end point Pb voltage will occur twice, and each of the rings 8 - two - human teeth The case of the reference voltage V-. For example, in the second phase p_n, when the cattle are salty and thundering, they enter the field, and the initial changes are made.

After the electric α core is completely removed by the element, the coil B goes to the Tang Mao v heart fine point pb electricity, that is, it returns to two: the electric MVref is below 'this is the first time crossover zc, the end of the coil B, the Pb voltage gradually rises. And then, at this time, it is happening from the tooth k test more than > 1 vref, I brother - the second crossover ZC2. Therefore, the zero-crossing event caused by the first six-phase noise, and the second-six-and-sixth-first-phase control of the zero-crossing of the commutator--ZC2 is the available speed sound... due to the motor The driving method, the propaganda, and the "how" change, only the second and the fourth to control the commutation of the crying six M t & a long time the father is available to you m zero-incident event, so according to the screening of the present invention The Thunder observation is designed to filter out the second ,, and the screening circuit 47 is sequentially connected to r ± and ZC2 〇 in other words, the sigma is output to the comparison circuit 45. The __大 10 1298972 crossover ZC1 and the first The second crossover ZC2' and only wait until the second crossover zc2 occurs to generate an indication signal to trigger the drive signal synthesizing circuit 46. The masking circuit 47' is equipped with a sensorless motor control circuit 4 in accordance with the present invention. It is necessary to use the masking circuit 34 of the prior art, so that there is no need to worry about the problem of not being able to completely obscure the drastic changes in the initial stage of the float. ° ''' * '

Fig. 6(A) shows a detailed circuit diagram of a first example of the screening circuit 6A according to the present invention. The comparison circuit 45 is implemented by the first comparator ... and the second comparator 45b for determining that the end voltage of the coil B is greater than or less than the reference voltage M Vref . The outputs of the first and second comparators Lo and 45b are exactly in inverse relationship with each other. NAND logic gates * The Μ system crosses and forms a --lock structure. N Na logic idle "the output signal U is applied to the clock terminal of the 13-type flip-flop 63", and the nand logic idle = output signal K2 is applied to the D-type flip-flop "clock end ... = positive and negative benefits 63 and The reset terminal R of 64 is controlled by the inversion 4 of the drive signal bd. The drive discrimination pp & BD BD is provided by the drive signal synthesizing circuit 46:: The drive signal is at a low level The representative coil B is in the floating NAmt: the output signals K3 and K4 of the D-type flip-flops 63 and 64 control the clock of the front and back counter 66 via the == gate 65. Here, the output of the signal 66 is zero-crossing indication signal 1ZC for supplying to the drive T-forming circuit 46 to appropriately control the commutation operation of the motor. Operation: The first example of the screening circuit 6 according to the present invention is applied to the reference circuit at time U' The voltage of the end point Pb of the coil B is a small high level, 2 ^', so the output signal K1 of the NAND logic gate 61 is at the low level 1299972 of the output signal κ2 of the NAND logic gate 62. In the interval t2, the coil B enters the floating state. , so the endpoint Pb voltage sleeps

The jump between the heights exceeds the watcher Thunder V test voltage V-. At time t3, the first-time crossover zc causes the output signal K3 of the D-type flip-flop 63 to transition to a high level. Bran and this ¥ D type is positive and negative! The output signal K4 of I 64 is still maintained at the low level. The flip-flop type 66 is not desired. At time t4, the second crossover 7 occurs, so that the D type is positive and 3! with > ^, C2 i anti-fasting 04 output signal K4 transitions to the high position. This day's due to D type positive; 5, one , 1 positive and negative state 63 and 64 output signal K3 and K4 ratio

For the south, the sentence τ = mouth white i positive and negative 66 is triggered and the zero crossing is IZC to the high level. Therefore, the teacher circuit 60 effectively screens out the flute once over the ZC2 and corrects the commutation of the motor from the old field. At time t5, the drive signal BD is turned from the low level to the old level, so that the output signal of the D-type flip-flop 63蛊! 〇 and reverse 4 are reset to /, 64 operations. The drought is to prepare for the next screening. At time t6, the coil b enters the floating chamber and falls below the beam voltage v ± voltage transient voltage Vw. At the time of the mouth, the first crossover occurred, making D sentence, not c mouth ^ ~ L1 wonderful and anti-64 output signal K4 turned to high position, but at this time D sentence ΓΡ e mouth χ Γ 7 m. The anti-burglary 63 output signal K3 remains at the low level. 2...66 is not triggered. (4). The second crossing ZC2 occurs, making D-type positive and crying a Xixi mountain item ZC2 This 0 Shi ^ Anti-63 output signal K3 transition to high position This % 'Because D type is positive and crying a life ^ H from the anti-TM 63 and 64 output signals K3 and K4tb horses with the same level 'so τ type positive and negative crying

Izr M At 66 is triggered again to make the zero crossover indication pass the IZC transition to the low level. Therefore, the power-on 吟 effectively screens out the 箪-夂乂越ZC2 and correctly controls the commutation of the motor. ~ BD from the low level to the energy, the 曰 ' drive letter early to evil to the same level, so that the D-type flip-flop 63 and 64 12 1298972 output numbers K3 and K4 reset to the low level, in preparation for the next time Filtering operations.

Fig. 7 shows a detailed circuit diagram of a second example of the screening circuit 7A according to the present invention. The screening circuit 70 of the second example mainly includes a sample recording circuit 71 and the same set analysis circuit 72. The sample recording circuit 71 samples and records the comparison signal of the comparison circuit 45 in accordance with a predetermined clock signal CLK, thereby forming a sample set having three samples [χι, Χ2, Χ3]. The subsequent sample set analysis circuit 72 analyzes the recorded sample set [XI, X2, X3] to eliminate the first crossover (: and select the second crossover ZC2 as a control for commutation. Zero crossover event. Please note that in the example of driving the motor in linear mode, the higher the frequency of the clock CLK, the larger the sampling density, the smaller the error range:

= In the example of driving the motor with pulse width modulation, the clock signal UK

The pulse width modulated clock signal must be used directly. U In the first step of the brother, the sample recording circuit 71 & M will record the comparison signal between the end point Pb voltage of the floating-shaped tether coil B and the reference electrode Ding Ding electric I V (6) Is the first element X1. At the second ^^^乂, after the coil B has been brought into a floating state, the recording circuit 71 is sampled.

Then, the comparison signal of the comparison circuit ^^^^ is sampled according to the period of the two connected signals of the clock signal CLK, and is sequentially recorded as the second element Χ2 and the second 兀I Χ3. With such a clip, the sample recording circuit 71 forms a sample set [XI, Χ2, Χ3] having two Χ2(3) Μ 山 韦 兀 - 兀 。. In the third step of the younger brother, the sample set is too coke ΠΜ ^ wood 0 knife analysis circuit 72 determines whether the sample set mouth [ , Χ 2, Χ 3] conforms to any arrangement of either the 仏山扪 or the old only ^, where L stands for the low level Η 乂 Table orientation. If 13 1298972 does not match, then repeat the second step 骡 'Update the second element X2 and the third element χ3 according to the clock signal CLK. Please note that the first element X" is maintained at the value recorded in the first step. Once the sample set [χι, χ2, χ3] is combined with any of [L, L, Η] or [H, H, L], the sample set analysis circuit 72 determines that this is the second crossover ZC2. It happened. The screening method of the second example can be clearly verified by referring back to Fig. 5. As shown in FIG. 5, 'assuming that the coil B is consumed by the ground potential before entering the floating state, that is, in the first phase Μ, the sample recording circuit "the first element X1 recorded in the first step is a low level. L. In the second phase ρ_π in which the subsequent coil B is in the floating state, the _th crossover occurs when the end point Pb of the coil turns from the reference voltage Vref to the reference voltage Vref. 'The second element Χ2 recorded in the first crossover heart is the high level h, and the third element sampled after the first a crossover ZC1 occurs is the low level ^ = =, ZC2 Then occurs at the end of the coil ...... the voltage is converted from J at the reference voltage Vref to be greater than the reference voltage, and is sampled before the second crossover ZC2 occurs; = 2 f is sampled after the second crossover ZC2 occurs The first pixel X3 recorded is the level H. It can be seen that when the recorded sample set is [L, L, H]; :: KI1, ZC2 occurs. The more similarly, 'assume that the coil B is entering the floating voltage energy source V, that is, in the fourth phase p_IV, ^^ The first element X1 to be recorded in the first step is the high level recording circuit 71 + H. In the fifth phase pv in which the coil B of the following 14 1298972 is in a floating state, the first crossing zc 1 occurs in the coil The voltage at the end of B is changed from the reference voltage v(4) to the value greater than the reference voltage Vref. Therefore, the second element χ2 recorded before the first crossover zci occurs is the low level L, and the first time is The third element χ3 recorded after the occurrence of ZC1 is a high level. However, the second crossing ZC2 occurs when the voltage of the terminal pb of the coil B is changed from the reference voltage Vref to be smaller than the reference voltage Vref. The second element 12+ recorded before the second crossover ZC2 occurs is the high level η, and the third element X3 sampled after the second crossover ZC2 occurs is the low level L. In the fifth phase p_v, when the recorded sample set is [H, H, L], it indicates the occurrence of the second crossover ZC2. Further, the reference sample circuit 7 mainly includes a multiplex Cry 73 and three D-type flip-flops F1 to F3. Drive signal BD applied Multi-selection of terminal s 73, and is applied to the square type flip-flop inverted and

15

1298972 (four) CLK cycle. The sample set analysis circuit 72 mainly includes a logic ^74 and a D-type flip-flop ".-to-third element magic to magic L]::rr path 74 to analyze whether it conforms to [l, l, h] or [ In other words, the warning circuit is the same as the second element Χ 2 卜 / 2 70 X X2 is different from the third element X3 ' Logic circuit 74 = that is: low level rotation The state is at a high level, which means that the second crossover is detected. Since the output of the logic circuit 74 is applied to the clock terminal Ck of the D-type positive and negative F4, whenever the logic circuit μ detects the second crossover, the D-type flip-flop F4 is triggered to be zero. The crossover indication «I sinks. Therefore, the screening circuit 7G effectively screens out the second father ZC2 and correctly controls the commutation operation of the motor. The present invention has been described by way of illustration of the preferred embodiments. It is understood that the invention is not limited to the disclosed embodiments. On the contrary, the present invention is intended to cover such modifications and modifications as those skilled in the art. The scope of the patent scope for &' should be based on the broadest interpretation to accommodate all such modifications and similar configurations. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a circuit diagram of a three-phase motor and a switching circuit. Figure 2 shows the timing diagram of the terminal voltage of the motor coil. Figure 3 shows a circuit block diagram of a conventional motor control circuit. Figure 4 shows a circuit block diagram of a motor control circuit in accordance with the present invention. Figure 5 is a schematic diagram showing the operation principle of the selection circuit in accordance with the present invention. Fig. 6(A) shows a detailed circuit diagram of the first example of the screening circuit according to the present invention. Fig. 6(B) is a timing chart showing the operation waveform of the first example of the screening circuit according to the present invention. Figure 7 shows a detailed circuit diagram of a second example of a screening circuit in accordance with the present invention.

[Main component symbol description] 11, 31, 41 Motor 12, 32, 42 Switching circuit 30, 40 Motor control circuit 33, 43 Resisting electromotive force detection 34 Masking circuit 35, 45, 45 a, 45b Comparison circuit 36, 46 Drive Signal synthesizing circuit 47, 60, 70 Screening circuit 61, 62, 65 NAND logic gate 63, 64, F1 to F4 D-type forward and reverse 66 T-type flip-flop 70 Resisting electromotive force detecting circuit 71 Sampling recording circuit 72 Sample set analysis circuit 73 夕夕工74 LOG, circuit A, B, C coil 17 1298972 N coil coupling center point

Pa, Pb, Pc coil end voltage

Vm supply voltage source SH1 ~ SH3, SL1 ~ SL3 upper side and lower side switch BD drive signal CLK clock signal IZC zero crossover indication signal

ZC1, ZC2 first crossover and second crossover

Vref reference voltage XI, X2, X3 first to third elements

18

Claims (1)

1298972 X. Patent application scope: ', control circuit, applied to a motor having a plurality of coils, comprising: - a detection circuit coupled to the plurality of coils for generating a detection signal The plurality of lines are selected as one end voltage of the coil in a floating state; a comparison circuit coupled to the detection circuit for comparing the detection signal with a reference voltage to generate a comparison signal; a screening circuit, Lightly coupled to the comparison circuit for receiving the comparison signal, wherein the screening circuit sequentially receives one of the first crossover and the second crossover of the comparison signal, and generates a response in response to the second crossover An indication signal; and a driving circuit that controls the commutation operation of the motor in response to the indication signal. 2. The motor control circuit of claim 1, wherein: the comparison signal has a first state and a second state, wherein the first state represents that the detection signal is greater than the reference voltage, and the second state It means that the detection signal is smaller than the reference voltage. 3. The motor control circuit of claim 2, wherein the first crossover is associated with the comparison signal transitioning from the first state to the second state, and the second crossover is associated The comparison signal transitions from the second state to the first state. 19 transitioning from the first state to the second state. 1298972 4. The motor control circuit of claim 2, wherein: the first crossover is associated with the comparison signal transitioning from the second state to the first state' and the second crossover is associated The comparison signal is the motor control circuit of claim 1, wherein: the reference voltage is generated by detecting a voltage of a center point of one of the plurality of coils. 6. The motor control circuit of claim 1, wherein: the reference voltage is implemented by a predetermined voltage value. 7. The motor control circuit of claim 1, wherein: the screening circuit comprises: a sampling recording circuit for sampling the comparison signal according to a predetermined clock signal, and recording a first element, a a second element, and a second element, wherein the first element is sampled before the coil selected as a floating shape enters the floating state, and the second element and the third element are both And the sampler is sampled when the coil selected to be in the floating state has entered the floating state, and an analysis circuit is configured to analyze the first element, the second element, and the third element to select the first Second crossover. 20 1298972 The motor control circuit of claim 7 of the patent scope, wherein: the first: ^ 八-兀素 is sampled by one of the clock signals, and has been recorded, and 兮 _ _ falls first The sputum is sampled by a sample taken before the current cycle. 9. The motor control circuit of claim 7, wherein the knife circuit is screened according to the first element being the same as the second element and the first element being different from the analysis criterion of the third element The younger brother crossed the meeting. 1 〇 · The motor control circuit of claim 1 of the patent scope, wherein the drive circuit comprises a drive signal synthesizing circuit and a switching circuit. 11 . A motor control method for a motor having a plurality of coils, comprising: detecting a terminal voltage of one of the plurality of coils selected to be in a floating state to generate a detection signal; comparing the detection The measurement signal generates a comparison signal with a reference voltage, the comparison signal has a first crossover and a second crossover; and the second pass is selected from the first crossover and the first parental crossover Transmitting; generating an indication signal in response to the second crossover; and controlling a commutation operation of the motor in response to the indication signal. 21 1298972 1 2 The motor control method of claim 1 , wherein: the comparison apostrophe has a first state and a second state, wherein the first sorrow represents that the detection signal is greater than the reference voltage And the second state represents that the detection signal is smaller than the reference voltage. 13. The motor control method of claim 12, wherein: the first crossover is associated with the comparison signal being switched from the first state to the second state, and the second crossover system The comparison signal is transitioned from the second state to the first state. 14. The motor control method of claim 12, wherein: the first crossover is associated with the comparison signal transitioning from the second state to the first state, and the second crossover is associated with The comparison signal transitions from the first state to the second state. 15. The motor control method of claim 11, wherein: the step of screening the second crossover comprises: sampling the comparison signal according to a predetermined clock signal, and recording a first element, a second element, and a third element, wherein the first element is sampled before the coil selected to be in a floating state enters the floating state, and the second element and the third element are both The sample is sampled when the coil selected to be in the floating state has entered the floating state, and the first element is the same as the second element and the second element 22 1298972 is not the same as the third element - Analyze the criteria and screen out the second crossover. The motor control method is as follows: (1) The second element is the one recorded by the current cycle of the clock signal. And the second element is recorded by the first cycle of the D-printing period. 17. A zero-crossing detection circuit 1 with a commutation operation of a control-motor, comprising: - a first circuit for generating a first signal representing one of the coils of the motor/over the state against the electromotive force The second circuit generates a second signal than the first signal and a reference voltage of the vehicle, the second signal has a first crossover and a second crossover; and - the third circuit, in sequence Receiving the first crossover and the second crossover' and generating a third signal in response to the second crossover, the third signal being used to control the commutation operation of the motor. 18 • A zero-crossing detection circuit as claimed in claim 17 wherein: the comparison signal has a -th state and a second state, the first state indicating that the detection signal is greater than the reference voltage, and The second state represents that the detection signal is less than the reference voltage. 23 1298972 1 9. A zero-crossing detection circuit as claimed in claim 18, wherein: the first crossover is associated with the comparison signal transitioning from the first state to the second state, and the The secondary crossover is associated with the comparison signal transitioning from the second state to the first state. 20. For example, the zero-crossing detection circuit of claim 18, wherein: The first crossover is associated with the comparison signal being transitioned from the second state to the first state, and the second crossover is associated with the comparison signal transitioning from the first state to the second state. twenty four