# US 10,370,800 B2 · Hopper spreader with back EMF control and hopper system speed control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,370,800 B2 - Document ID: US10370800B2 - Status: Granted - Kind: B2 - Application number: 15/237,326 - Filed: 2016-08-15 - Published: 2018-02-15 - Granted: 2019-08-06 - Earliest claimed: 2016-08-15 - Assignees: Sno-Way International, Inc. - Applicants: Robert N. Gamble, II; Terry Wendorff - Inventors: Robert N. Gamble, II; Terry Wendorff - Web page: https://patentgrep.com/patent/US10370800B2 ## CPC - E01C 19/20: Apparatus for distributing, e.g. spreading, granular or pulverulent materials, e.g. sand, gravel, salt, dry binders ({E01C19/21, E01C19/4813, E01C19/482, E01C23/098, E01C23/166 take precedence; } fertiliser distributors A01C15/00 {; permanently-installed devices for applying gritting or thawing materials E01H10/005; mobile spreaders specially adapted for treating wintry roads E01H10/007}) - E01C 19/203: {Centrifugal spreaders with substantially vertical axis} - H02P 5/46: for speed regulation of two or more dynamo-electric motors in relation to one another - H02P 7/29: using pulse modulation - H02P 7/2913: {whereby the speed is regulated by measuring the motor speed and comparing it with a given physical value} - H02P 27/08: with pulse width modulation - E01C 2019/208: {with longitudinal auger} - H02P 6/17: and for generating speed information - H02P 6/182: using back-emf in windings - E01C: CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR (forming roads or like surfaces by compacting or grading snow or ice E01H) - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract A method of controlling a DC motor that includes the step of providing a pulse-width modulation (PWM) signal to the DC motor. The PWM signal provides a voltage to operate the DC motor. The method also includes the steps of measuring a voltage generated by the DC motor when the PWM signal is off. In more particular embodiments, the method includes measuring a current being supplied to the DC motor when the PWM signal is off. The method may further require determining a motor speed of the DC motor based on the measured voltage. The method further includes controlling the DC motor to maintain a relatively constant motor speed with varying loads on the DC motor. ## Claims ### Claim 1 A method of controlling a DC motor of a hopper spreader, the method comprising the steps of: providing a pulse-width modulated (PWM) signal to operate the DC motor; measuring a voltage generated by the DC motor when the PWM signal is turned off, wherein measuring the voltage comprises using a microprocessor to count the number of back EMF pulses from the DC motor; determining a motor speed of the DC motor based on the measured voltage; controlling the DC motor to maintain a relatively constant motor speed which corresponds to a desired motor speed setting, the relatively constant motor speed being maintained with varying loads placed on the DC motor; providing a second pulse-width modulated (PWM) signal to operate an auger motor; measuring a voltage generated by the auger motor when the second PWM signal is turned off; determining a material flow rate through the auger based on the measured voltage; and automatically activating a vibrator when the material flow rate is below a first threshold value. ### Claim 2 (depends on 1) The method of claim 1, wherein controlling the DC motor to maintain the relatively constant motor speed comprises controlling the PWM signal to increase the voltage to the DC motor as the load on the DC motor increases, and to decrease the voltage to the DC motor as the load on the DC motor decreases. ### Claim 3 (depends on 1) The method of claim 1, wherein measuring the voltage using a microprocessor comprises measuring the voltage using a microprocessor with an integral analog-to-digital converter. ### Claim 4 (depends on 1) The method of claim 1, further comprising measuring the current supplied to the DC motor when the PWM signal is turned off. ### Claim 5 (depends on 4) The method of claim 4, wherein the voltage and current measurements occur within 3 milliseconds of each other. ### Claim 6 (depends on 1) The method of claim 1, further comprising determining a torque produced by the DC motor based on the measured current. ### Claim 7 (depends on 6) The method of claim 6, further comprising utilizing a full torque potential of the DC motor at all speeds of the DC motor. ### Claim 8 (depends on 1) The method of claim 1, further comprising: providing a third pulse-width modulated (PWM) signal to operate a second DC motor; measuring a voltage generated by the second DC motor when the third PWM signal is turned off; and automatically activating a light when the measured voltage indicates that the second DC motor is operating. ### Claim 9 (depends on 8) The method of claim 8, wherein the second DC motor is one of a spinner motor, and a wetting system motor and the DC motor is one of an auger motor, and a conveyor motor. ### Claim 10 (depends on 1) The method of claim 1, further comprising automatically deactivating the vibrator when the material flow rate is above a second threshold value. ### Claim 11 (depends on 1) The method of claim 1, further comprising using GPS data to correlate a material dispersion pattern to vehicle location coordinates and/or weather patterns. ### Claim 12 (depends on 1) The method of claim 1, further comprising automatically activating a wetting system if the material flow rate is above a second threshold value, and automatically deactivating the wetting system if the material flow rate is below a third threshold value. ### Claim 13 (depends on 1) The method of claim 1, further comprising storing the desired motor speed setting in the microprocessor. ### Claim 14 A motor control system configured to vary a motor speed of a DC motor, the system comprising: a microprocessor coupled to one or more DC motors, the microprocessor configured to supply a pulse-width-modulated (PWM) signal to the one or more DC motors, the PWM signal providing a voltage to operate the one or more DC motors; wherein the microprocessor is configured to measure an electric current supplied to the one or more DC motors, and being further configured to measure a voltage generated by the one or more DC motors when the PWM signal is turned off, wherein the microprocessor is configured to measure the voltage by counting back EMF pulses from each of the one or more DC motors; wherein the microprocessor is configured to determine a motor speed of the one or more DC motors based on the measured voltage, and further configured to control the motor speed to maintain a relatively constant motor speed with varying loads placed on the one or more DC motors; and further comprising an electric auger motor operated by a respective PWM signal, wherein the microprocessor is configured to measure a voltage generated by the electric auger motor when its respective PWM signal is turned off; and wherein the microprocessor is configured to determine a material flow rate through the auger based on the measured voltage from the electric auger motor, and further configured to automatically activate a vibrator motor when the material flow rate is below a first threshold value. ### Claim 15 (depends on 14) The motor control system of claim 14, further comprising an analog-to-digital converter used in the measurement of the voltage generated by the one or more DC motors. ### Claim 16 (depends on 14) The motor control system of claim 14, wherein the microprocessor is configured to maintain the relatively constant motor speed by controlling the PWM signal to increase the voltage to each of the one or more DC motors as the load on that DC motor increases, and to decrease the voltage to each of the one or more DC motors as the load on that DC motor decreases. ### Claim 17 (depends on 14) The motor control system of claim 14, wherein the microprocessor is configured to measure the voltage and measure the current within three milliseconds of each other. ### Claim 18 (depends on 14) The motor control system of claim 14, wherein the microprocessor is configured to determine a torque of the one or more DC motors based on the measured current. ### Claim 19 (depends on 18) The motor control system of claim 18, wherein the microprocessor further configured to operate the DC motor at full torque at all speeds of the DC motor. ### Claim 20 (depends on 14) The motor control system of claim 14, wherein the microprocessor is configured to automatically deactivate the vibrator motor when the material flow rate is above a second threshold value. ### Claim 21 (depends on 14) The motor control system of claim 14, wherein the microprocessor is configured to automatically activate two or more vibrator motors either simultaneously or in an alternating manner when the material flow rate is below the first threshold value, and to automatically deactivate the two or more vibrator motors when the material flow rate is above a second threshold value. ### Claim 22 (depends on 14) The motor control system of claim 14, wherein the microprocessor is configured to use GPS data to correlate a material dispersion pattern to vehicle location coordinates and/or weather patterns. ### Claim 23 (depends on 14) The motor control system of claim 14, further comprising a lighting system, wherein the microprocessor is configured to measure a voltage generated by a second DC motor when a second PWM signal to the second motor is turned off, and further configured to automatically activate the lighting system when the second DC motor is operating. ### Claim 24 (depends on 23) The motor control system of claim 23, wherein the second DC motor is one of an auger motor, a spinner motor, and a wetting system motor. ### Claim 25 (depends on 14) The motor control system of claim 14, wherein the microprocessor is configured to automatically activate a wetting system if the material flow rate is above a second threshold value, and automatically deactivate the wetting system if the material flow rate is below a third threshold value. ### Claim 26 A method of controlling a first DC motor of a hopper spreader, the method comprising the steps of: providing a pulse-width modulated (PWM) signal to operate a second DC motor; measuring a voltage generated by the second DC motor when the PWM signal is turned off; and controlling the first DC motor based on the measured voltage. ### Claim 27 (depends on 26) The method of claim 26, wherein the first DC motor is one of a vibrator motor, a spinner motor, and a wetting system motor. ### Claim 28 (depends on 26) The method of claim 26, wherein the second DC motor is a conveyor motor and the first DC motor is a vibrator motor. ### Claim 29 (depends on 28) The method of claim 28, wherein, when the measured voltage corresponds to a first load on the conveyor motor that is below a threshold value, the vibrator motor is activated; and when the measured voltage corresponds to a second load on the conveyor motor greater than the first load, the vibrator motor is deactivated. ### Claim 30 (depends on 29) The method of claim 29, wherein, when the measured voltage corresponds to the first load on the conveyor motor that is below the threshold value, two or more vibrator motors are activated either simultaneously or in an alternating manner; and when the measured voltage corresponds to the second load on the conveyor motor greater than the first load, the two or more vibrator motors are deactivated. ### Claim 31 (depends on 26) The method of claim 26, wherein the second DC motor is a conveyor motor driving a conveyor and the first DC motor is a motor running a wetting system, the method further comprising determining a material flow rate provided by the conveyor; automatically activating the first DC motor if the material flow rate is above a first threshold value, and automatically deactivating the first DC motor if the material flow rate is below a second threshold value. ### Claim 32 (depends on 26) The method of claim 26, wherein the second DC motor is a conveyor motor driving a conveyor and the first DC motor is a vibrator motor running a vibrator, the method further comprising determining a material flow rate provided by the conveyor; automatically activating the first DC motor if the material flow rate is below a first threshold value, and automatically deactivating the first DC motor if the material flow rate is above a second threshold value. ### Claim 33 (depends on 26) The method of claim 26, wherein the second DC motor is a conveyor motor driving a conveyor and the first DC motor is a vibrator motor running a vibrator, the method further comprising determining a load on the conveyor motor; automatically activating the first DC motor if the determined load is below a first threshold value, and automatically deactivating the first DC motor if the determined load is above a second threshold value. ### Claim 34 A motor control system configured to vary a motor speed of a DC motor for a hopper spreader, the motor control system comprising: a microprocessor coupled to a first DC motor, the microprocessor configured to supply a pulse-width-modulated (PWM) signal to the first DC motor, the PWM signal providing a voltage to operate the first DC motor; wherein the microprocessor is configured to measure an electric current supplied to the first DC motor, and further configured to measure a voltage generated by the first DC motor when the PWM signal is turned off; and wherein the microprocessor is configured to control a speed of a second DC motor of the hopper spreader based on the voltage measured from the first DC motor. ### Claim 35 (depends on 34) The motor control system of claim 34, wherein the microprocessor is further configured to operate the DC motor at full torque potential at all speeds of the DC motor. ### Claim 36 A method of controlling a DC motor of a hopper spreader, the method comprising the steps of: providing a pulse-width modulated (PWM) signal to operate the DC motor; counting a number of back EMF pulses generated by the DC motor when the PWM signal is turned off; determining a motor speed of the DC motor based on the number of counted pulses; controlling the DC motor to maintain a relatively constant motor speed which corresponds to a desired motor speed setting, the relatively constant motor speed being maintained with varying loads placed on the DC motor; providing a second pulse-width modulated (PWM) signal to operate an auger motor; measuring a voltage generated by the auger motor when the second PWM signal is turned off; determining a material flow rate through the auger based on the measured voltage; and automatically activating a vibrator when the material flow rate is below a first threshold value. ### Claim 37 (depends on 36) The method of claim 36, wherein the DC motor operates an electric auger, the method further comprising determining a material flow rate through the electric auger based on the number of counted pulses. ### Claim 38 A method of controlling a first DC motor of a hopper spreader, the method comprising the steps of: providing a pulse-width modulated (PWM) signal to operate a second DC motor; counting a number of back EMF pulses generated by the second DC motor when the PWM signal is turned off; controlling the first DC motor based on the number of counted pulses. ### Claim 39 (depends on 38) The method of claim 38, wherein the second DC motor operates an electric auger, the method further comprising determining a material flow rate through the electric auger based on the number of counted pulses.