Calnetix has created a detailed white paper explaining how power electronics work. To download a copy, click here.
Excerpt from Calnetix’s white paper entitled, “General Overview of How Power Electronics Work”:
Calnetix’s Vericycle™ Bidirectional Drives typically interface with high-speed Permanent Magnet Synchronous Machines (PMSM). The power electronics can be configured for a variety of PMSM pole numbers, including more complex, higher pole configurations. On the utility side, Calnetix drives are capable of interfacing with U.S. and international power networks that are within the voltage/frequency range defined in our specifications.
Calnetix’s power electronics power architecture has a very simple hardware configuration consisting of two identical inverter modules interconnected by a DC link capacitor. The DC link capacitor provides a low voltage ripple DC energy buffer for the modules. Both modules are similar in construction and configuration. Therefore, Vericycle™ drives are capable of bidirectional power flow operation (motoring mode or generating mode).
The supervisory controls automatically assign different functional modes of operation to the modules based on the system application. The module that is connected to the utility grid assumes an active rectification role for motor drive applications and assumes a grid tie inverter role for generating applications. The module that is connected to the motor assumes variable voltage and frequency inverting mode for motor drive applications and assumes variable voltage and frequency active rectification mode for generating applications.
Figure 1 illustrates the basic building block of the Vericycle™ power electronics.
In generating mode, high frequency AC power, generated from the machine, is converted to regulated DC power by the machine side inverter thus charging the DC-Link capacitors. The machine side inverter uses field oriented controls and maintains current to be sinusoidal, thus optimizing the power draw from the machine while maintaining optimum power conversion efficiency. This DC power is then inverted to an alternating current of either 50 Hz or 60 Hz to pass on to a commercial AC power grid (utility grid).
In motoring mode, 50 or 60 Hz AC power from utility grid is converted to regulated DC power by the grid side inverter in the active rectification role, thus charging the DC-Link capacitors. Energy from the DC-Link is then inverted by the motor side inverter to 3 phase variable –voltage and variable-frequency AC power to drive the PMSM.