电力电子题库

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What are the general Tasks of Power Electronics

Common tasks of power electronics are transforming and controlling the flow of electrical energy with minimal energy losses. These include power conversion, control, conditioning, motor control, and renewable energy.

Make 10 Examples where Power Electronics are used

Smartphone, Server, PC, Notebook, Motor Control, Automotive, E-Mobility, Medical Ventilator, Solar Power, Lightning, Induction Heating.

Present current and voltage limits for controllable power semiconductors?

What are the key aims for further development in semiconductors?

1. Increasing the switching performance (current, voltage)
2. Reducing losses in the semiconductors as well as in control and protective circuits
3. Expanding the operating temperature range
4. Improved service life, ruggedness and reliability
5. Reducing the amount of control and protection required; improving component behavior in the event of error / failure
6. Cost reduction

What are development directions for Semiconductor materials(写5条就行)

1. New semiconductor materials (e.g. wide bandgap materials) Chip technology
2. Higher permissible chip temperatures or current densities (reduction of chip area)
3. Finer structures (reduction of chip area)
4. New structures (improvement of chip characteristics)
5. Integration of functions on the chip (e.g. gate resistance, temperature measurement, monolithic system integration)
6. New monolithic components by combining functions (RC-IGBT, ESBT)
7. Improved stability of chip characteristics under different climatic conditions.

Please depict the distinctions of Semiconductor devices

Please give a schematic view on Schematic layout of a PN diode (a) and a Schottky diode (b)

Schematic layout of a pn-diode (a) and a Schottky diode (b);

What are Schottky Diodes?

Schottky diodes are unipolar and have no reverse current or defined reverse recovery time, due to no excess charge build-up during on-state current flow.

What is the “Avalanche breakdown effect”?

Charge carriers (electrons or holes) are generated by thermal or optical energy in the space charge region and can create more charge carrier pairs through ionization by collision when accelerated by the electric field intensity in the avalanche effect.

What is the “Zener Breakdown effect”?

外教认可的答案：In highly doped n-type diodes, the intense field in the space charge region can create free charge carrier pairs by snatching electrons from silicon atom bonds. Wikipedia答案：Zener effect is the type of breakdown that occurs when the P-N junction diode is reverse biased. During this, the free minority charge carrier of P-N junction tunnels from valance band to conduction band of semiconductor causes sudden reverse current flow.

What are the characteristics of Thyristor

Thyristors are semiconductor devices used as switches for high-power applications. They have advantages such as high current and voltage handling capability, but also limitations such as unidirectional current flow and limited frequency of operation. Thyristors are widely used in various applications.

What is a snubber in general?

Snubbers suppress voltage spikes and electromagnetic interference to prevent component damage. They use passive components and improve circuit performance and reliability.

What is the main purpose of introducing a Snubber Diode in electronic circuits?

The main purpose of snubber diodes is to protect sensitive components from voltage spikes generated by inductive loads, thereby improving circuit reliability and lifespan.

What does the maximum forward Voltage VF indicate as an on-state behavior?

The maximum forward voltage VF indicates the voltage drop across a diode when it is conducting current in the forward direction. It is typically around 0.7 volts for a standard silicon diode and is important to choose appropriately for reliable operation.

Please depict the blocking behavior of Snubber Diode with an example of the reverse current of a 1700 V CAL Diode at operating temperature of 25 degrees and 125 degrees.

What are parameters as a function of the soft-recovery behavior of Snubber Diodes?

Current; Temperature; Voltage applied; Rate of rise for di/dt.

What does MOSFET Stand for?

Metal-oxide-semiconductor field-effect transistors

What does IGBT stand for?

Insulated Gate Bipolar Transistor.

What does BJT stand for?

Bipolar Junction Transistor

What are the main differences between BJT and MOSFET

Operating principles: BJTs are current-controlled devices, while MOSFETs and IGBTs are voltage-controlled devices. Switching speed: MOSFETs and IGBTs have a faster switching speed than BJTs. Cost: BJTs are generally less expensive than MOSFETs/IGBTs, making them a more economical choice for some applications. Power dissipation: BJTs have a higher power dissipation than MOSFETs/IGBTs, which means that they generate more heat and require larger heatsinks to dissipate the heat.

What are areas of application for BJT an IGBT

BJTs are used for low-power applications, such as audio amplifiers and low-power switching circuits. IGBTs are used for high-power applications, such as motor drives and power supplies. The choice depends on the specific requirements of the application.

What is a SJ-Mosfet?

Is a type of power MOSFET that utilizes a unique structure to achieve lower on-resistance and higher breakdown voltage compared to conventional MOSFETs. Electrons flow in a very rich doped n-area, which gives naturally a low on-state resistance.

应用范围: high-voltage and high-power applications, such as motor drives

What is the Miller-effect?

The Miller effect is a phenomenon in electronics where a parasitic capacitance appears to be increased due to feedback.

What is the Safe Operating Area (SOA) for Power-MOSFET Robustness

It defines the conditions under which the MOSFET can safely operate without being damaged due to excessive temperature, current, or voltage stress.

What are advantages of a SiC MOSFET?

Low capacitances → fast switching speeds Fast body diode with low Qrr Excellent thermal behavior Increased avalanche capability Higher breakdown voltage Higher temperature operation Lower on-state resistance

What are disadvantages of a SiC MOSFET?

Sensitivity to parasitic capacitance; Limited availability

What is the main purpose of Packaging?

Packaging protects and mechanically supports electronic components and circuits in power electronic systems from environmental factors, such as moisture, dust, temperature variations, and mechanical stresses. This ensures their performance and prevents damage.

What is the difference between Soldering and Sintering?

Soldering: Soldering is the connection of two (metal) materials by means of liquid metal or a liquid alloy. Diffusion sintering (low-temperature joining technology): At a temperature of around 250°C, fine silver powder is sintered under high pressure to form a low-porous silver bond layer between the parts to be connected.

What is Wire Bonding used for?

Wire bonding is often used to connect a power semiconductor chip face with other chips or connecting elements.

What forms of Pressure contact can you distinguish?

Large-surface pressure contact: Here, the surfaces of the parts being connected, which are pressed against each other under high force, must be clean and planar. Small-surface pressure contact: Here, the contact area is line-shaped or almost dot-shaped.