Vehicle electronic control apparatus

A vehicle electronic control apparatus comprising:

• an opening/closing device connected in series with a single inductive load or each corresponding one of a plurality of inductive loads to which a battery voltage Vbb is supplied from a vehicle battery mounted in a vehicle;
• and
• a rapid cutoff circuit for suppressing a surge voltage generated when the opening/closing device is opened and for rapidly attenuating a driving current for the inductive load,
• wherein the rapid cutoff circuit includes
• a discharging diode connected with the single inductive load or each corresponding one of the plurality of the inductive loads, and
• a surge suppression capacitor that suppresses an induction voltage generated by the inductive load to a predetermined limit voltage V0 and is shared by the inductive loads,
• wherein the surge suppression capacitor is charged to an initial voltage from which the predetermined limit voltage V0 is obtained, with an initial charging voltage obtained by making any one of the opening/closing devices perform on/off energization of the inductive load or obtained from a voltage boosting control circuit,
• wherein the rapid cutoff circuit further includes a discharge control circuit that discharges charges charged in the surge suppression capacitor, when the charging voltage V of the surge suppression capacitor or the value of a target voltage [V−Vbb] obtained by subtracting the battery voltage Vbb from the charging voltage V exceeds the limit voltage V0,
• wherein the discharge control circuit includes
• a voltage limiting diode for setting at least the limit voltage V0,
• a discharging transistor that applies a discharge current Ix to the discharge control circuit when the charging voltage V of the surge suppression capacitor exceeds the target voltage, and
• a series resistor that is an equivalent discharging resistor formed of a discharging resistor for limiting the discharge current Ix to a value proportional to the target voltage or a constant current circuit for obtaining the discharge current Ix that is constant for a change in the target voltage,
• wherein in the case where the vehicle battery exists in a charging path of an initial charging or in an energization path of the discharge current Ix, the charging voltage V becomes an addition voltage [V0+Vbb] obtained by adding the battery voltage Vbb to the limit voltage V0, and in the case where the vehicle battery exists neither in the charging path nor in the energization path, the discharge current Ix is controlled so that the charging voltage V becomes equal to the limit voltage V0,
• wherein the lower limit of each of individual on/off periods T0i, which are the respective individual on/off periods of the opening/closing devices, is restricted in such a way as to become the same as or larger than a representative on/off period [T0=ΣTfi×2], which is twice as large as the sum value of individual cutoff times Tfi in each of which the individual opening/closing device is opened and an individual cutoff current I0i flowing in the individual inductive load is attenuated to zero.