Auxiliary battery voltage/temperature compensation for automotive 12 volt system for electric vehicles
First Claim
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1. A power system for an electric motor vehicle and accessories thereof, comprising:
- a first DC power source generating a relatively high DC voltage for powering a vehicle propulsion motor;
a second DC power source comprising a DC to DC converter powered by said first power source and generating a relatively low DC voltage for powering certain accessories of said accessories of said motor vehicle;
an auxiliary DC power source comprising a battery having an output voltage which varies as a function of temperature for powering said accessories upon failure of said first DC power source and consequently said DC to DC converter,said battery further being coupled to said DC to DC converter and including means for being charged thereby; and
means for regulating the output voltage of said DC to DC converter in response to a feedback signal corresponding to the output voltage of said converter and in response to a temperature reference signal corresponding to the output voltage of said battery so that the DC to DC converter will charge the battery with a voltage which matches a voltage vs. temperature profile of the battery and thus preventing the battery from being overcharged.
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Abstract
A battery temperature compensation circuit for a DC/DC converter which is used to charge an auxiliary battery for an electric vehicle and including, among other things, a voltage sensitive resistance, such as a thermistor, coupled to a clamped voltage divider network which generates a resistance vs. temperature characteristic so as to control the DC/DC converter and provide an output voltage for charging the auxiliary battery which matches the voltage vs. temperature profile of the battery.
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Citations
18 Claims
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1. A power system for an electric motor vehicle and accessories thereof, comprising:
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a first DC power source generating a relatively high DC voltage for powering a vehicle propulsion motor; a second DC power source comprising a DC to DC converter powered by said first power source and generating a relatively low DC voltage for powering certain accessories of said accessories of said motor vehicle; an auxiliary DC power source comprising a battery having an output voltage which varies as a function of temperature for powering said accessories upon failure of said first DC power source and consequently said DC to DC converter, said battery further being coupled to said DC to DC converter and including means for being charged thereby; and means for regulating the output voltage of said DC to DC converter in response to a feedback signal corresponding to the output voltage of said converter and in response to a temperature reference signal corresponding to the output voltage of said battery so that the DC to DC converter will charge the battery with a voltage which matches a voltage vs. temperature profile of the battery and thus preventing the battery from being overcharged. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of powering an electric vehicle and accessories thereof, comprising the steps of:
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(a) powering a vehicle propulsion motor by a relatively high voltage DC power source; (b) powering certain vehicle accessories by a relatively low voltage DC to DC converter, said DC to DC converter being powered by said relatively high voltage DC power source; (c) powering said accessories by an auxiliary DC battery having an output voltage which varies with temperature when said relatively high voltage DC power source and consequently said DC to DC converter are inoperative; (d) charging the auxiliary DC battery by the DC to DC converter; and (e) regulating the output voltage of said DC to DC converter in response to a feedback signal having a value which is a function of the value of said output voltage of said DC to DC converter and in response to a temperature reference signal which is a function of the value of the output voltage of said auxiliary DC battery so that the DC to DC converter will charge the battery with a voltage which matches a voltage vs. temperature profile of the battery so as not to overcharge the battery. - View Dependent Claims (18)
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Specification