JP2013526260A - Ceiling fan - Google Patents

Abstract

  An EC motor for driving a plurality of fan blades and a motor controller configured to determine a rotor position using a back EMF and configured to pressurize the motor according to the rotor position and a predetermined command Ceiling fan to prepare. Also a method for controlling the ceiling fan.

Description

  The present invention relates to ceiling fans, and more particularly, but not limited to, sensorless sinusoidal ceiling fans and methods for controlling ceiling fans.

  Ceiling fans are typically powered by a high pole AC induction motor that operates directly with the utility AC line voltage, with a high degree of frequency slip that makes operation very poor. . A typical household ceiling fan may be optimized for low cost and long life, but may not be optimal for electrical efficiency. For example, a typical household ceiling fan consumes about 75 W of electrical input power, but only produces about 15 W of mechanical shaft power, with an efficiency of just 20%.

  Ceiling fan efficiency replaces an AC induction motor with an electronic commutation (EC) motor comprising a permanent magnet rotor with a plurality of alternating magnetic poles and a stator with one or more phase windings controlled by an electronic switch. It can be greatly improved by doing. EC motors are generally capable of achieving efficiencies of 60% and higher, so that only 25 W of electrical input power is required to generate 15 W of mechanical shaft power.

  The use of an EC ceiling fan can potentially reduce energy consumption by as much as 66% compared to typical AC motor ceiling fans. As the use of ceiling fans is prevalent throughout the world in temperate, tropical and subtropical areas, improvements to EC ceiling fan technology are about reducing global energy consumption and global weather. Can play an important role in its effect on variation.

  The EC ceiling fan detects the position of the rotor magnetic poles so that a current of the correct magnitude and polarity flows through the windings in order to generate the required rotational torque (DOR) motoring torque. Requires an electronic controller to pressurize the windings.

  Also, the winding current waveform, amplitude and phasing can be controlled to achieve an acoustically quiet operation that may be desirable to the consumer.

  The electronic controller requires rotor position sensing (RPS) means to determine the position of the rotor poles with respect to the stator windings. One possibility is to use a high resolution encoder, which is very expensive. Another option is a magnetically sensitive electronic Hall effect switch located in close proximity to the rotor magnet, which directly senses the polarity of the magnet. These Hall effect sensor outputs can then be decoded by a logic circuit or microprocessor to determine the location of the rotor and thus the timing of the winding switching pattern. However, Hall effect sensors are relatively fragile electronic components that, when embedded in a stator, can cause reliability problems due to interconnection with the device itself and the main controller circuit.

  U.S. Pat. No. 7,157,872 discloses a ceiling fan having an outer rotor DC brushless motor with an additional magnetic ring mounted on the outside of the outer rotor. As a result, the Hall effect device can determine the rotor position from the outside of the motor. However, using Hall effect devices and their interconnections can increase the mechanical complexity of the motor and reduce motor efficiency due to the misalignment of the secondary magnetic disk with the actual rotor poles. , May lead to an increase in acoustic noise, which may cause errors in communication timing.

  Generally speaking, the present invention proposes a ceiling fan that uses a high efficiency electronic commutation (EC) motor with a sensorless motor controller. Sensorless controllers have the advantage of eliminating the use of Hall effect devices or encoders to determine rotor position, thereby improving start-up reliability and providing smooth and quiet operation.

  The sensorless controller can include a PWM DC-DC converter with output filtering, for example, the converter can be a synchronous buck converter. The converter may employ sinusoidal pulse width modulation (SPWM) using one or more switching configurations that are speed dependent. For example, at low speeds, the switching waveform is roughly sinusoidal, with low harmonic content and can achieve very quiet operation, and at high speeds, higher order harmonics may be added to the switching waveform. , Thereby improving the efficiency. Output filtering and / or switching configurations may have the advantage of optimizing efficiency and / or minimizing noise.

  The sensorless controller can include a stop sequence that saves the position of the rotor at the time of stop in a non-volatile program memory, thereby retaining information when the power is shut off. The sensorless controller can include a start-up sequence that depends on the rotor position when the fan last stopped. This can have the advantage of improving the chances of success of the startup sequence.

  A sensorless controller can employ switching logic that results in each phase being sequentially connected to a common rail over one third of the electrical frequency. This has the advantage that the current can be determined based on the voltage drop across the switch and the current can be used during the start sequence to determine if the start sequence was successful. obtain.

  In addition, AC: DC isolated power supplies (SMPS) provide safe isolation from incoming utility power supplies and provide users with low voltage, such as power supplies that meet IEC safety extra low voltage and / or UL 1310 class 2 limits It can be used to convert the line voltage to a level that protects against electrical shock due to the level. The power source can be separated from the motor at the sealed portion of the mounting tube. Alternatively, the AC: DC power supply can be a non-isolated converter topology, thereby preventing the user from contacting live components due to the structural characteristics of the fan. Alternatively, the AC: DC power supply can be rectified and filtered directly from the incoming AC power supply.

  According to a first specific description of the invention, a ceiling fan according to claim 1 is provided.

  One or more exemplary embodiments of the invention will now be described with reference to the following drawings.

1 is a perspective view from below of an EC ceiling fan according to an exemplary embodiment. FIG. FIG. 3 is an exploded perspective view showing the details of mounting on the blade 10, the upper cover 15, and the EC motor 30. It is the fragmentary perspective view of the EC fan seen from the bottom which shows EC motor 30 and electronic controller PCBA351. 2 is an exploded perspective view of an EC motor 30. FIG. It is the detailed perspective view of EC motor stator 350 seen from the bottom. 3 is a schematic electrical block of a power source 136 and a printed circuit board assembly (PCBA) 351. 5 is a graph of voltages Abmf420, Bbmf421, and Cbmf422 based on the winding common point 413. It is a figure of the software state of a main controller operation state. It is a software flowchart of a standby state (STANDBY STATE) operation | movement. It is a software flowchart of a start state (START STATE) operation | movement. It is a software flowchart of a driving | running state (RUN STATE) operation | movement. It is a software flowchart of a driving | running state PWM interruption | blocking (RUN STATE PWM INTERRUPT) operation | movement. It is a graph of voltage Aph410, Bph411, and Cph412 on the basis of 0V. It is a graph of voltage Aph410 on the basis of 0V. It is a software flowchart of a shutdown state (SHUTDOWN STATE) operation | movement.

  Rotor position sensing according to an exemplary embodiment uses electronic sensing means (back EMF RPS) that measures commutation timing by measuring the back EMF voltage associated with the winding, and thus Hall effect The device is eliminated.

  The simplest buck EMF RPS method employs a three-phase inverter controlled by a 2-ON / 1-OFF 6-step switching pattern. In this method, a three-phase motor is driven such that at any instant two phases are pressurized and the voltage is measured in a third unconnected phase where the current is zero. Thus, the controller can directly sense the back emf voltage (Vbmf) generated in the third phase by the movement of the rotor magnet. The controller generally detects when the sensed phase Vbmf crosses zero, and this is sensed via analog or digital means when the sensed phase is turned ON and of the pressurized phase. Is used as the basis for calculating the timing of the next commutation time when one of the The motor speed is controlled either by varying the DC bus voltage or by one or more pulse width modulation (PWM) of the inverter switching devices.

  Back EMF RPS with 2-ON / 1-OFF rectification offers the advantage of simplicity, but has the major disadvantage of generating acoustic noise at each moment when the winding is switched from ON to OFF. . The generated noise may be unacceptable for ceiling fans operating in close proximity to people in the home environment, including the bedroom.

  Optimal smoothness and low acoustic noise for motor drive can be improved by the use of an EC motor driven by an SPWM inverter, and the winding voltage or current is controlled to be a sine wave. And is maintained in synchronization with the motor Vbmf.

  The implementation of a back EMF RPS using an SPWM inverter has the problem that all windings must be continually pressurized so that the Vbmf of the motor cannot be measured directly under zero current conditions. is there. The motor terminal voltage is the applied PWM voltage and cannot be used directly to determine the back EMF. In such cases, a high speed microprocessor is required that performs sophisticated mathematical transformations on the measured voltage and current to determine the rotor position. The cost and complexity of these devices and associated support circuitry may be less desirable for ceiling fans.

  According to an exemplary embodiment, back EMF sensing is employed with a synchronous buck converter. Since the synchronous buck converter output is separated from the SPWM of the inverter switching device by a filter component, the winding voltage is measured to approximate the back EMF.

  This allows accurate sensing of the rotor position in the sine wave motor and eliminates the need for complex calculations to determine the back EMF.

Fan Structure FIG. 1 shows an EC ceiling fan according to an exemplary embodiment. A lower cover 11 with three fan blades 10 mounted radially around the central tube assembly 13 and an infrared LED lens 12 in the center provides reasonable ingress protection against dust and water from below. Therefore, the blade 10 is closely fitted to the lower end portion of the blade 10.

  2 and 3 are exploded views of the blade mounting configuration. The blade 10 is aligned with the blade mounting web 331 of the motor 30 and is fixed in place by screws 312.

  Referring to FIG. 3, the raised turret 314 of the lower cover 11 can be aligned with the mounting slot 315, whereby the lower cover 11 can be pushed up and rotated in the vertical direction to be locked in place. I understand that I can do it. A motor controller PCBA 351 having an infrared signal detector 352 is mounted at the center of the motor 30.

  FIG. 4 shows an exploded view of the EC motor 30. The motor 30 is an external rotor, has a two-rotor configuration of axial magnetic flux without slots, and is generally called a torus motor.

  The motor 30 can be formed from a non-ferromagnetic material of suitable strength, such as die cast aluminum or injection molded thermoplastic aluminum, and the mounting of the blade mounting web 331 and the upper and lower bearings 324 and 326. And a rotor shell 330 that provides a bearing turret 332 that performs the following. Alternatively, the rotor shell 330 and the upper cover 15 may be formed as a single integral component.

  The upper rotor 340 includes an annular disk made of a ferromagnetic material, and the annular magnetic ring 341 is composed of permanent magnet material, is bonded in place, and faces sixteen equally spaced pole sectors facing the upper surface of the stator 350. Is magnetized using The upper rotor 340 is attached to the rotor shell 330 from the inside of the motor by three mounting screws 327.

  The stator 350 has a plastic injection-molded core, and the main motor shaft 351 is pushed and held in place by a spline 357 and a circlip 358.

  The rotor shell 330 fitted to the upper rotor 340 and the bearings 324 and 326 slides down the shaft 351 to a fixed position and is held in place by the circlip 322 and the washer 323. The corrugated washer 325 provides a bearing preload.

  The lower rotor 342 comprises an annular disk made of a ferromagnetic material, and the annular magnetic ring 343 is made of permanent magnet material, glued in place, and 16 equally spaced facing the lower surface of the stator 350. Magnetized using a pole sector.

  Both the upper ring magnet 341 and the lower ring magnet 343 are preferably made of ceramic magnetic materials that are widely available at low cost, such as those used in loudspeaker ring magnets. Alternatively, a complete ring can be formed from a plurality of magnet segments. Alternatively, rare earth, neodymium iron boron or other high strength permanent magnet materials can be used in the complete ring or can be formed from multiple magnet segments.

  FIG. 5 shows a detailed perspective view of the lower surface of the stator 350, which is wound 15 times for each pole of a 0.9 mm diameter enamel-coated copper magnet wire with a resistance of 0.4 ohms. A 16-pole three-phase winding having an inductance per phase of 180 uH is annularly wound. The stator teeth 355 are formed from an injection molded thermoplastic material and are used to guide the magnet wire during winding and do not form the active part of the motor magnetic circuit.

  A molded turret 356 extends from the lower surface of the stator core and provides a housing for PCBA 351 that is held in place by a mounting clip 354. The stator windings terminate directly to the PCBA through the loom and plug 353.

Motor Controller According to an exemplary embodiment, the EC motor is pressurized by the motor controller 351 shown in FIG. Motor controller 351 is electrically connected to 12V DC power source 136 and motor stator winding 350.

  The motor controller 351 generally includes a three-phase synchronous step-down converter 409, a microcontroller 368, a driver circuit 367 for the converter 409, voltage sensing filters 386 to 397, and a 3.3V power source 381 for the microcontroller 368. Including. The motor controller 351 is disposed on a printed circuit board assembly (PCBA).

  The user makes desired control settings, such as speed, via the infrared transmitter 373, which is provided by the infrared receiver 352. Microcontroller 368 then measures the back EMF from voltage sense filters 386-397 and provides the appropriate switching signal amplified by driver 367 to converter 409. Generally speaking, when the fan speed needs to be increased, the level of the applied voltage from the converter 409 increases, and vice versa. The frequency of the applied voltage from the converter 409 is always synchronized with the motor speed (measured from the back EMF).

  The SMPS 136 provides a 12 Vdc power supply (12 Vdc supply) to the controller 351. The SMPS 136 provides output current and overload protection for the 12Vdc power rail. The thermal switch 374 shuts off power to the motor controller 351 if the internal temperature exceeds a safety limit due to motor or controller failure or excessive ambient temperature.

  The 3.3V power supply 381 includes a voltage regulator for generating a 3.3V power supply rail for the microcontroller 368. Capacitors 382 and 383 provide sufficient charge storage to power the microcontroller 368 until the fan speed is reduced from maximum rpm and quiesced when the AC power supply 135 is shut off. Diode 380 prevents capacitor 382 from discharging during the 12Vdc rail.

  The 12Vdc power rail is periodically measured by the microcontroller 368. Resistors 384 and 385 attenuate the 12Vdc supply voltage to below 3.3V so that measurement by the microcontroller 368 is possible. The attenuated power rail voltage is connected to an analog-to-digital converter (A / D) input AN4. When the voltage drops below 9.5V, the microcontroller 368 enters a very low power shutdown state (SHUTDOWN STATE). When the 12Vdc rail returns above 10.5V, the motor drive is reactivated. Converter 409 includes a set of mosfet switches 361-366 for converting a 12V supply DC voltage into a three-phase pulse width modulated voltage. The PWM is smoothed by filter inductors 400 to 402 each having a value of 50 uH and filter capacitors 403 to 405 each having a value of 47 uF, resulting in a substantially sinusoidal voltage (ie, harmonics are reduced). )

  The switches 361 to 366 are controlled to an enhanced sinusoidal PWM (ESPWM). In other words, the PWM duty cycle varies across each electrical frequency approximately according to a sinusoid. As a result of combining filters 400 to 405 and ESPWM, the operation of the motor can be made nearly silent.

  The ESPWM switching pattern of each electric frequency is stored in the internal memory of the microcontroller 368 as a data table (WaveTablePWM). Multiple tables can be used to optimize performance at various operating speeds, for example, one table is optimized for low noise at low speed and another table is optimized for optimal efficiency at high speed Turn into.

According to the switching pattern, the outputs Adrv, Bdrv, Cdrv, Aen, Ben, and Cen of the microcontroller 368 are supplied to the driver circuit 367. The driver 367 then sends a drive signal to the gate of each switch according to the Mosfet drive logic shown in the table below.

  Electronic protection is provided via microcontroller software to detect and shut down motor stalls or abnormal operating conditions.

  User control of the fan function is executed via the infrared remote control transmitter 373 using a control signal received by the infrared receiver 352 directly attached to the motor controller PCBA 351. Alternatively, a radio frequency (RF) remote control transmitter and input module may be used. Alternatively, a low level analog voltage or current signal, such as 0-10V or 4-20 mA, can be connected directly to the input port IRX of the microcontroller 368.

Back EMF Sensing As described above, when using a synchronous buck converter, the voltage on the motor winding 350 is very close to the back EMF. Thus, according to an exemplary embodiment, a three phase winding voltage is applied to the filter circuits 386-397 to attenuate signal voltage levels and reduce electrical noise.

  The back EMF shown in FIG. 7 has three phases that are approximately sinusoidal. Microcontroller 368 detects the zero crossing of the winding voltage and determines the frequency and phase of the back EMF. By monitoring the frequency and phase of the back EMF, the PWM voltage can be applied synchronously to ensure that the winding is pressed in the desired direction in the correct sequence.

Motor Control Strategy A motor control strategy generally consists of a start algorithm, an operation algorithm, and a stop algorithm. Start and stop is usually upon user activation or may depend on stored data such as scheduled start and stop times.

  FIG. 8 shows a software state diagram when the main controller is operating. When the power-on reset (POR) signal is received, the main controller enters a standby state (STANDBY). Upon receipt of a valid speed or ON signal from the infrared controller 373, the main controller will start the motor step by step until it reaches an RPM sufficient to enter a running (RUN) operation. become. If an OFF or SPEED = 0 control signal is received at START or RUN, the controller returns to STANDBY. If VDC drops below 9.5V in any mode, the main controller will enter shutdown state (SHUTDOWN) and be terminated by reset (RESET) when power is applied again and reaches 10.5V I can only do that.

  Also, during start-up, back EMF sensing faces difficulties. Since Vbmf induced by the stator winding is zero when the rotor is stationary, a special start-up routine is required. The simplest approach is to pressurize the windings in a predefined sequence and periodically sample Vbmf until the rotor speed is sufficient to detect the direction of rotation (DOR), allowing back EMF RPS operation Could be. The main disadvantage of this method may be that from an unknown starting position, there is only 50% opportunity for the rotor to start rotating in the correct direction. Since the ceiling fan rotor has substantial repulsion due to the mass and diameter of the blade assembly, it takes tens of seconds to stop the rotor and repeat the start-up sequence if the first step DOR is incorrect Sometimes. Fan start errors are clearly visible in the ceiling fan and may be undesirable.

  Other approaches include applying large current pulses to the windings to induce and detect magnetic saturation in the motor, or injecting high frequency voltage signals and measuring transducer coupling between phases. . However, these methods complicate the drive and detection circuitry and can generate acoustic noise in the motor during the detection sequence, which can be undesirable in a ceiling fan.

  According to an exemplary embodiment, the final position of the rotor is stored when the fan stops. This position can be used to improve the chances of a successful start sequence. It measures the Vbmf of each phase at the inputs AN0-2 of the microcontroller 368 in standby and shutdown, and has the highest Vbmf measurement (Vbmf (max)) and the lowest Vbmf measurement (Vbmf (min)). This is done by determining the phase. The 10-bit A / D converter in the exemplary embodiment has a resolution of about 3.2 mV / bit relative to the 3.3V power rail. Taking into account A / D conversion errors and signal noise, this allows for reliable Vbmf measurements down to about 10 mV. In a preferred embodiment, an EC ceiling fan motor designed to operate at 12 Vdc has a peak winding voltage coefficient of 28 V / 1000 rpm. Thus, the lowest rpm that can be reliably detected is obtained by 28 V / 10 mV × 1000 rpm = 0.36 rpm, or 2.7 minutes / rotation. This is slow enough so that the rotor fan assembly does not continue to rotate significantly beyond the last valid Vbmf measurement and the starting performance is invalidated.

In order to ensure a valid reading, the peak-to-peak Vbmf voltage (Vbmf (pp)) is calculated and the minimum effective Vbmf (Vbmf (valid)) amplitude is used to ensure that the reading is reliable.
Vbmf (pp) = Vbmf (max) −Vbmf (min), and Vbmf (valid) <Vbmf (pp)
To be specified.

  There are six possible combinations of the initial maximum Vbmf: AB, BC, CA, BA, CB, AC. The last measured combination is saved as a changeable VBMF state (VBMFSTATE) and is used during the start-up procedure to determine which phase to pressurize to ensure that the start direction is correct .

  During shutdown, the VBMF state is monitored, and when the VBMF state is read a continuous number of values without changing state, the rotor is considered stationary and the final VBMF state value is Stored in EEPROM memory for recall when applied. The shutdown mode places the microcontroller 368 in an ultra-low power mode of operation so that the capacitors 382 and 383 hold enough charge to supply power to the controller until the fan stops. Alternatively, a standby battery supply can be used to allow continuous monitoring of rotor position when AC power source 135 is shut off.

  The ceiling fan rotor blade assembly has a relatively large mass and repulsion, so it is difficult to rotate due to air movement over the blade when power is interrupted, thus preserving the last known rotor position Doing provides an effective means to improve step starting reliability.

  If the rotor is moved when the controller's 3.3V supply drops below the minimum required for operation, the controller automatically recovers on the first restart by following a standard open loop step pattern To do.

  FIG. 9 shows a flowchart of the standby operation. When first entering standby after power-on reset, the variable VBMF state and speed are recalled from the EEPROM memory. At this time, the VBMF state includes the last known rotor position during the previous shutdown. If the recalled speed value is non-zero, the controller starts immediately.

  The standby continuously polls the infrared control input 352, the VDC input of AN4, and the Vbmf inputs of AN0, AN1, and AN2, and updates the VBMF state. When a valid speed input or ON request is received from the infrared remote control transmitter 373, the controller is started. If VDC drops below 9.5V, the controller is shut down (SHUTDOWN).

  FIG. 10 shows a flowchart of the START operation. The software checks the motor rpm to determine if the motor is stationary or already rotating. When stationary, the output of the DC: DC converter is pressurized according to the VBMF state, and an open loop stepping pattern is initiated to sequentially pressurize the phase from the VBMF state start position. After the start sequence, the output of the DC: DC converter is disabled and the motor Vbmf is measured. If the motor has reached a sufficient rpm such that Vbmf (run) <Vbmf (pp), the controller exits to run (RUN). If Vbmf (pp) <Vbmf (run), the controller turns the windings according to the VBMF state pattern until Vbmf (run) <Vbmf (pp) or until a restart timeout occurs where the entire START routine is repeated. Continue to pulse.

  FIG. 11 shows a flowchart of the operation (RUN) operation. Run (RUN) continuously polls the infrared control input 352, the VDC input of AN4, and the Vbmf and lower mosfet 364-366 Vds voltages of AN0, AN1 and AN2, and updates the VBMF state. While the motor is running, Vbmf detection of the DC: DC converter output waveform timing does not require sensitive A / D readings, therefore the inputs AN0-AN2 are referenced to the common connection Com413 of the motor windings. Is multiplexed in the comparators 406 to 408.

  During operation (RUN), one of the lower mosfets 364-366 is fully ON and the mosfet drain-source voltage (Vds (on)) is measured at the corresponding A / D inputs AN0-AN2. be able to. Since the mosfet 364-366 drain-source resistance (Rds (on)) and the resistance (Rf) of the filter inductors 400-402 are known, this gives the association obtained by Iw = Vds (on) / (Rds (on) + Rf) The estimated motor winding current can be estimated. This makes it possible to detect an excessive winding current in which an overload or errory mode of operation is identified that is higher than that experienced in normal operation (RUN) operation.

  FIG. 12 shows a flowchart of operation (RUN) mode synchronization of a DC: DC output waveform with the motor Vbmf and generation of a PWM signal for generating a desired output waveform. In the preferred embodiment, this is an interrupt service routine (ISR) triggered by a PWM counter / timer. Alternatively, it may be triggered from an independent timer or polled.

  When comparators 406-408 detect that motor winding voltages 410, 411, and 412 intersect with motor Com 413, the state of the associated comparator output changes and a Vbmf zero crossing (Vzx) event is detected.

  The interval between successive Vzx events can be referred to as a step time and corresponds to a motor back emf waveform of 60 electrical angles.

  The duration of the step time is measured by a step timer that is incremented by the microprocessor 368 internal clock. At each Vzx event, the current step timer value is stored in a variable Tstep, and the step timer is reset to time the next step period.

  WaveTablePWM data is indexed by a variable WaveAddress that must be continuously updated by the PWM ISR and synchronized to the motor Vbmf waveform.

  WaveTablePWM data is divided into 128 increments per step with 7-bit amplitude resolution. This can provide a good compromise between low acoustic noise, motor rpm range, microprocessor clock speed, and PWM peripheral specifications. Alternatively, higher or lower resolution may be employed to suit different microprocessor hardware platforms, as well as different motors or operating conditions.

  If blockage occurs every 5 PWM periods, the PWM frequency is 125 kHz and the PWM block rate is 25 kHz.

  The motor is a 3-phase 16 pole machine with 48 steps or 6144 WaveTablePWM increments per revolution.

  The maximum rpm is limited by the maximum WaveTablePWM update frequency, which is 25 kHz / 6144 increments × 60 seconds = 244 rpm. This is appropriate for ceiling fans where rpm is typically limited to about 200 rpm for safety reasons.

  Vbmf comparators 406-408 are polled during the main RUN routine to update the VBMF state. If a change in VBMF state is detected upon entry to the RUN PWM ISR, the step timer is saved to Tstep before being reset and all PWM outputs are set to the correct WaveTablePWM value for the new VBMF state.

  If the DC: DC output voltage waveform at 410, 411 and 412 is behind the actual motor Vbmf 420, 421 and 422, then the motor Vbmf advances the DC: DC output and triggers the next Vzx event earlier, Thus, the subsequent Tstep is reduced and the phase lag error is reduced.

  If the DC: DC output waveform at 410, 411 and 412 is leading the actual motor Vbmf 420, 421 and 422, the motor Vbmf will place an additional load on the converter output, thereby delaying the next Vzx event. , Increase the next Tstep, thereby reducing phase read errors.

  If the DC: DC converter output waveform and Vbmf come out of synchronization with an electrical frequency fraction less than 60 degE, the electrical load applied to the DC: DC converter output by the motor Vbmf will later be returned to synchronize the system. Shift timing of Vzx event. Due to the high fan repulsion, the motor rpm does not change significantly over one electrical frequency, so the Vzx detection routine can continually correct for synchronization errors.

  Filter inductors 400-402 and capacitors 403-405 decouple the DC: DC output waveform at 410, 411 and 412 from the outputs of SPWM inverter switches 361-366, so that motors Vbmf 420, 421 and 422 are Vzx. The event detection timing can be influenced, and the SPWM modulation of the motor winding can be used in conjunction with the back EMF RPS detection.

After updating Tstep, the period of each WaveTablePWM increment for the next Step is
Tinc = step timer / 128
And the first increment is
Tinc-> Tupdate
It becomes.

  For each PWM ISR, check the step timer to determine whether WaveAddress should be incremented.

  When Tupdate <step timer, WaveAddress is incremented and Tupdate is increased by Tinc.

  When WaveAddress is updated, WaveTablePWM data for that value is retrieved from memory, scaled by the set speed value, and then used to update the actual DC: DC converter PWM duty cycle register.

  The resulting voltage applied to the motor winding is an analog version of the digitized WaveTable PWM data, synchronized to the motor Vbmf voltage, and the overall amplitude is proportional to the speed control signal.

  FIG. 13 shows the output drive voltage waveforms 410, 411 and 412 of the DC: DC converter and the common point 413 of the winding relative to the 0V rail where the lowest phase Vbmf is switched to 0V in each cycle.

  FIG. 14 shows only the details of the A-phase 410 inverter output drive voltage waveform.

  Referring to FIG. 13, it can be seen that the voltage of the A phase 410 is lower than Bph411 or Cph412 during the period of 210 to 330 degE. Looking at FIG. 14, it can be seen that this translates into a lower A-phase move 364 that is continuously pressurized to pull the output of Aph 410 to 0V during this period. In practice, the voltage is slightly above zero due to the voltage drop across the switch and filter inductor. This can be used to determine a reasonable estimate of the phase current since the switch-on resistance and filter inductor resistance are known. This can be used to determine fault conditions (instability or oscillation during start-up, or synchronous dropout during operation), to log or display actual power usage, or to control the motor more precisely Can be used for monitoring purposes.

  FIG. 15 shows a flowchart of the shutdown (SHUTDOWN) operation. Shutdown (SHUTDOWN) is triggered from all states when VDC drops below 9.5V.

  All microcontroller 368 peripherals and I / O are set to the lowest current drain state, and the current rate value is stored in EEPROM before entering the low power sleep (SLEEP) mode.

  When Sleep (SLEEP) is activated, the A / D of microcontroller 368 is re-enabled and reads the AN4, Aph410, Bph411 and Cph412 VDC inputs and AN0, AN1 and AN2 inputs and updates the VBMF state.

  If VDC rises above 10.5V, shutdown (SHUTDOWN) ends and reset (RESET).

  If the VBMF state has remained unchanged for a number of cycles, the rotor is considered stationary and the VBMF state is saved in EEPROM memory for recall at the next power-on reset.

  Although exemplary embodiments of the present invention have been described in detail, many variations are possible within the scope of the present invention, as will be apparent to those skilled in the art.

Embodiment
(1) an EC motor for driving a plurality of fan blades;
A ceiling fan comprising: a motor controller configured to determine a rotor position using a back EMF and configured to pressurize the motor according to the rotor position and a predetermined command.
(2) The fan according to embodiment 1, wherein the controller includes a DC-DC converter having an output filter.
(3) The fan according to embodiment 2, wherein the output filter is a polyphase LC filter.
(4) The fan according to embodiment 2 or 3, wherein the converter is a synchronous step-down converter.
(5) The fan according to any one of embodiments 1 to 4, wherein the controller is configured to determine the rotor position based on a zero crossing of a terminal voltage of the motor.

(6) The fan according to embodiment 4, wherein the output filter separates the PWM output voltage switched by the converter from the winding of the motor.
(7) The fan according to any one of embodiments 1 to 6, wherein the predetermined command includes a stop sequence for storing the rotor position when the predetermined command is stopped.
(8) The fan according to embodiment 7, wherein the predetermined command includes a start sequence depending on the position of the rotor that has stopped last.
(9) A fan according to any of embodiments 1-8, wherein the predetermined command includes at least one SPWM switching configuration.
10. The fan of embodiment 9, wherein the predetermined instruction includes a plurality of SPWM switching configurations, and the controller is configured to select a switching configuration based on speed.

(11) The fan according to any of embodiments 1-10, wherein the predetermined command includes a shutdown state based on one or more fault conditions.
12. The fan of embodiment 11, wherein the fault condition includes a low input voltage, an overtemperature, and a high starting current.
(13) The embodiment 12, wherein the high starting current is determined based on the single-phase voltage of the motor when the single-phase of the motor is sequentially connected to the negative DC power supply rail sequentially. Fans.
(14) The fan according to embodiment 5, further comprising an attenuation and filter circuit for supplying a terminal voltage of the motor to the controller to determine the back EMF.
(15) The fan of embodiment 8, wherein the chance of success of the start sequence is better than 50%.

(16) The fan according to any one of embodiments 1-15, wherein the predetermined command includes an ultra-low power standby state.
(17) The fan according to any one of embodiments 1 to 16, wherein the motor is a three-phase motor and the controller is a three-phase controller.
(18) A method for controlling a ceiling fan,
Determining the back EMF of the EC motor;
Pressurizing the motor to drive the fan based on the back EMF and a predetermined command.
19. The method of embodiment 18, wherein the predetermined instruction includes one or more SPWM switching configurations.
20. The method of embodiment 18 or 19, further comprising output filtering a synchronous buck converter to pressurize the motor.

21. A method according to any of embodiments 18-20, further comprising stopping the motor and storing the location of the rotor when stopped.
22. The method of embodiment 21, further comprising starting the motor based on the last stopped rotor position.

Claims (22)

An EC motor for driving a plurality of fan blades;
A ceiling fan comprising: a motor controller configured to determine a rotor position using a back EMF and configured to pressurize the motor according to the rotor position and a predetermined command.   The fan of claim 1, wherein the controller includes a DC-DC converter with an output filter.   The fan according to claim 2, wherein the output filter is a polyphase LC filter.   The fan according to claim 2 or 3, wherein the converter is a synchronous step-down converter.   The fan according to any one of claims 1 to 4, wherein the controller is configured to determine the rotor position based on a zero crossing of a terminal voltage of the motor.   The fan of claim 4, wherein the output filter separates PWM output voltage switched by the converter from windings of the motor.   The fan according to claim 1, wherein the predetermined command includes a stop sequence for storing the rotor position when stopped.   The fan of claim 7, wherein the predetermined command includes a start sequence that depends on the last stopped rotor position.   9. A fan as claimed in any preceding claim, wherein the predetermined command includes at least one SPWM switching configuration.   The fan of claim 9, wherein the predetermined command includes a plurality of SPWM switching configurations and the controller is configured to select a switching configuration based on speed.   11. A fan as claimed in any preceding claim, wherein the predetermined instruction includes a shutdown state based on one or more fault conditions.   The fan of claim 11, wherein the fault conditions include low input voltage, overtemperature, and high starting current.   The fan of claim 12, wherein the high starting current is determined based on the single phase voltage of the motor when the single phase of the motor is sequentially connected to a negative DC power rail sequentially.   The fan of claim 5, further comprising an attenuation and filter circuit for supplying a terminal voltage of the motor to the controller to determine the back EMF.   9. A fan according to claim 8, wherein the chance of success of the start sequence is better than 50%.   16. A fan as claimed in any one of the preceding claims, wherein the predetermined instruction includes an ultra low power standby state.   The fan according to any one of claims 1 to 16, wherein the motor is a three-phase motor and the controller is a three-phase controller. A method for controlling a ceiling fan,
Determining the back EMF of the EC motor;
Pressurizing the motor to drive the fan based on the back EMF and a predetermined command.   The method of claim 18, wherein the predetermined instruction includes one or more SPWM switching configurations.   20. The method of claim 18 or 19, further comprising output filtering a synchronous buck converter to pressurize the motor.   21. A method as claimed in any one of claims 18 to 20, further comprising stopping the motor and storing the location of the rotor when stopped.   The method of claim 21, further comprising starting the motor based on a last stopped rotor position.

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