Power supply arrangement for a fuel injector drive circuit

The invention relates to a power supply arrangement (60,70,80) for an injector drive circuit (12) configured to operate in an energy recovery mode. The power supply arrangement receives an input voltage and includes: voltage boost means (24,124) for increasing the input voltage to a power supply output voltage (V SUPPLY ), switch means (28;28a,28b,28c) operable between open and closed states to control current flow through said voltage boost means (24,124), and a controller (14) for generating at least one control signal (130; 230,64,130A,130B,130C) for the switch means to control switch status. The controller (14) includes a predictive control algorithm for receiving an input signal that is representative of an injection running condition and for adjusting a parameter of the control signal in dependence upon the injection running condition, thereby to regulate the power supply output voltage (V SUPPLY ).