HL601A Dual-Level Protector Thick Film Integrated Circuit and Its Application

The power electronic operation device is the core of power electronic technology. The stability and reliability of a device after it is put into operation are closely related to whether its protection performance is perfect and responsive. Usually, the protection set for power electronic devices includes: overvoltage, overcurrent, direct connection, short circuit, lack of phase and many other types. The protection circuit uses sensors to detect the operating parameters of the device and compares them with the threshold value set by the design. When the threshold value is exceeded, the corresponding protection is performed. The commonly used method is to use a comparator and a potentiometer to set the threshold. For mass-produced power electronic devices, this debugging method has a large workload, and factors such as whether the contact of the potentiometer slider is reliable and the dispersion of parameters will affect the reliability of the equipment. The dual-level protector thick film integrated circuit HL601A produced by Shaanxi High-Tech Power Electronics Co., Ltd. can make up for the above shortcomings. It uses integrated circuit packaging and the flip threshold is fixed, which brings great convenience to the debugging and maintenance of power electronic complete sets.

2 HL601A Introduction

HL601A can realize dual-level protection of overcurrent, overvoltage, overheating and other signals. It has set a precedent for multi-level protectors and has the characteristics of accurate action threshold, rapid action and high reliability. It has two-level flip levels. When the first flip level is reached (120% of the rated value), an alarm signal is given, and it can automatically reset after the overload signal disappears. This level can remind the duty personnel to pay attention, so that the duty personnel and the control computer can take measures to reduce the given value. When the second flip level is reached (160%), the circuit automatically flips and maintains and memorizes the flip state, so that the protected device is automatically blocked. This protection circuit is suitable for protection in power electronic devices with thyristors, GTRs, IGBTs, power MOSFETs, GTOs, etc. as main power devices.

2.1 Pinout, pin names, functions and usage

HL601A is a thick film integrated circuit with 15 pins in single in-line package. The pin arrangement is shown in Figure 1. The name, function and usage of each pin are listed in Table 1. The overall dimensions are length × width × thickness = 40mm × 28mm × 6mm.

Figure 1 HL601A appearance and pin arrangement

Table 1 HL601A pin description

2.2 Brief description of internal structure and working principle

The internal structure and working principle of HL601A are shown in Figure 2. As can be seen from the figure, its internal structure consists of three parts: absolute value circuit, dual-level comparator, and protection circuit. Its working principle is: the sample value of the protected signal from the user circuit (can be of any polarity) is converted into a positive signal through the absolute value circuit. When it is greater than the first-level protection threshold, the first-level protection is activated, and the output end (pin 10) is converted from a high level (greater than 9V) to a low level (less than 1V). Through the external circuit, the on-duty personnel or the main control computer are reminded to take control measures, usually by reducing the given value of the protected signal. If the value of the controlled quantity decreases and is lower than the first-level action threshold after taking measures, the system returns to normal; if the detection value of the controlled quantity continues to increase and reaches the second-level protection threshold, the second-level comparator is activated, and the action state is memorized by the holding circuit, so that the operator can check the cause of the fault and take timely treatment measures.

Figure 2 Internal structure and working principle diagram of HL601A

2.3 Main electrical parameters and limitations

(1) Power supply voltage: ±15V±10%;

(2) Power supply current: ≤10mA;

(3) Protection action threshold voltage: first level (6±0.5) V, second level (8±0.5) V;

(4) Protection output voltage: first level high level>9V, low level<1V; second level high level>12V, low level<1V;

(5) Minimum action delay time of the second level protection: <1μs;

(6) The second level protection delay time can be calculated as follows: td = 3.6 × 10-3C + 0.6 (μs);

(7) Maximum load capacity: high-level source current ≤10mA, low-level sink current ≤10mA.

3 Application Technology

The excellent performance of HL601A determines that it can be conveniently used as a protection element in various power electronic devices.

3.1 Typical application waveform

The typical working waveform of HL601A is shown in Figure 3, where Figure 3 (a) is the input waveform, Figure 3 (b) is the voltage waveform of the first-stage protection output terminal, and Figure 3 (c) is the voltage waveform of the second-stage output terminal.

Figure 3 Output waveform after HL601A protection

3.2 Typical application wiring

Figure 4 shows the typical application wiring diagram of HL601A. Figure 5 shows the principle diagram of HL601A used for overvoltage protection in a three-phase variable frequency speed regulation system. In order to ensure isolation, a Hall voltage sensor (HLV) is used to detect DC voltage as the protection input of HL601A. The first-level protection output of HL601A is used to block pulses, and the second-level protection output is used to disconnect the main circuit for centralized protection.

(a) Input waveform (b) First-level flip level waveform (c) Second-level flip level waveform

Figure 4 Typical application wiring diagram of HL601A

Figure 5 Schematic diagram of HL601A for three-phase SPWM IGBT variable frequency speed regulation system

4 Conclusion

HL601A can be used for two-level protection of overcurrent, overvoltage, direct-through, short circuit, overheating and other faults in power electronic devices. Because it is an integrated circuit package, it has strong environmental adaptability, few peripheral components, is easy to use, has high reliability and strong anti-interference ability, its application prospects will be very broad.