An electric system for an electric vehicle includes a main battery used for driving the vehicle, an auxiliary battery used for accessories of the vehicle, an AC motor for driving one or more wheels, an inverter for converting DC power supplied from the main battery to AC power to be supplied to the AC motor, and an auxiliary battery charging circuit for charging the auxiliary battery by using the AC power from the inverter. When charging the auxiliary battery, the AC power is insulatedly transformed and then rectified. In another example, an input capacitor in the inverter is charged by a DC-DC converter connected with the auxiliary battery as its power supply when the inverter starts. The system enables the auxiliary battery charging circuit to be small, light and low cost. The system can also charge the auxiliary battery for accessories even when the vehicle is stopping.
An electric power system for an electric vehicle includes an electric drive motor, a high voltage bus for supplying operating power to energize the drive motor, and an inverter including power switching devices and having an inverter output. The inverter is coupled between the high voltage bus and the electric drive motor and a controller is coupled to the inverter and provides motor control signals and high frequency injection signals to the inverter. An auxiliary power unit is coupled to the inverter output and has a DC output for supplying DC operating power. The auxiliary power unit supplies DC power in response to the high frequency injection signals. The electric drive motor operates in response to the motor control signals and is substantially unaffected by the high frequency injection signals.
The step-up circuit has first and second input terminals for connection to a battery, first and second output terminals for connection to an electronic device to be fed by a DC/DC converter having a first and second input terminals connected respectively to the first and second input terminals of the step-up circuit. The second output terminal of the step-up circuit is connected to the second input terminal of the step-up circuit, one output terminal of the converter is connected to the first input terminal of the step-up circuit and the other output terminal of the converter is linked to the first output terminal of the step-up circuit, therefore, when operating, the output of the step-up circuit is the sum of the power of the battery and of the output of the converter. The step-up circuit is smaller, supplies the same output, is cheaper to produce and offers improved performance over the prior art.
An onboard electric vehicle charger is provided which incorporates a forward converter with dynamic balancing of the primary drive currents of its ferrite core transformer to produce 5,000 watt charging power with a power density of 333 watts per kilogram and full safety isolation between the input power source and the batteries plus small size (approximately 15" by 9" by 6") and weight (less than 15 kilograms) and a power factor correcting boost preregulator with dynamic adjustment of its compensation networks which produces full correction to substantially unity (99.9+%) for power factor with current total haromonic distortion (THD) of 2% to 3% over the entire power range of 100 watts to 5,000 watts. The same boost preregulator circuit allows operation from power sources of 95 to 145 VAC or 200 to 275 VAC. The combination of the boost converter, (boost preregulator) and forward converters with the invention's control scheme enables constant throughput (in watts) during each step of the charging process and a constant pulse width modulation (PWM) duty cycle near maximum at all power levels by varying the output voltage of the boost preregulator in direct relation to the power level. A second forward converter, using the same dynamic balancing of primary currents utilized in the main forward converter described, works with the boost preregulator described to permit integration of a DC to DC converter function with 1 KW (75 A @ 14 VDC) capability plus full safety isolation between the high voltage propulsion batteries and the auxiliary (12 volt) electrical system of the vehicle.
An apparatus for diagnosing a low voltage battery includes a high voltage battery for powering an electric automobile, a voltage converter that reduces the output of the high voltage battery to a low voltage, a low voltage battery for powering the auxiliaries of the automobile, a current/voltage sensor, a controller, and a warning indicator. The low voltage battery is connected to the high voltage battery through the voltage convertor and a resistor is connected to the low voltage battery. The current/voltage sensor detects electric currents and voltages of the low voltage battery and the resistor. The controller diagnoses the degradation of the low voltage battery at the start of operation of the automobile by referring the output of the current/voltage sensor to a set of selected predetermined reference values. A battery relay interrupts the connection between the high voltage battery and the low voltage battery to diagnose the low voltage battery and the warning indicator alerts to a degradation of the low voltage battery.
A power supply control device for an electric vehicle capable of reducing the power consumption in a battery monitor assembly adapted for monitoring a residual electric charge in a main battery 4. In response to an operation which causes increasing or decreasing the residual charge in the main battery 4, a start-up unit 200 produces a start-up demand pulse P3. Upon receiving the start-up demand pulse P3, a power supply controller circuit 60 closes a switch 59 to allow the power from a sub battery 5 to be supplied the battery monitor assembly 100. When the battery monitor assembly 100 is activated, its power supply maintaining means 102 delivers a self-hold signal S4 to maintain the switch 59 being closed. The battery monitor assembly 100 keeps monitoring the residual charge in the main battery 4 while it is energized by the sub battery 5.
