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Electric Motor Drives
Published in Iqbal Husain, Electric and Hybrid Vehicles, 2021
The electric motor drive is the integrated power electronic converter and motor controller that processes and controls the electrical energy flowing from the source to the electric machine or vice versa in response to a user demand. In a BEV, the drive converts the stiff DC battery voltage to either a DC voltage for DC motors or an AC voltage for AC motors. The controller generates the gating signals for the power electronic circuit devices based on the driver input command, the sensor feedback signals and the control algorithm for the type of electric machine used. The driver input is translated into a torque command for the motor drive. The torque command in conjunction with the feedback signals set up the operating point parameters for the electric motor and accordingly controls the turn-on and turn-off of the power switches inside the drive system. The drive controller includes the inverter control modulation scheme in the case of AC drives to convert the motor control current commands into gate signals for the power converter. During vehicle propulsion, the motor drive delivers power at the desired voltage and frequency to the motor, which in turn provides the desired torque at the wheels. During regeneration, the motor drive processes power flow from the wheels to the energy storage system.
Entrepreneurship in Electric Machines and Drive Systems
Published in R. Krishnan, Entrepreneurship in Power Semiconductor Devices, Power Electronics, and Electric Machines and Drive Systems, 2020
Startups in permanent magnet synchronous and brushless dc (PMBDC) motors, their drive systems, switched reluctance motors (SRMs) and their drive systems are presented with emphasis on products addressing select markets and technology developments in these fields. Apart from these electromagnetic machines and their drives’ startups, a new entrant in the electrostatic machine space is also presented. The technology basis and innovation aspects are presented when individually presenting the startups. The applications cover appliance motor drives, motorbikes, electric vehicle (EV) motors and drives, electric aircraft motors and drive systems, air conditioner drive systems and some general-purpose variable-speed motor drive systems too. The market for these motors and their drive systems are presented briefly to understand the scope for the startups in these topics.
Step Motor Drives
Published in Timothy L. Skvarenina, The Power Electronics Handbook, 2018
When a constant current is passed through one phase of a step motor, the motor generates a torque. This torque is typically a sinusoidal function of rotor displacement from the detent position that causes the rotor to minimize this displacement. When the phases of the motor are excited so that the motor "runs," the generated torque is still a function of position and current, but the current becomes a varying quantity, dependent on time, position, velocity, and of course, the drive circuit and drive scheme. Selection of a motor, drive circuit, and drive scheme depends on predicting the performance and the dynamic torque-speed characteristics of a particular motor with a drive circuit and drive scheme. These performances of step motors can be predicted to within reasonable accuracy using mathematical models for both the motor and drive circuit. Ways to model the motor and drive circuit are presented in this section. As with modeling most physical systems, more accurate models produce more accurate results. Tradeoffs between accuracy and simplicity are also discussed with each model.
Review of recent progresses on gallium nitride transistor in power conversion application
Published in International Journal of Sustainable Energy, 2020
Jiangbo Tian, Chunyan Lai, Guodong Feng, Debmalya Banerjee, Wenlong Li, Narayan C. Kar
In the high frequency, high efficiency DC/AC power conversion area, GaN HEMTs have also brought new innovations to solve the demanding requirements from industry. For example, drives for servo motors and other high-speed motors may demand a fundamental excitation frequency of 1 kHz or more, with comparable sample and feedback rates for feedback and control. This requires the carrier frequency to be increased with the proportional ratio of motor speed. In conventional motor drive design, silicon-based IGBTs were used as the switching devices in the bridge leg of the inverter. Systems such as these were always constrained to a choice between coarse control, with barely ten steps per control cycle at a 12 kHz of switching frequency, and high switching loss incurred by switching IGBTs at higher frequencies of tens of kilo hertz. GaN HEMTs which can switch at over several hundred kilo-hertz with relative low switching loss, can eliminate this constraint. Besides, the increase of the PWM frequency also brings other advantages in motor drive applications such as reduced motor current ripple, lower motor losses and reduced filter size and cost. Figure 6 shows an example setup with a GaN-based motor drive.