JP3107293B2 - Motor speed control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed control device for a motor, and more particularly to a speed control device suitable for speed control of a motor having a booster chopper circuit and a power converter. Things. 2. Description of the Related Art Japanese Patent Laid-Open No. Sho 59-198873 discloses a rectifier circuit for rectifying an AC power supply and converting it into a DC power supply, and having a circuit for suppressing harmonics of the power supply current. A synchronous error signal and current obtained by connecting a reactor and a switching element as a step-up jumper circuit to the output terminal of the rectifier circuit and multiplying a voltage signal of an AC power supply having a difference between a DC output voltage and a set voltage. Compared with the waveform, the switching element is turned on / off according to the polarity of the difference. In the above prior art, the load connected to the DC power supply is a power converter, and no consideration is given to the case where the electric motor is driven by the power converter. . That is, if the DC input voltage applied to the power converter is changed to change the rotation speed, in applying the above-described conventional technology to a motor having a characteristic in which the rotation speed changes, the set voltage with respect to the DC output voltage is changed. It is necessary to add a speed control circuit for generating the above-mentioned speed and the command speed for this speed, and the circuit scale becomes complicated. Further, in the conventional technology using the boosting chopper circuit, the magnitude of the DC input voltage applied to the power converter cannot be controlled to a value equal to or less than the peak value of the AC input voltage, and the speed control range of the motor is limited. There was a problem. An object of the present invention is to provide a motor speed control device capable of controlling the speed of a motor over a wide range. [0005] According to one aspect of the present invention,
Then, the above-mentioned object is achieved by boost boost chopper circuit and boost boost chopper circuit.
A power converter connected to the power conversion circuit;
A brushless motor connected to the
Speed command and rotor of the brushless motor
The switch of the step-up chopper circuit is switched in accordance with the position detection signal.
A first control area for controlling the intermittent operation of the switching element;
A speed command of the brushless motor;
The power converter according to the rotor position detection signal of the rotor.
And a second control region for performing pulse width modulation control of the
This is achieved by providing a control device. Other of the present invention
According to the view, the above purpose is to rectify the AC input.
Path, a boost chopper circuit connected to the rectifier circuit,
A power converter connected to the boost chopper circuit;
A brushless motor connected to the power converter,
In the high speed range of the brushless motor, the brushless motor
Speed command and rotor of the brushless motor
The switch of the step-up chopper circuit is switched in accordance with the position detection signal.
A first control area for controlling the intermittent operation of the switching element;
In the low speed range of the brushless motor, the brushless
Motor speed command and the brushless motor rotor
The pulse width of the power converter according to the position detection signal
A second control area for performing modulation control, and a step-up chopper
The intermittent operation of the switching elements that make up the circuit
The AC input voltage is controlled by controlling the AC input voltage.
A control device having a function of controlling the flow waveform.
Is achieved by [0006] In the high-speed region, if the command speed is increased, the deviation speed increases, whereby the current command and the synchronous current command signal increase, and the difference from the power supply current increases accordingly. As a result, the ON time of the switching element is increased. And the power supply current increases. As a result, the DC voltage applied to the power converter increases, and the speed of the motor increases. The above operations are repeated until the deviation speed becomes zero, and the speed of the electric motor can be controlled by changing the magnitude of the power supply current according to the deviation speed. In the low-speed region, if the command speed is increased, the deviation speed increases, and the voltage applied to the motor by PWM (Pulse Width Modulation) control in the power converter increases, so that the speed of the motor increases. The above operation is repeated until the deviation speed becomes zero, and the speed of the electric motor can be controlled. The present invention will be described below in detail with reference to the embodiment shown in FIGS. 1 and 4 and FIGS. 2 and 3. FIG. 1 is a circuit diagram showing an embodiment of a motor speed control device according to the present invention, which is for a brushless DC motor. In FIG. 1, an AC power supply 1 is converted into a DC voltage Ed via a rectifier circuit 2 and a step-up chopper circuit 3, supplies DC power to an inverter 4, and drives a synchronous motor 5 by the inverter 4. A control circuit for controlling the speed of the synchronous motor 5 includes a microcomputer 6 and a rotor 5 of the synchronous motor 5.
a position detecting circuit 8 for detecting the position of the magnetic pole a from the motor terminal voltage 7;
Inverter control unit 9 for a to 4f, power supply current control unit 11 for controlling the waveform and magnitude of power supply current 10, DC voltage comparison unit 12 for switching between low-speed mode and high-speed mode
And a DC current detector 13 for detecting a DC current. [0010] The micro computer 6 includes a synchronous motor 5.
, Such as speed control processing, position detection signal 14 from position detection circuit 8, speed command 15, DC voltage comparison signal 16, and detected DC current 17.
In addition, processing such as taking an inverter drive signal 18 to the inverter driver 9a, outputting a current command 19 to the power supply current control unit 11, and outputting a voltage signal 20 to the inverter control unit 9 is executed. The step-up chopper circuit 3 includes a reactor 3a,
A drive signal for the transistor 3b is created by the power supply current control unit 11, and the instantaneous magnitude of the power supply current 10 is changed by changing the on-time and off-time of the transistor 3b. Is to be changed. FIG. 2 shows the power supply voltage 21 and the power supply current 10 of FIG.
As shown in FIGS. 2 (a) and 2 (b), the power supply current control unit 11 and the
Is a sine wave having the same phase as that of the power supply voltage 21, and the magnitude of the sine wave is represented by the micro computer 6.
Is controlled in accordance with the current command 19 output from the controller. The power supply current control section 11 generates a voltage signal 22 having a full-wave rectified waveform synchronized with the power supply voltage 21 from the output voltage of the rectification circuit 2. The power supply voltage detection circuit 11 a includes the voltage signal 22 and a digital signal. A multiplying D / A converter 11b for generating a synchronous current command signal 23 which is an analog signal by multiplying the current command 19 by a current command 19, and a power supply current amplifier 11d for detecting and amplifying a full-wave rectified waveform of the power supply current 10 with a resistor 11c. A current control amplifier 11e that compares the output of the detected power supply current 24 with the synchronous current command signal 23 and operates so as to make the difference voltage zero, and outputs the error signal 25 and the output of the triangular wave oscillator 11f. A comparator 11g for generating a chopper signal 27 for the transistor 3b by comparing a certain triangular wave 26 and a chopper driver for the transistor 3b. It is composed of a bus 11h. The inverter control section 9 includes a DA converter 9b for converting a voltage signal 20 which is a digital signal into an analog signal, a voltage signal 28 which is an output of the DA converter 9b,
It comprises a comparator 9d for generating a chopper signal 30 for the inverter 4 by comparing the triangular wave 29 which is the output of c, and an inverter driver 9a for the inverter 4. The DC current detector 13 includes a DC current amplifier 13a for detecting and amplifying the DC current Id by the resistor 31, and an A / D converter 13b for converting the output to a digital signal.
It consists of. The DC voltage comparing section 12 has a DC setting voltage Edc.
And a comparator 12b for comparing the output of the set voltage amplifier 12a with the signal detected by the resistors 32 and 33. In the brushless DC motor having the speed control device according to the embodiment of the present invention, the present invention uses a different control method in the high-speed region and the low-speed region, and is characterized by switching between them. The reason for using different control methods and the method of switching between them will be described below. The speed of the brushless DC motor can be controlled by changing the output voltage of the inverter. The methods include a method of changing the DC voltage Ed and a PWM control by the inverter. As a method of changing the DC voltage Ed, there is a method using a step-up chopper circuit. However, since this method uses a step-up chopper circuit, when the DC voltage Ed is lower than the peak value of the power supply voltage 21, the peak value of the power supply voltage 21 The booster does not operate in the vicinity, and the power supply current 10 cannot be controlled to a sine wave. Therefore, in order to perform speed control in such a region, it is necessary to perform PWM control using an inverter. Therefore, it is necessary to use different speed control methods in a high-speed region and a low-speed region. Therefore, the DC voltage Ed is always equal to the power supply voltage 2
In a region larger than 1, that is, in a region where the DC voltage Ed is larger than the peak value of the power supply voltage 21, the DC voltage control is performed using the boosting chopper circuit, and the inverter performs the high-speed control mode without performing the PWM control. It can be seen that in the region (2), the boosting chopper circuit should perform control so that the DC voltage Ed becomes a constant voltage, and the inverter should perform low-speed control mode in which PWM control is performed. Switching between the two modes is performed by the inverter PW
When the duty of the M control becomes 100%, the mode is changed from the low speed mode to the high speed mode. It can be seen that it is only necessary to switch from the low speed mode to the low speed mode. Hereinafter, a specific implementation method will be described with reference to FIGS. FIG. 3 is a waveform diagram of the position detection signal 14, and FIG.
The state of the three-phase signal changes every degree. Then, the times t _{1 to} t ₆ are measured at every 60 °, and the speed T of the synchronous motor 5 is detected by obtaining the time T of one cycle. FIG. 4 is a flow chart showing one embodiment of the speed control processing executed in the microcomputer 6 of FIG. 1, and shows a procedure for generating a current command 19 and a voltage signal 20 to the inverter control unit 9. In process I,
A command speed Nr is calculated based on a speed command 15 given from outside the microcomputer 6, and in a process II, a time T of one cycle of the position detection signal 14 is obtained.
The speed N is calculated from the time T of one cycle and the proportional constant K. Thereafter, the current mode is determined. If the high-speed mode is selected, if the DC voltage Ed is smaller than the set voltage Edc selected to take a value larger than the peak value of the power supply voltage 21, the processing IV is performed. If it is larger, the processing V is performed. If the current mode is the low-speed mode, when the voltage signal 20 to the inverter control unit 9 becomes 100% duty, it is set to $ FF (FF in hexadecimal). When the voltage signal 20 becomes ＄ FF, the processing V
Otherwise, processing IV is performed. The process IV is a process in which the current command 19
r is Id, which is the DC current signal 17, and the proportionality constant K _L
As the product, Er where a voltage signal 20 creates a deviation velocity .DELTA.N = Nr-N from the proportional term P _L and the integral term I _L between the command speed Nr and speed output speed N, each determined as the sum You. Created here, the proportional term P _L, as a product of the proportional gain K _PL and deviation velocity .DELTA.N, also integral term I _H, in addition the product of the integral gain K _IL and deviation velocity .DELTA.N the integral term at that time I do. After that, the current command value Ir and the voltage signal Er are output to set the low speed mode. In the process V, the voltage signal 20 as $ FF, the current command 19 is output as the sum of the proportional term P _H and the integral term I _H. Here, the proportional term P _H as the product of the proportional gain K _PH and deviation velocity .DELTA.N, also integral term I _H is prepared by adding the product of the integral gain K _{the IH} and deviation velocity .DELTA.N the integral term at that time. After that, the current command value Ir and the voltage signal Er are output, and the high-speed mode is set. By repeatedly executing the above speed control processing, control is performed so that the speed command Nr and the detected speed N become equal. In the above embodiment, the case where the present invention is applied to a brushless DC motor has been described. However, it is needless to say that the present invention can be applied to other synchronous motors. that's all
According to the described embodiment, the boost chopper circuit
To control the speed of the motor using the road
It is not necessary to perform PWM control, and loss in the power converter
And reduce harmonic components of motor winding current.
And the direct current applied to the power converter
The input voltage is smaller than the peak value of the AC input voltage
In such a region, that is, only the boost chopper circuit
In low-speed areas where speed control is not possible, power conversion
Low speed due to the configuration to perform PWM control in the device
Enables speed control in the area, speed control over a wide range
There is an effect that it becomes possible. According to the present invention, the electric motor is spread over a wide range.
Motor speed control device that can control the speed
Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit configuration diagram showing one embodiment of a motor speed control device of the present invention. FIG. 2 is a waveform diagram of a power supply voltage and a power supply current in FIG. FIG. 3 is a waveform diagram of a position detection signal. FIG. 4 is a flowchart showing one embodiment of a speed control process in the microcomputer of FIG. 1; [Description of Signs] 1 AC power supply 2 Rectifier circuit 3 Boost chopper circuit
4 ... Inverter, 5 ... Synchronous motor, 6 ... Microcomputer, 8 ... Position detection circuit, 9 ... Inverter control unit, 9
a ... Driver for inverter, 9b ... DA converter, 9
c: triangular wave oscillator, 9d: comparator, 11: power supply current control unit, 11a: power supply voltage detection circuit, 11b: DA converter with multiplication, 11d: power supply current amplifier, 11e: current control amplifier, 11f: triangular wave oscillator, 11g ... Comparator, 11h ... Chopper driver, 12 ... DC voltage comparator, 12a ... Setting voltage amplifier, 12b ... Comparator, 13 ... DC current detector, 13a ... DC current amplifier,
13b ... AD converter.

Continuing from the front page (72) Inventor Susumu Kashiwazaki 800 Tomita, Ohira-cho, Shimotsuga-gun, Tochigi In-house Hitachi, Ltd. In the factory (56) References JP-A-59-198897 (JP, A) JP-A-62-53178 (JP, A) JP-A-61-280785 (JP, A) JP-A-60-139177 (JP, A) JP-A-57-211621 (JP, A) JP-A-63-224698 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 7/63 H02P 5/408 H02P 6 / 06

Claims (1)

(57) [Claims] Connected to the boost chopper circuit and the boost chopper circuit
Power converter, and connected to the power converter
A brushless motor, and a speed with respect to the brushless motor.
Degree command and the rotor position detection signal of the brushless motor,
According to the switching element of the boost chopper circuit.
A first control area for controlling an intermittent operation;
Motor speed command and rotor position of the brushless motor
Pulse width change of the power converter in accordance with the position detection signal.
A control device having a second control area for performing key control.
A speed control device for a motor. 2. The first control area is provided for controlling the operation of the brushless motor.
A high-speed area of the operation area, wherein the second control area is
2. A low-speed region in an operation region of the brushless motor.
An electric motor speed control device as described in the above. 3. A rectifier circuit for rectifying the AC input;
Connected to the boost chopper circuit and the boost chopper circuit.
A power converter connected to the power converter,
Brushless motor and the high speed of the brushless motor
Speed command to the brushless motor in the region
According to the rotor position detection signal of the brushless motor.
Intermittent operation of the switching element of the boost chopper circuit
A first control area for controlling operation, and the brushless motor
Speed command of the brushless motor in the low speed range of
And a rotor position detection signal of the brushless motor.
Secondly, the pulse width modulation control of the power converter is performed in the second
And the switches constituting the boost chopper circuit.
Intermittent operation of the switching element in relation to the AC input voltage.
Controlling the waveform of the AC input current.
Characterized by comprising a control device having a function
Machine speed control device.