Motor controller, power system, vehicle and heating method of power battery

The invention provides a motor controller, a power system, a vehicle and a heating method of a power battery. The motor controller comprises a power module which is provided with a direct current bus and an alternating current bus, the direct current bus is used for receiving direct current output by a power battery, the power module is used for converting the direct current into alternating current, and the alternating current bus is used for outputting the alternating current to a motor; the control module is connected with the power module and used for sending a first control signal to the power module, the first control signal is used for controlling the power module to input target square-wave voltage to a direct shaft of the motor, the target square-wave voltage is square-wave voltage with frequency change and/or amplitude change, and the target square-wave voltage is used for generating alternating pulse current on a direct-current bus; the pulse current is used for heating the power battery, so that c