US-12620919-B2 - Motor driver for starting up motor having any resistance

US12620919B2US 12620919 B2US12620919 B2US 12620919B2US-12620919-B2

Abstract

A motor driver for starting up a motor having any resistance is provided. The motor driver outputs a motor startup signal to the motor according to an initial startup duty cycle, senses a current value of a current signal of the motor multiple times, compares the current value of the motor that is sensed for multiple times with a reference current value and accordingly sets a plurality of pulse waves of a pulse width modulation signal. Then, the motor driver detects duty cycles of the pulse waves of the pulse width modulation signal as startup detection duty cycles. Then, the motor driver outputs a motor startup signal to the motor according to the startup detection duty cycles.

Inventors

Kun-Min Chen
Yi-Cheng Liu
Yen-Ping Wang

Assignees

ANPEC ELECTRONICS CORPORATION

Dates

Publication Date: 20260505
Application Date: 20240613
Priority Date: 20240422

Claims (19)

1 . A motor driver for starting up a motor having any resistance, comprising: a motor driving circuit connected to a motor, and configured to output a motor starting signal to the motor according to an initial startup duty cycle within an initial startup time interval in a motor startup mode; a current limiting circuit connected to the motor, wherein the current limiting circuit, within the initial startup time interval in the motor startup mode, senses a current value of a current signal of the motor for multiple times, compares the current value of the current signal sensed each time with a reference current value to generate a current sensed result, sets a plurality of pulse waves of a pulse width modulation signal according to the current sensed result, and outputs the pulse width modulation signal; and a duty cycle detecting circuit connected to the current limiting circuit and the motor driving circuit, wherein the duty cycle detecting circuit, within a duty cycle detection time interval in the motor startup mode, detects a duty cycle of each of the plurality of pulse waves of the pulse width modulation signal as a startup detection duty cycle, and outputs a duty cycle detected signal according to the startup detection duty cycle of each of the plurality of pulse waves of the pulse width modulation signal; wherein the motor driving circuit, within a modulation startup time interval in the motor startup mode, sets a modulation startup duty cycle according to the duty cycle detected signal from the duty cycle detecting circuit, and outputs the motor starting signal to the motor according to the modulation startup duty cycle; wherein the motor driving circuit includes: a control circuit connected to the duty cycle detecting circuit, and configured to output a startup control signal having the initial startup duty cycle within the initial startup time interval in the motor startup mode; a driving circuit connected to the control circuit, and configured to output a startup driving signal according to the startup control signal within the initial startup time interval in the motor startup mode; and an output stage circuit connected to the driving circuit and the motor, and configured to operate to output the motor starting signal according to the startup driving signal within the initial startup time interval in the motor startup mode; wherein, within the modulation startup time interval in the motor startup mode, the control circuit sets a modulation startup duty cycle according to the duty cycle detected signal, the control circuit outputs the startup control signal according to the modulation startup duty cycle, the driving circuit outputs the startup driving signal according to the startup control signal, and the output stage circuit outputs the motor starting signal to the motor according to the startup driving signal.
2 . The motor driver according to claim 1 , wherein the motor driving circuit further includes: a rotor position detecting circuit disposed on the motor and connected to the control circuit; wherein, after the motor startup mode ends, the motor enters a motor steady state rotation mode; wherein in the motor startup mode, the motor steady state rotation mode or a combination thereof, the rotor position detecting circuit detects a position of a rotor of the motor to output a rotor position detected signal, and the control circuit controls the driving circuit according to the rotor position detected signal.
3 . The motor driver according to claim 1 , wherein the output stage circuit includes: a first high-side switch, wherein a first terminal of the first high-side switch is coupled with a common voltage; a first low-side switch, wherein a first terminal of the first low-side switch is connected to a second terminal of the first high-side switch, a node between the first terminal of the first low-side switch and the second terminal of the first high-side switch is connected to a first terminal of the motor, and a second terminal of the first low-side switch is grounded; a second high-side switch, wherein a first terminal of the second high-side switch is coupled with the common voltage; and a second low-side switch, wherein a first terminal of the second low-side switch is connected to a second terminal of the second high-side switch, a node between the first terminal of the second low-side switch and the second terminal of the second high-side switch is connected to a second terminal of the motor, and a second terminal of the second low-side switch is grounded; wherein a control terminal of the first high-side switch, a control terminal of the first low-side switch, a control terminal of the second high-side switch and a control terminal of the second low-side switch are connected to the driving circuit.
4 . The motor driver according to claim 3 , wherein the output stage circuit further includes: a third high-side switch, wherein a first terminal of the third high-side switch is coupled with the common voltage; and a third low-side switch, wherein a first terminal of the third low-side switch is connected to a second terminal of the third high-side switch, a node between the first terminal of the third low-side switch and the second terminal of the third high-side switch is connected to a third terminal of the motor, and a second terminal of the third low-side switch is grounded; wherein a control terminal of the third high-side switch and a control terminal of the third low-side switch are connected to the driving circuit.
5 . The motor driver according to claim 1 , wherein the motor driving circuit is continually coupled with a common voltage, and the motor driving circuit starts up and drives the motor by using the common voltage; wherein, within the duty cycle detection time interval in the motor startup mode, the motor driving circuit estimates a resistance of the motor according to the common voltage, the duty cycle detected signal and the reference current value.
6 . The motor driver according to claim 5 , wherein, within the duty cycle detection time interval in the motor startup mode, the motor driving circuit sets the modulation startup duty cycle according to the resistance of the motor.
7 . The motor driver according to claim 5 , wherein, within the duty cycle detection time interval in the motor startup mode, the motor driving circuit calculates the resistance of the motor using an equation of: Rmt = VCC × PWMref / Iref , wherein Rmt represents the resistance of the motor, VCC represents the common voltage, PWMref represents the duty cycle of each of the plurality of pulse waves of the pulse width modulation signal, and Iref represents the reference current value.
8 . The motor driver according to claim 7 , wherein, within the duty cycle detection time interval in the motor startup mode, the motor driving circuit sets the modulation startup duty cycle according to the resistance of the motor.
9 . The motor driver according to claim 5 , wherein, within the duty cycle detection time interval in the motor startup mode, the motor driving circuit calculates the resistance of the motor using an equation of: Rmt = VCC × { DTref / ( 2 ⁢ n - 1 ) } / Iref , wherein Rmt represents the resistance of the motor, VCC represents the common voltage, DTref represents a digital value of the startup detection duty cycle, n represents a number of bit values, and Iref represents the reference current value.
10 . The motor driver according to claim 9 , wherein, within the duty cycle detection time interval in the motor startup mode, the motor driving circuit sets the modulation startup duty cycle according to the resistance of the motor.
11 . The motor driver according to claim 1 , wherein within the duty cycle detection time interval in the motor startup mode, the motor driving circuit multiplies the startup detection duty cycle by a preset gain to form the modulation startup duty cycle.
12 . The motor driver according to claim 1 , wherein, within the modulation startup time interval in the motor startup mode, the motor driving circuit performs an equation of: DTstup = ( Istup / Iref ) × DTref , wherein DTstup represents a digital value of the modulation startup duty cycle, Istup represents a current of the motor, Iref represents the reference current value, and DTref represents a digital value of the startup detection duty cycle.
13 . The motor driver according to claim 1 , wherein, within the duty cycle detection time interval in the motor startup mode, the motor driving circuit calculates a variable soft switching duty cycle by substituting the startup detection duty cycle into an equation of: DTsof = DTref × DTmodu / ( 2 ⁢ n - 1 ) , wherein DTsof represents a digital value of the variable soft switching duty cycle, VCC represents the common voltage coupled to the motor driving circuit, DTref represents a digital value of the startup detection duty cycle, DTmodu represents a digital value of a variable soft reference duty cycle, and n represents a number of bits; wherein, within the modulation startup time interval in the motor startup mode, the motor driving circuit outputs the motor starting signal to the motor according to the variable soft reference duty cycle.
14 . The motor driver according to claim 1 , wherein, within the duty cycle detection time interval in the motor startup mode, the duty cycle detecting circuit sets the startup detection duty cycle that is outputted when the current signal reaches the reference current value as a startup reference duty cycle, the duty cycle detecting circuit outputs the duty cycle detected signal according to the startup reference duty cycle, and the motor driving circuit sets the modulation startup duty cycle according to the startup reference duty cycle.
15 . The motor driver according to claim 1 , further comprising: a target duty cycle setting circuit connected to the motor driving circuit; wherein, after the motor startup mode ends, the motor enters a motor steady state rotation mode; wherein, in the motor steady state rotation mode, the target duty cycle setting circuit outputs a target duty cycle instructing signal according to a target rotational speed instructed by a motor target rotational speed instruction, and the motor driving circuit outputs a rotation driving signal to the motor according to the target duty cycle instructing signal.
16 . The motor driver according to claim 15 , wherein a current of the motor started up by the motor driving circuit in the motor startup mode is smaller than the current of the motor started up by the motor driving circuit in the motor steady state rotation mode.
17 . The motor driver according to claim 15 , wherein a current of the motor started up by the motor driving circuit in the motor startup mode is larger than the current of the motor started up by the motor driving circuit in the motor steady state rotation mode.
18 . The motor driver according to claim 1 , wherein the motor is a single-phase motor.
19 . The motor driver according to claim 1 , wherein the motor is a three-phase motor.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATION This application claims the benefit of priority to Taiwan Patent Application No. 113114844, filed on Apr. 22, 2024. The entire content of the above identified application is incorporated herein by reference. Some references, which may include patents, patent applications and various publications, may be cited and discussed in the description of this disclosure. The citation and/or discussion of such references is provided merely to clarify the description of the present disclosure and is not an admission that any such reference is “prior art” to the disclosure described herein. All references cited and discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference. FIELD OF THE DISCLOSURE The present disclosure relates to a motor, and more particularly to a motor driver for starting up a motor having any resistance. BACKGROUND OF THE DISCLOSURE Fans are often used to cool down processors and other heat-generating components in electronic devices. In a conventional motor driver, a control circuit controls a driver circuit to drive a high-side switch and a low-side switch for starting up a motor of the fan. However, no matter what a resistance of the motor of the fan is, the driver circuit of the conventional motor driver outputs a driving signal having a constant duty cycle to a control terminal of the high-side switch for driving the high-side switch. Since the motors of the fans may have different resistances, the driving signal having the constant duty cycle is not applicable for various resistances of the motors. For example, when the constant duty cycle of the driving signal outputted by the conventional motor driver is a small value and is used for starting up a motor having a large resistance, only a small current flows through the motor having the large resistance. As a result, the motor having the large resistance cannot be successfully started up. SUMMARY OF THE DISCLOSURE In response to the above-referenced technical inadequacies, the present disclosure provides a motor driver for starting up a motor having any resistance. The motor driver includes a motor driving circuit, a motor driving circuit and a duty cycle detecting circuit. The motor driving circuit is connected to a motor. The motor driving circuit is configured to output a motor starting signal to the motor according to an initial startup duty cycle within an initial startup time interval in a motor startup mode. The current limiting circuit is connected to the motor. The current limiting circuit, within the initial startup time interval in the motor startup mode, senses a current value of a current signal of the motor multiple times, compares the current value of the current signal sensed each time with a reference current value to generate a current sensed result, sets a plurality of pulse waves of a pulse width modulation signal according to the current sensed result, and outputs the pulse width modulation signal. The duty cycle detecting circuit is connected to the current limiting circuit and the motor driving circuit. The duty cycle detecting circuit, within a duty cycle detection time interval in the motor startup mode, detects a duty cycle of each of the plurality of pulse waves of the pulse width modulation signal as a startup detection duty cycle, and outputs a duty cycle detected signal according to the startup detection duty cycle of each of the plurality of pulse waves of the pulse width modulation signal. The motor driving circuit, within a modulation startup time interval in the motor startup mode, sets a modulation startup duty cycle according to the duty cycle detected signal from the duty cycle detecting circuit, and outputs the motor starting signal to the motor according to the modulation startup duty cycle. As described above, the present disclosure provides the motor driver for starting up the motor having any resistance. The motor driver of the present disclosure compares the current of the motor sensed for multiple times with the reference current value for setting the plurality of pulse waves of the pulse width modulation signal. Further, the motor driver of the present disclosure sets the motor starting signal for starting up the motor, according to the duty cycles of the plurality of pulse waves of the pulse width modulation signal. The motor driver of the present disclosure is capable of calculating a resistance of the motor according to the duty cycles of the plurality of pulse waves of the pulse width modulation signal, the common voltage and the reference current value. The motor driver of the present disclosure is capable of setting the motor starting signal according to the resistance of the motor. Therefore, when the motor driver of the present disclosure receives the common voltage having any voltage value for starting up the motor, the motor driv