Motor driver having a booster circuit and an inverter both controlled by pulse width modulation

A driver for an electric motor comprising:

• an inverter having at least one arm including two switching elements connected in series, the inverter converting a direct current to an alternating current to supply the alternating current to the motor;
• a booster circuit connected between the inverter and a DC power supply and including a reactor, a switching element and a diode to prevent a reverse current, the booster circuit supplying the direct current from the DC power supply to the inverter;
• a first current detecting element which detects current flowing into the booster circuit;
• a second current detecting element which detects current flowing into the inverter;
• a speed detecting element which detects a rotational speed of the motor;
• and
• a controller comparing a speed value detected by the speed detecting element with a set speed value to determine a command value, the controller controlling the inverter on the basis of the command value by pulse width modulation and further controlling the booster circuit by pulse width modulation, wherein the booster circuit carries out a voltage boosting operation to prevent the detected current values from exceeding upper limit values respectively in the booster circuit;
• and
• a diode connected in series to the switching element of the booster circuit to protect circuit against a reverse-connection.