Hopper spreader with back EMF control and hopper system speed control

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.

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.

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.

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.