A drive circuit of a permanent magnet motor comprising a stator and a permanent magnet rotor , the stator comprising a stator core and a stator winding wound on the stator core and adapted to be connected in series with an AC power source between a first node (A) and a second node (B), the drive circuit comprising: a controllable bidirectional AC switch connected between the first node (A) and the second node (B), the controllable bidirectional AC switch , if switched on, being adapted to remain on in the absence of a drive current; an AC-DC conversion circuit connected in parallel with the controllable bidirectional AC switch between the first node and the second node; a position sensor configured to detect a magnetic pole position of the permanent magnet rotor; and characterized by a switch control circuit configured to control the controllable bidirectional AC switch to be switched between a conductive state and a non-conductive state in a predetermined way, based on an output of the position sensor and the polarity of the AC power source such that the stator winding drives the rotor to rotate only in a predetermined direction when the magnetic pole position of the permanent magnet rotor has a first polarity and the AC power source is in a positive half-cycle or when the magnetic pole position of the permanent magnet rotor has a second polarity and the AC power source is in a negative half-cycle, the controllable bidirectional AC switch being switched into the conductive state when a drive current to the controllable bidirectional AC switch exceeds a gate triggering current (Ig), and the controllable bidirectional AC switch being switched into the non-conductive state when the drive current falls below the gate triggering current (Ig) and a current flowing through the controllable bidirectional AC switch is less than a holding current (Ihold), and wherein there is no current flowing through the AC-DC conversion circuit when the first node (A) and the second node (B) are short circuited by the controllable bidirectional AC switch . a controllable bidirectional AC switch connected between the first node (A) and the second node (B), the controllable bidirectional AC switch , if switched on, being adapted to remain on in the absence of a drive current; an AC-DC conversion circuit connected in parallel with the controllable bidirectional AC switch between the first node and the second node; a position sensor configured to detect a magnetic pole position of the permanent magnet rotor; and characterized by a switch control circuit configured to control the controllable bidirectional AC switch to be switched between a conductive state and a non-conductive state in a predetermined way, based on an output of the position sensor and the polarity of the AC power source such that the stator winding drives the rotor to rotate only in a predetermined direction when the magnetic pole position of the permanent magnet rotor has a first polarity and the AC power source is in a positive half-cycle or when the magnetic pole position of the permanent magnet rotor has a second polarity and the AC power source is in a negative half-cycle, the controllable bidirectional AC switch being switched into the conductive state when a drive current to the controllable bidirectional AC switch exceeds a gate triggering current (Ig), and the controllable bidirectional AC switch being switched into the non-conductive state when the drive current falls below the gate triggering current (Ig) and a current flowing through the controllable bidirectional AC switch is less than a holding current (Ihold), and wherein there is no current flowing through the AC-DC conversion circuit when the first node (A) and the second node (B) are short circuited by the controllable bidirectional AC switch . <EOS>