A power supply (900, 1400), comprising: a power block configured to receive an input power and to generate an output power; and a control system coupled to the power block (904, 1404), wherein the power block (904, 1404) and control system are configured to provide unidirectional current flow and bipolar voltage during operation of the power supply, wherein the power block (904, 1404) comprises a primary side and a secondary side, the primary side and secondary side being coupled to one another via a transformer, wherein the secondary side comprises an active rectifier block formed from a first and a second controlled rectifier, where the first and second controlled rectifiers provide equivalent operation to a first and second switch coupled in series to a respective first and second diode, characterized in that: the power block (904, 1404) comprises a primary current transducer that is configured to sense current in a primary coil of the transformer and a secondary current transducer that is configured to sense current after the rectifier block; and the control system includes a sign alternator, being configured to be driven by an output of a PWM phase trigger which is configured to drive PWM circuitry (D10, D11, D12, D13), the sign alternator is configured to receive an output of the primary current transducer and to supply an output (+I 1) to a node which is configured to subtract from the output (+I 1) an output of the secondary current transducer, wherein the node is configured to provide a control signal (IMAG) proportional to just the absolute value of a magnetizing current of the transformer, wherein the control signal (IMAG) is coupled to the first and second switches of the active rectifier block through the PWM circuitry to control the switching of the first and second switches. a power block configured to receive an input power and to generate an output power; and a control system coupled to the power block (904, 1404), wherein the power block (904, 1404) and control system are configured to provide unidirectional current flow and bipolar voltage during operation of the power supply, wherein the power block (904, 1404) comprises a primary side and a secondary side, the primary side and secondary side being coupled to one another via a transformer, wherein the secondary side comprises an active rectifier block formed from a first and a second controlled rectifier, where the first and second controlled rectifiers provide equivalent operation to a first and second switch coupled in series to a respective first and second diode, characterized in that: the power block (904, 1404) comprises a primary current transducer that is configured to sense current in a primary coil of the transformer and a secondary current transducer that is configured to sense current after the rectifier block; and the control system includes a sign alternator, being configured to be driven by an output of a PWM phase trigger which is configured to drive PWM circuitry (D10, D11, D12, D13), the sign alternator is configured to receive an output of the primary current transducer and to supply an output (+I 1) to a node which is configured to subtract from the output (+I 1) an output of the secondary current transducer, wherein the node is configured to provide a control signal (IMAG) proportional to just the absolute value of a magnetizing current of the transformer, wherein the control signal (IMAG) is coupled to the first and second switches of the active rectifier block through the PWM circuitry to control the switching of the first and second switches. the power block (904, 1404) comprises a primary current transducer that is configured to sense current in a primary coil of the transformer and a secondary current transducer that is configured to sense current after the rectifier block; and the control system includes a sign alternator, being configured to be driven by an output of a PWM phase trigger which is configured to drive PWM circuitry (D10, D11, D12, D13), the sign alternator is configured to receive an output of the primary current transducer and to supply an output (+I 1) to a node which is configured to subtract from the output (+I 1) an output of the secondary current transducer, wherein the node is configured to provide a control signal (IMAG) proportional to just the absolute value of a magnetizing current of the transformer, wherein the control signal (IMAG) is coupled to the first and second switches of the active rectifier block through the PWM circuitry to control the switching of the first and second switches.