Abstract:
A drive control device for a brushless motor includes a full-wave rectifying-filtering circuit, a voltage regulating circuit, a drive control circuit and a protection circuit. A combination of the rectifying-filtering and voltage regulating circuit provides both the motor coil and the drive control circuit capable of operating at a normal working status to ensure the brushless motor with safe and reliable operation. Therefore, the brushless motor does not need a bulk and complex transformer for voltage drop, which may reduce the reliability of the operation.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a drive control device for a brushless motor of a fan. 
   2. Related Art 
   The conventional brushless motor of the fan includes a transformer connected with a power source for voltage drop to output for rectifying and filtering to provide for a motor coil and a drive control circuit. However, the existing transformer increases cost, volume and complexity of the motor due to its weight, bulk body and working requirement and reduces reliability and stability of the motor due to heat generation. Moreover, the brushless motor utilizes a current limit protection to keep a working current below a limited value when a supply current is higher than the limited value. However, the motor circuit does not break off and the motor coil is continuously working. As such, the motor coil is easy to overheat or burn out under the high loading situation in a long run. 
   SUMMARY OF THE INVENTION 
   The present invention is to provide a reliable and stable drive control device for a brushless motor. 
   The drive control device of the present invention can ensure the motor coil of the brushless motor works in a safe and reliable situation for a long run. 
   Accordingly, the drive control device for the brushless motor of the present invention comprises a rectifying circuit with an input connected to a power source and an output connected to one terminal of each of a first and a second inductors of the brushless motor, a regulating circuit with an input connected to the output of the rectifying circuit, a drive control circuit with an input connected to an output of the regulating circuit and an output connected to the other terminal of each of the first and the second inductor, and a protection circuit connected between the output of the rectifying circuit and ground. The rectifying circuit includes a bridge rectifier with four diodes bridging in parallel and a capacitor filter with a capacitor. The regulating circuit includes two resistors and a regulator tube. The resistors are connected between the output of the rectifying circuit and the ground in series, and the regulator tube is connected between a junction of two resistors and the ground in series. The drive control circuit includes a first and a second integrated chips, a first and a second complementary metal oxide semiconductors (CMOS), a first, a second, a third, a fourth, a fifth and a sixth resistors and a first, a second and a third capacitors. The first resistor has one terminal connected to the output of the rectifying circuit and the other terminal connected to a first pin of the first integrated chip. The second resistor is connected between a third pin of the first integrated chip and the ground in series. The first integrated chip has a second and a fourth pins connected to two input pins of the second integrated chip, respectively. The second integrated chip has a Vcc pin connected to the output of the regulating circuit and a GND pin directly connected to the ground. The first capacitor is connected between a CT pin of the second integrated chip and the ground in series. The fourth resistor is connected between the first output pin of the second integrated chip and a gate of the first CMOS in series. The fifth resistor and the second capacitor connected in parallel are connected between the gate of the first CMOS and ground in series. A drain of the first CMOS is connected to the other terminal of the first inductor, and a source of the first CMOS is connected to the ground. The third resistor is connected between the second output pin of the second integrated chip and a gate of the second CMOS in series. The sixth resistor and the first capacitor connected in parallel are connected between the gate of the second CMOS and the ground in series. A drain of the second CMOS is connected to the other terminal of the second inductor, and a source of the second CMOS is connected to the ground. The protection circuit includes a regulator tube connected between the output of the rectifying circuit and the ground. 
   Furthermore, the drive control device comprises a current limit circuit including a first and a second diodes, a triode, a seventh, a eighth and a ninth resistors and a capacitor. The first and the second diode are connected between the first and the second output pin of the second integrated chip and a collector of the triode in series, respectively. An emitter of the triode is connected to the ground. A base of the triode connected with the seventh resistor in series is connected to each source of the first CMOS and the second CMOS. The eighth resistor connected with the capacitor in parallel is connected between the base of the triode and the ground. The ninth resistor is connected between each source of the first CMOS and the second CMOS and ground in series. 
   Furthermore, the drive control device comprises a voltage limit circuit including a CMOS, a triode, a regulator tube and a first, a second and a third resistors. A drain and a source of the CMOS are connected to the output of the rectifying circuit and each of the first and the second inductors in series, respectively. A gate of the CMOS connected with the third resistor in series is connected to a collector of the triode. The first resistor is connected between the drain and the gate the CMOS in parallel. An emitter of the triode is connected to the ground. A base of the triode connected with the regulator tube and the second resistor in series is connected the source terminal of the CMOS. 
   Using a combination of the rectifying and regulating circuit provides both the motor coil and the drive control circuit capable of operating at a normal working status to ensure the brushless motor with safe and reliable operation. Therefore, the brushless motor does not need a bulk and complex transformer for voltage drop, which may reduce the reliability of the operation. By two diodes and a triode forming the current limit circuit, when the current over a limit, the motor coil will stop under the control of triode. As such, it can prevent the motor coil from overheating or burning out under the high loading situation in a long run. 
   Other objects, advantages and novel features of the present invention will be drawn from the following detailed embodiments of the present invention with attached drawings, in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a circuit diagram of a drive control device for a brushless motor according to a first preferred embodiment of the present invention; 
       FIG. 2  is a circuit diagram of a drive control device for a brushless motor according to a second preferred embodiment of the present invention; and 
       FIG. 3  is a circuit diagram of a drive control device for a brushless motor according to a third preferred embodiment of the present invention 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , a drive control device for a brushless motor of the present invention includes a full-wave rectifying-filtering circuit  10 , a voltage regulating circuit  20 , a drive control circuit  30  and a protection circuit  40 . 
   The rectifying-filtering circuit  10  has the input connected to a power source and the output connected to the input of the regulating circuit  20  and one terminal of each inductor L 1 , L 2  of the motor. The output of the regulating circuit  20  is connected to the input of the drive control circuit  30  so that a steady working voltage can be obtained. The output of the drive control circuit is connected to the other terminal of each inductor L 1 , L 2 . The protection circuit is connected between the output of the rectifying-filtering circuit  10  and ground. 
   The full-wave rectifying-filter circuit  10  includes a bridge rectifier with four diodes D 1 , D 2 , D 3 , D 4  bridging in parallel and a capacitor filter with a capacitor C 1 . The diodes D 1 , D 2 , D 3  D 4  can be chosen from the group of 1N4001, 1N4005 and 1N4007 rectifier diodes. 
   The voltage regulating circuit  20  includes two resistors R 1 , R 2  and a regulator tube Z 1  chosen from the group of BZX85C18, BZX85C15 and 1N5931B regulator diodes. The resistors R 1 , R 2  are connected between the output of the rectifying-filtering circuit  10  and ground in series. The regulator tube Z 1  is connected between the junction of two resistors R 1 , R 2  and ground in series. 
   The drive control circuit includes two integrated chips U 1 , U 2 , two complementary metal oxide semiconductors (CMOS) TN 1 , TN 2 , a plurality of resistors R 3 , R 4 , R 7 , R 8 , R 9 , R 10  and a plurality of capacitors C 2 , C 3 , C 4 . The integrated chip U 1  is chosen from the group of HW104A, SH12A and HW101 Hall sensors, and the integrated chip U 2  is chosen from the group of BA6406, PT308F-B, and AP1307 drive integrated circuits (ICs). CMOS TN 1 , TN 2  is chosen from the group of 2SK2996, RDX120N60 and RDX100N60 power MOSFETs (metal oxide semiconductor field effect transistors). The resistor R 3  has one terminal connected to the output of the rectifying-filtering circuit  10  and the other terminal connected to a first pin (IN+) of the integrated chip U 1  for providing the working voltage. The resistor R 4  is connected between a third pin (IN−) of the integrated chip U 1  and ground in series. Second and fourth pins of the integrated chip U 1  are connected to two input pins HS(−) and HS(+) of the integrated chip U 2 , respectively. Vcc pin of the integrated chip U 2  is connected to the output of the regulating circuit  20 . The capacitor C 2  is connected between CT pin of the integrated chip U 2  and ground in series. GND pin of the integrated chip U 2  is directly connected to ground. The resistor R 8  is connected between the first output pin (Output  1 ) of the integrated chip U 2  and the gate (G terminal) of CMOS TN 1  in series. The resistor R 9  and the capacitor C 4  connected in parallel are connected between the G terminal of CMOS TN 1  and ground in series. The drain (D terminal) of CMOS TN 1  is connected to the other terminal of the inductor L 1 , and the source (S terminal) of CMOS TN 1  is connected to ground. Similarly, the resistor R 7  is connected between the second output pin (Output  2 ) of the integrated chip U 2  and the G terminal of CMOS TN 2  in series. The resistor RIO and the capacitor C 3  connected in parallel are connected between the G terminal of CMOS TN 2  and ground in series. The D terminal of CMOS TN 2  is connected to the other terminal of the inductor L 2 , and the S terminal of CMOS TN 2  is connected to ground. 
   The protection circuit includes a regulator tube Z 2  connected between the output of the rectifying-filtering circuit  10  and ground. The regulator tube Z 2  is chosen from the group of 1N5955B and 1N5956B regulator diodes. 
   In order to ensure the motor coil works in a safe and reliable range, the drive control device of the present invention further includes a current limit circuit  50 , as shown in  FIG. 2 . The current limit circuit  50  includes two diodes D 5 , D 6 , a triode Q 1 , a plurality of resistors R 11 , R 12 , RA and a capacitor C 5 . The diodes D 5 , D 6  are chosen from the group of 1N4148, 1N4448 and RLS4148 regulator diodes. The triode Q 1  is chosen from the group of UMT2222A, SST2222A and MMST2222A triodes. The diode D 5  is connected between the Output  1  of the integrated chip U 2  and the collector of the triode Q 1  in series, and the diode D 6  is connected between the Output  2  of the integrated chip U 2  and the collector of the triode Q 1  in series. The emitter of the triode Q 1  is connected to ground. The base of the triode Q 1  connected with the resistor R 11  in series is connected to each S terminal of the CMOS TN 1  and TN 2 . The resistor R 12  connected with the capacitor C 5  in parallel is connected between the base of the triode Q 1  and ground. The resistor RA is connected between each S terminal of the CMOS TN 1  and TN 2  and ground in series. 
   Furthermore, in order to provide the voltage on the motor coil in a safe and reliable range, the drive control device of the present invention includes a voltage limit circuit  60 , as shown in  FIG. 3 . The voltage limit circuit  60  includes a CMOS TN 3 , a triode Q 2 , a regulator tube Z 3  and a plurality of resistors R 13 , R 14 , R 15 . The CMOS TN 3  is chosen from the group of 2SK2996, RDX120N60 and RDX100N60 power MOSFETs. The triodes Q 2  is chosen from the group of UMT2222A, SST2222A and MMST2222A triodes. The regulator tube Z 3  is chosen from the group of 1N5955B and 1N5956B regulator diodes. The D and S terminals of the CMOS TN 3  are connected to the output of the rectifying-filtering circuit  10  and each of the inductors L 1  and L 2  of the motor coil in series, respectively. The G terminal of the CMOS TN 3  connected with resistor R 15  in series is connected to the collector of the triode Q 2 . The resistor R 13  is connected between the D and G terminals of the CMOS TN 3  in parallel. The emitter of the triode Q 2  is connected to ground. The base of the triode Q 2  connected with regulator tube Z 3  and the resistor R 14  in series is connected the S terminal of the CMOS TN 3 . 
   The principle of the drive control device for the brushless motor of the present invention is as follows. 
   As shown in  FIG. 1 , an alternative current (AC) power is inputted through the transistors D 1 , D 2 , D 3 , D 4  for bridging rectification and through the capacitor C 1  for filtrating to obtain a direct current (DC) power. The DC power is directly provided to the inductors L 1 , L 2  of the motor coil in a constant voltage. Moreover, the CMOS TN 1 , TN 2  can be protected to avoid voltage supplying to S and D terminals thereof over a permitted endurable value. 
   The resistors R 1 , R 2  and the regulator tube Z 1  constitute the voltage dropping and regulating circuit. The resistors R 1  and R 2  are connected in parallel to be a divider. When the resistor R 1  receives the voltage lower than a regulation voltage of the regulator tube Z 1 , the voltage V 0  outputted to the drive control circuit is the dividing voltage of the resistor R 2 . Conversely, when the dividing voltage of the resistor R 2  higher than the regulation value, according to the regulating characteristic of the regulator tube Z 1 , V 0  will not exceed the regulation voltage. 
   The integrated chip U 1  is a magnetic Hall sensor, which will be induced by the switch of N pole and S pole in the magnetic field. When the second pin of the integrated chip U 1  has high level output, the fourth pin will have low level output, vice versa. It is impossible for two pins to have both high level or low level outputs. The output signal is compared and amplified by the integrated chip U 2  to output by Output  1  and Output  2 . The integrated chip U 2  is mainly used for pre-driving. Alternatively, if Output  1  has high level output, Output  2  will have low level output, and if Output  1  has low level output, Output  2  will have high level output. When the high level output from Output  1  is inputted to G terminal of the CMOS TN 1  and the low level output from Output  2 , CMOS TN 1  will open to drive inductor L 1  and CMOS TN 2  will close to stop inductor L 2 , respectively. Alternatively, when the high level output from Output  2  is inputted to G terminal of the CMOS TN  2  and the low level output from Output  1 , CMOS TN 2  will open to drive inductor L 2  and CMOS TN 1  will close to stop inductor L 1 , respectively. 
   As shown  FIG. 2 , the diodes D 5 , D 6 , the triode Q 1 , the resistors R 11 , R 12 , RA and the capacitor C 5  constitute the current limit circuit  50 . When the resistor RA detects a predetermined current limit, via the resistor R 11  to base of the triode Q 1 , the triode Q 1  will open. As such, two output pins of the integrated chip U 1 , via the diodes D 5 , D 6 , will reduce outputting voltage level to zero. Each G terminal of the CMOS TN 1 , TN 2  receives zero voltage level so that the CMOS TN 1 , TN 2  will close to stop both inductors L 1 , L 2 . Therefore, the current limit circuit  50  can provide the protection function to reduce the temperature of inductors L 1 , L 2 . 
   As shown in  FIG. 3 , the CMOS TN 3 , the triode Q 2 , the regulator tube Z 3  and the resistors R 13 , R 14 , R 15  constitute the voltage limit circuit  60 . When the voltage is over a regulation limit of the regulator tube Z 3 , due to the breakdown characteristic of the diode, current passing via the regulator tube Z 3  to the base of the triode Q 2 , the triode Q 2  will open. As such, G terminal of the CMOS TN 3  receive zero voltage level so that the CMOS TN 3  will close to provide the over voltage protection. When the voltage becomes normal, no current passing the regulator tube Z 3 , the triode Q 2  will close. That is, CMOS TN 3  opens and the drive control device can work normally. 
   It is understood that the invention may be embodied in other forms without departing from the spirit thereof. Thus, the present examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.