WO2012025904A2 - Verfahren zum ansteuern eines einphasigen bldc kleinmotors - Google Patents
Verfahren zum ansteuern eines einphasigen bldc kleinmotors Download PDFInfo
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- WO2012025904A2 WO2012025904A2 PCT/IB2011/053744 IB2011053744W WO2012025904A2 WO 2012025904 A2 WO2012025904 A2 WO 2012025904A2 IB 2011053744 W IB2011053744 W IB 2011053744W WO 2012025904 A2 WO2012025904 A2 WO 2012025904A2
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- WIPO (PCT)
- Prior art keywords
- voltage
- motor
- time
- fan
- induced voltage
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/14—Electronic commutators
- H02P6/16—Circuit arrangements for detecting position
- H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
- H02P6/182—Circuit arrangements for detecting position without separate position detecting elements using back-emf in windings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D25/00—Pumping installations or systems
- F04D25/02—Units comprising pumps and their driving means
- F04D25/06—Units comprising pumps and their driving means the pump being electrically driven
- F04D25/0606—Units comprising pumps and their driving means the pump being electrically driven the electric motor being specially adapted for integration in the pump
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
- F04D27/004—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids by varying driving speed
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
Definitions
- fans equipped with a control In order to ensure adequate ventilation of homes, offices and commercial areas such as kitchens, carpentry workshops and other establishments, it is preferable to use fans equipped with a control.
- the control can be designed centrally, so that it connects several devices and sensors.
- each fan can have its own decentralized control.
- Decentralized regulations offer the advantage that they are simple and cost-effective and can be easily retrofitted.
- industry standards for a fan it can be determined for a given application whether a fan meets certain requirements such as guaranteed air flow, economical use of heating or cooling energy, avoidance of excess and negative pressure and low power consumption. For example, a defined dependence between pressure difference and volume flow is given by industry standards.
- fan motors are suitable, which also have sufficient torque to achieve a desired air flow.
- brushless motors such as shaded pole motors, brushless DC motors (BLDC motors) and synchronous motors has proven itself.
- BLDC motors brushless DC motors
- synchronous motors it is generally required that the fan motor be operated in a defined direction of rotation. While this property is given by the construction in the case of a shaded-pole motor, the defined start-up direction for other types of motor is generally ensured by the actuation and / or by special design features. For example, it is known to watch a so-called auxiliary winding for starting single-phase or two-phase BLDC motors.
- Tasks of the application include the provision of an improved engine control for starting a fan motor, for operating the fan motor and for maintaining a predetermined volume flow.
- the application discloses a method for generating a predetermined volume flow of a fan with a fan motor, in particular with an electronically commutated DC motor.
- a first voltage U (t 1) is measured at a first time t 1 within a pause time of the fan motor via a measuring input of a motor controller.
- Break time is characterized in that the fan motor is not driven during the break time.
- a value of a first induced voltage U ind (t 1) is determined, for example, on the basis of a calculation rule or on the basis of a look-up table. The determination can also include further measured variables, such as a current through a stator coil of the fan motor.
- the value of the first induced voltage U ind (t 1) is stored in a computer readable memory.
- a second electrical voltage U (t 2) is measured via the measuring input of the motor controller and, based on the second electrical voltage U (t 2), a second induced voltage U ind (t 2) certainly.
- an actual value is determined, for example a cooldown or a voltage drop.
- This actual value is a measure of the pressure difference on the fan motor and depends on a speed difference of a rotor of the fan motor. The fan motor is driven based on the actual value according to a control method.
- a method for generating a constant volume flow according to the application requires this no pressure sensor or other separate sensors. Therefore, a fan that operates according to this method is particularly inexpensive to manufacture. Furthermore, this results in an increased reliability, since no pressure sensor is present, which could fail or clog.
- the cooldown of a rotor of the fan motor after switching off a fan motor depends on the pressure difference. This dependency will be used according to the application in order to control the fan motor so precisely that a given volume flow is maintained within the prescribed limits. This is also the case with changing load conditions and especially in overrun mode.
- the load required by the engine can be accurately determined according to the application resulting in increased smoothness and increased efficiency of the engine.
- Determining the volumetric flow rate for a given engine performance in accordance with the application also helps to determine if an airflow device is clogged. This makes it possible, for example, to determine the time of a filter change. Furthermore, this can implement a protective function for hot air devices. Thus, in case of blockage of the device, the performance can be reduced or The device is switched off completely before overheating occurs.
- a separate engine injecting device for selecting adapted volume flow rates in real estate using a method mentioned in the application enables saving of heating energy by limiting the delivered volume flow to a required set point.
- a volume flow control for a decentralized kitchen ventilation can be realized with an appropriate procedure. Because of the heavy pollution, the avoidance of a pressure sensor in this environment is particularly advantageous.
- the method can also be used to promote a desired amount of liquid.
- circulating pumps for heating systems can be operated efficiently.
- Other parameters, such as temperature, humidity and gas spectrum, which are related to the volume of air delivered, can also be adjusted more accurately using the method according to the application.
- the procedure can in principle be carried out with all engine types which have an electronic control.
- the use of electronically commutated DC motors has proven to be particularly advantageous, in particular the use of single-phase electronically commutated DC motors, which have a particularly simple and robust design.
- both internal and external rotor motors can be used.
- a pulse width modulation advantageous because the supplied voltage or the current can be controlled solely by switching on and off of transistors or relays, with transistors are very easy to control electronically.
- the regulatory procedure may in particular the following
- Steps include: comparing the actual value with a target value and, if the value of the actual value is above the target value, reducing an external voltage on a stator coil of the fan motor and then gradually increasing the external voltage. If the value of the actual value is below the setpoint, the external voltage on the stator coil of the fan motor is increased and then gradually reduced. In this case, only the mean value of the external voltage can be reduced or increased.
- External voltage is here, possibly over other components such as resistors and transistors, voltage applied to the stator coil of a power supply. The lowering or raising of the external voltage can, in particular, take place such that a pulse duty factor of a pulse width modulation is reduced or increased.
- the first time t 1 is located within the off period substantially at the beginning of the pause time
- the second time t 2 is located substantially at the end of the pause time, in particular at a distance of 0 - 10% of the pause time from Beginning or end of the break time.
- At least one further electrical voltage is determined at least one further time within the pause time, and from this a further induced voltage is determined.
- the actual value is determined from the first induced voltage, the second induced voltage, and the at least one further induced voltage.
- a first induced voltage from a first electrical voltage and a second induced voltage from a second electrical voltage are determined during at least one further pause time.
- a first difference is formed between the first induced voltage and the second induced voltages of the first pause time, and a second difference is formed between the first induced voltage and the second induced voltage of the second pause time.
- An average value is formed using the first difference and the second difference, and the actual value is determined from the mean value.
- electrical angles of the rotor are determined for at least two times during at least one pause time and the actual value is calculated using the electrical angle of the rotor, the actual value being in particular a decay time of the rotor.
- the comparison of the actual value with the desired value may in particular comprise the following steps. Reading in a setpoint for a volume flow. Reading a further setpoint to the setpoint for the flow rate from a lookup table, which is stored in a computer-readable memory and comparing the actual value with the other setpoint.
- the look-up table can in particular by calibration measurements under introduction of the fan motor in a measuring section and under Use of one or more pressure sensors in the measuring section are automatically created.
- the application discloses a device for achieving a predetermined volume flow.
- the device comprises an electronically commutated fan motor, an Ii bridge, wherein the electronic DC motor is arranged in a middle branch of the H-bridge and a motor control for controlling the fan motor.
- the motor controller in turn comprises a decoupling for determining a first electrical voltage and a second electrical voltage during a pause time of the electronically commutated fan motor, an evaluation unit for determining a first induced voltage based on the first electrical voltage and for determining a second induced voltage based on the second electrical voltage, and for determining an actual value, from the first induced voltage and the second induced voltage.
- the actual value is, for example, a pressure difference or a decay time.
- the motor control comprises a comparator for comparing the actual value with a desired value.
- the setpoint which depends on the given volume flow, may be preset, for example, or transmitted by a controller.
- the motor controller comprises a control unit for controlling the fan motor, based on an output of the comparator, wherein the control unit further comprises a control electronics for driving transistors of the H-bridge, and wherein the control electronics comprises a pulse width control for driving the transistors according to a duty cycle.
- the coupling may be connected to connection points, which are located in the circuit in front of and behind a stator coil of the fan motor.
- control electronics comprises a microcontroller, wherein the measuring input of the motor control is designed as a measuring input of the microcontroller and wherein the pulse width control is designed as a program in a computer-readable memory of the microcontroller.
- the application discloses a fan which includes a device according to any one of claims 10 to 13 and in which the fan motor is connected to fan blades of the fan.
- a ventilation system which comprises a fan according to the application and a ventilation control, wherein the ventilation control comprises an output for transmitting a pressure setpoint.
- the fan has an input for receiving the pressure setpoint and an interface for processing the pressure setpoint according to a transmission protocol.
- FIG. 1 shows a single-phase BLDC external rotor motor and a motor controller for controlling the same
- FIG. 2 shows the H-bridge from FIG. 1,
- FIG. 3 shows the motor control from FIG. 1
- FIG. 4 shows pulses of a pulse width modulation
- FIG. 5 shows pulses of a pulse width modulation
- FIG. 6 shows a definition of pulse widths
- FIG. 7 shows a voltage curve of a back-induced
- Figure 8 shows a current waveform of a coil current
- FIG. 9 shows a pressure-volume flow characteristic of a fan when using a speed control
- FIG. 10 shows a pressure-volume-flow characteristic of a fan when using a volume flow control according to the application
- FIG. 11 shows a current direction during a voltage pulse
- FIG. 12 shows a current direction after switching off the voltage pulse
- Figure 13 shows measured current and voltage characteristics during and after a positive voltage pulse
- Figure 14 shows measured current and voltage characteristics during and after a negative voltage pulse.
- FIG. 1 shows a single-phase BLDC (Brushless Direct Current) small motor 2 and a motor controller 1 for driving the single-phase BLDC motor 2.
- BLDC motor here stands for a brushless DC motor, in particular an electronically commutated brushless DC motor Permanent magnet. This can be both an external rotor and an internal rotor motor.
- the motor controller 1 includes an H-bridge 4 and a control electronics 3.
- the single-phase BLDC motor 2 is designed as an external rotor motor having a rotor 5 and a stator 6.
- the rotor 5 of the single-phase BLDC motor 2 is mounted about a rotational axis arranged perpendicular to the plane of the drawing.
- the rotor 5 includes a four-pole ring magnet 7, which is arranged on a rotor body 8 of the rotor 5.
- the poles of the ring magnet 7 are each located on one of the central axes of four sectors of the ring magnet 7.
- the sectors of the ring magnet 7 are marked in Fig. 1 by dividing lines.
- the stator 6 of the single-phase BLDC motor in turn has four pole shoes 10, which are each wound with a coil portion of a stator coil 11.
- the pole shoes 10 are opposite the ring magnet 7, so that an air gap is formed between the pole shoes 10 and the ring magnet 7.
- the pole shoes 10 are further shaped so that the end 12 of a pole piece 10, which is located in the direction of rotation 9, is made thicker than the end 13 of the same pole piece 10, which is in the opposite direction. This results in an asymmetric air gap between the pole piece 10 and the opposite ring magnet 7, which becomes narrower in the direction of rotation 9 and wider in the opposite direction.
- the counterclockwise direction with respect to the plane of the drawing is assumed here as the direction of rotation 9.
- the structure of the stator 6 causes the rotor settles after switching off the coil current in one of four rest positions.
- the H-bridge 4 has four field effect transistors whose gates are controlled by the control electronics 3. The field effect transistors are shown in simplified form in FIG. 1 as ordinary semiconductor transistors.
- the H-bridge 4 is connected to a DC voltage source 15, at whose poles an operating voltage VB is applied.
- the single-phase BLDC motor 2 is connected to the H-bridge through the terminals labeled "A" and "B".
- the structure of the H-bridge 4 is particularly well recognizable in the following Fig. 2.
- the control electronics 3 has a calculation unit 17 for calculating the induced counter voltage, a control unit 18 and a pulse generator 19.
- An input of the calculation unit 17 is connected to an output of a measuring resistor 39.
- An input of the control unit 18 is connected to an output of the calculation unit 17.
- Another input of the control unit 18 is connected to a setpoint signal Ns.
- An input of the pulse generator is connected to the output of the control unit.
- the four gates of the four transistors of the H-bridge are connected via separate lines with four outputs of the pulse generator 19.
- FIG. 2 shows the H-bridge 4 from FIG. 1.
- the H-bridge 4 contains four field-effect transistors 30, 31, 32 and 33, which are each because they are labeled 1H, IL, 2H and 2L.
- the left branch of the H-bridge 4 contains the field effect transistors 30 and 33.
- the right branch contains the field effect transistors 31 and 32.
- the middle branch characterized by the connection points "A" and "B", contains the single-phase BLDC motor second
- the source electrodes of the field effect transistors 30 and 32 are connected to the positive pole of the DC power source 15, which is at the operating voltage V B.
- the drains of the field effect transistors 30 and 32 are respectively connected to the
- Source electrodes of the field effect transistors 31 and 33 connected.
- the drain electrodes of the field effect transistors 31 and 33 are connected to a zero potential, here marked "0V".
- the connection point of the H-bridge 4, to which the operating voltage is applied, is also referred to as "high-side", while the connection point of the H-bridge 4, which is at zero potential, is also referred to as "low-side".
- the gate electrodes of the field-effect transistors 30, 31, 32 and 33 are connected via separate connecting lines to the pulse generator 19, which is not shown in Fig. 2.
- the drain electrode is connected to the source electrode via a flywheel diode 35, 36, 37, 38, respectively.
- the free-wheeling diodes 35, 36, 37, 38 are designed as body diodes of MOSFETs (metal oxide semiconductor field effect transistors), in particular of power MOSFETS.
- the single-phase BLDC motor 2 is connected to the H-bridge 4 via the terminals labeled "A" and "B".
- the stator 6 of the single-phase BLDC motor 2 is identified by a coil symbol, and in FIG. gates of the ring magnet 7 characterized by lines connected with rectangles.
- FIG. 3 shows the single-phase BLDC motor 2 with the motor controller 1 in a representation which illustrates the logical structure of the motor controller 1.
- the four sectors of the permanent magnet 7 are symbolized by boxes connected by lines.
- the polarity of a sector of the permanent magnet 7 in Fig. 3 is denoted by "N" and "S", respectively.
- the supply lines to the single-phase BLDC motor 2 are connected via two decoupling lines with a signal output 40.
- the signal extraction 40 is connected to the signal and level adjustment 41 via an output channel and an input channel.
- the signal and level adaptation 41 is connected to a control unit 42 via an output channel and an input channel.
- the signal extraction lines are not shown in FIG. 1 for reasons of clarity.
- the control unit 42 includes a signal conversion and evaluation unit 43, a motor logic 44, and a pulse generation unit 45 for generating the digital drive pulses for controlling the single-phase BLDC motor 2.
- the control unit 42 has an output and an input channel with a pulse match 46 connected.
- the pulse match 46 is connected to power stages 47 via an output and an input channel.
- the decoupling 40, the signal and level adaptation 41, the 43, the pulse adjustment 46 and the power stages 47 are connected to the primary switching power supply 48 via power supply lines.
- Fig. 1 the structure shown in Fig. 3 is shown in simplified form. In this case, the signal extraction 40 and the signal and level adaptation 41 correspond to the calculation unit 17.
- the pulse generation unit 45 and the pulse adaptation 46 correspond to the control unit 18.
- the power stage 47 corresponds to the H-bridge 8.
- the primary switched-mode power supply 48 corresponds to the DC power source 15.
- FIGS. 9 and 10 the pressure difference between inflow and outflow sides of a fan is plotted against the amount of air delivered by a fan. Furthermore, a 60 m ' TÜV characteristic field is shown.
- 80 is the setpoint curve and 82 and 81 are the lower and upper tolerance limits, respectively.
- FIG. 9 shows a characteristic 83 of a fan with a speed control which is operated in accordance with the DIN standard of 60 m 3 , and a characteristic curve 84 of the same device when operated according to the DIN standard of 30 m 3 . It is particularly noticeable that the characteristic field is not maintained in the negative pressure range, ie in overrun operation.
- a characteristic curve 85 of a fan is entered in FIG. 10, which is operated with a method for controlling the volume flow according to the application. It can be seen here that the characteristic is almost everywhere close to the setpoint curve 80 and that even in the negative pressure range there is still a clear distance to the upper tolerance limit 81.
- the single-phase BLDC motor shown in FIG. 1 is supplied with current via the DC voltage source 15.
- the control electronics 3 controls the gates of the transistors of the H-bridge 4 via control signals. there a transistor is opened via an applied high signal and closed again via a low signal.
- the control electronics 6 determines the control signals such that the current through the stator coil 11 is suitably commutated. This means that a suitable torque is exerted on the ring magnet 7 of the rotor 5 by the magnetic field of the pole shoes 9.
- the control electronics 3 regulates the current flowing through the single-phase BLDC motor by pulse width modulation (PWM).
- PWM pulse width modulation
- the control electronics 3 divides the time into successive periods T PWM. During a period of time T PWM, a negative or positive voltage pulse is generated.
- the pulse duration of a voltage pulse is in each case a specific fraction of a time interval T PWM.
- the ratio pulse duration / T PWM is the duty cycle (duty cycle) of the pulse width modulation.
- the control electronics 3 controls the single-phase BLDC motor 2 by means of the pulse width modulation over successive
- the duration of a commutation cycle is the time between two successive ones
- a wiring of the transistors 30, 31, 32, 33 is described according to a "fast-decay” mode in which during a turn-off time, the current in the stator coil 11 is actively decelerated by the operating voltage V B.
- a "slow-decay” mode in which the transistors are switched during the switch-off time in such a way that a circulating current is produced by which the magnetic field in the stator coil 11 is reduced or a mixed form of both.
- the single-phase BLDC motor is driven by a series of positive voltage pulses.
- a current flows from "A" to "B".
- the single-phase BLDC motor is driven by a train of negative voltage pulses.
- a current flows from "B" to "A".
- the control electronics 6 opens the transistors 30 and 31 during a turn-on time and closes the transistors 32 and 33.
- the opening of the transistors 30 and 31 takes place via a positive voltage pulse.
- the connection point "A” is connected via the transistor 30 to the operating voltage VB and the connection Termination point “B” is connected via the transistor 31 to ground.
- This voltage difference leads to a current flow from "A” to "B”.
- the transistors 30, 31, 32, 33 are closed. Due to the inductance of the stator coil 11 continues to flow a coil current from "A” to "B", which is passed through the freewheeling diodes 38 and 37. On the one hand, this prevents a voltage peak at the transistors 30, 31, 32, 33. On the other hand, the operating voltage now counteracts the coil current and leads to a faster decay of the coil current.
- control electronics 6 For control via a negative voltage pulse, the control electronics 6 opens the transistors 32 and 33, so that the connection point "A" is connected to ground via the transistor 33 during a turn-on time and the connection point "B" is connected via the transistor 32 to the operating voltage VB is.
- control electronics 6 closes the field-effect transistors 30, 31, 32, 33. Due to the inductance of the stator coil 11, a current continues to flow from "B” to "A”, which is now conducted via the freewheeling diodes 36 and 35.
- the speed of the BLDC motor 2 is adjusted by increasing or decreasing the duty cycle. As a result, the current flowing through the stator coil 11 is increased or decreased.
- the torque exerted on the rotor 5 at a given current depends on the angular position of the rotor 5. In particular, there are rotor positions where the applied torque disappears. These angles are electrical angle 180 ° el. away from each other and are referred to as "dead centers".
- the motor logic 44 determines appropriate parameters for voltage pulses to drive the power stages 47 to determine the rotor position of the rotor. These parameters include pulse width, pulse height, and pulse spacing.
- the pulse generation unit 45 uses these parameters to generate digital drive pulses for determining the position of the rotor 5.
- the pulse adaptation 46 further modifies the digital drive pulses and thus activates the transistors of the power stages 47, the power stages in the embodiment of FIG. Bridge 4 correspond.
- the power stage then generates a current which flows via the supply lines of the single-phase BLDC motor 2 into the coil winding of the stator coil 11.
- a measuring signal is then coupled out. This measurement signal is transmitted to the signal output 40.
- the signal extraction 40 generates a current signal from the measurement signal.
- This current signal is modified by the signal and level adjustment and forwarded to the signal conversion and evaluation 43 of FIG.
- the signal conversion and evaluation then calculates parameters for the required voltage pulses for starting the single-phase BLDC motor 2. From the parameters for the required voltage pulses, the motor logic subsequently determines suitable parameters for the digital drive pulses for driving the power stages 47. From the parameters for the digital drive pulses, the pulse generation unit 45 generates digital drive pulses.
- the pulse match 46 then further modifies the digital drive pulses and thereby drives the transistors of the power stages 47, the power stages 47 in the embodiment of FIG. 1 corresponding to the H-bridge 4.
- the power stage then generates a current which flows via the supply lines of the single-phase BLDC motor 2 into the coil winding of the stator coil 11.
- the rotor 5 stops in one of four rest positions after switching off the voltage supply.
- FIG. 4 shows the change of the duty cycle during a commutation cycle at the change of the voltage characteristic at a gate of one of the transistors 30, 31, 32, 33.
- the pulse width x of a voltage pulse 60 is here indicated in units of 2mus.
- the cycle time 61 is denoted by Tl.
- the pulse width increases in FIG. 4.
- the first two voltage pulses 60 are at the beginning of a commutation cycle, whereas the last two voltage pulses 60 are at the end of a commutation cycle.
- FIG. 5 shows the driving of one of the transistors by voltage pulses on the basis of the voltage curve at a gate of a transistor. nes of the transistors. Each time D voltage pulses 63 of the same length follow each other. Subsequently, the duty cycle changes. The increase of the duty cycle takes place according to a scheme for a sine pulse width modulation.
- FIG. 6 shows two averaged current profiles resulting from the driving of the transistors by means of a predetermined pulse width modulation scheme in the stator coil 11. Current waveforms for two different power levels are shown. The time axis extends over a period of time 68.
- the time period 68 corresponds to the length of a half cycle, ie 180 ° el.
- the evaluation unit 43 of the control unit shown in FIG. 3 uses the zero crossing of the induced voltage as a trigger to determine the beginning of the time period 68.
- the beginning of the period 68 is determined so that the zero crossing of the induced voltage in the middle of the pause time 69 occurs.
- Fig. 7 shows the voltage waveform of the back-induced voltage V ind in the stator coil 11 during a pause time of a commutation cycle.
- the back-induced voltage V ind is plotted against the electrical angle ⁇ el. Because of the asymmetrical structure of the pole shoes 10 shown in FIG. 1, the course of the back-induced voltage is likewise asymmetrical.
- the back-induced voltage V ind is present at the measuring points A and B when no current flows through the stator coil 11 and otherwise has to be determined by calculation.
- the maximum occurs in the case of an asymmetrical pole shoe, as shown in FIG. 1, but later. While the poles of the ring magnet 7 are between the pole pieces, the back-induced voltage drops to zero. As can be seen in FIG. 7, this occurs approximately at the electrical angles 90 ° and 270 °.
- the voltage and the current flow between the connection points A and B are determined. This voltage is the sum of the back induced voltage V ind generated by the permanent magnets of the rotor and the voltage generated by the continuation of the current in the stator coil 11.
- I the current in the stator coil 11
- L is the inductance of the stator coil 11
- R is the resistance of the stator coil 11. Therefore, the back-induced voltage V ind can be determined from the measurement of current I and voltage V when the constants VB, L, R are known. After the coil current has decayed substantially, approximately applies
- V V_ind, (2) so that the re-induced voltage in this case can be tapped directly between the connection points "A" and "B".
- FIG. 8 shows the voltage curve 75 of the back-induced voltage and the current profile 67 of the coil current I. From FIG. 8, the phase position of the voltage profile 75 to the current profile 67 becomes clear. As described above, the phase shift 76 is determined by the control unit 42 so that the zero crossing of the induced voltage 75 occurs in the middle of the pause time 69. From the measurement of current I and voltage V determines the
- V_ind co * K_ind * cos (9_el). (3)
- co means the angular velocity of the rotor
- K ind a suitably chosen constant
- ⁇ el the electric one Angle.
- the angle dependence of the back-induced voltage V ind is given by a cosine-like shape function f ( ⁇ el), as seen in FIG.
- the constant K ind and the electrical angle ⁇ el can thus determine the angular velocity co of the rotor.
- the knowledge of the angular velocity can be used in particular for controlling the single-phase BLDC motor 2 for driving a fan. This fan is not shown in Fig. 1.
- FIG. 8 is a graph showing the averaged coil current I of FIG. 5 and the back-induced voltage V ind. By means of the back-induced tension determined during the pause time, it is possible to determine the speed drop.
- a suitable rule for determining the pulse widths is set first, the Includes pause time 69, in which there is no external voltage at the stator coil 11. Such a provision for pulse width determination is explained in the description of FIGS. 4-6.
- This rule is stored in the control unit 42 shown in FIG.
- the control unit 42 advantageously determines the pause time 69 in such a way that the beginning and the end of the pause time 69 occur in each case substantially at predefined start and end positions of the rotor.
- a reference angle or a reference time can be determined by determining a commutation time.
- the control unit 42 determines the start and end times of the pause time 69 based on an averaged rotor speed.
- An average rotor speed can be determined, for example, by the time period between two zero crossings of the induced voltage.
- the voltage induced in the stator coil 11 is measured at at least two points in time and a speed difference of the rotor is determined therefrom. From this difference in speed, a pressure difference is determined by means of a calibration curve. Based on a further calibration curve, a pulse width modulation of the motor 2 is then controlled so that the motor 2 promotes a predetermined amount of air per time.
- the back-induced voltage depends not only on the speed but also on the rotor position.
- the rotor position is derived from the induced voltage, so that it is possible to dispense with a separate position sensor.
- the control unit 42 calculates the value U (0) of the induced voltage based on the relationship (1) of the current and the voltage between the terminal points "A" and "B".
- the evaluation unit 43 stores a value U (0) of the induced voltage.
- the evaluation unit 43 determines the value U (a) of the induced voltage.
- the evaluation unit uses the values U (0) and U ( ⁇ ) to determine the decay time t 0 according to equation (7).
- the evaluation unit 43 compares the decay time t 0 with a setpoint value. If the cooldown is above the setpoint, the controller incrementally increases the half-cycle to half-cycle duty cycle until the cooldown equals the setpoint.
- the controller 42 lowers the duty cycle by an amount that depends on the difference to the setpoint. Subsequently, the control unit 42 again increases the duty cycle step by step until the decay time corresponds to the setpoint value.
- control unit 42 may also apply counter pulses to decelerate the rotor when the decay time t 0 is below the setpoint.
- control unit 42 may also reduce the pulse width to zero for one or more half-cycles when the cooldown t 0 is below the setpoint.
- a method for obtaining a predetermined constant volume flow is given. In this case, the desired value is determined from t 0 to a desired volume flow on the basis of a relationship between decay time and volume flow. This relationship was previously measured by a calibration and is stored as a table in the memory of the control unit 42.
- the evaluation unit 43 determines from the speed increase of the rotor 5 a turn-off time during which no external voltage is applied to the stator coil 11. In this way it can be achieved that the rotational speed of the rotor falls by friction below a desired maximum speed, before the stator coil 11 is charged again with voltage.
- the control unit 42 can also apply one or more counter-pulses in order to actively decelerate the rotor 5.
- the control unit 42 determines the value of the induced voltage at a plurality of points in time, in particular at least three points in time, within the pause time 69.
- the evaluation unit 43 determines the rotor angles from the course of the induced voltage at the points in time within the pause time 69 Furthermore, the evaluation unit determines rotor speeds at the times within the pause time 69 from the rotor angles and from the induced voltages at the points in time within the pause time 69. From the rotor speeds, the evaluation determines The speed reduction is used by the control unit 42 in order to control the pulse width control.
- the control unit 42 determines the value of the induced voltage at a plurality of times, in particular at least three points in time, within a first pause time 69.
- the evaluation unit 43 determines a first average of the induced voltages at the times within the first pause time.
- the aforementioned steps are repeated and a second mean value of the induced voltages determined at times within a second pause time.
- the evaluation unit 43 determines from the first and the second mean value in each case a first and second average rotor speed.
- this method can also be carried out for several mean values. From the averaged rotor speed, the evaluation unit 43 determines an averaged speed drop or an averaged decay time of the rotor 5. This speed drop is used by the control unit 42 to control the pulse width control.
- the averaging according to the third method can also be combined with the first or second method in such a way that, for two or more pause times 69, in each case averaged induced voltages are determined at specific times within the pause times.
- FIG. 11 shows a current path for the above-mentioned "Fast-
- FIG. 11 shows a current path for the "fast-decay" circuit at the beginning of a turn-off time of the first half period.
- the transistors 30, 31, 32, 33 are turned off. Due to the degradation of the magnetic field in the stator coil 11, a current is generated by the freewheeling diodes 38 and 37. The operating voltage counteracts this current flow.
- the coil current drops to zero before the coil voltage drops noticeably. As long as a coil current flows, the operating voltage and the coil voltage approximately compensate, so that approximately zero potential 0V is present at both measuring points A and B.
- FIG. 13 shows a current profile 90 and a voltage curve 91 when a positive voltage pulse is applied during a first half-period of the H-bridge
- FIG. 14 shows a current profile 92 and a voltage curve 93 when a negative voltage pulse is applied during a second half-period of the H-bridge
- the current waveforms 90, 92 are determined by the voltage drop U mess at the measuring resistor 39. This results in the current I mess through the single-phase BLDC motor 2 by means of division by the measuring resistor 39
- I mess U mess / R mess.
- the voltage curve in FIG. 13 relates to the voltage UA measured at the measuring point A against the zero potential, whereas the voltage curve in FIG Fig. 14 refers to the measured at the measuring point B against the zero potential voltage UB.
- the vertical axes in FIGS. 13 and 14 are each normalized such that a division corresponds to 0.2 volts for the upper curve and a division corresponds to 20 volts for the lower curve.
- the horizontal axis is normalized so that a division corresponds to 0.5 milliseconds.
- the voltage zero points for the vertical axes are indicated on the right side and for the second curve the operating voltage V B on the right side is plotted in each case.
- the current flowing through the stator coil 11 of the single-phase BLDC motor 2 increases to a maximum value I max during the opening time of the transistors 30 and 31.
- the opening time of the transistors is approximately 1.5 ms, so that a 1.5 ms-second voltage pulse is applied to the stator coil 11 at the level of the operating voltage V B.
- the current flows through the freewheeling diodes 38 and 37 of the transistors 33 and 32 against the operating voltage.
- the current direction in the measuring resistor 39 reverses.
- zero potential 0V is present at measuring point A via freewheeling diode 38.
- the coil current decreases relatively rapidly, while the voltage between the measuring points A and B initially increases only slowly. As soon as the current through the stator coil 11 has dropped to zero, the coil voltage also drops to zero. As a result, half of the operating voltage VB / 2 is present at the measuring point A, whereas on the other side of the freewheeling diode 37 the full operating voltage VB / 2 is applied. Voltage VB is present. Thus, the free-wheeling diode blocks 37. In the following, due to the generator effect of the stator coil 11, the voltage at the measuring point A again decreases slightly. A voltage curve corresponding to FIG. 13 is measured at the measuring point B, wherein a voltage is measured at the measuring point B which corresponds to the voltage curve 91 mirrored at VB / 2 at the measuring point A.
- the curves 90, 91 in FIG. 13 deviate from the curves 92, 93 of FIG.
- the flux generated by the permanent magnet 7 cooperates with the magnetic flux generated by the coil current or counteracts it.
- the field of the permanent magnet 7 increases the magnetization of the coil core, while the magnetization is attenuated in the second case.
- the inductance of the coil core and thus the inductance of the stator coil 11 decreases due to the increasing orientation of elementary magnets.
- the rotor 5 is at start already in the region of a rest position, which is behind one of the pole pieces 10 in the direction of rotation.
- the energy previously introduced into the stator coil 11 is released again during a time ⁇ t. This energy serves to charge the battery or an additionally provided capacitor. The energy E released during the time ⁇ t is again through
- This energy corresponds to the previously introduced into the stator coil 11 according to formula (8) energy, apart from losses due to heating and remanence effects of the coil core.
- the time At over which the current drops to zero and in which the freewheeling diodes 37, 38 are conductive, depends on the initial maximum current I max and thus on the bias. This can also be seen in FIGS. 13 and 14: the fall time ⁇ t 1 according to FIG. 13 is slightly longer than the fall time
- the thus-determined orientation is used by the control electronics 3 to set a polarity of a first half period to start the single-phase BLDC motor 2 so as to start in a predetermined direction.
- the voltage measuring points A and B are connected by the coupling 40 respectively to inputs of the control electronics 3.
- At ports A and B becomes a positive one rectangular voltage pulse placed.
- a measuring pulse is applied to an input of the control electronics 3.
- a microcontroller of the control electronics 3 is programmed so that it measures the voltages UA (t 1) and UB (t 1) at the measuring points A and B, which are present during the measuring pulse and the voltage is converted into a digital value.
- the digital value of the voltages UA and UB is stored in a memory.
- a negative rectangular voltage pulse is applied to the terminals A and B.
- a measuring pulse is again applied to an input of the control electronics 3.
- the digital value of the voltages U A (t 2) and U B (t 2) is stored in a memory.
- the sign of the voltage between the measuring points AB in the first half-cycle is determined from the sign of the voltage difference AU AB.
- a positive rectangular voltage pulse is first applied to the stator coil 11. After switching off the positive voltage pulse, a timer is started. As soon as the voltage U mess at the measuring resistor 39 has dropped substantially to zero, a switch-off of the timer is triggered. The fall time At 1 of the timer is stored in a memory and the timer is set to zero.
- a negative rectangular voltage pulse is applied to the stator coil 11.
- the timer is started. As soon as the voltage U mess at the measuring resistor 39 has fallen substantially to zero, a switch-off of the timer is triggered.
- the fall time At 2 of the timer is stored in a memory and the timer is set to zero. In a comparison step, the fall times At 1 and
- the sign of the voltage between the measuring points A and B in the first half period is determined from the sign of the difference of the fall times At_2-At_l.
- the height and length of the voltage pulse must be dimensioned such that a sufficiently high maximum current I max is achieved.
- the height and length of the voltage pulse is limited by the fact that the rotor should not move much further by the applied torque until starting the rotor. In a determination of the rotor orientation over the maximum coil current according to the application, a particularly high sensitivity of the orientation determination can be achieved the different bias of the bobbin at the maximum coil current has the greatest effect.
- a determination of the rotor orientation over a decay time of the coil current offers the advantage of a particularly simple feasibility. Only comparisons of an input voltage to the zero potential and a time measurement are required. The time measurement can advantageously take place with the aid of a timer which is already integrated in a microcontroller for controlling the motor. By comparison with the zero potential can be dispensed with the use of a comparator.
- the Ii bridge can also be operated with IGBT (Insulated Gate Bipolar) transistors or conventional semiconductor transistors.
- IGBT Insulated Gate Bipolar
- MOSFETs are particularly advantageous because the MOSFETs already include a freewheeling diode in the form of the body diode.
- multiple series-connected transistors or power stages can be used in the H-bridge.
- the commutation can be done before the dead center of the rotor 5, to limit the coil current.
- the rotor 5 can also be selectively braked by a counter-pulse.
- a fan according to the application is also suitable for mobile applications that can be operated with regenerative energy.
- a method for starting a DC motor according to the application not only allows starting of the motor in a preferred direction but also in the opposite direction. This can be used to temporarily operate the fan in the opposite direction. Startup in both directions can also be used for other applications of small engines, where the engine must rotate in both directions, such as a power window.
- the voltage measurement via a shunt resistor can also be replaced by another form of current measurement, for example with the aid of a Hall probe.
- Steps includes:
- Method according to one of the points A1 to A.3, wherein determining the first current and determining the second current comprises:
- a device for starting an electronically commutated DC motor according to one of claims A.l to A.4, which includes:
- Calculation unit for determining a control for starting the electronically commutated DC motor, which is electrically connected to a connection point on the measuring resistor and with the coupling-out.
- Steps includes: Opening a transistor 1H and a transistor IL of an H-bridge for a predetermined opening duration;
- B.5 Device for starting an electronically commutated DC motor according to one of claims B.l or B.2, which includes:
- Duty cycle in the range 1: 8 to 1 is varied.
- Apparatus for driving an electronically commutated DC motor with pulse width modulation according to any one of Cl to C.4, which includes: - Motor control with an H-bridge and a control electronics, wherein the electronically commutated DC motor is located in a central branch of the H-bridge,
- Calculating unit for determining a control of the electronically commutated DC motor according to one of claims 1 to 3, which is electrically connected to a connection point on the measuring resistor and the coupling.
- C.6 The device according to item C.5, wherein the connection points of the decoupling in the circuit are located immediately before and immediately behind a stator coil.
- Fan comprising a device according to item C.4 to C.6, wherein the electronically commutated DC motor is connected to fan blades of the fan.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Motors That Do Not Use Commutators (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
Description
Claims
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DE112011102832T DE112011102832A5 (de) | 2010-08-27 | 2011-08-26 | Verfahren zum Ansteuern eines einphasigen BLDC Kleinmotors |
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Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
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WO2014208095A1 (ja) * | 2013-06-28 | 2014-12-31 | パナソニックIpマネジメント株式会社 | 換気装置 |
JP2015010530A (ja) * | 2013-06-28 | 2015-01-19 | パナソニックIpマネジメント株式会社 | 換気装置 |
JP2015028301A (ja) * | 2013-07-30 | 2015-02-12 | パナソニックIpマネジメント株式会社 | 換気装置 |
JP2015048795A (ja) * | 2013-09-03 | 2015-03-16 | パナソニックIpマネジメント株式会社 | 換気装置 |
CN105971867B (zh) * | 2016-05-04 | 2018-04-13 | 珠海格力电器股份有限公司 | 压缩机故障的检测方法和装置 |
EP3372843A1 (de) * | 2017-03-10 | 2018-09-12 | MAICO Elektroapparate-Fabrik GmbH | Verfahren zum betreiben eines lüftungsgeräts sowie entsprechendes lüftungsgerät |
WO2020099276A1 (de) * | 2018-11-13 | 2020-05-22 | Beckhoff Automation Gmbh | Verfahren zum bestimmen einer rotorstellung eines bldc-motors |
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DE10035829C2 (de) * | 1999-08-14 | 2002-07-18 | Ziehl Abegg Gmbh & Co Kg | Verfahren zum Betreiben einer Lüftungseinrichtung sowie Lüftungseinrichtung |
US6754151B2 (en) * | 2001-01-25 | 2004-06-22 | Dphi Acquisitions, Inc. | BEMF timing system |
US8164285B2 (en) * | 2008-11-13 | 2012-04-24 | Marvell World Trade Ltd. | External disturbance detection system and method for two-phase motor control systems |
-
2011
- 2011-08-26 WO PCT/IB2011/053744 patent/WO2012025904A2/de active Application Filing
- 2011-08-26 DE DE112011102832T patent/DE112011102832A5/de not_active Withdrawn
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Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2014208095A1 (ja) * | 2013-06-28 | 2014-12-31 | パナソニックIpマネジメント株式会社 | 換気装置 |
JP2015010530A (ja) * | 2013-06-28 | 2015-01-19 | パナソニックIpマネジメント株式会社 | 換気装置 |
US10041496B2 (en) | 2013-06-28 | 2018-08-07 | Panasonic Intellectual Property Management Co., Ltd. | Ventilation device |
JP2015028301A (ja) * | 2013-07-30 | 2015-02-12 | パナソニックIpマネジメント株式会社 | 換気装置 |
JP2015048795A (ja) * | 2013-09-03 | 2015-03-16 | パナソニックIpマネジメント株式会社 | 換気装置 |
CN105971867B (zh) * | 2016-05-04 | 2018-04-13 | 珠海格力电器股份有限公司 | 压缩机故障的检测方法和装置 |
EP3372843A1 (de) * | 2017-03-10 | 2018-09-12 | MAICO Elektroapparate-Fabrik GmbH | Verfahren zum betreiben eines lüftungsgeräts sowie entsprechendes lüftungsgerät |
WO2020099276A1 (de) * | 2018-11-13 | 2020-05-22 | Beckhoff Automation Gmbh | Verfahren zum bestimmen einer rotorstellung eines bldc-motors |
CN113424432A (zh) * | 2018-11-13 | 2021-09-21 | 倍福自动化有限公司 | 用于确定bldc马达的转子姿态的方法 |
US11496078B2 (en) | 2018-11-13 | 2022-11-08 | Beckhoff Automation Gmbh | Method for determining the rotor position of a BLDC motor |
Also Published As
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DE112011102832A5 (de) | 2013-06-13 |
WO2012025904A3 (de) | 2013-05-10 |
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