WO2021031138A1 - 交流电动工具及其启动方法 - Google Patents

交流电动工具及其启动方法 Download PDF

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Publication number
WO2021031138A1
WO2021031138A1 PCT/CN2019/101690 CN2019101690W WO2021031138A1 WO 2021031138 A1 WO2021031138 A1 WO 2021031138A1 CN 2019101690 W CN2019101690 W CN 2019101690W WO 2021031138 A1 WO2021031138 A1 WO 2021031138A1
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WO
WIPO (PCT)
Prior art keywords
power
brushless motor
voltage
stator winding
output
Prior art date
Application number
PCT/CN2019/101690
Other languages
English (en)
French (fr)
Inventor
徐天啸
冯继丰
Original Assignee
南京德朔实业有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 南京德朔实业有限公司 filed Critical 南京德朔实业有限公司
Priority to CN201980098822.9A priority Critical patent/CN114846735A/zh
Priority to EP19942221.3A priority patent/EP4020786B1/en
Priority to PCT/CN2019/101690 priority patent/WO2021031138A1/zh
Publication of WO2021031138A1 publication Critical patent/WO2021031138A1/zh
Priority to US17/586,485 priority patent/US20220149760A1/en

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    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B23/00—Portable grinding machines, e.g. hand-guided; Accessories therefor
    • B24B23/02—Portable grinding machines, e.g. hand-guided; Accessories therefor with rotating grinding tools; Accessories therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • H02M1/007—Plural converter units in cascade
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/083—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the ignition at the zero crossing of the voltage or the current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/36—Means for starting or stopping converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/539—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
    • H02M7/5395—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation
    • 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
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/02—Details of starting control
    • H02P1/04—Means for controlling progress of starting sequence in dependence upon time or upon current, speed, or other motor parameter
    • 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
    • H02P6/08—Arrangements for controlling the speed or torque of a single motor
    • 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
    • H02P6/08—Arrangements for controlling the speed or torque of a single motor
    • H02P6/085—Arrangements for controlling the speed or torque of a single motor in a bridge configuration
    • 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
    • H02P6/10—Arrangements for controlling torque ripple, e.g. providing reduced torque ripple

Definitions

  • the application relates to an AC electric tool and a starting method thereof.
  • power tools powered by alternating current usually use large electrolytic capacitors to stabilize the input voltage.
  • the overall structure of the power tool will be larger, which will affect the assembly of the power tool.
  • the continuous charging and discharging of the large electrolytic capacitor causes the electrolytic capacitor to generate a large amount of heat, resulting in a short life of the electrolytic capacitor and also affecting the heat dissipation performance of the power tool.
  • the voltage input to the motor will produce large pulsations, and when the power tool is started, there will be a high probability of starting failure.
  • the present application provides an electric tool and a starting method thereof that can effectively reduce the probability of starting failure.
  • an AC power tool including: a brushless motor, a power module, a voltage conversion module, a drive circuit, and a controller;
  • the brushless motor includes a stator winding and a rotor;
  • the power module is set to, AC power is connected to supply power to the stator winding;
  • the voltage conversion module is configured to access the AC power accessed by the power module and operably output the DC bus voltage;
  • the drive circuit is electrically connected to the power conversion module and is configured to Drive the brushless motor;
  • the controller is set to start timing at the zero-crossing point of the alternating current connected to the power module; within the preset time interval [T1, T2] of each half cycle, output the first control signal to
  • the driving circuit is to power on the stator winding, wherein the start time of the preset time interval is T1, and the end time of the preset time interval is T2.
  • An AC electric tool comprising: a brushless motor, a power module, a voltage conversion module, a drive circuit, and a controller;
  • the brushless motor includes a stator winding and a rotor;
  • the power module is configured to connect to AC power for the The stator winding is powered;
  • the voltage conversion module is configured to access the AC power accessed by the power supply module and operably output the DC bus voltage;
  • the drive circuit is electrically connected to the power conversion module and is configured to drive the The brushless motor;
  • the controller is set to output a first control signal to the drive circuit to make the stator windings when the instantaneous voltage value of the alternating current in each half cycle is greater than or equal to the preset voltage value V0 Electricity.
  • a starting method for an AC power tool includes a brushless motor and a power module for accessing AC power.
  • the starting method includes: starting a timer when the AC power connected to the power module crosses the zero point; Within the preset time interval [T1, T2] within a half cycle, output a first control signal to power up the stator windings of the brushless motor; obtain the rotor position of the brushless motor; In the preset time interval [T1, T2], the second control signal is output to the drive circuit according to the position of the rotor to make the brushless motor generate continuous torque, wherein the beginning of the preset time interval The time is T1, and the end time of the preset time interval is T2.
  • Figure 1 is a schematic structural view of an embodiment of an electric tool
  • Figure 2 is a circuit block diagram of an embodiment of a motor drive system of an electric tool
  • Figure 3 is a circuit diagram of a drive circuit in the electric tool
  • FIG. 4 is a circuit block diagram of the controller in the embodiment shown in FIG. 2;
  • FIG. 5 is a circuit block diagram of another embodiment of a motor drive system of an electric tool
  • FIG. 6 is a circuit block diagram of the controller in the embodiment shown in FIG. 5;
  • FIG. 7 is a graph of the corresponding PWM signal and AC voltage in the embodiment shown in FIG. 2;
  • FIG. 8 is a flowchart of the power tool starting method of the embodiment shown in FIG. 2;
  • Figure 9a is a waveform diagram of the AC voltage provided by the power module;
  • Figure 9b is a waveform diagram of the DC pulsating voltage after the filter capacitor is processed;
  • Figure 9c is a corresponding PWM signal diagram;
  • Fig. 10 is a flow chart of the power tool starting method of the embodiment shown in Fig. 5.
  • the sanding machine 100 includes: a tool housing 10, a receiving part 12, a handle part 11, a switch 13, a bottom plate 14 and a power cord 15.
  • the tool housing 10 is configured to form an outer shell of the entire sander 100, and an accommodation space for accommodating the motor is formed inside.
  • the motor is configured to convert electrical energy into power that can be transmitted to the bottom plate 14.
  • the bottom plate 14 is located outside the tool housing 10, and the bottom plate 14 can install or hold accessories such as sandpaper.
  • the handle portion 11 is provided for the user to hold, and the receiving portion 12 forms a receiving cavity for accommodating the motor and the fan.
  • the handle 11 is also connected with a switch 13 for starting the motor.
  • the power cord 15 is configured to connect to an AC power source and supply power to the motor.
  • this embodiment relates to a sanding machine, it should be understood that this application is not limited to the disclosed embodiment, but can be applied to other types of electric tools, including but not limited to angle grinders, electric drills, electric wrenches, and electric saws.
  • Fig. 2 shows a block diagram of a control system of an electric tool as one of the embodiments.
  • the electric tool 200 further includes: a power module 20, a brushless motor 21, a power sub-module 22, a voltage conversion module 23, a drive circuit 24, a drive chip 25, an alternating current detection module 26, a controller 27, and voltage detection Module 28.
  • the power module 20 is configured to be connected to AC power to supply power to the brushless motor 21.
  • the power module 20 includes an alternating current plug and a peripheral circuit electrically connected to the alternating current plug.
  • the AC plug is inserted into the AC socket to connect to the AC mains, so as to provide the brushless motor 21 with an electric power source.
  • the power supply module 20 includes other structural forms and peripheral circuits that can be connected to AC power, for example, the AC power plug is connected to a movable substation to connect to the AC power. It should be noted that the power supply module 20 only needs to be able to connect to alternating current, and its structure and form are not limited here. Wherein, the value range of the alternating current that the power module 20 can access is 110V-130V or 210V-230V.
  • the brushless motor 21 includes a stator winding and a rotor.
  • the brushless motor 21 is a three-phase brushless motor, which includes a rotor with permanent magnets and three-phase stator windings U, V, and W that are commutated electronically.
  • the three-phase stator windings U, V, and W are connected in a star shape (as shown in Figure 2).
  • the three-phase stator windings U, V, and W are connected in an angular shape. connection.
  • Brushless motors may include less than or more than three phases.
  • the voltage conversion module 23 is configured to be connected to the AC power supplied by the power module 20, and to be operable to output a DC bus voltage.
  • the voltage conversion module 23 includes a rectifier circuit 231 and a filter capacitor 232.
  • the rectifier circuit 231 is configured to convert alternating current into direct current for output.
  • the rectifier circuit 231 is connected in series between the power module 20 and the filter capacitor 232, and is configured to receive AC power and convert the AC power into pulsating DC power.
  • the rectifier circuit 231 includes four rectifier bridges.
  • the filter capacitor 232 is configured to filter the pulsating direct current from the rectifier circuit 231.
  • the filter capacitor 232 is connected in series between the rectifier circuit 231 and the drive circuit 24.
  • the filter capacitor 232 is a small electrolytic capacitor.
  • the filter capacitor 232 is a film capacitor.
  • the value range of the capacitance value C of the filter capacitor is 1.46Y uF ⁇ C ⁇ 6YuF, where Y is the rated current of the AC power tool, and the unit is A.
  • the film capacitor is small in size and not easy to be damaged by heating, which is more conducive to the overall assembly of the electric tool and ensures the service life of the electric tool.
  • the power sub-module 22 is configured to supply power to at least one of the driving chip 25 and the controller 27.
  • the power sub-module 22 is connected to the power module 20 to convert the alternating current connected through the power module 20 into a power supply voltage output suitable for at least one of the driving chip 25 and the controller 27.
  • the power sub-module 22 reduces the AC power supply voltage from the power module 20 to 15V to power the controller 27, and the power supply voltage to 3.2V to power the driver chip 25.
  • the power sub-module 22 is connected to the voltage conversion module 23 to convert the alternating current connected through the power module 20 into a power supply voltage output adapted to at least one of the driving chip 25 and the controller 27.
  • the switching device 29 is configured to start or stop the motor.
  • the switch device 29 is located between the power sub-module 22 and the driving chip 25.
  • the switch device 29 is used as a trigger switch of the electric tool and can be set at the position shown in FIG. 1.
  • At least one of the chip 25 and the controller 27 is electrically connected to the power sub-module 22, and the motor is powered off.
  • the driving chip 25 is configured to control the on or off state of the electronic switch in the driving circuit 24.
  • the drive chip 25 is connected in series between the controller 27 and the drive circuit 24, and according to the control signal from the controller 27, controls the on or off state of the electronic switch in the drive circuit 24.
  • the control signal from the controller 27 is a pulse width modulation (Pulse Width Modulation, PWM) control signal.
  • PWM Pulse Width Modulation
  • the driving chip 25 is shown as being separated from the controller 27. In other embodiments, the driving chip 25 and the controller 27 may be integrated as a whole.
  • the driving circuit 24 is configured to drive the brushless motor 21 and is electrically connected to the voltage conversion module 23.
  • the input terminal of the drive circuit 24 receives the DC pulsating voltage from the voltage conversion module 23, and under the drive of the drive signal output by the drive chip 25, the power of the DC pulsating voltage is distributed to each phase winding on the motor stator in a certain logical relationship to Start the motor and generate continuous torque.
  • the drive circuit 24 includes a plurality of electronic switches.
  • the electronic switch includes a field effect transistor (FET), and in other embodiments, the electronic switch includes an insulated gate bipolar transistor (IG-BT), etc.
  • FET field effect transistor
  • IG-BT insulated gate bipolar transistor
  • the driving circuit 24 is a three-phase bridge circuit.
  • the drive circuit 24 includes three drive switches Q1, Q3, and Q5 provided as high-side switches and three drive switches Q2, Q4, Q6 provided as low-side switches.
  • the three drive switches Q1, Q3, Q5 as high-end switches are respectively arranged between the power supply line and each phase coil of the motor.
  • the three switching elements Q2, Q4, and Q6 as low-side switches are respectively arranged between each phase coil of the motor and the ground.
  • Each gate terminal UH, UL, VH, VL, WH, WL of the six drive switches Q1-Q6 is electrically connected to the controller 27, and each drain or source of the drive switch is connected to the stator winding of the motor.
  • the driving switches Q1-Q6 change the on or off state at a certain frequency according to the control signal output by the controller 27, thereby changing the power state of the power module 20 loaded on the winding of the brushless motor 21.
  • the drive circuit 24 is a circuit for rotating and driving the motor by switching the energization state of each phase winding of the motor and controlling the respective energization current of each phase winding.
  • the turn-on sequence and time of each phase winding depend on the position of the rotor.
  • the drive circuit 24 has multiple drive states. In one drive state, the stator winding of the motor generates a magnetic field.
  • the controller 27 outputs control signals based on different rotor positions to control the drive circuit 24 to switch the drive state.
  • the magnetic field generated by the stator winding is rotated to drive the rotor to rotate, thereby driving the brushless motor 21.
  • the AC power detection module 26 is configured to detect the AC voltage connected to the power supply module 20. As shown in FIG. 7, it is a waveform diagram of the AC voltage detected by the AC detection module 26, where the abscissa represents time, the ordinate represents the AC voltage, and the unit is V.
  • the alternating current detection module 26 is a voltage sensor. In other embodiments, the alternating current detection module 26 is a voltage detection circuit including a resistor.
  • the voltage detection module 28 is configured to detect the phase voltage of the brushless motor 21.
  • the voltage detection module 28 is a voltage sensor.
  • the voltage detection module 28 includes a voltage detection circuit with a voltage divider resistor.
  • the controller 27 is configured to receive the AC power from the AC power detection module 26 and the phase voltage from the voltage detection module 28. In some embodiments, the controller 27 is configured to perform the following operations: receiving AC power from the AC power detection module 26, where the AC power is a voltage signal that changes in a certain period.
  • the controller 27 When the instantaneous voltage value of the alternating current in each half cycle is greater than or equal to the preset voltage value V0, the controller 27 outputs the first control signal to the driving circuit 24 to power on the stator winding to start the motor. At this time, current flows through the stator windings, causing the stator windings to generate a stator magnetic field. The interaction between the stator magnetic field and the rotor makes the motor start to rotate.
  • the controller is further configured to perform the following operations: obtain the position of the rotor, and output the second control according to the rotor position when the instantaneous voltage value of the alternating current in each half cycle is greater than or equal to the preset voltage value V0
  • the signal is sent to the driving circuit 34 to make the motor generate continuous torque, and then the motor is started and works normally.
  • the starting process of the above-mentioned motor will be described in detail with reference to the drawings.
  • the controller 27 further includes an AC voltage acquisition unit 271, a control unit 272, and a rotor position calculation unit 273.
  • the AC voltage acquisition unit 271 is configured to receive the AC power from the AC power detection module 26, wherein the voltage waveform of the AC power is a voltage with a certain period of periodic fluctuations (as shown in FIG. 7).
  • the rotor position calculation unit 273 is configured to obtain the rotor position of the brushless motor 21 and send the rotor position of the brushless motor 21 to the control unit 272.
  • the voltage detection module 28 is configured to detect the phase voltage of the brushless motor 21.
  • the electric tool also includes a current detection module (not shown), which is configured to detect the current applied to the stator winding.
  • the rotor position calculation unit 273 is configured to estimate the rotor position of the brushless motor 21 at least based on the phase voltage of the brushless motor 21 and the stator winding current. For example, the inductance value of the stator winding is estimated based on the phase voltage of the brushless motor 21 and the current of the stator winding, and the one-to-one matching relationship between the inductance value and the rotor position is established (using a table look-up method or formula modeling, etc.). Get the position of the rotor.
  • other parameters related to the rotor position may also be obtained to obtain the rotor position.
  • the control unit 272 is configured to perform the following operations: receive a supply voltage, where the supply voltage comes from the power sub-module 22.
  • the first control signal is output to the drive circuit 24 to power up the stator winding.
  • the first control signal is a first PWM signal
  • the control unit 272 outputs the first PWM signal to the driving circuit 24 to make one of the high-side switches and one of the low-side switches conduct, so that current is applied to the stator winding. Electricity on the stator winding generates a magnetic field, which drives the rotor to rotate.
  • the second control signal is output to the drive circuit 24 according to the rotor position obtained by the rotor position calculation unit 273 to make the motor generate continuous rotation Moment.
  • the second control signal is a second PWM signal, and the second PWM signal is related to the rotor position.
  • the instantaneous voltage value of the alternating current in each half cycle is greater than or equal to the preset voltage value V0, it depends on the rotor
  • the second PWM signal is output for different positions to switch the conduction sequence and time of different high-side switches or low-side switches, so that the alternating current is distributed on the motor windings with a certain power, so that the motor generates continuous torque.
  • the power tool works normally under continuous torque.
  • control unit 272 does not output a control signal to the driving circuit 24.
  • the influence of the phase voltage drop caused by the discharge of the filter capacitor can be reduced, so that the phase voltage collected by the voltage detection module 28
  • the voltage has a higher sampling accuracy, which in turn makes the rotor position calculated based on the phase voltage more accurate, thereby reducing the probability of motor startup failure caused by the calculation of the rotor position.
  • the value range of the preset voltage V0 is 60% Vm ⁇ V0 ⁇ Vm, where Vm is the maximum voltage amplitude of the acquired instantaneous voltage. If the preset voltage V0 is less than 60% Vm, the probability of startup failure will be greatly increased.
  • the value range of V0 is 70% Vm ⁇ V0 ⁇ Vm. In other embodiments, the value range of V0 is 80%Vm ⁇ V0 ⁇ Vm, or the value range of V0 is 90%Vm ⁇ V0 ⁇ Vm.
  • the controller 27 In every half cycle, when the instantaneous voltage value of the AC voltage is greater than or equal to the preset voltage V0, the controller 27 outputs a PWM signal to the drive circuit 24 to start the motor; when the instantaneous voltage value of the AC voltage is less than the preset voltage V0 When the voltage V0 is set, the controller 27 does not output a PWM signal. It can be understood that in each half cycle, when the rotor is at a rotor position and the instantaneous voltage V0 of the AC voltage is in the range of 60%Vm ⁇ V0 ⁇ Vm as shown in FIG.
  • the controller 27 outputs A PWM signal is sent to the driving circuit 24 to start the motor, and the controller 27 does not output a PWM signal to the driving circuit 24 to start the motor if it is not within the range of 60% Vm ⁇ V0 ⁇ Vm. In the next half cycle, when the rotor is at another rotor position, the controller 27 still performs this operation.
  • a method for starting an AC power tool as described above includes steps S1 to S8.
  • step S1 power on.
  • the user presses the switch device 29 to connect the electric tool to AC power.
  • step S2 the instantaneous voltage value of the alternating current is acquired.
  • the AC power detection module 26 can be used to detect the AC voltage connected to the power module 20 to obtain the AC voltage waveform.
  • the controller 27 is configured to receive the AC voltage detected by the AC power detection module 26.
  • the AC voltage obtaining unit 271 in the controller 27 is configured to receive the AC voltage of the AC power detection module 26, so that the instantaneous voltage value of the AC voltage at each moment can be obtained.
  • step S3 it is determined whether the instantaneous voltage value of the alternating current is greater than or equal to the preset voltage value V0 in each half cycle, based on the judgment result that the instantaneous voltage value of the alternating current is greater than or equal to the preset voltage value V0 within each half cycle , Go to step S4; based on the judgment result that the instantaneous voltage value of the alternating current is less than the preset voltage value V0 in each half cycle, go to step S5.
  • step S4 the first control signal is output to the drive circuit 24 to power up the stator winding of the brushless motor 21.
  • step S5 no control signal is output to the drive circuit 24.
  • step S6 the rotor position is acquired.
  • step S6 includes sub-step S61 to sub-step S62.
  • the phase voltage of the brushless motor 21 is detected; for example, the voltage detection module 28 is used to detect the phase voltage of the brushless motor 21.
  • the three phase voltages of the three-phase brushless motor 21 are collected respectively.
  • the rotor position of the brushless motor 21 is obtained according to the detected phase voltage and the stator winding current.
  • the controller 27 estimates the inductance value of the electronic winding based on the phase voltage and the stator winding current, and establishes a functional relationship model between the inductance value and the position of the rotor of the brushless motor 21, based on the detected phase The voltage and stator winding current are calculated to obtain the rotor position of the brushless motor 21.
  • the controller 27 estimates the inductance value of the electronic winding based on the phase voltage and the stator winding current, establishes a one-to-one correspondence table of the position relationship between the inductance value and the rotor of the brushless motor 21, and obtains it according to the look-up table method.
  • the rotor position of the brushless motor 21 is not limited to the phase voltage and the stator winding current.
  • step S7 it is determined whether the instantaneous voltage value of the alternating current is greater than or equal to the preset voltage value V0 in each half cycle, based on the judgment result that the instantaneous voltage value of the alternating current is greater than or equal to the preset voltage value V0 within each half cycle , Go to step S8; based on the judgment result that the instantaneous voltage value of the alternating current is less than the preset voltage value V0 in each half cycle, go to step S5.
  • step S8 a second control signal is output to the drive circuit 24 according to the rotor position to make the brushless motor 21 generate continuous torque.
  • Figure 5 shows another embodiment of a motor control system that can be employed by an electric tool.
  • the electric tool includes a zero-crossing detection circuit 36.
  • the zero-crossing detection circuit 36 is configured to be connected to the AC power connected by the power module 30 and output a zero-crossing signal to the controller 37 when the AC voltage crosses the zero point.
  • the controller 37 is configured to receive the zero-crossing signal from the zero-crossing detection circuit 36 and the phase voltage from the voltage detection module 38. In some embodiments, the controller is configured to perform the following operations: receiving a zero-crossing signal from a zero-crossing detection circuit.
  • the zero-crossing signal triggers the timing, and in the preset time interval [T1, T2], the first control signal is output to the drive circuit 34 to power on the stator winding to start the motor. At this time, current flows through the stator windings, causing the stator windings to generate a stator magnetic field. The interaction between the stator magnetic field and the rotor makes the motor start to rotate.
  • the controller is further configured to perform the following operations: obtain the rotor position, and output a second control signal to the drive circuit 34 according to the rotor position within a preset time [T1, T2] to make the motor generate continuous rotation Moment, and then make the motor start to complete normal work.
  • T1, T2 a preset time
  • the controller 37 further includes a timing unit 371, a control unit 372 and a rotor position calculation unit 373.
  • the timing unit 371 receives the zero-crossing signal of the zero-crossing detection circuit 36, and the zero-crossing signal triggers the timing unit 371 to start timing.
  • the rotor position calculation unit 373 is configured to obtain the rotor position of the brushless motor 31 and send the rotor position of the brushless motor 31 to the control unit 372.
  • the control unit 372 is configured to perform the following operations: receive a supply voltage, where the supply voltage comes from the power sub-module 32.
  • the first control signal is output to the drive circuit 34 to power up the stator winding.
  • the first control signal is the first PWM signal.
  • the control unit 372 outputs the first PWM signal to the driving circuit 34 so that one of the high-side switches and the low-side switch One of the switches is turned on, so that current is applied to the stator winding. Electricity on the stator winding generates a magnetic field, which drives the rotor to rotate.
  • the second control signal is output to the drive circuit 34 according to the rotor position obtained by the rotor position calculation unit 373 to make the motor generate continuous torque.
  • the second control signal is a second PWM signal, and the second PWM signal is related to the rotor position.
  • the second PWM signal is output according to the rotor position to switch between different The turn-on sequence and time of the high-side switch or the low-side switch, so that the alternating current is distributed to the motor windings with a certain power, so that the motor generates a continuous torque.
  • the power tool works normally under continuous torque.
  • control unit 372 when the timing time is not within the preset time [T1, T2], the control unit 372 does not output a control signal to the driving circuit 34.
  • the value range of the start time T1 and the end time T2 is 2.5ms ⁇ T1 ⁇ T2 ⁇ 7ms. In some embodiments, the value range of the start time T1 and the end time T2 is 3ms ⁇ T1 ⁇ T2 ⁇ 7ms. In some other embodiments, the value range of the start time T1 and the end time T2 is 4ms ⁇ T1 ⁇ T2 ⁇ 6ms. If the start time T1 ⁇ 3ms and the end time T2>6ms, the probability of startup failure will be greatly increased. In some other embodiments, the value range of the start time T1 and the end time T2 is 2.5ms ⁇ T1 ⁇ T2 ⁇ 5.8ms. In other embodiments, the value range of the start time T1 and the end time T2 is 3.3 ms ⁇ T1 ⁇ T2 ⁇ 5.0 ms.
  • FIG. 9a is a waveform diagram of the AC voltage provided by the power supply module 30, wherein the abscissa represents time, the ordinate represents the AC voltage, and the unit is V.
  • FIG. 9b is a waveform diagram of the DC pulsating voltage after being processed by the filter capacitor 332.
  • FIG. 9c shows that within the timing time [T1, T2], the controller 37 outputs a PWM signal to the driving circuit 34 to start the motor. When the timing time is not within the timing time [T1, T2], the PWM signal is not output to the driving circuit 34.
  • a starting method of the AC electric tool as described above includes steps S1' to S9'.
  • step S1' power is turned on.
  • the user presses the switch device 39 to connect the electric tool to alternating current.
  • step S2' the AC zero-crossing signal is acquired.
  • the zero-crossing detection circuit 36 can be used to connect the AC power connected to the power module 30 and output a zero-crossing signal to the controller 37 at the zero-crossing point of the AC.
  • the controller 37 is set to receive the cross-over signal from the zero-crossing detection circuit 36. Zero signal.
  • step S3' timing is started.
  • the controller 37 can be used to receive the zero-crossing signal from the zero-crossing detection circuit 36, and trigger the timing in response to the zero-crossing signal.
  • the timing unit 371 in the controller 37 receives the zero-crossing signal from the zero-crossing detection circuit 36, and the zero-crossing signal triggers the timing unit 371 to start timing.
  • step S4' it is determined whether the timing signal is within the preset time [T1, T2]; based on the determination result that the timing signal is within the preset time [T1, T2], step S5' is executed; based on the timing signal is not within the preset time For the judgment result in [T1, T2], step S6' is executed.
  • step S5' the first control signal is output to the drive circuit 34 to power up the stator winding of the brushless motor 31.
  • step S6' no control signal is output to the drive circuit 34.
  • step S7' the rotor position is acquired.
  • step S7' includes sub-steps S71 to S72.
  • the voltage detection module 38 is used to detect the phase voltage of the brushless motor 31.
  • the three phase voltages of the three-phase brushless motor 31 are collected respectively.
  • the controller 27 estimates the inductance value of the electronic winding based on the phase voltage and the stator winding current, and establishes a functional relationship model between the inductance value and the position of the rotor of the brushless motor 21, based on the detected phase The voltage and stator winding current are calculated to obtain the rotor position of the brushless motor 21.
  • the controller 27 estimates the inductance value of the electronic winding based on the phase voltage and the stator winding current, establishes a one-to-one correspondence table of the position relationship between the inductance value and the rotor of the brushless motor 21, and obtains it according to the look-up table method.
  • the rotor position of the brushless motor 21 is not limited to the phase voltage and the stator winding current.
  • step S8' it is determined whether the timing signal is within the preset time [T1, T2]; based on the determination result that the timing signal is within the preset time [T1, T2], step S9' is executed; based on the timing signal is not within the preset time For the judgment result in [T1, T2], step S6' is executed.
  • step S9' the second control signal is output to the drive circuit 34 according to the rotor position to make the brushless motor 31 generate a continuous torque.
  • the electric tool and its starting method disclosed in the present application can effectively reduce the probability of starting the electric tool to fail.

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Abstract

一种交流电动工具，包括无刷电机（21）；电源模块（20），其设置为接入交流电以为定子绕组供电；电压转换模块（23），其设置为接入电源模块接入的交流电，并可操作地输出直流总线电压；驱动电路（24），其与电源转换模块电性连接，设置为驱动无刷电机；控制器（27），其设置为在电源模块接入的交流电过零点时开始计时；在每半个周期的预设时间区间[T1,T2]内，输出第一控制信号至驱动电路以使定子绕组上电，其中，预设时间区间的起始时刻为T1，预设时间区间的截止时刻为T2。

Description

交流电动工具及其启动方法 技术领域
本申请涉及一种交流电动工具及其启动方法。
背景技术
相关技术中，使用交流电供电的电动工具通常采用大电解电容来稳定输入电压。一方面，由于大电解电容的尺寸较大，将导致电动工具的整机结构较大，会影响电动工具整机的组装。另一方面，在电动工具工作时，大电解电容不断充放电使得电解电容发热量大，导致电解电容的寿命短，也影响了电动工具的散热性能。然而，如果不使用大电解电容，输入至电机的电压将会产生较大的脉动，电动工具启动时，会出现大概率的启动失败。
发明内容
本申请提供一种能有效降低启动失败概率的电动工具及其启动方法。
本申请采用如下的技术方案：一种交流电动工具，包括：无刷电机，电源模块，电压转换模块，驱动电路，以及控制器；所述无刷电机包括定子绕组和转子；电源模块设置为，接入交流电以为所述定子绕组供电；电压转换模块设置为，接入所述电源模块接入的交流电，并可操作地输出直流总线电压；驱动电路与所述电源转换模块电性连接，设置为驱动所述无刷电机；控制器设置为，在所述电源模块接入的交流电过零点时开始计时；在每半个周期的预设时间区间[T1，T2]内，输出第一控制信号至所述驱动电路以使所述定子绕组上电，其中，所述预设时间区间的起始时刻为T1，预设时间区间的截止时刻为T2。
一种交流电动工具，包括：无刷电机，电源模块，电压转换模块，驱动电路，以及控制器；所述无刷电机包括定子绕组和转子；所述电源模块设置为，接入交流电以为所述定子绕组供电；所述电压转换模块设置为，接入所述电源模块接入的交流电，并可操作地输出直流总线电压；所述驱动电路与所述电源转换模块电性连接，设置为驱动所述无刷电机；控制器设置为，在每半个周期内交流电的瞬时电压值大于或等于预设电压值V0的情况下，输出第一控制信号至所述驱动电路以使所述定子绕组上电。
一种用于交流电动工具的启动方法，交流交流电动工具包括无刷电机和用于接入交流电的电源模块，启动方法包括：在所述电源模块接入的交流电过零点时开始计时；在每半个周期内的预设时间区间[T1，T2]内，输出第一控制信号使所述无刷电机的定子绕组上电；获取所述无刷电机的转子位置；在每半个周期内的预设时间区间[T1，T2]内，依据所述转子的位 置输出第二控制信号至驱动电路以使所述无刷电机产生持续不断的转矩，其中，所述预设时间区间的起始时刻为T1，所述预设时间区间的截止时刻为T2。
附图说明
图1是电动工具的一个实施例的结构示意图；
图2是电动工具的电机驱动系统的一个实施例的电路框图；
图3是电动工具中的驱动电路的电路图；
图4是图2所示的实施例中的控制器的电路框图；
图5是电动工具的电机驱动系统的又一个实施例的电路框图；
图6是图5所示的实施例中的控制器的电路框图；
图7是图2所示实施例的PWM信号与交流电压对应的曲线图；
图8是图2所示实施例的电动工具启动方法流程图；
图9a为电源模块提供的交流电压波形图；图9b为经过滤波电容处理后的直流脉动电压波形图；图9c为对应的PWM信号图；
图10是图5所示实施例的电动工具启动方法流程图。
具体实施方式
参考图1，砂光机100包括：工具壳体10、容纳部12、把手部11、开关13，底板14以及电源线15。
工具壳体10设置为形成整个砂光机100的外壳，内部形成容纳电机的收容空间。电机设置为将电能转化成能传递至底板14的动力。底板14位于工具壳体10外，底板14能够安装或者夹持砂纸等附件。把手部11设置为供用户握持，容纳部12形成容纳电机和风扇的容纳腔。把手部11还连接有用于启动电机的开关13。电源线15设置为连接交流电源，为电机供电。
虽然本实施例涉及到砂光机，但是应该理解本申请不限于所公开的实施例，而是可应用于其他类型的电动工具，包括但不限于角磨机，电钻，电扳手，电锯。
图2示出了作为实施例之一的电动工具的控制系统框图。如图2所示，电动工具200还包括：电源模块20、无刷电机21、电源子模块22、电压转换模块23、驱动电路24、驱动芯片25、交流电检测模块26、控制器27和电压检测模块28。
电源模块20，设置为接入交流电以为无刷电机21供电。在一些实施例中，电源模块20包括交流电插头和与交流电插头电连接的外围电路。其中，交流电插头插入交流电插座以接 入交流市电，从而为无刷电机21提供电能来源。在另一实施例中，电源模块20包括其它的能够接入交流电的结构形式及外围电路，例如，交流电插头接入可移动的变电站等方式接入交流电。需要说明的是，电源模块20只需满足能够接入交流电即可，其结构和形式在此不作限制。其中，电源模块20所能接入的交流电的取值范围为110V～130V或210V～230V。
无刷电机21，包括定子绕组和转子。在一些实施例中，无刷电机21为三相无刷电机，包括具有永磁体的转子和以电子方式换向的三相定子绕组U、V、W。在一些实施例中，三相定子绕组U、V、W之间采用星型连接(如图2所示)，在另一些实施例中，三相定子绕组U、V、W之间采用角型连接。然而，必须理解的是其他类型的无刷电动机也在本申请的范围。无刷电动机可包括少于或多于三相。
电压转换模块23设置为接入电源模块20接入的交流电，并可操作地输出直流总线电压。其中，电压转换模块23包括整流电路231和滤波电容232。
整流电路231设置为将交流电转换为直流电输出。整流电路231串联在电源模块20和滤波电容232之间，设置为接收交流电并将交流电转换为脉动直流电。在一些实施例中，整流电路231包括四个整流桥。
滤波电容232设置为为来自整流电路231的脉动直流电滤波。滤波电容232串联在整流电路231和驱动电路24之间。在一些实施例中，滤波电容232为小电解电容。在另一些实施例中，滤波电容232是薄膜电容。滤波电容的电容值C的取值范围为1.46Y uF≤C≤6YuF，其中Y为交流电动工具的额定电流，单位为A。薄膜电容尺寸小而且不容易发热损坏，更有利于电动工具的整体组装和保证电动工具的使用寿命。
电源子模块22设置为为驱动芯片25和控制器27中至少一个供电。在一些实施例中，电源子模块22与电源模块20连接，以将经电源模块20接入的交流电转换为适配于驱动芯片25和控制器27中至少一个的供电电压输出。例如，在一些实施例中，为了给驱动芯片25供电，电源子模块22将来自电源模块20的交流电电源电压降到15V以为控制器27供电，将电源电压降到3.2V以为驱动芯片25供电。在另一实施例中，电源子模块22与电压转换模块23连接，以将经电源模块20接入的交流电转换为适配于驱动芯片25和控制器27中至少一个的供电电压输出。
开关装置29设置为启动或者关闭电机。开关装置29位于电源子模块22和驱动芯片25之间。在一些实施例中，开关装置29作为电动工具的扳机开关，可设置在如图1所示的位置。用户按压扳开关装置29使开关装置29位于接通位置，驱动芯片25和控制器27中至少一个从电源子模块22接收电信号，电机上电；用户按压扳机开关装置29位于切断位置，切断驱动芯片25和控制器27中至少一个与电源子模块22之间的电性连接，电机断电。
驱动芯片25设置为控制驱动电路24中的电子开关的导通或关断状态。驱动芯片25串联在控制器27和驱动电路24之间，根据来自控制器27的控制信号，控制驱动电路24中电子开关导通或关断的状态。在一些实施例中，来自控制器27的控制信号为脉冲宽度调制(Pulse width modulation，PWM)控制信号。在此实施例中，驱动芯片25被示出为与控制器27分离。在其他实施例中，驱动芯片25和控制器27可以集成为一个整体。
驱动电路24设置为驱动无刷电机21，与电压转换模块23电性连接。驱动电路24的输入端接收来自电压转换模块23的直流脉动电压，在驱动芯片25输出的驱动信号的驱动下将直流脉动电压的功率以一定的逻辑关系分配给电机定子上的各相绕组，以使电机启动并产生持续不断的转矩。在一些实施例中，驱动电路24包括多个电子开关。在一些实施例中，电子开关包括场效应晶体管(Field Effect Transistor，FET)，在另一些实施例中，电子开关包括绝缘栅双极晶体管(Insulated Gate Bipolar Transistor，IG-BT)等。参考图3，在一些实施例中，驱动电路24为三相桥式电路。驱动电路24包括作为高侧开关设置的三个驱动开关Q1、Q3、Q5和作为低侧开关设置的三个驱动开关Q2、Q4、Q6。
作为高端开关的三个驱动开关Q1、Q3、Q5分别设在供电线与电机的各相线圈之间。作为低端开关的三个开关元件Q2、Q4、Q6分别设在电机的各相线圈与地线之间。
六个驱动开关Q1-Q6的每个栅极端UH、UL、VH、VL、WH、WL与控制器27电性连接，驱动开关的每个漏极或源极与电机的定子绕组连接。驱动开关Q1-Q6依据控制器27输出的控制信号以一定频率改变导通或关断状态，从而改变电源模块20加载在无刷电机21绕组上的功率状态。
驱动电路24是用于通过切换对电机的各相绕组的通电状态、控制各相绕组各自的通电电流来使电机旋转驱动的电路。各相绕组导通顺序和时间取决于转子的位置。为了使无刷电机21转动，驱动电路24具有多个驱动状态，在一个驱动状态下电机的定子绕组会产生一个磁场，控制器27基于不同的转子位置输出控制信号以控制驱动电路24切换驱动状态使定子绕组产生的磁场转动以驱动转子转动，进而实现对无刷电机21的驱动。
交流电检测模块26设置为检测电源模块20接入的交流电压。如图7所示，为交流电检测模块26检测到的交流电压波形图，其中，横坐标表示时间，纵坐标表示交流电压，单位为V。在一些实施例中，交流电检测模块26为电压传感器。在另一些实施例中，交流电检测模块26为包括电阻的电压检测电路。
电压检测模块28设置为检测无刷电机21的相电压。在一些实施例中，电压检测模块28为电压传感器。在另一些实施例中，电压检测模块28包括分压电阻的电压检测电路。
控制器27设置为，接收来自交流电检测模块26的交流电和来自电压检测模块28的相电 压。在一些实施例中，控制器27设置为执行以下操作：接收来自交流电检测模块26的交流电，其中，交流电为一个以一定周期变化的电压信号。
控制器27在每半个周期内交流电的瞬时电压值大于或等于预设电压值V0的情况下，输出第一控制信号至驱动电路24以使定子绕组上电以启动电机。此时，电流流经定子绕组，使得定子绕组产生定子磁场，定子磁场和转子相互作用使得电机开始转动。
在一些实施例中，控制器还设置为执行以下操作：获取转子的位置，在每半个周期内交流电的瞬时电压值大于或等于预设电压值V0的情况下，依据转子位置输出第二控制信号至驱动电路34以使电机产生持续不断的转矩，进而使电机启动完成，正常工作。后文将结合附图对上述电机的启动过程进行详细描述。
如图4所示，控制器27还包括交流电压获取单元271、控制单元272和转子位置计算单元273。
交流电压获取单元271设置为接收交流电检测模块26的交流电，其中，交流电的电压波形为具有一定周期的周期性波动的电压(如图7所示)。
转子位置计算单元273设置为获取无刷电机21的转子位置，并将无刷电机21的转子位置发送至控制单元272。
在一些实施例中，电压检测模块28设置为检测无刷电机21的相电压。电动工具还包括电流检测模块(未示出)，设置为检测加载至定子绕组的电流。转子位置计算单元273设置为至少依据无刷电机21的相电压和定子绕组的电流估算无刷电机21的转子位置。例如，依据无刷电机21的相电压和定子绕组的电流估算出定子绕组的电感值，建立电感值与转子位置的一一匹配关系(以查表法或公式建模等方式)，据此以获取转子的位置。
在另一些实施例中，也可获取其它的与转子位置相关的参数获取转子位置。
控制单元272设置为执行以下操作：接收供电电压，这里的供电电压来自电源子模块22。
在每半个周期内交流电的瞬时电压值大于或等于预设电压值V0的情况下，输出第一控制信号至驱动电路24以使定子绕组上电。在一些实施例中，第一控制信号为第一PWM信号，在每半个周期内交流电的瞬时电压值大于或等于预设电压值V0的情况下，控制单元272输出第一PWM信号至驱动电路24以使高侧开关中的一个和低侧开关中的一个导通，从而使得电流加载至定子绕组。定子绕组上电产生磁场，进而带动转子转动。
在每半个周期内交流电的瞬时电压值大于或等于预设电压值V0的情况下，依据转子位置计算单元273获取的转子位置输出第二控制信号至驱动电路24以使电机产生持续不断的转矩。在一些实施例中，第二控制信号为第二PWM信号，第二PWM信号与转子位置相关，在每半个周期内交流电的瞬时电压值大于或等于预设电压值V0的情况下，依据转子位置的 不同输出第二PWM信号以切换不同的高侧开关或低侧开关的导通顺序和时间，由此使得交流电以一定功率分配在电机绕组上，从而使得电机产生持续不断的转矩。电动工具在持续不断的转矩下正常工作。
需要说明的是，在半个周期内若瞬时电压的电压值小于预设电压值的情况下，控制单元272不输出控制信号至驱动电路24。
这样，在每半个周期内，交流电压的瞬时电压值大于或等于预设电压值的情况下，可减小因滤波电容放电使得相电压降低的影响，从而使得电压检测模块28采集到的相电压具有较高的采样精度，进而使得依据相电压计算得到的转子位置更为准确，由此降低了由于转子位置计算错误所导致的电机启动失败概率。
预设电压V0的取值范围为60％Vm≤V0≤Vm，其中，Vm为获取的瞬时电压的最大电压幅值。如预设电压V0小于60％Vm，则会大大增加启动失败概率。
在一些实施例中，V0的取值范围为70％Vm≤V0≤Vm。在另一些实施例中，V0的取值范围为80％Vm≤V0≤Vm，或者V0的取值范围为90％Vm≤V0≤Vm。
参考图7所示的PWM信号与交流电压对应的曲线图。在每半个周期内，在交流电压的瞬时电压值大于或等于预设电压V0的情况下，控制器27输出PWM信号至驱动电路24以启动电机；在交流电压的瞬时电压的电压值小于预设电压V0的情况下，控制器27不输出PWM信号。可以理解的，在每半个周期内，在转子位于一个转子位置且当交流电压的瞬时电压V0处于如图7所示的60％Vm≤V0≤Vm的范围区间的情况下，控制器27输出一个PWM信号至驱动电路24以启动电机，不在60％Vm≤V0≤Vm的这一范围区间的情况下，控制器27不输出PWM信号至驱动电路24以启动电机。在下一个半周期，在转子位于另一个转子位置时，控制器27仍然执行此操作。
参考图8所示，一种如前述的交流电动工具的启动方法，包括步骤S1至步骤S8。
在步骤S1中，上电。
此步骤中，用户按压开关装置29以使电动工具接入交流电。
在步骤S2中，获取交流电的瞬时电压值。
此步骤中，可利用交流电检测模块26检测电源模块20接入的交流电压以获得交流电压波形。控制器27设置为接收交流电检测模块26检测的交流电压。控制器27中的交流电压获取单元271设置为接收交流电检测模块26的交流电压，这样可获取每个时刻的交流电压的瞬时电压值。
在步骤S3中，判断每半个周期内，交流电的瞬时电压值是否大于或等于预设电压值V0，基于每半个周期内，交流电的瞬时电压值大于或等于预设电压值V0的判断结果，转至步骤 S4；基于每半个周期内，交流电的瞬时电压值小于预设电压值V0的判断结果，转至步骤S5。
在步骤S4中，输出第一控制信号至驱动电路24以使无刷电机21的定子绕组上电。
在步骤S5中，不输出控制信号至驱动电路24。
在步骤S6中，获取转子位置。
作为实施例的一种，步骤S6包括子步骤S61至子步骤S62。
在子步骤S61中，检测无刷电机21的相电压；例如，采用电压检测模块28检测无刷电机21的相电压。示例性的，分别采集三相无刷电机21的三个相电压。
在子步骤S62中，依据检测到的相电压和定子绕组的电流获得无刷电机21的转子位置。例如，在一些实施例中，控制器27中依据相电压和定子绕组的电流估算出电子绕组的电感值，建立电感值与无刷电机21转子的位置的函数关系模型，依据所检测到的相电压和定子绕组的电流计算得到无刷电机21的转子位置。在另一些实施例中，控制器27中依据相电压和定子绕组的电流估算出电子绕组的电感值，建立电感值与无刷电机21转子的位置关系的一一对应表格，依据查表法获取无刷电机21的转子位置。
在步骤S7中，判断每半个周期内，交流电的瞬时电压值是否大于或等于预设电压值V0，基于每半个周期内，交流电的瞬时电压值大于或等于预设电压值V0的判断结果，转至步骤S8；基于每半个周期内，交流电的瞬时电压值小于预设电压值V0的判断结果，转至步骤S5。
在步骤S8中，依据转子位置输出第二控制信号至驱动电路24以使无刷电机21产生持续不断的转矩。
图5示出了可由电动工具采用的电动机控制系统的另一个实施例。与图2所示实施例不同的是该电动工具包括过零检测电路36。
过零检测电路36设置为接入电源模块30接入的交流电并在交流电压过零点时输出一个过零信号给控制器37。
控制器37设置为接收来自过零检测电路36的过零信号和来自电压检测模块38的相电压。在一些实施例中，控制器设置为执行以下操作：接收来自过零检测电路的过零信号。过零信号触发计时，在预设时间区间[T1，T2]内，输出第一控制信号至驱动电路34以使定子绕组上电以启动电机。此时，电流流经定子绕组，使得定子绕组产生定子磁场，定子磁场和转子相互作用使得电机开始转动。
在一些实施例中，控制器还设置为执行以下操作：获取转子位置，在预设时间[T1，T2]内，依据转子位置输出第二控制信号至驱动电路34以使电机产生持续不断的转矩，进而使电机启动完成正常工作。后文将结合附图对上述电机的启动过程进行详细描述。如图6所示，控制器37还包括计时单元371、控制单元372和转子位置计算单元373。
计时单元371接收过零检测电路36的过零信号，过零信号触发计时单元371开始计时。转子位置计算单元373设置为获取无刷电机31的转子位置，并将无刷电机31的转子位置发送至控制单元372。
控制单元372设置为执行以下操作：接收供电电压，这里的供电电压来自电源子模块32。
在预设时间[T1，T2]内，输出第一控制信号至驱动电路34以使定子绕组上电。在一些实施例中，第一控制信号为第一PWM信号，在预设时间[T1，T2]内，控制单元372输出第一PWM信号至驱动电路34以使高侧开关中的一个和低侧开关中的一个导通，从而使得电流加载至定子绕组。定子绕组上电产生磁场，进而带动转子转动。
在预设时间[T1，T2]内，依据转子位置计算单元373获取的转子位置输出第二控制信号至驱动电路34以使电机产生持续不断的转矩。在一些实施例中，第二控制信号为第二PWM信号，第二PWM信号与转子位置相关，在预设时间[T1，T2]内，依据转子位置的不同输出第二PWM信号以切换不同的高侧开关或低侧开关的导通顺序和时间，由此使得交流电以一定功率分配在电机绕组上，从而使得电机产生持续不断的转矩。电动工具在持续不断的转矩下正常工作。
需要说明的是，在计时时间不在预设时间[T1，T2]内的情况下，控制单元372不输出控制信号至驱动电路34。
这样，在计时时间[T1，T2]内，可减小因滤波电容放电使得相电压降低的影响，从而使得电压检测模块38采集到的相电压具有较高的采样精度，进而使得依据相电压计算得到的转子位置更为准确，由此降低了由于转子位置计算错误所导致的电机启动失败概率。
其中，起始时刻T1、截止时刻T2的取值范围为2.5ms≤T1≤T2≤7ms。在一些实施例中，起始时刻T1、截止时刻T2的取值范围为3ms≤T1≤T2≤7ms。在另一些实施例中，起始时刻T1、截止时刻T2的取值范围为4ms≤T1≤T2≤6ms。如起始时刻T1<3ms、截止时刻T2>6ms，则会大大增加启动失败概率。在另一些实施例中，起始时刻T1、截止时刻T2的取值范围为2.5ms≤T1≤T2≤5.8ms。在另一些实施例中，起始时刻T1、截止时刻T2的取值范围为3.3ms≤T1≤T2≤5.0ms。
参考图9所示，图9a为电源模块30提供的交流电压波形图，其中，横坐标表示时间，纵坐标表示交流电压，单位为V。图9b为经过滤波电容332处理后的直流脉动电压波形图。图9c为在计时时间[T1,T2]内，控制器37输出PWM信号至驱动电路34以启动电机。在计时时间不在计时时间[T1,T2]内的情况下，不输出PWM信号至驱动电路34。
参考图10所示，一种如前述的交流电动工具的启动方法，包括步骤S1'至步骤S9'。
在步骤S1'中，上电。
此步骤中，用户按压开关装置39以使电动工具接入交流电。
在步骤S2'中，获取交流电过零点信号。
此步骤中，可利用过零检测电路36接入电源模块30接入的交流电并在交流电过零点时输出一个过零信号给控制器37，控制器37设置为接收来自过零检测电路36的过零信号。
在步骤S3'中，开始计时。
此步骤中，可利用控制器37接收来自过零检测电路36的过零信号，响应过零信号触发计时。控制器37中的计时单元371接收来自过零检测电路36的过零信号，过零信号触发计时单元371开始计时。
在步骤S4'中，判断计时信号是否在预设时间[T1，T2]内；基于计时信号在预设时间[T1，T2]内的判断结果，执行步骤S5'；基于计时信号不在预设时间[T1，T2]内的判断结果，执行步骤S6'。
在步骤S5'中，输出第一控制信号至驱动电路34以使无刷电机31的定子绕组上电。
在步骤S6'中，不输出控制信号至驱动电路34。
在步骤S7'中，获取转子位置。
作为实施例的一种，步骤S7'包括子步骤S71至步骤S72。
S71、检测无刷电机31的相电压；例如，采用电压检测模块38检测无刷电机31的相电压。示例性的，分别采集三相无刷电机31的三个相电压。
S72、依据检测到的相电压和定子绕组的电流获得无刷电机21的转子位置。例如，在一些实施例中，控制器27中依据相电压和定子绕组的电流估算出电子绕组的电感值，建立电感值与无刷电机21转子的位置的函数关系模型，依据所检测到的相电压和定子绕组的电流计算得到无刷电机21的转子位置。在另一些实施例中，控制器27中依据相电压和定子绕组的电流估算出电子绕组的电感值，建立电感值与无刷电机21转子的位置关系的一一对应表格，依据查表法获取无刷电机21的转子位置。
在步骤S8'中，判断计时信号是否在预设时间[T1,T2]内；基于计时信号在预设时间[T1，T2]内的判断结果，执行步骤S9'；基于计时信号不在预设时间[T1，T2]内的判断结果，执行步骤S6'。
在步骤S9'中，依据转子位置输出第二控制信号至驱动电路34以使无刷电机31产生持续不断的转矩。
本申请公开的电动工具及其启动方法能有效降低电动工具启动失败的概率。

Claims (19)

  1. 一种交流电动工具，包括：无刷电机，电源模块，电压转换模块，驱动电路，以及控制器；
    所述无刷电机包括定子绕组和转子；
    所述电源模块设置为，接入交流电以为所述定子绕组供电；
    所述电压转换模块设置为，接入所述电源模块接入的交流电，并可操作地输出直流总线电压；
    所述驱动电路与所述电源转换模块电性连接，设置为驱动所述无刷电机；
    所述控制器设置为，在所述电源模块接入的交流电过零点时开始计时；在每半个周期的预设时间区间[T1，T2]内，输出第一控制信号至所述驱动电路以使所述定子绕组上电，其中，所述预设时间区间的起始时刻为T1，所述预设时间区间的截止时刻为T2。
  2. 根据权利要求1所述的交流电动工具，其中，所述控制器还设置为：
    获取所述无刷电机的转子位置；
    在所述预设时间区间[T1，T2]内，依据所述转子的位置输出第二控制信号至所述驱动电路以使所述无刷电机产生持续不断的转矩。
  3. 根据权利要求1所述的交流电动工具，其中，所述交流电动工具为砂光机。
  4. 根据权利要求1所述的交流电动工具，还包括：
    过零检测电路设置为，接入所述电源模块接入的交流电并在所述交流电过零点时输出一个过零信号；
    控制器设置为，接收所述过零信号。
  5. 根据权利要求1所述的交流电动工具，其中，所述起始时刻T1的取值范围为：2.5ms≤T1≤T2；所述截止时刻T2的取值范围为：T1≤T2≤7ms。
  6. 根据权利要求1所述的交流电动工具，其中，所述电压转换模块包括：整流电路，滤波电容；
    所述整流电路设置为，将所述电源模块接入的交流电转换为直流电输出；
    所述滤波电容与所述整流电路连接，设置为为所述整流电路输出的直流电滤波；
    所述滤波电容的电容值C的取值范围为1.46Y uF≤C≤6Y uF，其中Y为所述交流电动工具的额定电流，单位为A。
  7. 根据权利要求6所述的交流电动工具，其中，所述滤波电容为薄膜电容。
  8. 一种交流电动工具，包括：无刷电机，电源模块，电压转换模块，驱动电路，以及控制器；
    所述无刷电机包括定子绕组和转子；
    所述电源模块设置为，接入交流电以为所述定子绕组供电；
    所述电压转换模块设置为，接入所述电源模块接入的交流电，并可操作地输出直流总线电压；
    所述驱动电路与所述电源转换模块电性连接，设置为驱动所述无刷电机；
    控制器设置为，在每半个周期内所述交流电的瞬时电压值大于或等于预设电压值V0的情况下，输出第一控制信号至所述驱动电路以使所述定子绕组上电。
  9. 根据权利要求8所述的交流电动工具，其中，所述控制器还设置为：
    获取所述无刷电机的转子位置；
    在每半个周期内所述交流电的瞬时电压值大于或等于预设电压值V0的情况下，依据所述转子的位置输出第二控制信号至所述驱动电路以使所述无刷电机产生持续不断的转矩。
  10. 根据权利要求8所述的交流电动工具，其中，所述交流电动工具为砂光机。
  11. 根据权利要求8所述的交流电动工具，其中，所述预设电压值V0的取值范围为60％Vm≤V0≤Vm，其中，Vm为所述交流电的最大电压幅值。
  12. 根据权利要求8所述的交流电动工具，其中，所述电压转换模块包括：整流电路，滤波电容；
    所述整流电路设置为，将所述电源模块接入的交流电转换为直流电输出；
    所述滤波电容与所述整流电路连接，设置为为所述整流电路输出的直流电滤波；
    所述滤波电容的电容值C的取值范围为1.46Y uF≤C≤6YuF，其中Y为所述交流电动工具的额定电流，单位为A。
  13. 根据权利要求12所述的交流电动工具，其中，所述滤波电容为薄膜电容。
  14. 一种用于交流电动工具的启动方法，所述交流电动工具包括无刷电机和用于接入交流电的电源模块，所述启动方法包括：
    在所述电源模块接入的交流电过零点时开始计时；
    在每半个周期内的预设时间区间[T1，T2]内，输出第一控制信号使所述无刷电机的定子绕组上电；
    获取所述无刷电机的转子位置；
    在每半个周期内的预设时间区间[T1，T2]内，依据所述转子的位置输出第二控制信号至驱动电路以使所述无刷电机产生持续不断的转矩，其中，所述预设时间区间的起始时刻为T1，所述预设时间区间的截止时刻为T2。
  15. 根据权利要求14所述的启动方法，还包括：
    在每半个周期内的超出所述预设时间区间的剩余时间内，使所述驱动电路不启动所述无 刷电机。
  16. 根据权利要求14所述的启动方法，其中，所述起始时刻T1的取值范围为：2.5ms≤T1≤T2；所述截止时刻T2的取值范围为：T1≤T2≤7ms。
  17. 根据权利要求14所述的启动方法，其中，所述获取所述无刷电机的转子位置，包括：
    检测所述无刷电机的相电压；
    检测加载至所述无刷电机的定子绕组的电流；
    至少依据所述无刷电机的相电压和所述定子绕组的电流估算所述无刷电机的转子位置。
  18. 根据权利要求17所述的启动方法，其中，至少依据所述无刷电机的相电压和所述定子绕组的电流，估算所述无刷电机的转子位置，包括：
    依据所述无刷电机的相电压和所述定子绕组的电流估算出所述定子绕组的电感值；
    建立所述电感值与所述无刷电机转子位置的函数关系模型，以获得所述无刷电机的转子位置。
  19. 根据权利要求17所述的启动方法，其中，至少依据所述无刷电机的相电压和所述定子绕组的电流，估算所述无刷电机的转子位置，包括：
    依据所述无刷电机的相电压和所述定子绕组的电流估算出所述定子绕组的电感值；
    建立所述电感值与所述无刷电机转子位置关系的一一对应表格，以获得所述无刷电机的转子位置。
PCT/CN2019/101690 2019-08-21 2019-08-21 交流电动工具及其启动方法 WO2021031138A1 (zh)

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