A throttle loss recovery system for a spark-ignition internal combustion engine, comprising: an electrical generator; a radial-inflow turbine coupled to the generator and arranged to receive incoming air destined for an intake of the spark-ignition engine, the turbine recovering energy from the air passing therethrough and the turbine in turn rotatably driving the generator, wherein the turbine comprises a high-leakage variable nozzle turbine that is controllable between a fully closed position and a fully open position and partially open positions therebetween; a bypass passage and an associated bypass valve arranged to allow air to bypass the VNT and be delivered directly to the air intake, the bypass valve being controllable to selectively vary a degree of opening of the bypass valve from closed to open and partially open positions therebetween; a throttle valve arranged upstream of and in series with the VNT and the bypass valve, the throttle valve being controllable to selectively vary a degree of opening of the throttle valve from closed to open and partially open positions therebetween; and a rectifier, a filter, and a pulse width modulation controller between the generator and a load served by the generator such that AC electrical power generated by the generator is rectified and filtered into DC current and is supplied to the load via the PWM controller, wherein: the PWM controller is arranged such that: the electrical power generation zone is bounded on the low side by a minimum generator speed threshold ω min; and the electrical power generation zone is bounded by a maximum generator speed threshold ω max above which the PWM duty cycle is set to 100% to control generator overspeed excursions. an electrical generator; a radial-inflow turbine coupled to the generator and arranged to receive incoming air destined for an intake of the spark-ignition engine, the turbine recovering energy from the air passing therethrough and the turbine in turn rotatably driving the generator, wherein the turbine comprises a high-leakage variable nozzle turbine that is controllable between a fully closed position and a fully open position and partially open positions therebetween; a bypass passage and an associated bypass valve arranged to allow air to bypass the VNT and be delivered directly to the air intake, the bypass valve being controllable to selectively vary a degree of opening of the bypass valve from closed to open and partially open positions therebetween; a throttle valve arranged upstream of and in series with the VNT and the bypass valve, the throttle valve being controllable to selectively vary a degree of opening of the throttle valve from closed to open and partially open positions therebetween; and a rectifier, a filter, and a pulse width modulation controller between the generator and a load served by the generator such that AC electrical power generated by the generator is rectified and filtered into DC current and is supplied to the load via the PWM controller, wherein: the PWM controller is arranged such that: the electrical power generation zone is bounded on the low side by a minimum generator speed threshold ω min; and the electrical power generation zone is bounded by a maximum generator speed threshold ω max above which the PWM duty cycle is set to 100% to control generator overspeed excursions. the electrical power generation zone is bounded on the low side by a minimum generator speed threshold ω min; and the electrical power generation zone is bounded by a maximum generator speed threshold ω max above which the PWM duty cycle is set to 100% to control generator overspeed excursions.