Electric throttle and motor control circuitry

• US 5,414,792 A
• Filed: 01/27/1994
• Issued: 05/09/1995
• Est. Priority Date: 01/27/1994
• Status: Expired due to Fees

• Current Assignee: DAX Industries, Inc. (Fluor Enterprises, Inc.)
• Original Assignee: DAX Industries, Inc. (Fluor Enterprises, Inc.)
• Inventors: Shorey, James L.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): MARTIN, DAVID S
• Application Number:
  US08/186,971
• Time in Patent Office: 467 Days
• Field of Search: 388/809-815, 388/819, 388/812, 388/829, 388/831, 388/837-838, 388/903, 388/907.2, 388/910, 388/917-919, 388/920, 388/930
• US Class Current: 388/811
• CPC Class Codes: B60L 50/52 characterised by DC-motors
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles
• CPC Class Codes: Y10S 388/903 Protective, e.g. voltage or current limit
• CPC Class Codes: Y10S 388/91 Operational/differential amplifier
• CPC Class Codes: Y10S 388/93 Load or torque

Abstract

A solid state, electric motor control circuit is provided in conjunction with a solid state throttle and vehicle sensor circuit that together incorporate; a Hall Effect throttle position sensor circuit, a throttle position signal amplifier circuit, a vehicle reverse condition circuit, a vehicle operation inhibit circuit, a pulse width modulation circuit, and inverting MOSFET driver circuit, a plurality of power MOSFET devices, a voltage regulator circuit, and a current delivery circuit associated with an external DC electric motor. These circuit elements combine to translate a mechanical throttle position into a voltage level signal that can be converted by pulse width modulation circuitry into a pulsed wave form signal that suitably drives a bank of MOSFET, solid state switches so as to control the flow of current through a DC electric motor. The circuit isolates the DC power source from the power drain components in the circuit and communicates vehicle conditions, such as reverse/forward direction and on/off operation, from the vehicle itself to the power controller circuitry. The circuitry incorporates internal elements that raise reliability while still providing versatility in application. Although the present circuitry involves voltage regulation components, it also utilizes current limiting elements as well as over-voltage protection and significant levels of signal filtering.

Claims

1. A motor control circuit that provides efficient control over a direct current electric motor by translating the mechanical position of a manipulable throttle into a current flow from a direct current power source, comprising:

a Hall Effect throttle position transducer;

a throttle signal amplifier circuit for amplifying and conditioning a

throttle signal from said Hall Effect transducer;

a reverse condition sensor for modifying said throttle signal in response to a reverse condition in a vehicle propelled by said electric motor;

a voltage regulator circuit;

a pulse width modulation (PWM) circuit for generating a first square waveform wherein the duration of each square wave pulse is inversely related to a voltage level of said throttle signal;

an inhibitor circuit for sensing an absence of an operational voltage and for canceling said first square waveform upon said absence or upon sensing an over-voltage condition;

an invertor circuit for inverting said first square waveform and converting it to a second square waveform; and

at least one MOSFET circuit acting as a current switch to regulate a flow of current through said electric motor, said MOSFET circuit controlled by said second square waveform.

2. A motor control circuit that provides efficient control over a direct current electric motor by translating the mechanical position of a manipulable throttle into an appropriate current flow from a direct current power source, comprising:

a Hall Effect throttle position transducer circuit comprising;

a. a magnetic component positioned on said throttle, and

b. a sensor component positioned so as to sense variations in magnetic flux density from said magnetic component and to generate an output voltage whose level is indicative of said magnetic flux density and therefore of a position of said throttle;

a throttle signal amplifier circuit for receiving, amplifying and filtering said output voltage from said Hall Effect position transducer;

a reverse condition sensor circuit comprising;

a. means for sensing a switch closure resulting from a reversing condition in a vehicle propelled by said electric drive motor,

b. a voltage modifier circuit connected to said throttle signal amplifier circuit for modifying said output voltage in response to said reversing condition in said vehicle, and

c. an optical coupler for isolating said means for sensing a reversing condition from said voltage modifier circuit;

an inhibitor circuit comprising;

a. means for sensing the presence of an operational voltage from said direct current power source at an inhibit connection point,

b. an inhibit signal circuit for providing a power inhibit signal indicative of an absence of said operational voltage at said inhibit connection point to said direct current power source, and

c. an optical coupler for isolating said means for sensing said operational voltage from said inhibit signal circuit;

a voltage regulator circuit for receiving said operational voltage and generating a circuit voltage;

a pulse width modulation (PWM) circuit comprising;

a. a control signal filter and amplifier circuit for the reception and conditioning of said output voltage from said throttle signal amplifier circuit,

b. an oscillator circuit for generating a sawtooth waveform having an amplitude that varies across the amplitude range of said output voltage,

c. a comparator circuit for comparing said received and conditioned output voltage with said sawtooth waveform and generating a first square waveform wherein the duration of each square wave pulse is inversely related to the level of said output voltage,

d. a PWM latching circuit for stabilizing said first square waveform generated by said comparator, and

e. an inhibit circuit for canceling said first square waveform upon reception of said inhibit signal from said inhibitor circuit or upon sensing an over-voltage condition in said circuit voltage;

an invertor circuit for receiving said first square waveform and converting it to a second square waveform directly related to said level of said output voltage; and

at least one MOSFET circuit, said MOSFET circuit acting as a current switch controlled by said second square waveform, said current being supplied from said direct current power source to said direct current electric motor through said MOSFET circuit.

3. A motor control circuit that provides efficient control over a direct current electric motor powered by a direct current power source, comprising:

a throttle input connector comprising;

a. a terminal for connection to an external control variable voltage circuit,

b. a terminal for connection to said direct current power source,

c. a terminal for communicating a circuit operating voltage, and

d. a terminal for receiving a power inhibit signal;

a voltage regulator circuit for receiving a voltage from said direct current power source and generating said circuit operating voltage;

a pulse width modulation (PWM) circuit comprising;

a. a control signal filter and amplifier circuit for the reception and conditioning of a variable voltage signal from said external control variable voltage circuit,

b. an oscillator circuit for generating a sawtooth waveform having an amplitude that varies across the amplitude range of said variable voltage signal,

c. a comparator circuit for comparing said received and conditioned variable voltage signal with said sawtooth waveform and generating a first square waveform wherein the duration of each square wave pulse is inversely related to the level of said variable voltage signal,

d. a PWM latching circuit for stabilizing said first square waveform generated by said comparator, and

c. an inhibit circuit for canceling said first square waveform upon reception of an inhibit signal through said power inhibit connection or upon sensing an over-voltage condition in said circuit operating voltage;

f. a current limit amplifier for limiting duty cycle during (1) power up conditions, and (2) low battery voltage conditions due to low change/excessive motor current;

an invertor circuit for receiving said first square waveform and converting it to a second square waveform directly related to said level of said variable voltage signal; and

at least one MOSFET circuit, said MOSFET circuit acting as a current switch controlled by said second square waveform, said current being supplied from said direct current power source to said direct current electric motor through said MOSFET circuit.

4. An throttle/vehicle condition sensor circuit for determining the mechanical position of a manipulable throttle for an electric drive motor and generating a variable voltage indicative of said position of said throttle, comprising:

a control output connector comprising;

a. a terminal for communicating said variable voltage to an external power control circuit,

b. a terminal for connecting said direct current power source to said external power control circuit,

c. a terminal for receiving a circuit operating voltage, and

d. a terminal for communicating a power inhibit signal;

a Hall Effect position transducer circuit comprising;

a. a magnetic component positioned on said throttle, and

b. a sensor component positioned so as to sense variations in magnetic flux density from said magnetic component and to generate an output voltage whose level is indicative of said magnetic flux density and therefore of a position of said throttle;

an amplifier circuit for receiving said output voltage from said Hall Effect position transducer, amplifying and filtering said output voltage, and communicating said output voltage through said control output connector;

a reverse condition sensor circuit comprising;

a. means for responding to a switch closure signaling a reversing condition in a vehicle propelled by said electric drive motor,

b. a voltage modifier circuit connected to said amplifier circuit for modifying said output voltage in response to said reversing condition in said vehicle, and

c. an optical coupler for isolating said means for sensing a reversing condition from said voltage modifier circuit; and

an inhibitor circuit comprising;

a. means for sensing the presence of an operational voltage from said direct current power source at an inhibit connection point,

b. an inhibit signal circuit connected to said terminal for communicating said power inhibit signal, said inhibit signal circuit for providing a power inhibit signal indicative of an absence of said operational voltage at said inhibit connection point to said direct current power source, and

c. an optical coupler for isolating said means for sensing said operational voltage from said inhibit signal circuit.