# US 8,569,983 B2 · Motor driving apparatus and method for control of motor revolution > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,569,983 B2 - Document ID: US8569983B2 - Status: Granted - Kind: B2 - Application number: 13/044,042 - Filed: 2011-03-09 - Published: 2011-06-30 - Granted: 2013-10-29 - Earliest claimed: 2007-08-23 - Assignees: Renesas Electronics Corporation - Applicants: Minoru Kurosawa; Yasuhiko Kokami - Inventors: Minoru Kurosawa; Yasuhiko Kokami - Web page: https://patentgrep.com/patent/US8569983B2 ## CPC - H02P 6/10: Arrangements for controlling torque ripple, e.g. providing reduced torque ripple - G11B 19/28: Speed controlling, regulating, or indicating (G11B19/24 takes precedence) - H02P 6/18: without separate position detecting elements - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract This invention provides a motor driving apparatus that made it possible to reduce torque ripples including those attributed to load variation of the motor and an associated method for control of motor revolution. An output stage to a multiphase DC motor is comprised of power elements to supply output voltages to multiphase coils and a predriver to supply drive voltages to the power elements. A resistor means detects a current flowing through the power elements. A supply current detector detects a voltage signal produced across the resistor means as a supply current, using a high-speed ADC and a moving average filter. An output controller generates a PWM signal with a frequency lower than the frequency of the high-speed ADC so that the current detected by the supply current detector conforms to a current signal indicating a motor revolving speed and transfers the PWM signal to the output stage. ## Claims ### Claim 1 A motor driving apparatus comprising: a multiphase DC motor including a plurality of multiphase coils; an output stage including: a plurality of power elements coupled to the multiphase coils and which supply output voltages to the multiphase coils, and a predriver coupled to the power elements and which supplies drive voltages to the power elements; a resistor coupled to the power elements and which detects a current flowing through the power elements; a supply current detector which includes an ADC and a digital filter and which detects a voltage signal produced across the resistor as a supply current, using the ADC and the digital filter; and an output controller which generates a PWM signal with a frequency lower than a sampling frequency of the ADC so that the current detected by the supply current detector conforms to a current command for controlling a motor revolving speed, and transfers the PWM signal to the output stage. ### Claim 2 (depends on 1) The motor driving apparatus according to claim 1, wherein the digital filter is a moving average filter with a transmission zero set at the frequency of the PWM signal. ### Claim 3 (depends on 1) The motor driving apparatus according to claim 1, wherein the ADC is a D-S ADC that performs oversampling at a higher frequency than the frequency of the PWM signal. ### Claim 4 (depends on 3) The motor driving apparatus according to claim 3, wherein the digital filter is a moving average filter with a transmission zero set at the frequency of the PWM signal. ### Claim 5 (depends on 4) The motor driving apparatus according to claim 4, wherein the power elements include: a plurality of upper power elements coupled to a supply voltage and a plurality of lower power elements coupled to a ground potential, and wherein the resistor is a DC shunt resistor disposed between a common connection node for the lower power elements and the ground potential. ### Claim 6 (depends on 4) The motor driving apparatus according to claim 4, further comprising: a current zero crossing detector that monitors whether a respective voltage to drive each of the power elements is equal to or greater than a predetermined voltage and detects a current zero crossing; and a profile generator that generates a drive voltage of 180-degree conduction, using the output of the current zero crossing detector for phase locked loop control that controls timing of conduction phase switching, wherein the output controller receives the drive voltage generated by the profile generator and generates a PWM signal to be transferred to the output stage. ### Claim 7 (depends on 6) The motor driving apparatus according to claim 6, further comprising: a back EMF zero crossing detector that selects a non-conducting phase and detects a back EMF zero crossing; and a selector that selects the back EMF zero crossing detector during low revolution, when the motor revolution is unstable, and transfers the back EMF zero crossing to the phase locked loop control, or selects the current zero crossing detector during high revolution at a higher number of revolutions than the low revolution, when the motor revolution falls in a stable region, and transfers the current zero crossing to the phase locked loop control. ### Claim 8 (depends on 7) The motor driving apparatus according to claim 7, wherein the current zero crossing detector includes a comparator that compares a gate-source voltage in the lower power elements to a reference voltage that is equal to or less than a threshold voltage of the lower power elements and greater than 0 V. ### Claim 9 (depends on 7) The motor driving apparatus according to claim 7, wherein phase error detection in the phase locked loop control uses as a phase error a quantity proportional to a difference of the number of detected polarity changes of a drive current during an error detection period. ### Claim 10 (depends on 9) The motor driving apparatus according to claim 9, wherein the output stage is the output stage to a three-phase DC motor having three-phase coils as the multiphase DC motor, and wherein the profile generator generates a sinusoidal drive voltage with a waveform pattern in which a down hook for a lowest voltage phase which corresponds to GND and an up hook for a highest voltage phase which corresponds to power supply alternate every electric angle of 60-degrees, and the waveform is represented by linear approximation. ### Claim 11 A method for control of motor revolution in an apparatus having: an output stage to a multiphase DC motor including a plurality of power elements to supply output voltages to a plurality of multiphase coils and a predriver to supply drive voltages to the power elements, a resistor for detecting a current flowing through the power elements, and a supply current detector which includes an ADC and a filter, the method comprising: detecting a voltage signal produced across the resistor as a supply current by using the ADC and the filter in the supply current detector; generating a PWM signal with a frequency lower than a sampling frequency of the ADC so that the detected supply current conforms to a current command for controlling the motor revolving speed; and transferring the PWM signal to the output stage for control of a motor revolving speed, wherein the filter has a transmission zero set at the frequency of the PWM signal. ### Claim 12 A motor driving apparatus comprising: an output stage to a multiphase DC motor including a plurality of power elements to supply output voltages to a plurality of multiphase coils and a predriver to supply drive voltages to the power elements; a resistor for detecting a current flowing through said power elements; a supply current detector that detects a voltage signal produced across said resistor means as a supply current, using an analog to digital converter performing oversampling operation and a digital filter; and an output controller that generates a PWM signal with a frequency lower than the sampling frequency of the analog to digital converter so that the current detected by the supply current detector conforms to a current command for controlling the motor revolving speed, and transfers the PWM signal to the output stage, wherein the digital filter has a transmission zero set at the frequency of the PWM signal. ### Claim 13 (depends on 12) The motor driving apparatus according to claim 12, wherein the analog to digital converter is a D-S ADC that performs oversampling at a higher frequency than the frequency of the PWM signal. ### Claim 14 (depends on 13) The motor driving apparatus according to claim 13, wherein the digital filter is a moving average filter.