KR960009037Y1 - Current control device of bldc motor - Google Patents

Abstract

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Description

Current control device of brushless motor

1 is a schematic block diagram of a current control device of a conventional brushless motor.

2 is a block diagram of a current control device of a brushless motor according to the present invention.

* Explanation of symbols for main parts of the drawings

1: Microprocessor 21: Dedicated chip for current control

22: proportional integral gain determination circuit 23: pulse width modulation frequency determination circuit

24: average absolute value circuit

The present invention relates to a current control device of a brushless motor, and more particularly, to a current controller of a brushless motor having improved current command transmission method and current feedback method using a dedicated chip.

The current control device of a conventional brushless (BLDC) motor, as is well known, responds to a parallel current command signal from a control means, for example, a microprocessor, and feeds back a current signal from the motor to control the current supplied to the motor. As a means for controlling, as shown in FIG. 1, a digital / analog converter 11 for converting a digital current command from a microprocessor into an analog signal, and a current sensor 13 for sensing and feeding back a motor 20 current. ), A proportional integration that inputs and integrates the difference signal from the adder 12 and the adder 12 generating a canine arc by summing the signal from the digital / analog converter 11 and the signal from the current sensor 13. The controller 14, the pulse width generation circuit 15 which provides the reference wave signal for the pulse width modulation to the proportional integral controller, and the proportional integral signal and the reference wave signal from the proportional integral controller 14 A comparator 16 for comparing and outputting a pulse width modulated signal, a rotor position feedback unit 18 for detecting and feeding back a rotor position of the motor from the motor 20, and a signal from the rotor position feedback unit 18; In response to a signal from the sign logic section 17 and a sign logic section 17 which determines in which phase of the motor 20 the pulse width modulated signal from the comparator is to be supplied. And a power device 19 for driving 20.

These components are mainly composed of independent hardware circuits, and the current command from the microprocessor 1 should be set so that the direction of the current in the digital / analog circuit 11 can be determined, and the digital / analog circuit 11 Depending on the current command, a signal with polarity (+) or (-) should be output. For this reason, there exists a limit of circuit element selection.

The conventional current control device described above has disadvantages in that it is quite disadvantageous in size and cost of the entire circuit since each circuit must be implemented on a substrate. On the other hand, there is a problem such that the error occurrence rate increases depending on whether the circuit characteristics match or the complexity of the circuit.

Accordingly, it is an object of the present invention to provide a current control device for a brushless motor that does not require maintaining the polarity of the current command provided, and can reduce the overall circuit size and greatly reduce the occurrence of errors.

According to the present invention, a current control device for inputting a current command from a control means to feedback-control a current of a brushless motor, inputs a current command and a direction command from the control means as serial data, and receives a current feedback signal. Inputs, proportionally integral according to the difference signal between the current command and the current feedback signal, and outputs a pulse width modulation signal for controlling the power device in an appropriate order according to a direction control signal, from the motor A current sensor for sensing and returning a current value, an average absolute value circuit for converting the current signal from the current sensor to an absolute value and converting it into the current feedback signal, and a configurable function capable of specifying a gain of the proportional integration function of the single chip control means; Proportional integral gain determining circuit, a main suitable for generating the pulse width modulation reference signal of the single chip control means. And a pulse width modulation frequency determining circuit for providing a wave number setting signal, and a rotor position feedback portion for detecting a rotational direction from the motor and supplying the rotational direction to the single chip control means.

Hereinafter, the present invention will be described in detail with reference to a block diagram of a current control device of a brushless motor according to the present invention. According to FIG. 2, the current control device inputs a current control chip 21 of a brushless motor, a current sensor 13 for detecting a current from the motor, and a current signal from the current sensor to convert the current signal into an absolute value signal. A mean absolute value (MAV) circuit 24, a rotor position feedback unit 18, and a proportional integral gain that can be set to the chip 21 by converting to a chip 21. An integrated gain determination circuit 22, a pulse width modulation (PWM) frequency determination circuit 23 which provides a configurable pulse width modulation (PWM) signal frequency value, and a power element 19 are included.

The current control chip 21 of the brushless motor includes a digital / analog circuit (11 in FIG. 1), a proportional integral controller 14, a PWM reference wave generator circuit 15, a comparator 16, and the like described above. It includes the same circuit function as the code logic unit 17, but unlike the conventional art, the current command and the direction command from the microprocessor 1 are separated and supplied to the dedicated chip 21 as serial data, and the MAV circuit ( 24, the current feedback signal can be supplied in absolute value, so that the polarity does not need to be set in advance by the digital / analog conversion circuit (11 in FIG. 1) in accordance with the motor direction.

Referring to FIG. 2, when the digital series current command and direction command from the microprocessor 1 and the absolute feedback current signal from the MAV circuit 24 are supplied to the current control chip 21 of the brushless motor, the current control chip ( In operation 21, the power device 19 is driven as described above. In this case, in the proportional integration operation, the gain value is adjusted through the proportional integral gain determining circuit 22 settable outside the chip 21, and a frequency (R) for the PWM is applied to the resistor R and the capacitor outside the chip 21. It is set by the circuit constant of the PWM frequency determination circuit 23 which can be set by the.

Therefore, the current controller of the brushless motor of the present invention has immunity to noise by inputting the current command and direction command from the microprocessor as a controller as serial data, and the sparking of the current is made because the current feedback is made using the MAV circuit. It prevents overcurrent detection against noise, and the analog-to-digital converter in a dedicated chip only has a unipolar output voltage, which has a big advantage in device volume and cost.

Claims (1)

In the current control device which inputs a current command from the control means 1 and feedback-controls the current to the brushless motor 20 by the control power element 19, the current command from the control means 1 and The direction command is input as serial data, the current feedback signal is input, proportionally integrated according to the difference signal between the current command and the current feedback signal, and the pulse width modulation signal for controlling the power element 19 is appropriately directed. The single-chip control means 21 for outputting according to the control signal, the current sensor 13 for sensing and returning the current value from the motor 20, and the current signal from the current sensor 13 with an absolute value An average absolute value circuit 24 for converting into the current feedback signal, and a pulse width modulated frequency sequential providing an appropriate frequency setting signal for generation of the pulse width modulated signal of the single chip control means 21; And a rotor position feedback unit (18) for detecting a rotational direction from the motor (20) and supplying it to the single chip control means (21).