Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
  • H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
  • H02P25/04—Single phase motors, e.g. capacitor motors
• • 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
  • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
  • H02P23/26—Power factor control [PFC]

Definitions

• the invention relates to a device for controlling the power supply of an electric induction motor.
• the torque of a motor is proportional to the square of the voltage applied to the motor. An engine that provides less than its full load therefore only needs part of its rated voltage.
• the current is high in a no-load induction motor, because the motor must supply all the energy of the magnetic field to make the motor run, even at idle, thus using a large part of its full load. Energy is expended on heating the engine, causing the engine to vibrate.
• the power factor is the cosine of the delay angle in degrees.
• Resistive loads such as electric heaters have a power factor of 1.0. An engine operating at full load may be very close to 1.0, but the same engine at idle may be as low as 0.1.
• the actual power that the engine uses is the product
• An engine idling or operating at low load has a low power factor. As the load increases, the power factor also increases. For a single-phase motor at full load, it is typical to have a power factor of 0.65, which is not very efficient.
• An object of the invention is to provide a device for controlling the power supply of an induction motor which automatically ensures the adaptation of the power supply to the load of the motor.
• Another object of the invention is to propose a device for controlling the power supply of an induction motor, which is inserted between the supply line and the motor and which does not need a external power source or a power transformer.
• the invention relates to a device for controlling the supply of power to an electric induction motor, mounted between the input terminals of the power supply and the output terminals of the motor, a neutral wire being disposed between a input terminal and an output terminal and a phase wire being disposed between the other input terminal and the other output terminal, characterized in that it comprises:
• a microcontroller powered by the rectification and filtering circuit, controlling the signals representative of the voltage and the current, measuring the phase shift between the zero crossings of the voltage and the current to deduce the power factor therefrom and by means of '' registered software, controlling the ignition of the triac at each power cycle to automatically adapt the power supplied to the engine to the actual engine load.
• the triac is controlled by the microcontroller via a light-emitting diode and an opto-triac;
• a clock is provided to provide a time base to the microcontroller and to measure the phase shift between the zero crossings of the voltage and the current;
• a transistor circuit is provided, supplied by the rectification and filtering circuit, to supply the starting power to the microcontroller;
• terminals 1 and 2 are the terminals of the single-phase current supply line, terminal 1 corresponding to the neutral wire and terminal 2 to the phase wire.
• Terminals 3 and 4 correspond to the terminals of the single-phase motor whose supply is controlled. Between the input terminals 1 and 2 and the output terminals 3 and 4 is mounted the device for controlling the power supply according to the invention. Between terminal 1 and terminal 3 is placed the neutral wire 5. Between terminal 2 and terminal 4, the phase wire consists of two sections 6 and 7 separated by a triac 8.
• a conductor 10 is connected on the one hand to the neutral wire 5 by a shock inductor 9 intended to protect the electronic components of the control device, on the other hand to the section 6 of the phase wire by a capacitance 11.
• the conductor 10 supplies a circuit 12 delivering at output on the conductor 13 the DC voltage Vcc necessary for the operation of the control device.
• the circuit 12 comprises in series on the conductor 13: a capacitance 14, a diode 15 and a resistor 16; and in parallel between the common terminal of the device and the conductor 13: a diode 17, a capacitance 18, a zener diode 19 and two capacitances 20, 21.
• the diodes 15, ⁇ 7 ensure the rectification of the voltage coming from the wire. phase.
• the capacitance 18 and the resistor 16 ensure smoothing by integration of the rectified voltage.
• the zener diode 19 provides a limitation of the rectified voltage.
• the capacitances 20, 21 provide filtering of the rectified voltage.
• the conductor 13 supplies the DC voltage Vcc to an 8-bit microcontroller 22, comprising recorded software, and a circuit 23 essentially consisting of a transistor 24 responsible for supplying the starting power of the " microcontroller 22.
• a clock 25 provides a time base to the microcontroller 22.
• the conductor 10 also supplies a circuit 26 essentially consisting of a differential amplifier 27 whose capacitance 28 limits the sensitivity to noise.
• the differential amplifier 27 provides the microcontroller 22 by the conductor 29, a signal representative of the supply voltage at the input terminal.
• the conductor 13 supplies a light-emitting diode 30 playing the role of an indicator of correct operation.
• the diode 30 is connected to the microcontroller 22 by a resistor 31.
• the conductor 13 supplies a transistor circuit 33, the base of which is connected, via a resistor 34, to the conductor 10 and to the capacitance 11.
• the transmitter of the transistor 33 is connected to the common terminal and, via a diode 35, to the base of transistor 33 and to resistor 34.
• Transistor 33 is used to detect zero crossings of the supply voltage available on input terminal 2.
• the microcontroller 22 is connected to the point common to the resistor 32 and to the transistor 33 to control the zero crossings of the supply voltage.
• a resistance bridge 36, 37 whose midpoint is connected to the microcontroller 22 by the conductor 44 to provide it with a signal representative of the current in engine.
• the section 7 of the phase wire connected to the motor is also connected via a resistor 38 to the second input of the differential amplifier 27, and via resistors 39, 40 to an opto-triac 41 which controls the power triac 8 of the phase wire.
• the point common to the resistors 39, 40 is connected to the common terminal by a capacitance 45.
• the opto-triac 41 is controlled by a light-emitting diode 42 supplied by the microcontroller 22 via a resistor 43.
• the microcontroller 22 controls the motor supply voltage by the differential amplifier 27, the zero crossing of the voltage by the transistor 33, and the current zero crossing by the signal on the triac 8. Thanks to the clock 25, it measures the difference between the zero crossings of the voltage and the current.
• the recorded software deduces the engine load from it via the power factor, and it controls, at each power cycle, the ignition of the triac to automatically adapt the power supplied to the engine to the actual engine load.
• the power supplied to the motor can be reduced by reducing the current in the motor. This can be achieved by reducing the average voltage applied to the motor, i.e. by delaying the ignition of the triac during the voltage cycle. The average value of the voltage then decreases.
• the microcontroller controls the voltage and the load of the motor and makes the corrections on the instant of ignition of the triac in less than 8 ms, that is to say well before any potential damage to the motor.
• the operating cost of the motors is reduced by the use of the control device, saving up to 58% in some cases. Furthermore, the device allows the motors to rotate more flexibly and with less vibration.
• the control device is applicable without adaptation to any domestic single-phase motor whose nominal power is of the order of 1 to 1.5 k at 110V and 3kW at 220V.
• the microprocessor of the control device calculates the load on the motor by measuring the time between zero crossings of the voltage and the current, which corresponds to the power factor.
• the microcontroller When the load is low, the microcontroller turns on the triac at exactly the right time to save energy.
• the voltage and the zero crossing are checked and adjusted at each cycle, according to the program of the microcontroller. Power can be saved up to 60% depending on the load and the type of engine. The operating temperature can be lowered by 24 ° C.
• An engine with the control device according to the invention in service will consume less current and its power factor will improve because the control device has intelligence. He anticipates the needs of the engine to ensure that he has enough power well before the time to do the job.
• the control device uses a specific calculation program which is installed in the microcontroller.
• the microcontroller improves and controls the power factor so that it is as close as possible to 1.
• the program of the control device controls the needs of the installation and admits and cuts the current at the exact moment when it is needed or not.
• the counter-electromotive force produced by the motor is used as an indicator to help the control device to control its needs.
• the counter electromotive force also produces a magnetic field for the engine to help maintain engine operation when the triac is open.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Ac Motors In General (AREA)

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=8847718

Family Applications (1)

Country Status (4)

Cited By (1)

Citations (3)

• 2000
  • 2000-10-06 IL IL14935300A patent/IL149353A0/xx unknown
  • 2000-10-06 WO PCT/FR2000/002792 patent/WO2002029967A1/fr not_active Ceased
  • 2000-10-06 AU AU2000277960A patent/AU2000277960A1/en not_active Abandoned
  • 2000-10-06 JP JP2002533467A patent/JP2004511198A/ja active Pending

Patent Citations (3)

Also Published As

Similar Documents

Legal Events