METHOD AND CIRCUIT FOR CONTROLLING MOTOR AND BRUSHLESS MOTOR SYSTEM USING THE SAME
First Claim
1. A method for controlling a motor, comprising:
- providing a motor, wherein the motor comprises at least three phase stator coils, each stator coil comprises a first terminal and a second terminal and the first terminals of the stator coils are coupled to a common node;
providing a first power voltage;
providing at least three upper-bridge switches, wherein each upper-bridge switch is respectively coupled between one of the second terminals of the above-mentioned three phase stator coils and the first power voltage;
providing at least three lower-bridge switches, wherein each lower-bridge switch is respectively coupled between one of the second terminals of the above-mentioned three phase stator coils and the first end of an impedance element, wherein the second end of the impedance element is coupled to a second power voltage and the second power voltage is less than the first power voltage;
among the stator coils, when there is no current flowing through a first stator coil, the upper-bridge switch coupled by the second terminal of the second stator coil is turned on and the lower-bridge switch coupled by the second terminal of the third stator coil is turned on;
detecting the voltage at the second terminal of the first stator coil and defining the detected voltage as a first specific voltage;
detecting the voltage drop across both ends of the impedance element and defining the detected voltage as a second specific voltage; and
judging whether a zero-crossing occurs by using the first power voltage, the first specific voltage and the second specific voltage.
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Accused Products
Abstract
A method and a circuit for controlling a motor and a brushless motor using the same are provided. The brushless motor includes three phase coils, wherein the first terminals of all the phase coils are coupled to a common node. The method includes following steps: among the above-mentioned three phase coils, when there is no current flowing through the first phase coil of the above-mentioned three phase coils and a current flows from the second terminal of the second coil to the second terminal of the third phase coil, detecting the voltage at the second terminal of the first phase coil to be a first specific voltage; detecting the voltage drop of a DC sensing resistor to be a second specific voltage; and utilizing the first specific voltage, the second specific voltage and the DC voltage supplied to the motor to estimate zero crossing points for controlling the motor.
43 Citations
20 Claims
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1. A method for controlling a motor, comprising:
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providing a motor, wherein the motor comprises at least three phase stator coils, each stator coil comprises a first terminal and a second terminal and the first terminals of the stator coils are coupled to a common node; providing a first power voltage; providing at least three upper-bridge switches, wherein each upper-bridge switch is respectively coupled between one of the second terminals of the above-mentioned three phase stator coils and the first power voltage; providing at least three lower-bridge switches, wherein each lower-bridge switch is respectively coupled between one of the second terminals of the above-mentioned three phase stator coils and the first end of an impedance element, wherein the second end of the impedance element is coupled to a second power voltage and the second power voltage is less than the first power voltage; among the stator coils, when there is no current flowing through a first stator coil, the upper-bridge switch coupled by the second terminal of the second stator coil is turned on and the lower-bridge switch coupled by the second terminal of the third stator coil is turned on; detecting the voltage at the second terminal of the first stator coil and defining the detected voltage as a first specific voltage; detecting the voltage drop across both ends of the impedance element and defining the detected voltage as a second specific voltage; and judging whether a zero-crossing occurs by using the first power voltage, the first specific voltage and the second specific voltage. - View Dependent Claims (2, 3, 4, 5)
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6. A circuit for controlling a motor, wherein the motor comprises at least three phase stator coils, each stator coil comprises a first terminal and a second terminal, the first terminals of all the stator coils are coupled to a common node, the second terminal of each of the stator coils is coupled to at least an upper-bridge switch and at least a lower-bridge switch, each of the upper-bridge switches respectively determines whether a power voltage is supplied to one of the stator coils and each lower-bridge switch is coupled to a common voltage via an impedance element;
- circuit for controlling a motor comprising;
a selection circuit, coupled to the second terminals of the stator coils, wherein when the upper-bridge switches or lower-bridge switches coupled by the second terminals of the first phase coil and the second phase coil are switched according to a pulse-width-modulation (PWM) signal, the voltage at the second terminal of the third phase coil is taken as a first voltage and coupled to the output terminal of the selection circuit; a zero-crossing detection unit, coupled to the output terminal of the selection circuit, wherein when the upper-bridge switch coupled by the second terminal of the first phase coil is turned on and the lower-bridge switch thereof is turned off, the power voltage and the voltage across the impedance element in the first voltage are removed to obtain a first back electromotive force voltage, the first back electromotive force voltage is compared with a first reference voltage and a first zero-crossing judgement signal is output; and a control circuit, for judging when a zero-crossing occurs according to the zero-crossing judgement signal so as to control the motor. - View Dependent Claims (7, 8, 9, 10, 11, 12)
- circuit for controlling a motor comprising;
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13. A brushless motor system, comprising:
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a motor, comprising at least three phase stator coils, wherein each stator coil comprises a first terminal and a second terminal, and the first terminals of all the stator coils are coupled to a common node; a plurality of upper-bridge switches, wherein at least one of the upper-bridge switches is coupled between the second terminal of each stator coil and a power voltage and each upper-bridge switch respectively decides whether a power voltage is supplied to the stator coils; an impedance element, wherein the first terminal of the impedance element is coupled to a common node voltage; a plurality of lower-bridge switches, wherein at least one of the lower-bridge switches is coupled between the second terminal of each stator coil and the second terminal of the impedance element; a selection circuit, coupled to the second terminals of the stator coils, wherein when the upper-bridge switches or lower-bridge switches coupled by the second terminals of the first phase coil and the second phase coil are switched according to a PWM signal, the voltage at the second terminal of the third phase coil is taken as a first voltage and coupled to the output terminal of the selection circuit; a zero-crossing detection unit, coupled to the output terminal of the selection circuit, wherein when the upper-bridge switch coupled by the second terminal of the first phase coil is turned on and the lower-bridge switch thereof is turned off, the power voltage and the voltage across the impedance element in the first voltage are removed to obtain a first back electromotive force voltage, the first back electromotive force voltage is compared with a first reference voltage and a first zero-crossing judgement signal is output; and a control circuit, for judging when a zero-crossing occurs according to the zero-crossing judgement signal so as to control the motor. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A method for controlling a motor, comprising:
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providing a zero-crossing indication signal and a commutation-indicating signal; calculating i pieces of zero-crossing time prior to a state transition of the commutation-indicating signal, wherein the definition of the plurality of zero-crossing time comprises the following (1) or (2);
(1) a time interval between a state transition of the zero-crossing indication signal from a first state to a second state and a state transition of the zero-crossing indication signal from the second state to the first state;
(2) a time interval between a state transition of the zero-crossing indication signal from the second state to the first state and a state transition of the zero-crossing indication signal from the first state to the second state, wherein the k-th zero-crossing time is represented by Tk, i and k are natural number and 0<
k≦
i;assigning each zero-crossing time with a weight value and the weight value of the k-th zero-crossing time is represented by Gk; defining a delay time Td with
Td=(G1×
T1+ . . . +Gk×
Tk+ . . . +Gi×
Ti)/2×
(G1+ . . . +Gi); andtransiting the state of the commutation-indicating signal in the delay time after the first zero-crossing time.
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Specification