JP4736815B2 - Inverter control device and motor start method. - Google Patents

Description

  The present invention relates to an inverter control device and a motor starting method that can suppress and stop an overvoltage when the brushless DC motor is rotating in reverse at the time of starting.

When the conventional inverter control device for driving a brushless DC motor is reversely rotated at the time of starting the motor, three low-side or three high-side switching elements of the six switching elements constituting the three-phase inverter Are turned on, the remaining three are turned off, the terminals of the motor are short-circuited, and are stopped by applying dynamic braking, so that they can be started almost from the stopped state. (For example, refer to Patent Document 1). In some cases, when the reverse rotation speed is equal to or higher than a predetermined value, driving of the motor is prohibited (for example, see Patent Document 2). Also, in an inverter control device that drives a brushless DC motor without a magnetic pole sensor, the rotational speed, direction, and magnetic pole are estimated from the phase current of each phase flowing through the motor, and when the rotational speed in the reverse direction is equal to or higher than a predetermined rotational speed, Motor drive is prohibited. When the rotational speed in the reverse direction is equal to or lower than the predetermined rotational speed, the motor is decelerated by short-circuiting the wires of each phase (see, for example, Patent Document 3).
Thus, in the inverter control apparatus that drives the conventional brushless DC motor, when starting, when rotating in the reverse direction, if the reverse rotation speed is greater than or equal to a predetermined value, the motor drive is prohibited and the reverse rotation speed is predetermined. Below the value, the phase of each phase was short-circuited, and the means of decelerating the motor during reverse rotation was taken.
In addition, a means for stopping the rotation in the reverse direction by regenerating motor power generated during deceleration to the power source has been used.
Japanese Patent Laid-Open No. 10-185252 JP 2000-14183 A JP 2001-128485 A

Depending on the use of the blower, even if the reverse rotation speed is rotating near the rated rotation speed of the motor, it is required to be able to start without prohibiting the motor drive. When the inverter control device for driving a conventional brushless DC motor is rotated in the reverse direction at the time of start-up, the motor drive is prohibited when the reverse rotation speed is equal to or higher than a predetermined value. there were. In addition, in the control that starts directly after decelerating and stopping during reverse rotation, if the reverse rotation speed is high to some extent, the regenerative power returns to the power source of the inverter control device, and the power supply capacitor is overcharged, resulting in overvoltage. .
The present invention has been made to solve such a problem, and an inverter control device and a motor starting method that can stably start up by suppressing an overvoltage caused by regenerative power even when the reverse rotation speed is high. The purpose is to provide.

In order to solve the above problem, the present invention is as follows.
The invention according to claim 1 is a speed signal generation unit that generates a speed signal from a first phase signal generated by a magnetic pole sensor of a brushless DC motor, a current detection unit that generates a current signal of the brushless DC motor, and a speed A speed control unit that generates a torque command based on a speed deviation between the command and the speed signal; a first phase correction signal generated from the speed signal; and a second phase correction signal generated from the current signal; A phase correction unit that adds a signal to generate a second phase signal; a current command generation unit that generates a three-phase current command from the torque command and the second phase signal; A voltage command generation unit for generating a phase voltage command; a PWM generation unit for converting the three-phase voltage command into a PWM signal; In an inverter control device comprising an inverter to be driven, when the brushless DC motor is rotating in reverse at the time of startup, a third phase correction signal is generated and added to the first phase signal to obtain a new first phase signal. A reverse rotation phase correction unit for generation is provided.
According to a second aspect of the present invention, in the inverter control device according to the first aspect, the reverse rotation phase correction unit determines that a reverse rotation occurs when the speed command and the speed signal have different polarities. To do.
According to a third aspect of the present invention, in the inverter control device according to the first aspect, the third phase correction signal is a function of the speed signal.
According to a fourth aspect of the present invention, in the inverter control apparatus according to the first aspect, the third phase correction signal is a predetermined fixed value.
According to a fifth aspect of the present invention, in the inverter control device according to the first aspect, the first phase correction signal advances in the torque generation direction in proportion to the speed signal.
According to a sixth aspect of the present invention, in the inverter control device according to the first aspect, the second phase correction signal advances in the torque generation direction in proportion to the amplitude of the current signal.
The invention according to claim 7 is a speed signal generation unit that generates a speed signal from a first phase signal generated by a magnetic pole sensor of a brushless DC motor, a current detection unit that generates a current signal of the brushless DC motor, and a speed A speed control unit that generates a torque command based on a speed deviation between the command and the speed signal; a first phase correction signal generated from the speed signal; and a second phase correction signal generated from the current signal; A phase correction unit that adds a signal to generate a second phase signal; a current command generation unit that generates a three-phase current command from the torque command and the second phase signal; A voltage command generation unit for generating a phase voltage command; a PWM generation unit for converting the three-phase voltage command into a PWM signal; In motor starting method of the inverter control device comprising an inverter for driving, and reading non-step the speed signal and the speed command,
A step of determining reverse rotation when the speed command and the speed signal have different polarities; and a step of starting normally after adding a predetermined fixed phase to the phase signal and decelerating and stopping when determining reverse rotation; A step of starting normally when it is determined that the rotation is normal.

  ADVANTAGE OF THE INVENTION According to this invention, even if reverse rotation speed is large, the inverter control apparatus and motor starting method which can suppress the overvoltage by regenerative electric power, can stop a motor, and can start stably can be provided.

  Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the inverter control device of the present invention. In FIG. 1, 1 is a speed control unit, 2 is a current command generation unit, 3 is a voltage command generation unit, 4 is a PWM signal generation unit, 5 is an inverter unit, 6 is a current detection unit, 7 is a speed signal generation unit, 8 Is a phase correction unit, 9 is a reverse rotation phase correction unit, 10 is a motor, and 11 is a magnetic pole sensor. FIG. 2 is a block diagram showing a main circuit configuration of the inverter unit. In FIG. 2, 12 is a rectification power supply unit, and 13 is a DC power supply capacitor unit.

Next, the operation will be described. The rectification power supply 12 rectifies the three-phase power supply R, S, and T-phase voltages to generate a DC power supply. The power supply capacitor 13 smoothes the DC power supply.
The magnetic pole sensor 11 generates a phase signal of the motor 10. The phase signal is usually a square wave having the same phase as the induced voltage during the positive rotation of the three-phase winding, U phase, V phase, and W phase of the brushless DC motor, but may be an absolute phase signal. The speed signal generation unit 7 generates a rotation direction and a rotation speed from the phase signals of the U phase, the V phase, and the W phase. The rotation direction can be determined by the change order of the U phase, the V phase, and the W phase. For example, the rotation speed is measured by counting the period of the U phase with a clock and taking the reciprocal of the period to obtain the rotation speed. Further, not only the U phase but also the V phase and the W phase can be similarly measured, and the speed data can be updated every time the phase of each phase is updated. The current signal is a polarized amplitude signal obtained by synchronously rectifying a three-phase current with a phase signal. Alternatively, a q-axis current may be generated by generating a sine wave signal obtained by synchronizing the three-phase current signal with the phase signal, multiplying each phase current, and adding them. The speed control unit 1 performs a PID (proportional, integral, derivative) control process on the speed deviation Δω of the difference between the speed command ωref and the speed signal ωfb, and generates a torque command Tref. The current command generation unit 2 generates the amplitude of the current command by dividing the torque command Tref by the induced voltage constant ke of the motor, and further, cosine functions cos (θfb), cos (θfb-2π / 3), cos of the phase signal θfb. Multiply (θfb + 2π / 3) to generate three-phase current commands Ireffu, Irefv, and Irefw. The voltage command generator 3 generates each phase induced voltage signal Emu, Emv, Emw from the current command, the speed signal, and the phase signal. Further, the impedance voltage drop voltages Ezu, Ezv, Ezw are added from the motor constant to generate a three-phase voltage command Erefu, Erefv, Erefw. The PWM signal generation unit 4 generates a PWM signal for each phase by comparing the voltage command with a triangular wave having a constant period. For the PWM signal, a space vector may be obtained from a three-phase voltage command for each carrier period, and a time pattern of the PWM signal may be obtained from the space vector. The inverter 5 is composed of six switching elements of a three-phase bridge, and the switching elements are turned on / off by a PWM signal to supply power to the motor.
The phase correction unit 8 corrects the current phase lag during high-speed rotation, and generates a reluctance torque by advancing the current in the direction of torque generation rather than the induced voltage when the brushless DC motor rotor has a salient pole. A first phase correction signal Δθ1 as a function of the speed signal ωfb and a second phase correction signal Δθ2 as a function of the amplitude of the current signal Ifb are generated and added to the first phase signal θfb1 to generate a second phase signal θfb2. Normally, the first phase correction signal Δθ1 is proportional to the speed signal ωfb, and the second phase correction signal Δθ2 is proportional to the current signal Ifb.
The reverse rotation phase correction unit 9 is for stopping the reverse rotation and starting it in the forward rotation direction when the motor is reversely rotated at a high speed at the time of activation. However, if a motor that rotates at high speed is stopped rapidly, the kinetic energy of the rotating system is converted into electrical energy by the motor and the inverter, and the energy is regenerated to the power supply of the inverter, the current charges the capacitor, and the voltage Rises. In order to keep this voltage rise below the withstand voltage level in the component, the current phase is shifted from the induced voltage, the current amplitude is increased, the joule loss of the motor is increased, and regenerative energy is consumed. Specifically, when the polarities of the speed command ωref and the speed signal ωfb are different, it is determined as reverse rotation, and the phase signal is added to the first phase signal θfb1 with the third phase correction signal Δθ3 having a predetermined fixed phase. A first phase signal. Normally, the third phase correction signal Δθ3 has a negative polarity, and the first phase correction signal Δθ1 and the second phase correction signal Δθ2 are zero during reverse rotation. Further, the third phase correction signal Δθ3 may be a function of a speed signal based on a constant of the brushless DC motor, and the Joule loss may be maximized within the loss allowable range or may be approximately proportional to the speed.

  FIG. 3 is a flowchart showing an embodiment of the motor starting method of the inverter device of the present invention. First, in step 1, the speed command and the speed signal are read. In step 2, when the speed command and the speed signal have different polarities, if it is the same as reverse rotation, it is determined as normal rotation, and if it is determined as reverse rotation, it is determined in step 3. When a predetermined fixed phase is added to the phase signal and when it is determined that the rotation is normal, normal activation is performed at step 4.

4A and 4B are simulations when the reverse rotation is detected and the vehicle is decelerated and stopped. FIG. 4A shows the case where the fixed phase = 0 degrees, and FIG. 4B shows the case where the fixed phase = −45 degrees. When the fixed phase = 0 degree, the voltage of the DC power supply capacitor of the inverter rises to 450V, whereas when the fixed phase = −45 degrees, if the deceleration rate is the same, the same torque is generated. The current of 1 / cos (45 °) = 1.4 times must be passed, and the joule loss of the motor increases to 1.4 ² = 2 times. Since the regenerative power of the motor is the same, (regenerative power-motor joule loss-inverter loss) is substantially the power for charging the power supply capacitor, so the voltage rise is reduced. The simulation conditions of FIG. 4 are as follows: the inverter unit is proportional to the speed control unit kv = 1 Nms / rad, the carrier frequency fc = 2 kHz, the inverter power supply capacitor capacity = 470 μF, the inverter circuit loss Pi = 200 W, and the motor unit is the induced voltage constant ke. = 0.2 Vs / rad, armature resistance = 0.5 Ω / phase, inductance L = 1 mH / phase, inertia J = 0.002 kgm ² , deceleration conditions are reverse rotation speed ωmax = 200 rad / s, deceleration time Tdc = 50 ms It is said. If the regenerative power is larger than the motor joule loss even if the fixed phase is shifted and the charging voltage exceeds the breakdown voltage characteristics of the component parts, the deceleration is suppressed, or a predetermined first voltage and a second voltage lower by about 10 V are applied. It may be set and the deceleration may be stopped when the first voltage is reached, and the deceleration may be started again when the voltage drops to the second voltage.

  Another embodiment performs current control. For example, FIG. 5 shows an example in which dq-axis current control is applied. A three-phase current / dq current coordinate conversion unit 23, a current control unit 21, and an induced voltage correction unit 22 are added to the embodiment of FIG. 1, and the dq axis voltage / three-phase voltage conversion is included in the voltage command unit 3. Except for this, the operation is the same as in the embodiment of FIG.

  The present invention is expected to be applied to applications that are easily turned from the outside at a reverse rotation speed, and applications that can damage equipment if it is rotated for a long time due to reverse rotation, for example, air conditioners for buildings. it can.

The block diagram which shows the structure of the inverter control apparatus of this invention Block diagram showing the main circuit configuration of the inverter section The flowchart which shows the motor starting method of this invention Simulation showing the operation of the present invention The block diagram which shows the structure of the inverter control apparatus of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Speed control part 2 Current command generation part 3 Voltage command generation part 4 PWM signal generation part 5 Inverter part 6 Current detection part 7 Speed signal generation part 8 Phase correction part 9 Reverse rotation phase correction part 10 Motor 11 Magnetic pole sensor 12 Rectification power supply part 13 power supply capacitor unit 21 current control unit 22 induced voltage correction unit 23 three-phase current / dq axis current conversion unit

Claims (7)

A speed signal generation unit that generates a speed signal from a first phase signal generated by a magnetic pole sensor of the brushless DC motor, a current detection unit that generates a current signal of the brushless DC motor, and a speed deviation between the speed command and the speed signal A speed control unit that generates a torque command based on the first phase correction signal generated from the speed signal and a second phase correction signal generated from the current signal is added to the first phase signal. A phase correction unit to generate, a current command generation unit to generate a three-phase current command from the torque command and the second phase signal, and a voltage command generation to generate a three-phase voltage command from the current command and the brushless DC motor constant A PWM generator that converts the three-phase voltage command into a PWM signal, and an inverter that amplifies the PWM signal to drive the brushless DC motor. In obtaining the inverter control device,
When the brushless DC motor is rotating in reverse at the time of startup, a reverse rotation phase correction unit is provided that generates a third phase correction signal and adds it to the first phase signal to generate a new first phase signal. Inverter control device characterized.   The reverse rotation phase correction unit receives the speed command, the speed signal, and the first phase signal, and determines that the rotation is reverse when the polarities of the speed command and the speed signal are different. 1. The inverter control device according to 1.   The inverter control device according to claim 1, wherein the third phase correction signal is a function of the speed signal.   The inverter control device according to claim 1, wherein the third phase correction signal is a predetermined fixed value.   The inverter control device according to claim 1, wherein the first phase correction signal is advanced in the torque generation direction in proportion to the speed signal.   The inverter control device according to claim 1, wherein the second phase correction signal is advanced in the torque generation direction in proportion to the amplitude of the current signal. A speed signal generation unit that generates a speed signal from a first phase signal generated by a magnetic pole sensor of the brushless DC motor, a current detection unit that generates a current signal of the brushless DC motor, and a speed deviation between the speed command and the speed signal A speed control unit that generates a torque command based on the first phase correction signal generated from the speed signal and a second phase correction signal generated from the current signal is added to the first phase signal. A phase correction unit to generate, a current command generation unit to generate a three-phase current command from the torque command and the second phase signal, and a voltage command generation to generate a three-phase voltage command from the current command and the brushless DC motor constant A PWM generator that converts the three-phase voltage command into a PWM signal, and an inverter that amplifies the PWM signal to drive the brushless DC motor. In motor starting method of obtaining the inverter control device,
Reading the speed command and the speed signal;
A step of determining reverse rotation when the speed command and the speed signal have different polarities;
When it is determined that the rotation is reverse, a step of normally starting after adding a predetermined fixed phase to the phase signal and decelerating and stopping;
When it is determined that the rotation is normal, the step of starting normally,
The motor starting method of the inverter apparatus characterized by the above-mentioned.

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