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US 2019/0199265 A1Published application
Motor drive device and motor system
AssigneeRenesas Electronics Corporation
InventorsMinoru KUROSAWA, Kichiya ITAGAKI
Life of this patent
Estimating the term…
Abstract
An output control unit controls a drive terminal for a BEMF detection object phase to a high-impedance state in a mask term. A BEMF detection unit detects a voltage of the drive terminal for the detection object phase when a center tap voltage is set as a reference as BEMF in a PWM on-term for remaining two phases per PWM period in the mask term and asserts a zero-crossing signal when the voltage is reduced to zero. A PWM fixing unit fixes the remaining two phases to the PWM on-terms in a first term from a predetermined timing after an amplitude level of BEMF becomes smaller than a BEMF threshold amplitude to assertion of the zero-crossing signal. The BEMF detection unit continuously detects BEMF in the first term.
Claims20
A motor drive device comprising:
- drive terminals for three phases which drive a three-phase motor;
- a three-phase driver which includes high-side transistors for three phases which are respectively coupled between the drive terminals for three phases and a high-potential-side power supply voltage and low-side transistors for three phases which are respectively coupled between the drive terminals for three phases and a low-potential-side power supply voltage;
- an output control unit which, in a state where both of the high-side transistor and the low-side transistor for a first phase which is one phase in the three phases are controlled to off-states, controls the high-side transistor and the low-side transistor for at least one phase in a second phase and a third phase which are remaining two phases with PWM signals in a mask term;
- a back electromotive voltage detection unit which detects a drive terminal voltage of the drive terminal for the first phase when a center tap voltage of the three-phase motor is set as a reference as a back electromotive voltage in a PWM on-term that both of the high-side transistor for the second phase and the low-side transistor for the third phase are turned on and asserts a zero-crossing signal in a case where the back electromotive voltage is reduced to zero per PWM period included in the mask term;
- and
- a PWM fixing unit which monitors the back electromotive voltage and the zero-crossing signal and fixes the high-side transistor for the second phase and the low-side transistor for the third phase to on-states regardless of the PWM period in a first term from a predetermined timing after an amplitude level of the back electromotive voltage becomes smaller than a predetermined threshold amplitude to assertion of the zero-crossing signal,
- wherein the back electromotive voltage detection unit continuously detects the back electromotive voltage in the first term.
4 more elements
A motor system comprising:
- a disk which stores data;
- a three-phase motor which rotates the disk;
- and
- a motor drive device which drives the three-phase motor,
- wherein the motor drive device has
- drive terminals for three phases which drive a three-phase motor,
- a three-phase driver which includes high-side transistors for three phases which are respectively coupled between the drive terminals for three phases and a high-potential-side power supply voltage and low-side transistors for three phases which are respectively coupled between the drive terminals for three phases and a low-potential-side power supply voltage,
- an output control unit which, in a state where both of the high-side transistor and the low-side transistor for a first phase which is one phase in the three phases are controlled to off-states, controls the high-side transistor and the low-side transistor for at least one phase in a second phase and a third phase which are remaining two phases with PWM signals in a mask term,
- a back electromotive voltage detection unit which detects a drive terminal voltage of the drive terminal for the first phase when a center tap voltage of the three-phase motor is set as a reference as a back electromotive voltage in a PWM on-term that both of the high-side transistor for the second phase and the low-side transistor for the third phase are turned on and asserts a zero-crossing signal in a case where the back electromotive voltage is reduced to zero per PWM period included in the mask term and
- a PWM fixing unit which monitors the back electromotive voltage and the zero-crossing signal and fixes the high-side transistor for the second phase and the low-side transistor for the third phase to on-states regardless of the PWM period in a first term from a predetermined timing after an amplitude level of the back electromotive voltage becomes smaller than a predetermined threshold amplitude to assertion of the zero-crossing signal and
- wherein the back electromotive voltage detection unit continuously detects the back electromotive voltage in the first term.
8 more elements
The motor system according to claim 13,
- wherein the PWM fixing unit has
- a first analog-to-digital converter which converts the back electromotive voltage to a digital value and
- a first digital comparator which compares the digital value from the first analog-to-digital converter with a digital value which corresponds to the predetermined threshold amplitude.
Dependencies are inferred from the claim text.