Abstract:
An integrated circuit includes a housing, a semiconductor substrate arranged in the housing, several pins extended out from the housing, and an electronic circuitry having a rectifier arranged on the semiconductor substrate. The rectifier includes a controllable switch.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 14/822,353, filed on Aug. 10, 2015, which claims priority under 35 U.S.C. §119(a) from Patent Application No. 201410390592.2 filed in the People&#39;s Republic of China on Aug. 8, 2014, and Patent Application No. 201410404474.2 filed in the People&#39;s Republic of China on Aug. 15, 2014. In addition, this application claims priority under 35 U.S.C. §119(a) from Patent Application No. PCTCN2015086422 as PCT application filed in Receiving Office of CN on Aug. 7, 2015, to Chinese Patent Application No. CN201610523521.4, filed with the Chinese Patent Office on Jul. 5, 2016, all of which are expressly incorporated herein by reference in their entireties and for all purposes. 
     
    
     FIELD 
       [0002]    The disclosure relates to a driving circuit for a motor, and in particular to an integrated circuit applied to a driving circuit for a motor, a motor assembly, and an application equipment using the driving circuit. 
       BACKGROUND 
       [0003]    In a starting process of a synchronous motor, an electromagnet of a stator generates an alternating magnetic field, which is equivalent to a resultant magnetic field of a forward rotating magnetic field and a backward rotating magnetic field. And the alternating magnetic field drags a permanent magnetic rotor to be oscillated with a deflection. Finally the rotation of the rotor in a direction is accelerated rapidly to be synchronized with the alternating magnetic field of the stator if deflection oscillation amplitude of the rotor is increased. Generally a starting torque of the motor is set to be large to ensure the synchronous motor capable of starting, and thus the motor operates at a working point with a low efficiency. In addition, the rotor cannot be ensured to the rotor start to rotate in a same direction each time since a stop position of the permanent magnetic rotor and a polarity of an alternating current (AC) in initial energizing are unfixed. Accordingly, a fan and a pump having a motor work in a low operational efficiency. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  shows a single-phase permanent magnetic synchronous motor according to an embodiment of the present disclosure; 
           [0005]      FIG. 2  shows a schematic circuit diagram of a single-phase permanent magnetic synchronous motor according to an embodiment of the present disclosure; 
           [0006]      FIG. 3  shows a circuit block diagram of an implementing way of the integrated circuit shown in  FIG. 2 ; 
           [0007]      FIG. 4  shows a circuit block diagram of an implementing way of the integrated circuit shown in  FIG. 2 ; 
           [0008]      FIG. 5  shows a circuit of the motor shown in  FIG. 2  according to an embodiment; 
           [0009]      FIG. 6  shows a waveform of the circuit of the motor shown in  FIG. 5 ; 
           [0010]      FIGS. 7, 8, 9, 9A, and 9B  show the circuit of the motor shown in  FIG. 2  according to other embodiments; 
           [0011]      FIG. 10  shows a schematic circuit diagram of a single-phase permanent magnetic synchronous motor according to an embodiment of the present disclosure; 
           [0012]      FIG. 11  shows a circuit block diagram of an implementing way of the integrated circuit shown in  FIG. 10 ; 
           [0013]      FIG. 12  shows a schematic circuit diagram of a single-phase permanent magnetic synchronous motor according to an embodiment of the present disclosure; 
           [0014]      FIG. 13  shows a water pump including the above-described motor; and 
           [0015]      FIG. 14  shows a fan using including the above-described motor. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0016]    Hereinafter, particular embodiments of the present disclosure are described in detail in conjunction with the drawings, so that technical solutions and other beneficial effects of the present disclosure are apparent. It can be understood that the drawings are provided only for reference and explanation, and are not used to limit the present disclosure. Dimensions shown in the drawings are only for ease of clear description, but are not limited to a proportional relationship. 
         [0017]      FIG. 1  shows a single-phase permanent magnetic synchronous motor according to an embodiment of the present disclosure. The synchronous motor  10  includes a stator and a rotor  11  rotatable relative to the stator. The stator includes a stator core  12  and a stator winding  16  wound on the stator core  12 . The stator core may be made of soft magnetic materials such as pure iron, cast iron, cast steel, electrical steel, silicon steel. The rotor  11  includes a permanent magnet, the rotor  11  operates at a constant rotational speed of 60 f/p rpm during a steady state phase in a case that the stator winding  16  is connected with an AC power supply in series, where f is a frequency of the AC power supply and p is the number of pole pairs of the rotor. In the embodiment, the stator core  12  includes two poles  14  opposite to each other. Each pole  14  includes a pole arc  15 , an outside surface of the rotor  11  is opposite to the pole arc  15 , and a substantially uniform air gap  13  is formed between the outside surface of the rotor  11  and the pole arc  15 . The “substantially uniform air gap” according to the present disclosure means that a uniform air gap is formed in most space between the stator and the rotor, and a non-uniformed air gap is formed in a small part of the space between the stator and the rotor. Preferably, a starting groove  17  which is concave may be disposed in the pole arc  15  of the pole of the stator, and a part of the pole arc  15  rather than the starting groove  17  may be concentric with the rotor. With the configuration described above, the non-uniform magnetic field may be formed, a polar axis S 1  of the rotor has an angle of inclination relative to a central axis S 2  of the pole  14  of the stator in a case that the rotor is at rest (as shown in  FIG. 1 ), and the rotor may have a starting torque every time the motor is powered on under the action of the driving circuit. Specifically, the “pole axis S 1  of the rotor” refers to a boundary between two magnetic poles having different polarities, and the “central axis S 2  of the pole  14  of the stator” refers to a connection line passing central points of the two poles  14  of the stator. In the embodiment, both the stator and the rotor include two magnetic poles. It can be understood that the number of magnetic poles of the stator may not be equal to the number of magnetic poles of the rotor, and the stator and the rotor may have more magnetic poles, such as 4 or 6 magnetic poles in other embodiments. 
         [0018]      FIG. 2  shows a schematic circuit diagram of a single-phase permanent magnetic synchronous motor  10  according to an embodiment of the present disclosure. The stator winding  16  of the motor and the integrated circuit  18  are connected in series between two terminals of the AC power supply  24 . The driving circuit for the motor is integrated into the integrated circuit  18 , and the driving circuit enables the motor to start in a fixed direction every time the motor is powered on. 
         [0019]      FIG. 3  shows an implementing way of the integrated circuit  18 . The integrated circuit includes a housing  19 , two pins  21  extended out from the housing  19 , and a driving circuit packaged in the housing  19 . The driving circuit is disposed on a semiconductor substrate, and the driving circuit includes a detecting circuit  20  configured to detect a magnetic field polarity of a rotor of the motor, a controllable bidirectional AC switch  26  connected between the two pins  21 , and a switch control circuit  30  configured to control the controllable bidirectional AC switch  26  to be switched between a switch-on state and a switch-off state in a preset way, based on the magnetic field polarity of the rotor detected by the detecting circuit  20 . 
         [0020]    Preferably, the switch control circuit  30  is configured to switch on the controllable bidirectional AC switch  26  in a case that the AC power supply  24  is in a positive half cycle and the magnetic field polarity of the rotor is a first polarity, or in a case that the AC power supply  24  is in a negative half cycle and the magnetic field polarity of the rotor is a second polarity opposite to the first polarity. The configuration enables the stator winding  16  to drag the rotor only in a fixed direction in a starting phase of the motor. 
         [0021]      FIG. 4  shows an implementing way of the integrated circuit  18 .  FIG. 4  differs from  FIG. 3  in that, the integrated circuit shown in  FIG. 4  further includes a rectifier  28 , which is connected in parallel with the controllable bidirectional AC switch  26  between the two pins  21 , and may generate a DC supplied for the detecting circuit  20 . In the embodiment, preferably, the detecting circuit  20  may be a magnetic sensor (may also be referred as a position sensor), and the integrated circuit is installed near the rotor so that the magnetic sensor can sense a magnetic field variation of the rotor. It can be understood that the detecting circuit  20  may not include a magnetic sensor, and the magnetic field variation of the rotor may be detected in other ways in other embodiments. In the embodiment according to the present disclosure, the driving circuit for the motor is packaged in the integrated circuit, and thus the cost of the circuit can be reduced, and the reliability of the circuit can be improved. In addition, the motor may not include a PCB, and it just needs to fix the integrated circuit in a proper position and connect the integrated circuit to a line group and a power supply of the motor via leading wires. 
         [0022]    In the embodiment according to the present disclosure, the stator winding  16  and the AC power supply  24  are connected in series between two nodes A and B. Preferably, the AC power supply  24  may be a mains AC power supply with a fixed frequency such as 50 Hz or 60 Hz, and a supply voltage may be, for example, 110V, 220V or 230V. The controllable bidirectional AC switch  26 , and the stator winding  16  and the AC power supply  24  connected in series, are connected in parallel between the two nodes A and B. Preferably, the controllable bidirectional AC switch  26  may be a TRIAC, of which two anodes are connected to the two pins  21  respectively. It can be understood that the controllable bidirectional AC switch  26  may include two unidirectional thyristors reversely connected in parallel, and the respective control circuit may be disposed to control the two unidirectional thyristors in a preset way. The rectifier  28  and the controllable bidirectional AC switch  26  are connected in parallel between the two pins  21 . An AC between the two pins  21  is converted by the rectifier  28  into a low voltage DC. The detecting circuit  20  may be powered by the low voltage DC output by the rectifier  28 , and be configured to detect the magnetic pole position of the permanent magnetic rotor  11  of the synchronous motor  10  and output a respective signal. 
         [0023]    A switch control circuit  30  is connected to the rectifier  28 , the detecting circuit  20  and the controllable bidirectional AC switch  26 , and is configured to control the controllable bidirectional AC switch  26  to be switched between a switch-on state and a switch-off state in a preset way, based on information on the magnetic pole position of the permanent magnetic rotor detected by the detecting circuit  20  and the polarity of the AC power supply  24 , such that the stator winding  16  drags the rotor  14  to rotate only in the above-mentioned fixed starting direction in the starting phase of the motor. According to the present disclosure, in a case that the controllable bidirectional AC switch  26  is switched on, the two pins  21  are shorted, and the rectifier  28  does not consume electric energy since there is no current flowing through the rectifier  28 , hence, the utilization efficiency of electric energy can be improved significantly. 
         [0024]      FIG. 5  shows a circuit of the motor shown in  FIG. 2  according to an embodiment. The stator winding  16  of the motor is connected in series with the AC power supply  24  between the two pins  21  of the integrated circuit  18 . Two nodes A and B are connected to the two pins  21  respectively. A first anode T 2  of the TRIAC  26  is connected to the node A, and a second anode T 1  of the TRIAC  26  is connected to the node B. The rectifier  28  is connected in parallel with the TRIAC  26  between the two nodes A and B. An AC voltage between the two nodes A and B is converted by the rectifier  28  into a low DC voltage (preferably, the low voltage is in a range from 3V to 18V). The rectifier  28  includes a first resistor R 1 , second resistor R 2  and a first zener diode Z 1  and a second zener diode Z 2  which are reversely connected in parallel between the two nodes A and B. A high voltage output terminal C of the rectifier  28  is formed at a connection point of the first resistor R 1  and a cathode of the first zener diode Z 1 , and a low voltage output terminal D of the rectifier  28  is formed at a connection point of the second resistor R 2  and an anode of the second zener diode Z 2 . The voltage output terminal C is connected to a positive power supply terminal of the position sensor  20 , and the voltage output terminal D is connected to a negative power supply terminal of the position sensor  20 . Three terminals of the switch control circuit  30  are connected to the high voltage output terminal C of the rectifier  28 , an output terminal H 1  of the position sensor  20  and a control electrode G of the TRIAC  26  respectively. The switch control circuit  30  includes a third resistor R 3 , a fifth diode D 5 , and a fourth resistor R 4  and a sixth diode D 6  connected in series between the output terminal H 1  of the position sensor  20  and the control electrode G of the controllable bidirectional AC switch  26 . An anode of the sixth diode D 6  is connected to the control electrode G of the controllable bidirectional AC switch  26 . One terminal of the third resistor R 3  is connected to the high voltage output terminal C of the rectifier  28 , and the other terminal of the third resistor R 3  is connected to an anode of the fifth diode D 5 . A cathode of the fifth diode D 5  is connected to the control electrode G of the controllable bidirectional AC switch  26 . 
         [0025]    In reference with  FIG. 6 , an operational principle of the above-mentioned circuit is described. In  FIG. 6 , Vac indicates a waveform of a voltage of the AC power supply  24 , and Iac indicates a waveform of a current flowing through the stator winding  16 . Due to the inductive character of the stator winding  16 , the waveform of the current Iac lags behind the waveform of the voltage Vac. V 1  indicates a waveform of a voltage between two terminals of the zener diode Z 1 , V 2  indicates a waveform of a voltage between two terminals of the zener diode Z 2 , Vcd indicates a waveform of a voltage between two output terminals C and D of the rectifier  28 , Ha indicates a waveform of a signal output from the output terminal H 1  of the position sensor  20 , and Hb indicates a rotor magnetic field detected by the position sensor  20 . In this embodiment, in a case that the position sensor  20  is powered normally, the output terminal H 1  outputs a logic high level in a case that the detected rotor magnetic field is North, or the output terminal H 1  outputs a logic low level in a case that the detected rotor magnetic field is South. 
         [0026]    In a case that the rotor magnetic field Hb detected by the position sensor  20  is North, in a first positive half cycle of the AC power supply, a supply voltage is gradually increased in a period of time from a time instant t 0  to a time instant t 1 , the output terminal H 1  of the position sensor  20  outputs a high level, and a current flows through the resistor R 1 , the resistor R 3 , the diode D 5  and the control electrode G and the second anode T 1  of the TRIAC  26  sequentially. The TRIAC  26  is switched on in a case that a driving current flowing through the control electrode G and the second anode T 1  is greater than a gate triggering current Ig. Once the TRIAC  26  is switched on, the two nodes A and B are shorted, a current flowing through the stator winding  16  in the motor is gradually increased until a large forward current flows through the stator winding  16 , and the rotor  14  is driven to rotate clockwise as shown in  FIG. 3 . Since the two nodes A and B are shorted, there is no current flowing through the rectifier  28  in a period of time from the time instant t 1  to a time instant t 2 . Hence, the resistors R 1  and R 2  do not consume electric energy, and the output of the position sensor  20  is stopped due to no power supply voltage. Since there is a sufficient large current flowing through two anodes T 1  and T 2  of the TRIAC  26  (which is greater than a holding current Ihold), the TRIAC  26  is kept to be switched on in a case that there is no driving current flowing through the control electrode G and the second anode T 1 . In a negative half cycle of the AC power supply, after a time instant t 3 , a current flowing through T 1  and T 2  is less than the holding current I hold , the TRIAC  26  is switched off, a current begins to flow through the rectifier  28 , and the output terminal H 1  of the position sensor  20  outputs a high level again. Since a potential at a point C is lower than a potential at a point E, there is no driving current flowing through the control electrode G and the second anode T 1  of the TRIAC  26 , and the TRIAC  26  is kept to be switched off. Since the resistances of the resistors R 1  and R 2  in the rectifier  28  are far greater than the resistance of the stator winding  16  in the motor, a current currently flowing through the stator winding  16  is far less than the current flowing through the stator winding  16  in a period of time from the time instant t 1  to the time instant t 2 , and there is no driving force for the rotor  14 . Hence, the rotor  14  continues to rotate clockwise due to the inertia effect. In a second positive half cycle of the AC power supply, similar to the first positive half cycle, a current flows through the resistor R 1 , the resistor R 3 , the diode D 5 , and the control electrode G and the second anode T 1  of the TRIAC  26  sequentially. The TRIAC  26  is switched on again, the current flowing through the stator winding  16  continues to drive the rotor  14  to rotate clockwise. Similarly, the resistors R 1  and R 2  do not consume electric energy since the two nodes A and B are shorted; in the negative half cycle of the power supply, the current flowing through the two anodes T 1  and T 2  of the TRIAC  26  is less than the holding current I hold , the TRIAC  26  is switched off again, and the rotor continues to rotate clockwise due to the inertia effect. 
         [0027]    At a time instant t 4 , the rotor magnetic field Hb detected by the position sensor  20  changes to be South from North, the AC power supply is in the positive half cycle and the TRIAC  26  is switched on, the two nodes A and B are shorted, and there is no current flowing through the rectifier  28 . After the AC power supply is in the negative half cycle, the current flowing through the two anodes T 1  and T 2  of the TRIAC  26  is gradually decreased, and the TRIAC  26  is switched off at a time instant t 5 . Then the current flows through the second anode Ti and the control electrode G of the TRIAC  26 , the diode D 6 , the resistor R 4 , the position sensor  20 , the resistor R 2  and the stator winding  16  sequentially. As the driving current is gradually increased, the TRIAC  26  is switched on again at a time instant t 6 , the two nodes A and B are shorted again, the resistors R 1  and R 2  do not consume electric energy, and the output of the position sensor  20  is stopped due to no power supply voltage. There is a large reverse current flowing through the stator winding  16 , and the rotor  14  continues to be driven clockwise since the rotor magnetic field is South. In a period of time from the time instant t 5  to the time instant t 6 , the first zener diode Z 1  and the second zener diode Z 2  are switched on, hence, there is a voltage output between the two output terminals C and D of the rectifier  28 . At a time instant t 7 , the AC power supply is in the positive half cycle again, the TRIAC  26  is switched off once the current flowing through the TRIAC  26  crosses zero, and then a voltage of the control circuit is gradually increased. As the voltage is gradually increased, a current begins to flow through the rectifier  28 , the output terminal H 1  of the position sensor  20  outputs a low level, there is no driving current flowing through the control electrode G and the second anode T 1  of the TRIAC  26 , hence, the TRIAC  26  is switched off. Since the current flowing through the stator winding  16  is small, no driving force is generated for the rotor  14 . At a time instant t 8 , the power supply is in the positive half cycle, the position sensor outputs a low level, the TRIAC  26  is kept to be switched off after the current crosses zero, and the rotor continues to rotate clockwise due to the inertia effect. According to the present disclosure, the rotor may be accelerated to be synchronized with the field of the stator by rotating only one circle after the stator winding is powered on. 
         [0028]    With the circuit according to the embodiment of the present disclosure, the motor can be ensured to start and rotate in a same direction every time the motor is powered on. In applications such a fan and a water pump, a flabellum and an impeller driven by the rotor may have curved vanes, and thus the efficiency of the fan and the water pump is improved. In addition, in the embodiment of the present disclosure, by taking advantage of a characteristic of the TRIAC that the TRIAC is kept to be switched on although there is no driving current flowing though the TRIAC once the TRIAC is switched on, it is avoided that the resistor R 1  and the resistor R 2  in the rectifier  28  still consumes electric energy after the TRIAC is switched on, hence, the utilization efficiency of electric energy can be improved significantly. 
         [0029]      FIG. 7  shows the circuit of the motor shown in  FIG. 2  according to an embodiment. The stator winding  16  of the motor is connected in series with the AC power supply  24  between the two pins  21  of the integrated circuit  18 . The two nodes A and B are connected to the two pins  21  respectively. A first anode T 2  of the TRIAC  26  is connected to the node A, and a second anode T 1  of the TRIAC  26  is connected to the node B. The rectifier  28  is connected in parallel with the TRIAC  26  between the two nodes A and B. An AC between the two nodes A and B is converted by the rectifier  28  into a low voltage DC, preferably, the low voltage is in a range from 3V to 18V. The rectifier  28  includes a first resistor R 1  and a full wave bridge rectifier connected in series between the two nodes A and B. The first resistor R 1  may be used as a voltage dropper, and the full wave bridge rectifier includes two rectifier branches connected in parallel, one of the two rectifier branches includes a first diode D 1  and a third diode D 3  reversely connected in series, and the other of the two rectifier branches includes a second zener diode Z 2  and a fourth zener diode Z 4  reversely connected in series, the high voltage output terminal C of the rectifier  28  is formed at a connection point of a cathode of the first diode D 1  and a cathode of the third diode D 3 , and the low voltage output terminal D of the rectifier  28  is formed at a connection point of an anode of the second zener diode Z 2  and an anode of the fourth zener diode Z 4 . The output terminal C is connected to a positive power supply terminal of the position sensor  20 , and the output terminal D is connected to a negative power supply terminal of the position sensor  20 . The switch control circuit  30  includes a third resistor R 3 , a fourth resistor R 4 , and a fifth diode D 5  and a sixth diode D 6  reversely connected in series between the output terminal H 1  of the position sensor  20  and the control electrode G of the controllable bidirectional AC switch  26 . A cathode of the fifth diode D 5  is connected to the output terminal H 1  of the position sensor, and a cathode of the sixth diode D 6  is connected to the control electrode G of the controllable bidirectional AC switch. One terminal of the third resistor R 3  is connected to the high voltage output terminal C of the rectifier, and the other terminal of the third resistor R 3  is connected to a connection point of an anode of the fifth diode D 5  and an anode of the sixth diode D 6 . Two terminals of the fourth resistor R 4  are connected to a cathode of the fifth diode D 5  and a cathode of the sixth diode D 6  respectively. 
         [0030]      FIG. 8  shows the circuit of the motor shown in  FIG. 2  according to an embodiment. The embodiment differs from the previous embodiment in that, the zener diodes Z 2  and Z 4  in  FIG. 7  are replaced by general diodes D 2  and D 4  in the rectifier in  FIG. 8 . In addition, a zener diode Z 7  as a voltage regulator is connected between the two output terminals C and D of the rectifier  28  in  FIG. 8 . 
         [0031]      FIG. 9  shows the circuit of the motor shown in  FIG. 2  according to an embodiment. The stator winding  16  of the synchronous motor is connected in series with the AC power supply  24  between the two pins  21  of the integrated circuit  18 . Two nodes A and B are connected to the two pins  21  respectively. A first anode T 2  of the TRIAC  26  is connected to the node A, and a second anode T 1  of the TRIAC  26  is connected to the node B. The rectifier  28  is connected in parallel with the TRIAC  26  between the two nodes A and B. An AC between the two nodes A and B is converted by the rectifier  28  into a low voltage DC, preferably, the low voltage is in a range from 3V to 18V. The rectifier  28  includes a first resistor R 1  and a full wave bridge rectifier connected in series between the two nodes A and B. The first resistor R 1  may be used as a voltage dropper. The full wave bridge rectifier includes two rectifier branches connected in parallel, one of the two rectifier branches includes two unidirectional thyristors S 1  and S 3  reversely connected in series, and the other of the two rectifier branches includes a second diode D 2  and a fourth diode D 4  reversely connected in series. The high voltage output terminal C of the rectifier  28  is formed at a connection point of a cathode of the unidirectional thyristor S 1  and a cathode of the unidirectional thyristor S 3 , and the low voltage output terminal D of the rectifier  28  is formed at a connection point of an anode of the second diode D 2  and an anode of the fourth diode D 4 . The output terminal C is connected to a positive power supply terminal of the position sensor  20 , and the output terminal D is connected to a negative power supply terminal of the position sensor  20 . The switch control circuit  30  includes a third resistor R 3 , an NPN triode T 6 , and a fourth resistor R 4  and a fifth diode D 5  connected in series between the output terminal H 1  of the position sensor  20  and the control electrode G of the controllable bidirectional AC switch  26 . A cathode of the fifth diode D 5  is connected to the output terminal H 1  of the position sensor. One terminal of the third resistor R 3  is connected to the high voltage output terminal C of the rectifier, and the other terminal of the third resistor R 3  is connected to the output terminal H 1  of the position sensor. A base of the NPN triode T 6  is connected to the output terminal H 1  of the position sensor, an emitter of the NPN triode T 6  is connected to an anode of the fifth diode D 5 , and a collector of the NPN triode T 6  is connected to the high voltage output terminal C of the rectifier. 
         [0032]    In this embodiment, a control signal is inputted into the control terminals of the two switches S 1  and S 3  via two terminals SC 1  and SC 2 . The S 1  and S 3  are switched on in a case that a control signal input from the terminal SC 2  is a high level, or S 1  and S 3  are switched off due to no driving current in a case that the control signal input from the terminal SC 2  is a low level. Based on the configuration, S 1  and S 3  may be switched between a switch-on state and a switch-off state in a preset way by inputting the high level from the terminal SC 2  in a case that the driving circuit operates normally. S 1  and S 3  are switched off by changing the control signal input from the terminal SC 2  from the high level to the low level in a case that the motor must be stopped because an exception occurs (for example, locked rotor in the motor). In this case, the TRIAC  26 , the rectifier  28  and the position sensor  20  are switched off to ensure the whole circuit to be in a zero-power state. Meanwhile, it is avoided that the voltage dropper is overheated due to still continuous power supply in case of the exception. 
         [0033]    It should be understood that the unidirectional thyristors S 1  and S 3  may be replaced by controllable semiconductor switches of other types. 
         [0034]      FIG. 9A  shows a circuit of the motor shown in  FIG. 2  according to another embodiment. Different from the embodiment shown in  FIG. 9 , in  FIG. 9A , the rectifier includes two optical couplers, one rectifying branch of the rectifier includes diodes D 2  and D 4  reversely connected in series, and the other rectifying branch includes two photosensitive semiconductor switches S 1  and S 3  reversely connected in series, one optical coupler is composed of each of the photosensitive semiconductor switches S 1 /S 3  and a light emitter D 1 /D 3 , and two light emitters D 1  and D 3  of the two optical couplers are connected in parallel between two terminals SC 1  and SC 2 . When a current flows between the terminals SC 1  and SC 2  to energize the light emitters D 1  and D 3  to emit light, the photosensitive semiconductor switches S 1  and S 3  receive light to generate a current. Based on the configuration, the two switches S 1  and S 3  may be switched between a switch-on state and a switch-off state in a preset way by flowing currents through the terminals SC 1  and SC 2  in a preset way in a case that the driving circuit operates normally. S 1  and S 3  are switched off by flowing no current through the terminals SC 1  and SC 2  in a case that the motor must be stopped because an exception occurs (for example, locked rotor in the motor). It is avoided that the voltage dropper is overheated due to still continuous power supply in case of the exception. In the embodiment, the photosensitive semiconductor switches S 1  and S 3  are photosensitive unidirectional thyristors. It should be understood that photosensitive semiconductor switches of other types may also be used in other embodiments. 
         [0035]      FIG. 9B  shows a circuit of the motor shown in  FIG. 2  according to yet another embodiment. Different from the embodiment shown in  FIG. 9A , in  FIG. 9B , the rectifier includes two optical couplers, one rectifying branch of the rectifier includes diodes D 2  and D 4  reversely connected in series, and the other rectifying branch includes two unidirectional thyristors S 1  and S 3  reversely connected in series. Control terminals of the two unidirectional thyristors S 1  and S 3  are respectively connected to current output terminals of two photosensitive semiconductor switches O 1  and O 3  of the two optical couplers, one optical coupler is composed of each of the photosensitive semiconductor switches O 1 /O 3  and a light emitter D 1 /D 3 , and two light emitters D 1  and D 3  of the two optical couplers are connected in parallel between two terminals SC 1  and SC 2 . When a current flows between the terminals SC 1  and SC 2  to energize the light emitters D 1  and D 3  to emit light, the photosensitive semiconductor switches O 1  and O 3  receive light to generate a current to drive the switches S 1  and S 3  to be switched on. Based on the configuration, the two switches S 1  and S 3  may be switched between a switch-on state and a switch-off state in a preset way by flowing currents through the terminals SC 1  and SC 2  in a preset way in a case that the driving circuit operates normally. Filters are respectively connected in parallel between two terminals of each of the switches S 1  and S 3  to absorb a surge current, thereby avoiding that the switches S 1  and S 3  are switched on by mistake in case of no triggering signal. Preferably, the filters include resistors and capacitors connected in series between the two terminals of switches S 1 /S 3 . S 1  and S 3  are switched off by flowing no current between the terminals SC 1  and SC 2  in a case that the motor must be stopped because an exception occurs (for example, locked rotor in the motor), thereby avoiding that the voltage dropper is overheated due to still continuous power supply in case of the exception. In the embodiment, the photosensitive semiconductor switches O 1  and O 3  are photosensitive unidirectional thyristors. It should be understood that photosensitive semiconductor switches of other types may also be used in other embodiments. The switches S 1  and S 3  are unidirectional thyristors, and it should be understood that controllable semiconductor switches of other types may also be used in other embodiments. In this embodiment, a larger driving current may be provided by the optical coupler, the rectifier is allowed to use switches S 1  and S 3  supporting a larger current. Thus, a larger driving current is supplied to the control terminal of the bidirectional AC switch, and a bidirectional AC switch with a larger current rating may be used. 
         [0036]      FIG. 10  shows a schematic circuit diagram of a single-phase permanent magnetic synchronous motor  10  according to an embodiment of the present disclosure. The stator winding  16  of the motor is connected in series with the integrated circuit  18  between two terminals of the AC power supply  24 . A driving circuit for the motor is integrated into the integrated circuit  18 , and the driving circuit enables the motor to start in a fixed direction every time the motor is powered on. In the present disclosure, the driving circuit for the motor is packaged in the integrated circuit, and thus the cost of the circuit can be reduced and the reliability of the circuit can be improved. 
         [0037]    In the present disclosure, based on actual situations, all or a part of the rectifier, the detecting circuit, the switch control circuit, the controllable bidirectional AC switch may be integrated into the integrated circuit. For example, as shown in  FIG. 3 , only the detecting circuit, the switch control circuit and the controllable bidirectional AC switch are integrated into the integrated circuit, and the rectifier is disposed outside the integrated circuit. 
         [0038]    For example, as shown in the embodiments of  FIG. 10  and  FIG. 11 , the voltage dropping circuit  32  and the controllable bidirectional AC switch  26  are disposed outside the integrated circuit, and the rectifier (which may only include the rectifier bridge but not include a voltage dropping resistor or other voltage dropping assemblies), the detecting circuit and the switch control circuit are integrated into the integrated circuit. In the embodiment, a low power part is integrated into the integrated circuit, and the voltage dropping circuit  32  and the controllable bidirectional AC switch  26  as high power parts are disposed outside the integrated circuit. In an embodiment as shown in  FIG. 12 , the voltage dropping circuit  32  may be integrated into the integrated circuit, and the controllable bidirectional AC switch is disposed outside the integrated circuit. In a case that rectifier as shown in  FIG. 9, 9A and 9B  is integrated into the integrated circuit, the integrated circuit is preferably provided with external pins respectively connected to the first signal terminal and the second signal terminal. Hence, the control signal is inputted from the integrated circuit to control the two semiconductor switches S 1  and S 3 . 
         [0039]      FIG. 13  shows a water pump  50  using the motor described above. The water pump  50  includes a pump housing  54  having a pump chamber  52 , an entrance  56  and an exit  58  in communication with the pump chamber, an impeller  60  rotatably disposed in the pump chamber, and a motor assembly configured to drive the impeller.  FIG. 14  shows a fan using the motor described above. The fan includes a flabellum  70  driven directly or indirectly via an output axis of the motor. 
         [0040]    With the single-phase permanent magnetic synchronous motor according to embodiments of the present disclosure, the single-phase permanent magnetic synchronous motor is ensured to start and rotate in a fixed direction every time the single-phase permanent magnetic synchronous motor is powered on. In applications of the fan such as an exhaust fan and a range hood, and the water pump such as a circulating pump and a wet-pit pump, a flabellum and an impeller driven by the rotor may have curved vanes, and thus the efficiency of the fan and the water pump is improved. 
         [0041]    In a motor assembly according to another embodiment, a motor may be connected in series with a bidirectional AC switch between a node A and a node B, and the node A and the node B may be connected to the two terminals of the AC power supply respectively. 
         [0042]    The motor assembly according to the embodiments of the disclosure may be applied to, but not limited to, a pump, a fan, a household appliance or a vehicle, and the household appliance may include such as a washing machine, a dishwasher, a range hood, a vent fan. 
         [0043]    What is described above is only preferred embodiments of the present disclosure and is not intended to define the scope of protection of the present disclosure. Any changes, equivalent substitution, improvements and so on made within the spirit and principles of the present disclosure are all contained in the scope of protection of the present disclosure. For example, the driving circuit according to the present disclosure not only is applied to the single-phase permanent magnetic synchronous motor, but also is applied to other types of permanent magnetic motors such as a single-phase brushless DC motor.