Apparatus and methods for supplying DC power to control circuitry of a matrix converter

A motor drive assembly including a motor drive circuit of an electric motor, comprising:

• a motor drive housing configured to mount to a motor frame of an electric motor;
• a motor drive circuit comprising:
• a plurality of AC inputs;
• a plurality of AC outputs;
• a direct AC-AC matrix converter comprising:
• an array of switches connected to the plurality of AC inputs and configured to receive a multi-phase AC input voltage from the plurality of AC inputs, and the array of switches configured to output a multi-phase AC output voltage at the plurality of AC outputs, the plurality of AC inputs connected through the array of switches to the plurality of AC outputs without an intermediate DC stage;
• control circuitry configured to control the array of switches to synthesize the multi-phase AC output voltage from the multi-phase AC input voltage;
• and
• a clamp circuit electrically connected at an input of the clamp circuit to the plurality of AC inputs and at an output of the clamp circuit to the plurality of AC outputs such that the clamp circuit is externally connected to AC nodes of the array of switches, the clamp circuit including a switched mode power supply attached to a discharge node of the clamp circuit, the discharge node in a direct discharge current path, the switched mode power supply operable to generate a DC supply voltage for the control circuitry, wherein the switched mode power supply is operable over a voltage range of at least 250 V DC, wherein the motor drive circuit is dimensioned to fit within the motor drive housing.

A method of supplying DC power in a direct AC-AC matrix converter, the method comprising:

• controlling an array of switches using control circuitry to synthesize a multi-phase AC output voltage from a multi-phase AC input voltage, the array of switches including a plurality of AC inputs configured to receive the multi-phase AC input voltage and a plurality of AC outputs configured to output the multi-phase AC output voltage, the plurality of AC inputs connected through the array of switches to the plurality of AC outputs without an intermediate DC stage;
• activating a clamp circuit connected at an input of the clamp circuit to the plurality of AC inputs of the array of switches and to the plurality of AC outputs of the array of switches such that the clamp circuit is externally connected to AC nodes of the array of switches;
• and
• generating a DC supply voltage for the control circuitry using a switched mode power supply of the clamp circuit, the switched mode power supply attached to a discharge node of the clamp circuit, the discharge node in a direct discharge current path, wherein the switched mode power supply is operable over a voltage range of at least 250 V DC, wherein the direct AC-AC matrix converter is contained within a motor drive mounted to a motor frame of an electric motor.