Single-phase motor with a conversion circuit

1. Field of the Invention

The present invention relates to a single-phase motor with a conversion circuit. In particular, the present invention relates to the use of a driver integrated circuit (model no. [US79KUA]), which is generally used with a two-phase motor, with a single-phase motor by means of connecting the driver integrated circuit with an external conversion circuit before connection to the single-phase motor. The output of the driver integrated circuit drives the single-phase motor under the control of the conversion circuit.

2. Description of the Related Art

A typical driver integrated circuit of model no. [US79KUA] includes three functional modules and three terminals. As illustrated in FIG. 1, the [US79KUA] single-phase motor driver integrated circuit (IC) includes a DC voltage-regulating circuit module, a control and protection circuit module, and a Hall latch module. The DC voltage-regulating circuit module supplies stabilized DC voltage to the control and protection circuit module and the Hall latch module, respectively, thereby providing a stable operational condition for the driver IC. The control and protection circuit module includes an auto-restart circuit, a locked rotor shutdown circuit, a reverse voltage protection circuit, and a Zener diodes protect outputs circuit. The Hall latch module includes a Hall element, a Hall voltage amplifier, and a motor driver. The Hall element detects a change in the magnetic field during rotation of the rotor, and the detected weak voltage is amplified by the Hall voltage amplifier and then outputted to drive the motor driver connected to the outputs (OUT 1 and OUT 2 ). Thus, a change in the current providing an alternate on/off function is generated in the Hall latch module. The stator of the motor is thus inducted to thereby turn the rotor, and the rotor turns continuously.

FIG. 2 depicts an application circuitry of the conventional [US79KUA] driver integrated circuit and a two-phase motor. FIG. 3 is a diagram illustrating output waves of the conventional [US79KUA] driver integrated circuit, wherein the abscissa denotes time and the ordinate denotes voltage. Referring to FIG. 2, a DC voltage (3-18V) of a power-supply is inputted via Vcc to power the driver IC. In this case, the Hall element of the driver IC detects a specific period of a change in a magnetic field generated by the permanent magnet of the rotor. When the terminal OUT 1 is close, the current passes the Coil 1 to drive the rotor through a certain angle. Due to the change in the angular position of the rotor, the Hall element detects another period of the change in the magnetic field generated by the permanent magnet. At this time, the terminal OUT 1 is open and the terminal OUT 2 is close such that the current passes the Coil 2 to drive the rotor through another certain angle. Referring to FIG. 3, the terminals OUT 1 and OUT 2 are alternately opened and closed in a synchronous manner to output square waves of identical frequency and inverted phases. Thus, the rotor is continuously driven by inducted repulsive forces generated by the Coil 1 and Coil 2 in alternative phases. However, such a driver IC can only be used with a two-phase motor having two coils; namely, it cannot be used with a single-phase motor having a single coil.

The primary object of the present invention is to provide a single-phase motor having a conversion circuit, wherein a [US79KUA] two-phase motor driver IC is connected to a single-phase motor via an external conversion circuit. The conversion circuit receives the output signals of the [US79KUA] driver IC to control alternate on/off of two transistors serially connected to two ends of a coil for a motor. The [US79KUA] two-phase motor driver IC can be selected to apply in a single-phase motor.

The secondary object of the present invention is to provide a single-phase motor having a conversion circuit, wherein the [US79KUA] two-phase motor driver IC can be used with a single-phase motor having a single coil and a simple structure. The coil structure is thus simplified, and the motor quality is improved.

A further object of the present invention is to provide a single-phase motor having a conversion circuit, wherein the [US79KUA] two-phase motor driver IC is connected to a single-phase motor via an external conversion circuit. The conversion circuit further comprises two sets of voltage-dividing circuits for reducing the power voltage to a proper extent. Thus, the available voltage of the motor is not limited by voltage feature of the [US79KUA] two-phase driver IC. As a result, the motor may work in a wider input voltage range.

The single-phase motor having a conversion circuit in accordance with the present invention comprises a [US79KUA] two-phase motor driver IC, a conversion circuit, and a coil for a motor. The driver IC includes two outputs that are serially connected to the conversion circuit and then connected to the coil. The conversion circuit includes two transistors respectively connected two ends of the coil. The outputs of the driver IC respectively send out alternate on/off signals to respectively turn the transistors on and off, thereby controlling directions of current passing the coil. Thus, the coil generates alternative magnetic fields as a result of alternative directions of the current to thereby drive the rotor. In addition, the conversion circuit comprises two sets of voltage-dividing circuits for reducing the power voltage to a proper extent such that the motor may work in a wider input voltage range. Thus, the available voltage of the motor is widened and not limited by voltage feature of the driver IC.

Other objects, specific advantages, and novel features of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings.

FIG. 1 is a schematic block diagram of a conventional [US79KUA] driver integrated circuit.

FIG. 2 is an application circuitry of the conventional [US79KUA] driver integrated circuit and a two-phase motor.

FIG. 3 is a diagram illustrating output waves of the conventional [US79KUA] driver integrated circuit.

FIG. 4 is a circuitry of a first embodiment of a single-phase motor in accordance with the present invention.

FIG. 5 is a circuitry of a second embodiment of the single-phase motor in accordance with the present invention.

Preferred embodiments in accordance with the present invention will now be described with reference to the accompanying drawings.

FIG. 4 is a circuitry of a first embodiment of a single-phase motor in accordance with the present invention. As illustrated in FIG. 4, the first embodiment of the single-phase motor in accordance with the present invention generally includes a driver IC (model no. [US79KUA]), a conversion circuit BLK 1 , and a coil (Coil in FIG. 4 ). The driver IC is externally serially connected to the conversion circuit BLK 1 and then connected to the coil. The driver IC includes two outputs OUT 1 and OUT 2 for outputting signals to the conversion circuit BLK 1 and the coil. The conversion circuit BLK 1 includes plural resistors R 1 , R 2 , R 3 and R 4 and two transistors Q 1 and Q 2 . The transistors Q 1 and Q 2 are respectively connected to a first end Cs and a second end Ce of the coil. The resistors R 1 and R 3 are connected to the base of the transistor Q 1 , and the resistors R 2 and R 4 are connected-to the base of the transistor Q 2 . The transistors Q 1 and Q 2 receive the singles from the outputs OUT 1 and OUT 2 of the driver IC through the conversion circuit BLK 1 to be alternately turned on and off, thereby controlling directions of the current passing the coil. Thus, the coil generates alternative magnetic fields resulting from the alternative directions of the current to thereby drive the rotor. Accordingly, the conversion circuit BLK 1 allows the driver IC to be used with a single-phase motor having a single coil.

Still referring to FIG. 4, in the operation of the motor of this embodiment, the DC voltage (3-18V) of the power source is inputted via Vcc to supply power to the driver IC. The Hall element of the driver IC detects a specific period of a change in the magnetic field generated by the permanent magnet on the rotor. When the output OUT 1 is close, the current passes the resistors R 1 and R 3 to create a bias on the base of the transistor Q 1 . A portion of the current pass the transistor Q 1 and the resistor R 3 to thereby turn the transistor Q 1 on. At this time, the first end Cs of the coil is at a high voltage, and the transistor Q 2 is off such that the second end Ce of the coil is at a low voltage (GND). The voltage difference between the first end Cs and the second end Ce of the coil causes the current to run from the first end Cs to the second end Ce, and the rotor is driven through a certain angle by means of the current passing the coil.

Due to the change in the angular position of the rotor, the Hall element detects another period of the change in the magnetic field generated by the permanent magnet. At this time, the output OUT 1 is open (off) and the output OUT 2 is close. The current passes the resistors R 2 and R 4 to bias the base of the transistor Q 2 . A portion of the current passes the transistor Q 2 and the resistor R 4 to thereby turn the transistor Q 2 on. At this time, the second end Ce of the coil is at a high voltage, and the transistor Q 1 is off such that the first end Cs of the coil is at a low voltage (GND). The potential difference between the first end Cs and the second end Ce of the coil causes the current to run from the second end Ce to the first end Cs, and the rotor is driven through another certain angle by means of the current passing the coil. Thus, by means of alternately turning the outputs OUT 1 and OUT 2 of the driver IC on and off and under the control of the conversion circuit BLK 1 , the transistors Q 1 and Q 2 are alternately turned on and off to synchronously change high/low voltages of inverted phases at the ends Cs and Ce of the coil in an alternate manner, thereby causing the stator to create alternating magnetic fields to drive the rotor.

FIG. 5 is a circuitry of a second embodiment of the single-phase motor in accordance with the present invention. The elements in FIG. 5 identical to those in FIG. 4 are denoted by identical numerals.

As illustrated in FIG. 5, the second embodiment of the single-phase motor in accordance with the present invention generally includes a driver IC (model no. [US79KUA]), a conversion circuit BLK 2 , and a coil (Coil in FIG. 5 ). The conversion circuit BLK 2 includes plural resistors R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 and six transistors Q 1 , Q 2 , Q 3 , Q 4 , Q 5 , and Q 6 .

The transistors Q 1 , Q 2 , Q 3 , Q 4 , Q 5 , and Q 6 are respectively connected to a first end Cs and a second end Ce of the coil. The transistors Q 5 and Q 6 are alternately turned on and off by two outputs OUT 1 and OUT 2 of the driver IC to thereby control the directions of the current passing the coil under the is control of the conversion circuit BLK 2 . The transistors Q 1 , Q 2 , Q 3 , and Q 4 together form a fully symmetric complimentary type driver circuit, wherein the transistors Q 1 and Q 4 and the transistors Q 2 and Q 3 are alternately turned on and off to cause the current to alternately run from the first end Cs to the second end Ce of the coil and from the second end Ce to the first end Cs of the coil.

The resistor R 3 and the transistor Q 5 form a switch control circuit that is electrically connected to the output OUT 1 of the driver IC. The resistor R 4 and the transistor Q 6 form another switch control unit that is electrically connected to the output OUT 2 of the driver IC. By means of using a voltage change between the collector of the transistors Q 5 and Q 6 , the control signals from the outputs OUT 1 and OUT 2 of the driver IC control the alternate on/off operation of the transistors Q 3 and Q 4 of the fully symmetric complimentary driver circuit. In addition, the transistors R 5 and R 7 and the transistors R 6 and R 8 respectively form two sets of voltage dividing circuits that, in addition to controlling the transistors Q 5 and Q 6 , reduces the DC input voltage to a value below 18V to assure that the voltage inputted to the driver IC shall not exceed the rated available voltage of the driver IC.

Still referring to FIG. 5, in the operation of the motor of this embodiment, the DC voltage (3-24V) of the power source is inputted via Vcc to supply power to the driver IC. The Hall element of the driver IC detects a specific period of a change in the magnetic field generated by the permanent magnet on the rotor. When the output OUT 1 is off, the current passes the resistors R 5 and R 7 and the transistor Q 5 to turn the transistor Q 5 on. Since the transistor Q 5 is on to allow the current from the Vcc to pass the resistor R 3 and the transistor Q 3 and then be connected to the ground GND, the base of the transistor Q 3 is not biased and is thus open. In this case, when the other output OUT 2 is on, the current passing the resistors R 6 and R 8 and the transistor Q 6 is connected to ground GND through the driver IC such that the base of the transistor Q 6 is not biased and is thus open. The resistors R 6 and R 8 cause a voltage drop in the output OUT 2 of the driver IC. Since the transistor Q 6 is off, the current passing the resistor R 4 is connected to the transistor Q 4 that is turned on accordingly. At this time, the second end Ce of the coil is at a low voltage (GND), and the bias current of the transistor Q 2 runs from Vcc through the transistor Q 1 , resistor R 1 , and transistor Q 4 , thereby turning the transistor Q 1 on. Meanwhile, the first end Cs of the coil is at a high voltage. The transistor Q 2 and the resistor R 2 are open, as there is no potential difference between two ends of the transistor Q 2 and the resistor R 2 . In this case, the current runs from Vcc to ground (GND) via the transistor Q 1 , the first end Cs of the coil, the second end Ce of the coil, and the transistor Q 4 . A magnetic field is generated by the current passing the coil to drive the rotor to turn through a certain angle.

Still referring to FIG. 5, after the rotor has turned through the certain angle as mentioned above, the Hall element detects the next period of the magnetic field generated by the permanent magnet. When the output OUT 1 of the driver IC is off, the current passes the resistors R 6 and R 8 and the transistor Q 6 to turn the transistor Q 6 on. Since the transistor Q 6 is on to allow the current from Vcc to pass the resistor R 4 and the transistor Q 4 and then be connected to ground GND, the base of the transistor Q 4 is not biased and is thus on. In this case, when the other output OUT 1 of the driver IC is on, the current passing the resistors R 5 and R 7 and the transistor Q 5 is connected to ground GND through the driver IC such that the base of the transistor Q 5 is not biased and is thus open. The resistors R 5 and R 7 also cause a step-down at the output OUT 1 of the driver IC. Since the transistor Q 5 is off, the current passing the resistor R 3 is thoroughly connected to the transistor Q 3 that is turned on accordingly. At this time, the first end Cs of the coil is at a low voltage (GND), and the bias current of the transistor Q 2 runs from Vcc through the transistor Q 2 , resistor R 2 , and transistor Q 3 , thereby turning the transistor Q 2 on. Meanwhile, the second end Ce of the coil is at a high voltage. The transistor Q 2 and the resistor R 2 are open, as there is no potential difference between two ends of the transistor Q 2 and the resistor R 2 . In this case, the current runs from the Vcc to the ground GND via the transistor Q 2 , the second end Ce of the coil, the first end Cs of the coil, and the transistor Q 3 . A magnetic field is generated by the current passing through the coil to drive the rotor to turn through another certain angle. Thus, by means of alternate on/off operation of the outputs OUT 1 and OUT 2 of the driver IC to alternately turn the transistors Q 1 and Q 2 on and off, synchronous change in high/low voltages of inverted phases is generated in two ends Cs and Ce of the coil. As a result, the stator generates alternating magnetic fields to drive the rotor.

Comparing FIG. 2 with FIG. 4, the conventional two-phase motor is directly connected to an application circuitry for the [US79KUA] driver IC, but the single-phase motor in accordance with the present invention uses a conversion circuit BLK 1 to allow the use of the [US79KUA] two-phase motor driver IC with the single-phase motor. The coil structure is thus simplified, and the motor quality is improved.

Comparing FIG. 2 with FIG. 5, the conventional two-phase motor is it directly connected to an application circuitry for the [US79KUA] driver IC powered by a DC voltage in a range of 3-18V. The single-phase motor in accordance with the present invention uses a conversion circuit BLK 2 comprising resistors R 5 and R 7 as well as resistors R 6 and R 8 that respectively form two sets of voltage dividing circuits to thereby reduce the input voltage higher than 24V to be below 18V. As a result, damage to the driver IC is avoided, as the available voltage of the driver IC would not exceed the rated voltage. Thus, the motor in accordance with the present invention may work in a wider input voltage range.

Although the invention has been explained in relation to its preferred embodiment as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the invention. It is, therefore, contemplated that the appended claims will cover such modifications and variations that fall within the true scope of the invention.