Phase change assisted heat sink

A vehicle including

• an electric traction drive machine;
• a source of electrical energy;
• a controllable switching arrangement coupled to said traction drive machine and to said source of electrical energy, for coupling energy between said source of electrical energy and said motor under the control of control signals;
• operator-controlled control means coupled to said switching arrangement, for controlling the amount of energy coupled between said source and said machine by synthesizing a current waveform;
• a cooling system coupled to said controllable switching arrangement, for transferring heat from said switching arrangement to ambient;
• and
• a phase change energy transducer coupled to said cooling system and to said switching arrangement, for transiently absorbing heat generated by said switching arrangement in excess of that which said cooling system can instantaneously trasfer.

An apparatus, comprising:

• an electrical machine:
• a source of electrical energy;
• controllable switching means coupled to said machine and to said source of electrical energy, for providing energy to said machine from said source in an amount which varies in time, whereby the energy handled by said switching means varies with time, and the power-loss-generated heat in said switching means also varies with time;
• cooling means coupled to said switching means, for transferring said heat from said switching means to ambient, whereby the instantaneous temperature of said switching means tends to vary in response to the power being handled by said switching means;
• and
• phase change energy transducing means thermally coupled to said switching means and to said cooling means, for absorbing heat from said switching means when said instantaneous temperature of said switching means tends to rise, and for releasing heat to said cooling means when said instantaneous temperature of said switching means tends to fall, thereby tending to maintain said temperature of said switching means constant.