Abstract: A motor current measurement circuit (7) includes a sense resistor (8) located in a path through which, in use of the motor (1), at least a part of the current flowing into or out of the motor flows, a first amplifier which comprises a differential amplifier (9) which has a first input and second input which are respectively connected to the opposing ends of the sense resistor and has an output at which the amplifier (9) is arranged to produce, in use, an output signal representative of a voltage dropped across the resistor (8) and hence the current flowing through the resistor (8), and an analogue to digital converter (12) having an input which is connected to the output of the first amplifier (9) and an output.

Abstract: A current measuring circuit for an electric motor provides an output indicative of the change in the current di/dt flowing in a phase of the electric motor over a measurement period of time. The circuit includes a current measurement element having a resistance; a switch which in use selectively permits transmission of a voltage dependent upon the instantaneous value of the voltage dropped across the current measurement element to a part of the circuit; and a switch controller which is adapted to operate the switch in response to timing signals supplied by the switch controller so as to define the measurement period of time.

Abstract: A motor current measurement circuit (7) includes a sense resistor (8) located in a path through which, in use of the motor (1), at least a part of the current flowing into or out of the motor flows, a first amplifier which comprises a differential amplifier (9) which has a first input and second input which are respectively connected to the opposing ends of the sense resistor and has an output at which the amplifier (9) is arranged to produce, in use, an output signal representative of a voltage dropped across the resistor (8) and hence the current flowing through the resistor (8), and an analogue to digital converter (12) having an input which is connected to the output of the first amplifier (9) and an output.

Abstract: A current measuring circuit for an electric motor provides an output indicative of the change in the current di/dt flowing in a phase of the electric motor over a measurement period of time. The circuit includes a current measurement element having a resistance; a switch which in use selectively permits transmission of a voltage dependent upon the instantaneous value of the voltage dropped across the current measurement element to a part of the circuit; and a switch controller which is adapted to operate the switch in response to timing signals supplied by the switch controller so as to define the measurement period of time.