Principles and Applications of Intelligent Power Devices

Abstract: At present, power devices are developing towards integration, intelligence and modularization. Intelligent power devices provide an ideal interface for the connection between weak current and strong current in mechatronic equipment. This paper introduces the characteristics, product classification, working principle and typical applications of intelligent power devices.

Keywords: intelligent power device; power switch regulator; power module; inverter

Principle and Application of Intelligent Power Device

SHA Zhan-you, WANG Shu-hai, AN Sheng-biao, ZHANG Xiu-qing

Abstract:Now,the power device is developing toward integration, intelligent and modularization. In mechanism-electricity equipment, intelligent power device support an ideal interface to connect weak and power electricity. The characteristic, product classification, operational principle and typical application of the intelligent power device are introduced.

Keywords:Intelligent power device; Power switching regulator; Power module; Transducer

Chinese Library Classification Number: TN492 Document Identification Code: A Article Number: 0219-2713(2003)04-0129-04

1. Characteristics and product classification of intelligent power devices

1.1 Characteristics of Intelligent Power Devices

The so-called intelligent power device is a new type of device that integrates power devices with sensors, detection and control circuits, protection circuits and fault self-diagnosis circuits and has power output capabilities. Since this type of device can replace manual work to complete complex power control, it is given intelligent features. For example, in intelligent power devices, common protection functions include undervoltage protection, overvoltage protection, overcurrent and short circuit protection, and overheating protection. In addition, some intelligent power devices also have protection circuits such as output voltage overshoot protection, transient current limiting, soft start and maximum input power limiting, which greatly improves the stability and reliability of the system.

智能功率器件具有体积小、重量轻、性能好、抗骚扰能力强、使用寿命长等显著优点，可广泛用于单片机测控系统、变频调速器、电力电子设备、家用电器等领域。

1.2 Product Classification of Intelligent Power Devices

Intelligent power devices can be divided into two categories, namely intelligent power integrated circuits and intelligent power modules.

1) Intelligent Power Integrated Circuit

There are many types of intelligent power integrated circuits, and only a few typical products are listed below.

——High Voltage Power Switching Regulator. For example, the MC33370 series products developed by Motorola in the United States.

——Intelligent Power Switch. For example, the Smart SIPMOS intelligent power switch produced by Siemens of Germany has product models such as BTS412B and BTS611.

2) Intelligent Power Module

Intelligent power module is a commercial component that uses microelectronic technology and advanced manufacturing technology to assemble intelligent power integrated circuits, microelectronic devices and peripheral power devices into one, which can realize intelligent power control. Most modules adopt a sealed structure to ensure good electrical insulation and seismic resistance. Users only need to understand the external characteristics of the module before using it. Therefore, it can simplify the design work and shorten the development cycle of the system. The products of many well-known module manufacturers at home and abroad have passed IEC950 (International Electrotechnical Commission) or UL1950 (USA), GS (Germany), CE (European Community) safety certification. They are reliable in quality, safe, strong in anti-harassment, meet electromagnetic compatibility (EMC) standards, easy to maintain, and the qualified rate of machine can reach 100%.

For example, the third-generation IPM series intelligent power module recently developed by Mitsubishi Electric Corporation of Japan has a wide range of uses. Recently, China has also developed new products such as intelligent power modules for variable frequency air conditioners and intelligent power modules for motors.

Figure 1 shows the operating frequency, capacity range and application fields of various power devices. Among them, SCR is a common thyristor, Triac is a bidirectional thyristor, GTO stands for turn-off thyristor, Tr Mod stands for a common power tube module, MOSFET stands for a power field effect tube, IGBT MOD IPM stands for an IPM series IGBT intelligent power module, and IGBT (Insulated Gate Bipolar Transistor) is the abbreviation of insulated gate field effect tube - bipolar transistor. As can be seen from the figure, the operating frequency of the IGBT intelligent power module is much higher than that of the common power tube module, and its capacity is 1 to 2 orders of magnitude higher than that of the power field effect tube.

Figure 1 Performance and application areas of various power devices

2 Principles and Applications of Intelligent Power Integrated Circuits

2.1 MC33370 Series High Voltage Power Switching Regulator

The MC33370 series is a high-voltage power switching regulator for microcontrollers (MCUs) developed by Motorola in the United States in 1999. It includes MC33369 to MC33374, with 17 models in total depending on the package form. It can be widely used in office automation equipment, instruments, wireless communication equipment and consumer electronic products to form high-voltage isolated AC/DC power converters below 150W.

The internal block diagram of the MC33370 series products is shown in the dotted box in Figure 2. The functions of each pin are as follows:

Figure 2 Internal block diagram of the MC33370 series products

UCC is the input terminal of the working power supply voltage.

FB is the feedback terminal.

GND is ground.

SCI is the state control terminal. It only needs a few peripheral components to realize the following 6 state control modes:

1) Use the button trigger method to select the working mode or standby mode;

2) Equipped with a microcontroller for shutdown operation;

3) The state controller is equipped with a low-voltage protection circuit so that the output voltage of the switching power supply will not fluctuate during the mode conversion process;

4) Use digital signals for control;

5) Connect the power-on delay circuit;

6) Operations on the state controller are prohibited.

D is the drain terminal of the power switch tube.

The internal structure of MC33370 mainly includes 9 parts:

1) Oscillator;

2) Shunt regulator/error amplifier;

3) PWM comparator and PWM trigger;

4) External shutdown circuit and shutdown trigger;

5) Current limit comparator and power switch tube;

6) Start circuit;

7) Undervoltage lockout circuit;

8) Overheat protection circuit;

9) State controller.

The circuit of the 15V/3.5A, 52W switching power supply composed of MC33374T/TV is shown in Figure 3. The allowable range of its AC input voltage u is 92V~276V. VD1~VD4 are rectifier bridges. The primary protection circuit is composed of an RC absorption circuit (R2, C2) and a clamping protection circuit (VDZ, VD5), which can effectively suppress the peak voltage generated by the leakage inductance of the high-frequency transformer and protect the power switch tube inside the MC33374 from damage. VDZ uses a P6KE200A transient voltage suppressor (TVS). The serial numbers of the resistor and capacitor components R1 and C3 in the figure are vacant. If needed, the series circuit of R2 and C2 can be changed to a parallel circuit of R1 (20 kΩ, 2 W) and C3 (0.1 μ F, 400 V) and then connected in series with an ultra-fast recovery diode to form an R, C, VD type protection circuit. C5 is a bypass capacitor at the UCC end. SB is a key to control the on/off state of the switch power supply. VD6 and C6 form a high-frequency rectifier filter at the output end of the feedback winding. The secondary high-frequency rectifier uses a Schottky diode of type MBR20100CT (20 A/100 V). This tube belongs to a common cathode pair tube, and the two cathodes are short-circuited internally. When using it, the two anodes need to be connected externally to make a parallel connection method. The output filter circuit is composed of C8, C11, L, C12 and C13. When designing the printed circuit board, the position of C9 and C10 can also be reserved in advance, so that the four capacitors C8 to C11 can be connected in parallel to form a filter capacitor, thereby reducing L0 to L0/4.

Figure 3 Circuit of 52W switching power supply composed of MC33374T/TV

The external error amplifier is composed of the adjustable precision shunt regulator TL431 B, and it also forms an optocoupler feedback circuit with the optocoupler MOC8103. The voltage regulation principle is that when the output voltage Uo fluctuates, the sampled voltage obtained after the voltage division by R5 and R6 is compared with the 2.5V reference voltage in TL431B to generate an external error voltage Ur', and then the feedback current IFB of the second foot is changed accordingly through the optocoupler, and the output duty cycle is adjusted to achieve the purpose of voltage regulation. C14 is used to filter out the common mode interference caused by the primary and secondary coupling capacitors of the high-frequency transformer. C7 is the compensation capacitor of the control loop.

2.2 BTS412B Intelligent Power Switch

The BTS412B intelligent power switch adopts TO-220 package, which has 5 leads:

UBB is the working power supply voltage terminal.

GND is the public ground.

IN is the control signal input terminal.

ST is the status output terminal.

OUT is the power output terminal.

The chip mainly includes logic circuit, voltage detection circuit, rectifier, charge pump, power MOSFET. In addition, there are protection circuits to prevent electrostatic discharge (ESD), overvoltage protection, overcurrent protection, load open circuit and short circuit protection circuits, protection circuits for inductive loads, and circuits to protect the gate of power MOSFET.

The main technical parameters of BTS412B are UBB>50V, continuous output load current IL=1.4A, maximum peak current ILIMIT=25A, and on-resistance RON=0.25Ω.

Using two BTS412B as high-side switches and two BUZ71L 50V, 14A, 40W N-channel field effect transistors as low-side switches, an H-bridge bidirectional DC motor drive circuit as shown in Figure 4 can be constructed. The on-resistance of BUZ71L is only 0.1Ω. When a fault occurs, the status signal output from the ST terminal drives the LED to light through the transistor JE9013 as an alarm indication.

Figure 4 H-bridge bidirectional DC motor drive circuit

3 Principle and Application of Intelligent Power Module

The IPM series products developed by Mitsubishi Electric Corporation of Japan belong to the third generation of intelligent power modules. It uses the third generation IGBT to replace the traditional power MOSFET and bipolar Darlington tube, and is equipped with a fully functional control and protection circuit to form an ideal high-frequency soft switching module. This type of module is particularly suitable for variable voltage and variable frequency (VVVF) inverters with sinusoidal wave output.

The internal block diagram of the IPM series is shown in Figure 5. The module mainly includes undervoltage protection circuit, IGBT driving circuit, overcurrent protection circuit, short circuit protection circuit, temperature sensor and overheat protection circuit, gate circuit and IGBT. The schematic diagram of the general VVVF inverter composed of this series of products with a 16-bit single-chip microcomputer is shown in Figure 6.

Figure 5 Internal block diagram of IPM series products

Figure 6 Schematic diagram of a general VVVF inverter