Background technology
Dc brushless motor is called for short BLDC, and it progressively replaces brush direct current motor.It is developed by brush direct current motor, and wherein, the stator of motor adopts coil windings, and rotor adopts permanent magnet.In the rotor operation process, use DC brushless motor controller detection rotor position, the power-up sequence of automatic switchover stator winding guarantees the rotor rotation and produces moment of torsion output.Wherein the key component that phase place switches to the Electric Machine Control process is carried out in the detection rotor position.The detection of rotor-position at present mainly contains two kinds:
One, sensor method:
Use the sensor rotor-position, the main at present hall device that uses.This kind method is converted to the signal of telecommunication with rotor-position signal, thereby conducting and the shutoff of commutation signal with the power device of control inverter is provided, thereby can control the rotation of rotor.But it is very accurate that it requires installation site of transducer, and alignment error will cause commutation inaccurate, and it is not suitable for motor and uses when high-speed cruising, because motor efficient when high-speed cruising descends fast, even can burn motor and controller.
Two, back electromotive force detection method:
P-m rotor is in rotary course, and stator coil produces induced electromotive force, and controller detects induced electromotive force and carries out commutation control to judge rotor-position.But when motor rotor speed was very low, the induced electromotive force amplitude was very low, make that the error that detects is bigger, thereby this method was not suitable for detection rotor position when the motor low cruise.
So for the detection of motor rotor position, first method is not suitable for the situation that motor runs up, and second method is not suitable for the situation of motor low-speed running.Therefore, the commutation control of above-mentioned two kinds of detection methods and dynamic adaptable all are subjected to certain restriction.
The utility model content
The technical problems to be solved in the utility model is the dynamically adapting scope smaller defect at DC brushless motor controller in the prior art, provide a kind of can be applicable to simultaneously motor at low speed and when running up accurate detection rotor position so that the DC brushless motor controller of the accurate commutation of motor.
The technical scheme that its technical problem that solves the utility model adopts is: construct a kind of DC brushless motor controller, it comprises and linking to each other with motor and in order to the drive circuit of drive motors, also comprise the control circuit that links to each other with described drive circuit, the rotor position detection circuit that links to each other with described motor and control circuit simultaneously in order to detection motor rotor position, described rotor position detection circuit comprises rotor sensor position detecting circuit and the back-emf sensing circuit that links to each other with motor, and described control circuit is included in the single-chip microcomputer that motor switches to described sensor detection circuit when reaching speed-changing back-emf sensing circuit.
In DC brushless motor controller described in the utility model, described rotor sensor position detecting circuit comprises position transducer, described position transducer be arranged at motor rotor the axle on.
In DC brushless motor controller described in the utility model, described position transducer is Hall switch sensor EW-632.
In DC brushless motor controller described in the utility model, the hall signal in the sensor input connection rotor position detection circuit of described single-chip microcomputer.
In DC brushless motor controller described in the utility model, described single-chip microcomputer is the MEGA48 single-chip microcomputer.
In DC brushless motor controller described in the utility model, described back-emf sensing circuit comprises zero cross detection circuit.
In DC brushless motor controller described in the utility model, described zero cross detection circuit comprises voltage comparator.
In DC brushless motor controller described in the utility model, described drive circuit comprise link to each other with motor in order to the control rotating speed of motor, turn to, and the power switch of torque.
In DC brushless motor controller described in the utility model, described drive circuit is the full bridge driving circuit that includes the electric power field effect transistor.
Implement DC brushless motor controller of the present utility model, have following beneficial effect: it mixes use rotor sensor position detecting circuit and back-emf sensing circuit, select to use different rotor position detecting methods by single-chip microcomputer in the control circuit and program with control under the different speeds of service of motor, thereby accurate detection rotor position, so that motor carries out accurate commutation, further control Driver Circuit is to the control of motor rotation, it has effectively adapted to motor and has started, low speed, the high speed different operating stage is to the requirement of commutation accuracy, widen motor dynamic duty scope, improved operating efficiency.
Embodiment
DC brushless motor controller provided by the utility model is applicable to that motor makes it in accurate commutation of different phase and normal operation at low speed or when running up.
Referring to Fig. 1 and Fig. 2, Fig. 1 is the theory diagram of the utility model DC brushless motor controller; Fig. 2 is the structural representation of the utility model DC brushless motor controller one embodiment.
The DC brushless motor controller that the utility model provides comprises: link to each other with motor 3 and in order to the drive circuit 2 of drive motors 3, the control circuit 1 that links to each other with drive circuit 2, the rotor position detection circuit 4 that links to each other with motor 3 and control circuit 1 simultaneously, rotor position detection circuit 4 is in order to detect the position of motor 3 rotors, and switching is the key of whole motor 3 control procedures because phase place is carried out in the detection rotor position.Rotor position detection circuit 4 comprises: rotor sensor position detecting circuit 41 that links to each other with motor 3 and back-emf sensing circuit 42; Control circuit 1 comprises and is used for switching according to the speed-changing of motor the single-chip microcomputer 11 of sensor detection circuit and back-emf sensing circuit 42.
Dc brushless motor 3 by the device for power switching in the control Driver Circuit 2 control motor 3 rotating speed, turn to, torque and the protection motor 3.Control circuit 1 mainly adopts single-chip microcomputer in the utility model, and controls the different rotor position detection circuit of switching by program.Different motors has different parameters, its coefficient of potential difference, the speed-changing of corresponding motor is also different, and promptly different motors carries out the switching from the sensor detection circuit to the back-emf sensing circuit when different speed-changings, and this switching is to realize by the plug-in of single-chip microcomputer.
The rotor sensor position detecting circuit comprises position transducer, position transducer be arranged at motor rotor the axle on.Hall signal in the sensor input connection rotor position detection circuit of single-chip microcomputer, promptly motor is when starting, and what it directly adopted is the rotor sensor position detecting circuit.Electric machine controller carries out the first location of rotor-position earlier according to the Hall output signal, stator current increases gradually, and rotor begins to quicken gradually, when speed reaches the motor speed-changing, back-emf is reliable and stable, and then single-chip microcomputer changes back electromotive force automatically over to and detects drive manner.Normally used motor speed (KV) value is more than 2000, if KV is 2000, then the motor speed-changing is 1000.When using the motor of other KV value, can change speed-changing.Therebetween, single-chip microcomputer will output signal make rotor position detection circuit enter back-emf sensing circuit according to the signal of position transducer.Concrete commutation principle is as follows:
In rotor position detection circuit 4, its by the rotor magnetic pole position signal as the commutation signal of electronic switch circuit, and and then give control circuit 1 with detected signal feedback, control circuit in time switches power device according to rotor-position.
Be installed on the position transducer on the armature spindle, realize the real-time detection of rotor-position.It is preferably the hall position sensor of Mageneto-sensitive type, and the utility model adopts Hall switch sensor EW-632, and its magnetic sensitivity reaches 3mT, and its output waveform such as Fig. 6 start and low-speed stage at motor 3 usually, uses hall signal to carry out commutation control.
In back-emf sensing circuit 42, preferably, the detection of back-emf adopts zero passage method to detect, and referring to Fig. 4, it is the circuit theory diagrams of the back-emf sensing circuit of an embodiment.It mainly detects the variation of pulse by single-chip microcomputer, present embodiment adopts four voltage comparator LM339, and input signal U, V, W are respectively three-phase voltage.When phase U back-emf arrives zero crossing, LM339 will produce a pulse; When back-emf is zero, 2uU=uV+uW is arranged, as seen from the figure, when uU from+→-process, LM339 exports a trailing edge pulse, when uU from-→+process, LM339 exports a rising edge pulse.So single-chip microcomputer can obtain the position of zero crossing by detecting the variation of pulse.Its operation principle as shown in Figure 5, Fig. 5 is the fundamental diagram that the back-emf of the utility model one embodiment detects.At any time, motor 3 three phase windings have only two to be conducted, the just anti-phase respectively 120 ° of electrical degrees of conducting of every phase winding.By measuring three-phase winding terminal and neutral point current potential with respect to dc bus negative terminal (or anode), when certain end points current potential equates with the neutral point current potential, then this this phase winding back electromotive force zero passage of moment just must be carried out commutation to power device after 30 ° of electrical degrees.Thereby learn the switching sequence of power device in the full bridge driving circuit.
From Fig. 5 as seen, each cycle is made up of 6 60 ° sector, 120 ° of each element conductive, i.e. conducting in two continuous sectors.Therefore two kinds of PWM modulation systems are arranged: half-bridge carrier wave and full-bridge carrier wave.The half-bridge carrier wave causes all the other biphase currents to produce fluctuation by all producing afterflow mutually.And adopt the full-bridge carrier wave, and then have two to be conducted all the time, by not producing afterflow mutually, current fluctuation and torque pulsation are all less.Preferably, adopt full bridge driving circuit, promptly use the field of electric force effect management and control system of a pair of P raceway groove and N raceway groove.
(reach as high as 250000r/min) when motor 3 runs up, the commutation of motor 3 realizes by Single Chip Microcomputer (SCM) program control.When the control that enters the state during stage, program is estimated this zero crossing time at first according to the time of last commutation, waits back-emf zero crossing to be detected then.Zero crossing is after the time accurately when detecting, and program calculates the theoretical time (30 ° of commutation time) of this commutation point.Do correction according to the parameter exchange phase time that is provided with subsequently, with the maximum efficiency of performance motor 3.When the commutation time arrived, the on off operating mode of program switching mosfet pipe entered control stage of NextState then.
Referring to shown in Figure 3, it is the connection diagram of 1 li single-chip microcomputer of control circuit among the utility model one embodiment.This single-chip microcomputer adopts MEGA48, and it is the core of control circuit.This single-chip microcomputer price is suitable with low-grade single-chip microcomputer, has high performance-price ratio, and it has 8 path 10 position A/D conversion, and 23 programmable I/O mouths are arranged at most, can define the output and the input direction of I/O mouth arbitrarily.For recommending output, can directly drive large current load during output.The input of this single-chip microcomputer connects hall signal, sees HA among Fig. 3, HB, three hall signals of HC.The MEGA48 single-chip microcomputer has 3 hardware PWM passages, can realize arbitrarily<16, the PWM pulse-width modulation output of phase place and frequency adjustable.Program uses the MEGA48 timer internal as the reference clock that detects speed-regulating signal.When MEAGE48 is operated in 16MHz, timer is operated in the following time of pattern of 8 frequency divisions, and the time precision of timer is 0.5 μ s, and the precision that program detects control signal reaches 0.5%.This series monolithic has certain flexibility, and can simplify external circuit, and its signal processor speed is fast, peripheral circuit is few, and system forms simple and reliable, has simplified the composition of dc brushless motor, improve motor properties greatly, and helped the miniaturization and the intellectuality of motor.
Drive circuit 2 is controlled by control circuit 1 with electromotive power output, and then driving power switch 21 is with the armature winding of drive motors 3.Can adopt the device for power switching of full-control type, for example: can turn-off transistor (GTO), field of electric force effect transistor (MOSFET), metal gate bipolar transistor IGBT module, integrated gate commutated thyristor (IGCT), reach electronics IEGT (IEGT).Preferably, drive circuit 2 is for including the full bridge driving circuit 2 of electric power field effect transistor.This drive circuit 2 adopts the full-controlled switch device, can be convenient to drive circuit 2 and realize intellectuality, high frequencyization, miniaturization.
In sum, the utility model binding site detection method and back-emf detection method are mixed use with dual mode.When electric motor starting, low cruise, use the sensor method, when high-speed cruising, use the back electromotive force detection method.This method has improved the dynamically adapting scope of DC brushless motor controller greatly, and speed adjustable range can be more than from 0 to 100,000 rev/min.
The above only is a preferred embodiment of the present utility model, not in order to restriction the utility model, all any modifications of being done in spirit of the present utility model and principle, is equal to and replaces or improvement etc., all should be included in the protection range of the present utility model.