Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
  • H02P6/14—Electronic commutators
  • H02P6/16—Circuit arrangements for detecting position
  • H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
  • H02P6/182—Circuit arrangements for detecting position without separate position detecting elements using back-emf in windings
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
  • H02P6/14—Electronic commutators
  • H02P6/16—Circuit arrangements for detecting position
  • H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
  • H02P6/185—Circuit arrangements for detecting position without separate position detecting elements using inductance sensing, e.g. pulse excitation

Definitions

• the present invention relates to a DC motor according to the preamble of claim 1 and a method for operating the DC motor according to the preamble of claim 2.
• Such a so-called brushless sensorless DC motor comprises a rotor having at least one permanent magnet, and a stator having at least three stator coils, wherein a control device is provided, which is adapted to determine a rotational position of the rotor and an energization of the stator coils from the rotational position of the rotor, and wherein the control means is arranged to determine the rotational position in a high speed range based on a voltage induced in one of the stator coils.
• a disadvantage is that at low speeds no sufficient voltages are induced in the stator coils. Therefore, the rotational position of the rotor can not be determined.
• the stator coils are therefore switched blind during startup of the engine in the low speed range. This can lead to the fact that the energization of the stator coils does not lead to an acceleration of the motor, but to a deceleration of the rotor. The rotor then reaches the high speed range only after a long time or not at all.
• the present invention has for its object to provide a DC motor of the type mentioned and a method for operating the DC motor, wherein the DC motor is controlled by the method in a low speed range depending on a rotational position of the rotor.
• the object underlying the invention is achieved by a DC motor having the features of the characterizing part of patent claim 1 and a method for operating the DC motor having the features of the characterizing part of patent claim 2.
• the present invention relates to a DC motor, wherein the control means is arranged to determine the rotational position in a low speed range based on a current when a voltage is applied to one of the stator coils.
• a low speed range is generally a speed range that is below a high speed range in which sufficient voltages are not induced in the stator coils to determine the rotational position, and in which the rotor speed is typically less than 500 rpm, while in the high Speed range the
• Rotor speed is typically more than 500 U / min.
• no further sensor is required to determine the speed in the low speed range.
• the DC motor is a follow-up pole motor (English: consequent pole motor).
• the present invention further relates to a method of operating the DC motor with the following steps in a low speed range: applying a voltage to one of the stator coils; Determining a current at the one of the stator coils; Determining the rotor position based on the course of the current; and energizing the stator coils in dependence on the detected rotational position.
• the determination of the current in connection with the invention does not mean that the current is determined numerically exactly. It can also be determined only a size that is proportional to the current.
• a voltage is applied to the at least one further stator coil, a further current is determined at the at least one further stator coil, and the rotational position is determined based on the course of the further current. This makes it possible to determine if the rotor is in one of several different rotational positions.
• the applied voltages are voltage pulses. These voltage pulses typically have a duration of several 100 ⁇ s. This allows the rotational position of the
• the voltage pulses are applied repeatedly, and the time interval between the repeated application of the voltage pulses decreases.
• the time interval between the repeated application of the voltage pulses is adapted to the increasing speed of the rotor.
• the applied voltages are reversed, currents are determined on the stator coils for the polarity reversed voltages, and the rotational position is determined based on the course of the currents for the polarity reversed voltages.
• the reversed voltages are preferably also voltage pulses and have the same duration as the aforementioned voltage pulses. By two opposite voltage pulses, the speed of the rotor is hardly affected.
• the amounts of current increases at each voltage and reverse voltage stator coil are added together to form a summed current increase, the maximum summed current increase is compared to the other current increases to determine the rotational position. Offset errors of the streams can thus be extracted.
• an angular range can be set, in which the rotational position of the rotor.
• Voltage values of the voltage induced in one of the stator coils are determined to be a multiple (at least twice) of the electrical angle of 360 °. These are voltage values for the same rotor position. This ensures that deviations between the poles of the rotor do not affect the determination of the rotational position.
• FIG. 1 is a schematic view of a DC motor with an associated power supply
• FIG. 2 is a detail view of the DC motor and its associated
• FIG. 3 is a view of the voltage comparator circuit of FIG. 1 ;
• FIG. 4 is a view of the voltage amplifier of FIG. 1 ;
• FIG. 1 shows a schematic view of a DC motor 1 with an associated energizing device 2.
• a DC motor is used, for example, for a coolant pump of a motor vehicle.
• the energizing device 2 provides a current to the DC motor 1 via the power lines 3, 4 and 5.
• the energizing device 2 comprises a control circuit 6, a driver circuit 7 with a charge pump, a switching device 8 with a plurality of switching transistors, a voltage comparator circuit 9 and a voltage amplifier circuit 10.
• a voltage regulation circuit 1 1 a polarity reversal protection circuit 12, an overvoltage protection circuit 13, a capacitor 14 and a resistor 15 are provided.
• the capacitor 14 buffers the recovered energy due to the inductive load of the stator coils (see FIG.2).
• the resistor 15 has a low value and ensures that the current flowing through the resistor 15 to the ground terminal can be amplified by the voltage amplifier circuit 10.
• the polarity reversal protection circuit 12 ensures that an incorrectly polarized supply voltage Vref does not damage the lighting device 2.
• the voltage regulation circuit 1 1 controls the voltage applied to the control circuit 6 to a certain value.
• Overvoltage protection circuit 13 ensures that the driver circuit 7 is not damaged by overvoltages.
• the control circuit 6 controls the driver circuit 7 depending on the signals from the voltage comparator circuit 9 or the voltage amplifier circuit 10.
• the driver circuit 7 applies voltages to the switching transistors of the switching device 9 to open or close the switching transistors.
• FIG. 2 shows a detailed view of the DC motor 1 and the associated switching device 8 from FIG. 1.
• the DC motor includes an iron core
• the two stator coils of a stator coil pair uu ', vv' and ww ' are each offset by 180 °.
• each stator coil pair uu ', vv' and ww ' is connected to two switching transistors T1 and T2, T3 and T4 and T5 and T6, respectively, which are closed or opened by the driver circuit 7.
• the switching transistors T1, T3 and T5 respectively connect or disconnect the stator coil pairs uu ', vv' and ww 'with a high voltage potential Vref.
• the switching transistors T2, T4 and T6 respectively connect or disconnect the stator coil pairs uu ', vv' and ww 'with a low voltage potential at a node 25.
• the other ends of each stator coil pair uu ', vv' and ww ' are connected to each other.
• Permanent magnet 27 is formed. Such a DC motor is known by the name "consequent pole motor.”
• Transistors are turned on, so that the current flows through two pairs of stator coils.
• FIG. 3 shows a view of the voltage comparator circuit 9 of FIG. 1.
• the voltage comparator circuit 9 comprises three identically formed
• Each of the comparator circuits comprises a plurality of resistors R1, R2, R3, R4 and R5, a plurality of capacitors C1, C2 and C3 and an operational amplifier OP1. As already noted, in normal operation only two pairs of stator coils are alternately energized.
• Operational amplifier OP1 which belongs to the third non-energized coil.
• the Voltages at the nodes 22, 23 and 24 are supplied to the control circuit 6.
• FIG. 4 shows a view of the voltage amplifier circuit 10 of FIG. 1 .
• the voltage amplifier circuit 10 comprises a plurality of resistors R6, R7, R8,
• the resistors R8 and R1 1 and R10 and R9 are each the same size. Nodes 25, 28 and 29 are also shown in FIG. 1 drawn.
• the resistors R6 and R7 are also the same size, so that at the non-inverting input of the operational amplifier OP2 and at the output of the
• Operational amplifier OP2 voltage Vref / 2 (internal voltage of 0 V) is applied.
• Vref / 2 internal voltage of 0 V
• the operational amplifier OP3 is connected as an inverting amplifier, so that at the output of the operational amplifier OP3 (node 28) a proportional voltage corresponding to the current direction across R15 is applied, as is necessary for the operation of the control circuit 6.
• the normal operation of the DC motor 1 is interrupted at a low speed by test pauses.
• two opposite voltage pulses are applied to each of the pairs of stator coils uu ', vv' and ww 'shortly after one another.
• the voltage pulses are all the same length and have the same amplitude. By applying two opposite voltage pulses possible offset errors are compensated.
• the movement of the rotor 26 is hardly affected.
• the transistors T1, T4 and T6 are turned on during the first voltage pulse and the transistors T2, T3 and T5 are switched on during the second voltage pulse.
• Each of the voltage pulses has a duration of a few 100 ⁇ s.
• the rotor 26 is therefore almost in the same rotational position during the entire test break.
• the transistors T3, T2 and T6 are turned on during the first voltage pulse and the transistors T4, T1 and T5 are turned on during the second voltage pulse.
• the stator coil pair ww 'during the first voltage pulse the stator coil pair ww 'during the first voltage pulse
• the magnetic field lines penetrate the permanent magnets 27 more or less.
• the inductance of the stator coil pair uu ' changes.
• the current increases in the
• a voltage value proportional to the current value is supplied to the control circuit 6.
• the control circuit 6 calculates when the rotor 26 is at a rotational position at which one of the transistors T1 to T6 is to be turned on or off. The control circuit 6 now causes the driver circuit 7, the
• Transistors T1 to T6 turn on or off as desired at certain rotational positions off.
• the test pauses are repeated continuously in the low speed range.
• the time interval of the test pauses is thereby continuously reduced in order to adapt the determination of the rotational position to the increased rotational speed.
• the DC motor 2 After a certain time, the DC motor 2 has reached a high speed (> 500 rpm).
• Rotor 26 can now induce a measurable voltage in the stator coil pairs uu ⁇ vv 'or ww'.
• the zero crossings of these induced voltages are recognized by control circuit 6 as changing the sign of the voltages at outputs 22, 23, and 24, respectively. Interrupting the normal operation of the DC motor to detect the rotational position of the rotor is not required. These zero crossings each correspond to a certain electrical angle ⁇ el.
• FIG. 6 shows the amplitude of the induced voltage as a function of the electrical angle.
• the control circuit 6 calculates the rotational speed and concludes from the rotational speed and the determined electrical angles ⁇ el when the rotor 26 is at a rotational position at which one of the transistors T1 to T6 is to be turned on or off.
• the control circuit 6 uses only sharply defined magnetic poles as formed in front of the permanent magnets 27 (poles S in FIG.2) but not between the permanent magnets 27 (poles N in FIG.2).
• the control circuit 6 also preferably compares zero crossings, each corresponding to a complete rotation of the rotor 26 by 360 ° and thus belong to a particular magnetic pole.
• control circuit analyzes the zero crossings, which belong to both sharply defined magnetic poles, to determine from as many data as possible a functional dependence of the rotational position of the rotor 26 on time. These two sharply defined magnetic poles are offset by one turn of the rotor by 180 °.
• the control circuit 6 now causes the driver circuit to turn on or off the transistors T1 to T6 as desired at certain rotational positions.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=42027656

Family Applications (1)

Country Status (5)

Families Citing this family (4)

Family Cites Families (10)

• 2008
  • 2008-10-23 DE DE200810043134 patent/DE102008043134A1/de not_active Ceased
• 2009
  • 2009-10-13 CN CN200980142103.9A patent/CN102197582B/zh not_active Expired - Fee Related
  • 2009-10-13 WO PCT/EP2009/063301 patent/WO2010046266A2/de active Application Filing
  • 2009-10-13 EP EP09736594A patent/EP2338223A2/de not_active Withdrawn
  • 2009-10-13 JP JP2011532583A patent/JP5535226B2/ja not_active Expired - Fee Related

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events