JP2011120365A - Motor drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor driving device where there exists the problem, wherein vibrations and noises of motors increase and step-out resistance conspicuously deteriorates in low-speed regions of the motor whose load torque variations are large, during the period in which a rotator of the motor, such as, a one-piston rotary compressor makes a single rotation. <P>SOLUTION: A target rotation number correction means 11 corrects a target rotation number, avoids the low-speed regions and prevents the vibrations and noises of the motor, while an overload is applied when a torque command value determined by a torque control means 21 and a value detected by a pipe temperature detection means 22 exceeds a predetermined value; and step-out of the motor is prevented, and continuous stable operations are attained. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric motor drive device that drives an electric motor such as a brushless DC motor at an arbitrary rotation speed.

  In recent years, in an apparatus for driving an electric motor such as a compressor in an air conditioner, there is an increasing need to reduce power consumption from the viewpoint of protecting the global environment. Among them, as one of the power saving technologies, an inverter that drives a highly efficient electric motor such as a brushless DC motor at an arbitrary frequency is widely used. Furthermore, as a driving technique, a sine wave driving technique that is more efficient and can reduce noise than a rectangular wave driving that is driven by a rectangular wave current is becoming mainstream. In addition, the mainstream of the compressor used is a highly efficient and inexpensive one-piston rotary compressor.

  When driving a motor having a large load torque fluctuation generated during one rotation of the rotor of the motor, such as a one-piston rotary compressor, torque control means (for example, Patent Document 1) is used to suppress the load torque fluctuation. ) Has been invented.

  FIG. 2 shows a system configuration for realizing the position sensorless sine wave drive described in Patent Document 1. 1 is a DC power source, 2 is an inverter, 3 is a brushless motor, 4 is a stator, 5 is a rotor, and 6 is a control unit.

  The brushless motor 3 includes a stator 4 to which three phase windings 4u, 4v, 4w Y-connected around a neutral point are attached, and a rotor 5 to which a magnet is attached. A U-phase terminal 8u is connected to the non-connection end of the U-phase winding 4u, a V-phase terminal 8v is connected to the non-connection end of the V-phase winding 4v, and a W-phase terminal 8w is connected to the non-connection end of the W-phase winding 4w.

  The inverter 2 has three series circuits in which a pair of switching elements are connected in series in a relationship between the upstream side and the downstream side of the current, for U phase, for V phase, and for W phase. A DC voltage output from the DC power source 1 is applied to these series circuits. The U-phase series circuit includes an upstream side switching element 12u and a downstream side switching element 13u. The series circuit for V phase includes an upstream side switching element 12v and a downstream side switching element 13v. The series circuit for W phase includes an upstream side switching element 12w and a downstream side switching element 12w. Free wheel diodes 14u, 14v, 14w, 15u, 15v, and 15w are connected in parallel with the switching elements.

  Terminals 8u, 8v, and 8w of the brushless motor 3 are connected to an interconnection point of the switching elements 12u and 13u, an interconnection point of the switching elements 12v and 13v, and an interconnection point of the switching elements 12w and 13w in the inverter 2, respectively. .

  The DC voltage applied to the inverter 2 is converted into a three-phase AC voltage by a circuit such as the switching element in the inverter 2 described above, and the brushless motor 3 is thereby driven.

In order to realize the target speed given from the outside, the PWM signal generating means 9 generates a PWM signal for driving the switching element of the inverter 2 in order to output the output voltage calculated from the error with the current speed. The drive signal for electrically driving the element is converted by the base driver 10, and each switching element 12u, 12v, 12w,
13u, 13v, and 13w operate.

  The control unit 6 includes the phase current of the brushless motor 3 detected by the current detection means 7 arranged on the inverter bus, the output voltage calculated by the PWM signal generation means 9 and the DC power source 1 detected by the inverter applied voltage detection means 16. The induced voltage of the brushless motor 3 is estimated by the induced voltage estimation means 17 from the DC voltage output from The estimated induced voltage is compared with the induced voltage determined based on the phase voltage equation of each phase of the brushless motor 3 by the rotor position speed detecting means 18, and the rotor magnetic pole position of the brushless motor 3 is determined based on the comparison result. And estimate the speed.

  Reference numeral 21 denotes torque control means for controlling the load torque of the brushless motor 3. The torque control means 21 includes a rotor acceleration detection means 19 for calculating acceleration using the speed detected by the rotor position speed detection means 18, and The acceleration control means 20 is configured to control the detected acceleration fluctuation to zero. The torque control means 21 detects the acceleration by the rotor acceleration detection means 19, determines the torque command amount from the current acceleration and the target acceleration by the acceleration control means 20, and outputs it to the PWM signal generation means 9.

  The rotor position speed detection means 18 calculates an estimated current value of the motor from the motor model equation using the current detected by the current detection means 7, the DC voltage output from the inverter 2, and the motor constant of the brushless motor 3. Then, the position of the rotor is estimated by using an error from the current detected by the current detection means 7. Here, the current value detected by the current detection means 7 and the current value estimated from the motor model equation are converted into a current iδ in the axis δ direction of the rotating magnetic field and a current iγ in the axis γ direction of the magnetic flux direction. By controlling it as a direct current value, torque control is easily realized.

  The PWM signal generation means 9 adds or subtracts a torque command amount for realizing the target acceleration to the output voltage calculated from an error from the current speed in order to realize the target speed given from the outside, and drives the switching element of the inverter 2. A PWM signal is generated and further converted into a drive signal for electrically driving the switching element by the base driver 10, and each switching element 12u, 12v, 12w, 13u, 13v, 13w operates.

  The drive control of the brushless motor 3 is performed with the circuit configuration as described above.

JP 2001-37281 A

  However, motors with large fluctuations in load torque during one rotation of the rotor of the motor, such as a one-piston rotary compressor, increased the torque command amount and further decreased the amount in an overload state. . For this reason, particularly in the low speed region, there has been a problem that the vibration and noise of the motor increase, and the deterioration of the step-out tolerance occurs remarkably.

  The present invention solves the above-described problem, and suppresses an increase in vibration and noise during an overload in a low speed region, can prevent motor step-out, and the overcurrent protection device operates. An object of the present invention is to provide an electric motor drive device capable of preventing and continuously operating stably.

In order to solve the above-described conventional problems, the motor drive device of the present invention is provided with a target rotational speed correction unit, and a value detected by a torque command amount and a pipe temperature determined by the torque control unit exceeds a preset value. In this case, by changing the target rotational speed and avoiding the low speed region, it is possible to prevent the motor from stepping out during an overload, and it is possible to suppress motor vibration and noise.

  The motor drive device according to the present invention avoids a low-speed region of a motor having a large torque fluctuation, thereby suppressing an increase in motor vibration and noise during an overload and preventing a step-out. It is possible to realize an electric motor drive device that can be operated smoothly.

The block diagram of the electric motor drive device in Embodiment 1 of this invention Block diagram of an electric motor drive device provided with a conventional torque control means

  The present invention avoids the low speed region by providing the target rotational speed correction means for correcting the target rotational speed when the torque command amount and the pipe temperature determined by the torque control means exceed preset values. An increase in vibration and noise at the time of load can be suppressed, the motor can be prevented from stepping out, and an electric motor drive device capable of continuous and stable operation is realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)

FIG. 1 is a block diagram according to the first embodiment of the present invention.

  1 is a DC power source, 2 is an inverter, 3 is a brushless motor, 4 is a stator, 5 is a rotor, and 6 is a control unit.

  The brushless motor 3 includes a stator 4 to which three phase windings 4u, 4v, 4w Y-connected around a neutral point are attached, and a rotor 5 to which a magnet is attached. A U-phase terminal 8u is connected to the non-connection end of the U-phase winding 4u, a V-phase terminal 8v is connected to the non-connection end of the V-phase winding 4v, and a W-phase terminal 8w is connected to the non-connection end of the W-phase winding 4w.

  The inverter 2 has three series circuits in which a pair of switching elements are connected in series in a relationship between the upstream side and the downstream side of the current, for U phase, for V phase, and for W phase. A DC voltage output from the DC power source 1 is applied to these series circuits. The U-phase series circuit includes an upstream side switching element 12u and a downstream side switching element 13u. The series circuit for V phase includes an upstream side switching element 12v and a downstream side switching element 13v. The series circuit for W phase includes an upstream side switching element 12w and a downstream side switching element 12w. Free wheel diodes 14u, 14v, 14w, 15u, 15v, and 15w are connected in parallel with the switching elements.

  Terminals 8u, 8v, and 8w of the brushless motor 3 are connected to an interconnection point of the switching elements 12u and 13u, an interconnection point of the switching elements 12v and 13v, and an interconnection point of the switching elements 12w and 13w in the inverter 2, respectively. .

  The DC voltage applied to the inverter 2 is converted into a three-phase AC voltage by a circuit such as the switching element in the inverter 2 described above, and the brushless motor 3 is thereby driven.

  The torque control means 21 detects the current speed at every certain period by the rotor acceleration detection means 19, compares the amount of change in the certain period as acceleration, and compares it with the target acceleration by the acceleration control means 20. The torque command amount for realizing is determined.

  The PWM signal generating means 9 drives the switching element of the inverter 2 by increasing or decreasing the torque command amount for realizing the target acceleration to the output voltage calculated from the error with the current speed in order to realize the target speed given from the outside. PWM signal to be generated is further converted into a drive signal for electrically driving the switching element by the base driver 10, and each switching element 12u, 12v, 12w, 13u, 13v, 13w operates.

  The control unit 6 includes the phase current of the brushless motor 3 detected by the current detection means 7 arranged on the inverter bus, the output voltage calculated by the PWM signal generation means 9 and the DC power source 1 detected by the inverter applied voltage detection means 16. The induced voltage of the brushless motor 3 is estimated by the induced voltage estimation means 17 from the DC voltage output from Further, the rotor position / velocity detecting means 18 estimates the rotor magnetic pole position and speed of the brushless motor 3 from the estimated induced voltage.

  The target rotational speed correction means 11 is used when the torque command amount determined by the torque control means 21 exceeds a preset value in the low speed region and when the value detected by the pipe temperature detection means 22 exceeds a preset value. In this case, by adding the corrected rotational speed to the target rotational speed that has already been set, the low speed region can be avoided, the increase in vibration and noise can be suppressed, and the motor can be prevented from stopping. An electric motor drive device capable of continuously operating stably is realized.

  As described above, the motor drive device according to the present invention prevents increase in motor vibration and noise during overload and avoids motor step-out by avoiding the low speed region of the motor with large torque fluctuation. Therefore, stable driving is possible, so that it can be used for industrial equipment, products, and the like using a position sensorless brushless DC motor.

1 DC power supply 2 Inverter 3 Brushless motor (three-phase motor)
6 Control section 7 Current detection means 9 PWM signal generation means 10 Base driver 11 Target rotation speed correction means 16 Inverter applied voltage detection means 17 Induced voltage estimation means 18 Rotor position speed detection means 19 Rotor acceleration detection means 20 Acceleration control means 21 Torque control means 22 Piping temperature detection means

Claims (1)

An electric motor comprising a three-phase motor, an inverter, and torque control means for controlling the inverter so that the torque generated by the three-phase motor matches the load torque generated by the load element driven by the three-phase motor In the torque control apparatus, a PWM signal generating means for generating a PWM signal for outputting an output voltage for driving the three-phase motor at a target rotational speed, a torque command amount and a pipe temperature determined by the torque control means An electric motor drive device comprising a target rotational speed correcting means for correcting a target rotational speed when a predetermined value is exceeded.

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