JP5634693B2 - Motor current control method and control apparatus - Google Patents

Description

  The present invention relates to a motor control device, and in particular, motor current control that achieves high speed and high output while ensuring stability by appropriately controlling and flowing d-axis current through a dq converted motor armature. The present invention relates to a method and a control device.

  The motor is driven by applying a voltage between the motor wires and causing a current to flow through the armature. On the other hand, a counter electromotive voltage is generated when the motor rotates. When the applied voltage is higher than the back electromotive voltage, current flows and the motor can be driven. As the motor speed increases, the back electromotive force also increases and the applied voltage has an upper limit, eventually causing voltage saturation in the motor armature, which prevents current from flowing, thereby generating torque. It becomes impossible to drive the motor.

  If a larger torque is required, the applied voltage may be increased. However, a large facility is required to realize this, and costs are increased. A method of increasing the capacity of the motor and the inverter that drives the motor is also conceivable, but this is also not desirable because it costs the same as described above. Therefore, in recent years, methods for preventing the occurrence of voltage saturation have been proposed in order to generate a larger torque at a low cost.

  As a method of preventing the occurrence of voltage saturation in the motor armature, torque is generated by reducing the back electromotive force generated when the motor rotates by applying d-axis current to the armature whose d-axis direction is the direction of the field field. Since a larger amount of q-axis current can be supplied, a current control method has been proposed that can output a larger output at a higher speed (for example, see Patent Document 1).

  In addition, as a method of increasing the output, the line voltage waveform of each phase of the motor is a rectangular wave or a pseudo-rectangular wave, so that the effective value voltage is compared to the general case of supplying a sinusoidal phase voltage to each phase. There has been proposed a control method for increasing (see, for example, Patent Document 2).

JP-A-9-84400 Japanese Patent No. 3939481

Although the control method of Patent Document 1 is stable, the inverter circuit that drives the motor has a sufficient margin to prevent voltage saturation by controlling the reactive current to flow from a set speed near the speed at which voltage saturation occurs. If there is, it cannot be said that the motor's capacity is being maximized. Since the control method of Patent Document 2 controls the waveform of the line voltage of each phase of the motor to be a rectangular wave or a pseudo-rectangular wave, if the inverter circuit that drives the motor has a sufficient margin, the motor capacity is maximized. However, it is not stable and in the worst case, the control may become unstable.
SUMMARY OF THE INVENTION An object of the present invention is to provide a current control method and a control device that can realize high speed and high output while ensuring the stability of the motor as much as possible.

  In order to achieve the above object, a converter unit that rectifies and smoothes an AC power supply and outputs a DC main circuit voltage, an inverter unit that supplies a current for driving the motor using the main circuit voltage, and a current that flows through the motor From the current detector that detects the armature current, the position detector that detects the motor speed attached to the motor, the q-axis current command (Iqr), the data from the current detector and the position detector It is equipped with a current control unit that outputs a signal that drives the inverter unit and controls the armature current that flows to the motor, and draws out the motor's capabilities as much as possible to achieve high speed and high output while ensuring stability It is characterized by realizing.

  The current control unit receives the q-axis current command (Iqr) and uses the maximum value (Imax) of the combined current of the q-axis and d-axis and the d-axis current command (Idr) described later to determine the q-axis current limit value (Iqlimit ) And limit Iqr so that it does not exceed Iqlimit, and to prevent speed overshoot, etc., a limit flag that informs the upper control unit that performs speed control etc. when the q-axis current command is limited Limit processing unit that turns ON, PI compensation unit to increase gain, and voltage command (Vq) output from PI compensation unit is limited to the preset limit value by the limit of parts used in the control device In order to actually drive the motor with the VqLimit processing unit (for Vq) and VdLimit processing unit (for Vd) and the two-phase clamped voltage command (Vql and Vdl) output from the VqLimit processing unit and VdLimit processing unit The signals output from the 2-phase → 3-phase converter that converts to 3-phase voltage and the 2-phase → 3-phase converter A PWM converter that converts the signal to the source, a d-axis current command generator that obtains the Idr using the Vql and Vdl, and an electrical angular velocity (ω) described later, and a signal from the current detector processed by the current controller A current detector that converts the data into possible data, a three-phase to two-phase converter that converts the three-phase current of each phase output from the current detector into a two-phase current, and a current controller that receives the signal from the position detector A position detection unit that converts the data into data that can be processed in

  ADVANTAGE OF THE INVENTION According to this invention, the electric current control method and control apparatus which draw out the capability of a motor as much as possible, and implement | achieve high-speed high output, ensuring stability are provided.

Example block diagram of current control method and control apparatus according to the present invention Flow chart of limit processing unit Block diagram of PI compensation unit Flow chart of d-axis current command generator Block diagram of integration S406 in FIG.

  Examples of the present invention will be described below.

  A first embodiment of a current control method and a control apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing Embodiment 1 according to the present invention. The power source shown in Fig. 1 is an AC power source and supplies an AC voltage. The supplied AC voltage is rectified and smoothed by the converter unit 1 and the main circuit DC voltage is output. FIG. 3 is a block diagram showing a motor current control method and a control device for driving the motor 5 by switching the inverter unit 2 using the control signal output from the main circuit DC voltage from the current control unit 3. The limit flag output from the current control unit 3 informs the host control unit that performs speed control and the like that the q-axis current command has been limited, and prevents speed overshoot and the like.

The current control unit 3 in FIG. 1 that controls the armature current flowing through the motor will be described below.
In response to an external q-axis current command (hereinafter referred to as Iqr), the limit processing unit 301 uses the maximum value (Imax) of the combined current of q-axis and d-axis and a d-axis current command (hereinafter referred to as Idr) described later. The q-axis current limit value (hereinafter referred to as Iqlimit) is obtained by √ (Imax ^ 2−Idr ^ 2).

  On the other hand, if Iqr is greater than 0 and greater than Iqlimit, the q-axis current limit command value (hereinafter referred to as Iqrl) is limited to Iqlimit and the limit flag is turned ON. If Iqr is 0 or more and Iqlimit or less or Iqr is 0 or less and -Iqlimit or more, Iqrl is set to Iqr and the limit flag is turned OFF. If Iqr is smaller than 0 and smaller than -Iqlimit, Iqrl is limited to -Iqlimit and the limit flag is turned ON. As described above, Iqrl is obtained and output from the limit processing unit 301. (See Figure 2 for details)

  The value obtained by subtracting the q-axis current (Iq) that is actually flowing to the motor from Iqrl output from the limit processing unit 301 is input to the PI compensation unit 302a (see FIG. 3 for details) for increasing the gain. . The voltage command (hereinafter referred to as Vq) output from the PI compensation unit 302a is input to the VqLimit processing unit 303a that limits the limit value set in advance from the limit of components used in the control device.

  In the VqLimit processing unit 303a, half of the main circuit DC voltage is set to the limit voltage VLimit (VLimit increases the phase voltage by moving the neutral point and increases the torque to the main circuit DC voltage / 2 × 1.15. If Vq is greater than VLimit, it will clamp to VLimit and output the clamped q-axis voltage command (hereinafter referred to as Vql).

  Further, a value obtained by subtracting a d-axis current (hereinafter referred to as Id) actually flowing in the motor from Idr described later is input to the PI compensation unit 302b). The voltage command (hereinafter referred to as Vd) output from the PI compensation unit 302b is input to the VdLimit processing unit 303b that limits to a preset limit value.

  If Vd is larger than the VLimit, the VdLimit processing unit 303b performs a process of clamping to the VLimit and outputs a clamped d-axis voltage command (hereinafter referred to as Vdl).

  Two-phase to three-phase conversion unit 304 that converts the two-phase clamped voltage commands (Vql and Vdl) output from the VqLimit processing unit 303a and the VdLimit processing unit 303b into a three-phase voltage to actually drive the motor. The two-phase to three-phase converter 304 is a general content and will not be described here. Refer to various documents.) And the signal output from the two-phase to three-phase converter 304 is converted into a pulse. A PWM conversion unit 305 for conversion (the PWM conversion unit 305 does not directly affect the present invention and will not be described. Refer to various documents) to drive the inverter unit to move the motor.

  In the explanation of FIG. 1, the current detection unit 307 that converts the signal from the current detector 4 into data that can be processed by the current control unit 3 converts the current of the second phase from the current of the second phase from Iv = − (Iu + Iw). Find and output. A current detector for three phases may be provided and the current detection unit 307 may simply convert the data into data that can be processed by the current control unit 3.

Iq and Id are output from the three-phase → two-phase conversion unit 308 that converts the three-phase current of each phase output from the current detection unit 307 into a two-phase current.
The position detector 309 that receives a signal from the position detector 6 attached to the motor converts and differentiates the signal from the position detector 6 into data that can be processed by the current controller 3, and calculates the electrical angular velocity ω of the motor. Output.

In the d-axis current command generation unit 306, when Vql is 0 or more and ω is 0 or less or Vql is less than 0 and ω is 0 or more, VdVqerr = Vdl ^ 2 + Vql ^ 2-VLimit ^ 2 VdVqerr is obtained, and in the case of other conditions, VdVqerr = Vdl ^ 2 + − Vqr ^ 2-VLimit ^ 2 is obtained.

  The VdVqerr is subjected to integral compensation (when the switch in FIG. 5 is OFF) or PI compensation (when the switch in FIG. 5 is ON) with an integrator having an integration constant ωi (see FIG. 5), and Idri is output. As for the ON / OFF switching of the switch in FIG. 5, there are a method of switching by a parameter or the like in view of controllability, a method of switching in real time by a program or the like.

If Idri is less than 0, Idr is 0. If Idri is greater than 0, Idmax (Idmax is a constant value determined in advance according to the motor characteristics. It is usually the same as Imax, but may be different depending on the motor. If it is greater than I), Idr is set to Idmax, and if Idri is 0 or more, if it is less than Idmax, Idr is set to Idri. (See Figure 4 for details)
The above processing is performed by the current control unit 3.

1 Converter section
2 Inverter section
3 Current controller
4 Current detector
5 Motor
6 Position detector

Claims (4)

A converter section for rectifying and smoothing an AC power supply and outputting a DC main circuit voltage;
An inverter section for supplying a current for driving the motor using the main circuit voltage;
A current detector for detecting the armature current flowing in the motor;
A position detector for detecting the motor speed attached to the motor;
A current that receives the q-axis current command (Iqr), uses the data from the current detector and the data from the position detector, outputs a signal for driving the inverter unit, and controls the armature current flowing through the motor A control unit;
With
The current controller is
A current detector that converts the signal from the current detector into data that can be processed by a current controller;
A three-phase to two-phase converter that converts the three-phase current of each phase output from the current detector into a two-phase current;
a d-axis current command generator for generating a d-axis current command value (Idr);
In response to the q- axis current command (Iqr) , the q-axis current limit value (Iqlimit) is calculated using the maximum value (Imax) of the combined current command value of the q-axis and the d-axis and the d-axis current command (Idr).
√ (lmax ^ 2-Idr ^ 2>
Calculated as,
If the q-axis current command (Iqr) is greater than 0 and greater than the q-axis current limit value (Iqlimit), the q-axis current limit command value (Iqrl) is limited to the q-axis current limit value (Iqlimit), and the limit flag ON,
If the q-axis current command (Iqr) is not less than 0 and not more than the q-axis current limit value (Iqlimit), or if the q-axis current command (Iqr) is not more than 0 and not less than -Iqlimit, Set q-axis current limit command value (Iqrl) to q-axis current command (Iqr), turn off the limit flag,
If the q-axis current command (Iqr) is smaller than 0 and smaller than -Iqlimit, the q-axis current limit command value (Iqrl) is limited to -Iqlimit and the limit flag is turned ON.
A limit processing unit that applies the q-axis current limit command value (Iqrl) and so on,
A PI compensation unit for increasing the gain, to which a value obtained by subtracting the q-axis current (Iq), which is the output value of the three-phase to two-phase conversion unit, is input from the output value (Iqrl) of the limit processing unit ;
A VqLimit processing unit (for Vq) that limits the voltage command (Vq) output from the PI compensation unit to a preset limit value ;
a second PI compensator for increasing the gain, to which a value obtained by subtracting a d-axis current (Id), which is an output value of the three-phase to two-phase converter, from a d-axis current command value (Idr);
A VdLimit processing unit (for Vd) that limits the voltage command (Vd) output from the second PI compensation unit to a preset limit value ;
A two-phase to three-phase conversion unit that converts the two-phase voltages (Vql and Vdl) output from the VqLimit processing unit (for Vq) and the VdLimit processing unit (for Vd) into a three-phase voltage to actually drive the motor; ,
A PWM converter that converts a signal output from the two-phase to three-phase converter into a pulse;
A motor current control method using a motor current control device characterized by comprising: Calculating the electrical angular velocity (ω) of the motor based on the signal from the position detector;
Compensating the d-axis current command value (Idr) using the two-phase voltage (Vql and Vdl) and the electrical angular velocity (ω);
The motor current control method according to claim 1, further comprising: A converter section for rectifying and smoothing an AC power supply and outputting a DC main circuit voltage;
An inverter section for supplying a current for driving the motor using the main circuit voltage;
A current detector for detecting the armature current flowing in the motor;
A position detector for detecting the motor speed attached to the motor;
A current that receives the q-axis current command (Iqr), uses the data from the current detector and the data from the position detector, outputs a signal for driving the inverter unit, and controls the armature current flowing through the motor A control unit;
With
The current controller is
A current detector that converts the signal from the current detector into data that can be processed by a current controller;
A three-phase to two-phase converter that converts the three-phase current of each phase output from the current detector into a two-phase current;
a d-axis current command generator for generating a d-axis current command value (Idr);
In response to the q- axis current command (Iqr) , the q-axis current limit value (Iqlimit) is calculated using the maximum value (Imax) of the combined current command value of the q-axis and the d-axis and the d-axis current command (Idr).
√ (lmax ^ 2-Idr ^ 2>
Calculated as,
If the q-axis current command (Iqr) is greater than 0 and greater than the q-axis current limit value (Iqlimit), the q-axis current limit command value (Iqrl) is limited to the q-axis current limit value (Iqlimit), and the limit flag ON,
If the q-axis current command (Iqr) is not less than 0 and not more than the q-axis current limit value (Iqlimit), or if the q-axis current command (Iqr) is not more than 0 and not less than -Iqlimit, Set q-axis current limit command value (Iqrl) to q-axis current command (Iqr), turn off the limit flag,
If the q-axis current command (Iqr) is smaller than 0 and smaller than -Iqlimit, the q-axis current limit command value (Iqrl) is limited to -Iqlimit and the limit flag is turned ON.
A limit processing unit that applies the q-axis current limit command value (Iqrl) and so on,
A PI compensation unit for increasing the gain, to which a value obtained by subtracting the q-axis current (Iq), which is the output value of the three-phase to two-phase conversion unit, is input from the output value (Iqrl) of the limit processing unit ;
A VqLimit processing unit (for Vq) that limits the voltage command (Vq) output from the PI compensation unit to a preset limit value ;
a second PI compensator for increasing the gain, to which a value obtained by subtracting a d-axis current (Id), which is an output value of the three-phase to two-phase converter, from a d-axis current command value (Idr);
A VdLimit processing unit (for Vd) that limits the voltage command (Vd) output from the second PI compensation unit to a preset limit value ;
A two-phase to three-phase conversion unit that converts the two-phase voltages (Vql and Vdl) output from the VqLimit processing unit (for Vq) and the VdLimit processing unit (for Vd) into a three-phase voltage to actually drive the motor; ,
A PWM converter that converts a signal output from the two-phase to three-phase converter into a pulse;
Current control device of a motor according to claim <br/> to have. The current control unit further includes a position detection unit that calculates an electrical angular velocity (ω) of the motor based on a signal from the position detector,
The d-axis current command generation unit is configured to compensate for a d-axis current command value (Idr) using the two-phase voltages (Vql and Vdl) and the electrical angular velocity (ω). The motor current control device according to claim 1.

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