p>

Abstract: This paper introduces the basic operating characteristics of the IPM and the IPM drive and protection circuitry commonly used design methods, and gives a driver and protection circuit design examples.
  Keywords: IGBT (insulated gate bipolar transistor) IPM (intelligent power module) PIC (Power IC)
  Intelligent Power Module (IPM) is the abbreviation of Intelligent Power Module is an advanced power switching device, with a GTR (power transistors) high current density, low saturation voltage and the advantages of high pressure, and MOSFET (field effect transistors) high input impedance,

 

High switching frequency and low drive power advantages. And IPM integrates a logic, control, detection and protection circuit, easy to use, not only reduces the system size and development time, but also greatly enhance the reliability of the system to adapt to the current direction of development of power devices - Modular , composite and power integrated circuits (PIC), in power electronics fields have been increasingly widely used. Mitsubishi PM100DSA120 this paper an example, the basic characteristics of IPM and IPM focuses on the drive and protection circuit design.
  1 IPM's basic operating characteristics
  1.1 IPM structure
  IPM by the high-speed, low power IGBT chips and the optimal gate drive and protection circuits shown in Figure 1. Which, IGBT and MOSFET are complex GTR, driven by the MOSFET GTR, IGBT which has the advantages of both.
  IPM according to the different internal power circuit configuration can be divided into four categories: H-type (internal package a IGBT), D-type (internal package of two IGBT), C-type (internal package of six IGBT) and R-type (internal package of seven IGBT). IPM uses low-power epoxy multi-layer insulation system, the power of IPM use of ceramic insulation.
  1.2 IPM mechanism of internal functions
  IPM functional block diagram shown in Figure 2. IPM internal drive and protection circuits to be isolated user interface circuit design.
  IPM drive and protection circuit built-in hardware to make the system simple, reliable, shortens the development time, and improved self-protection under fault. Compared with the normal IGBT modules, IPM in terms of system performance and reliability have further improved.

Can control voltage protection circuit undervoltage protection, thermal protection, over current and short circuit protection. IPM module if there is a protection circuit operation, IGBT gate drive unit will shut off gate current and output a fault signal (FO). Various protection functions, as follows:
  (1) control voltage under-voltage protection (UV): IPM using a single +15 V power supply, if the supply voltage falls below 12.5V, and longer than toff = 10ms, occurred undervoltage protection, blocking gate drive circuit, the output fault signal.
  (2) Over temperature protection (OT): near the IGBT chips installed on the insulation substrate, a temperature sensor, temperature sensor to detect when the IPM the substrate temperature exceeds the temperature of its value, the occurrence of over-temperature protection, blocking gate drive circuit, output fault signal.
  (3) over current (OC): If the current flowing through the IGBT exceeds the over flow for the current and longer than toff, the occurrence of over-current protection, blocking gate drive circuit, the output fault signal. To avoid excessive di / dt, most of the IPM model using two off, over current and short circuit protection operation can be found in Figure 3. Which, VG to internal gate drive voltage, ISC is short-circuit current value, IOC current value for the over-current, IC the collector current, IFO for the fault output current.

 

(4) short-circuit protection (SC): If the load short circuit or control system failure cause a short circuit, current flows through the IGBT exceeds short-circuit trip current, the immediate short-circuit protection, blocking gate drive circuit, the output fault signal. As with the over-current protection, so as to avoid excessive di / dt, most of the IPM with two shutdown mode. To reduce the current over-current protection and fault detection response time between action, IPM internal use real-time current control circuit (RTC), the response time of less than 100ns, which effectively inhibited the peak current and power to improve the protective effect.
  IPM occurs when UV, OC, OT, SC in any of the fault, the fault output signal duration tFO as 1.8ms (SC continued to take longer), this time, IPM will block the gate drive shutdown IPM; failure after the end of the output signal duration, IPM internal automatic reset, gate drive channel opening.
  It can be seen, the device's own fault signals generated by non-retention, if tFO after the source of the problem is still not ruled out, IPM will repeat the process of automatic protection, repeated movements. Over-current, short circuit, overheat protection action are very poor health, repeated movements should be avoided, so the internal protection circuit IPM alone can not fully achieve self-protection devices. To make the system truly safe, reliable operation, the external protection circuit need assistance.
  2 IPM drive circuit
  Drive circuit is the main circuit and control circuit IPM interface between the good circuit design of the device driver efficiency, reliability and security are important.

2.1 IGBT driving circuit design of discrete
  IGBT MOSFET driver design that is driven by design, the design should note the following: ? IGBT gate voltage is generally about ± 20V, so the gate drive circuit to give added output voltage protection, the usual practice is to gate shunt regulator diode or resistor. The former defect is to increase the equivalent input capacitance Cin, thus affecting the switching speed, the latter defect is to reduce the input impedance, increasing the drive current should be used as necessary trade-offs. Figure 4 shows the schematic diagram IGBT gate protection, which, RG, DZ, Cin are the equivalent gate resistance, the regulator and the equivalent input capacitance. ? Although the IGBT drive power required is small, but because there MOSFET input capacitor Cin, the process needs to switch capacitor charge and discharge, so the driver circuit output current should be large enough that the designer is often overlooked. Assume that opening drive, the linear rise time tr to MOSFET input capacitance Cin of the charge, the drive current Igt = CinUgs / tr, where desirable tr = 2.2RCin, R to enter the loop resistance. ? to be reliable off IGBT, to prevent the engine lived phenomenon, plus give a negative gate bias, it is best to use dual power supply.
  2.2 IGBT driver circuit integrated
  Discrete IGBT drive circuit of discrete components and more complex, more complete protection even more complex discrete circuitry, reliability and performance than the poor, so in most cases, the practical application of integrated drive circuit. Japan's Fuji EXB series of integrated circuits, the French Thomson company UA4002 integrated circuits and other applications are very extensive.
  2.3 IPM driving circuit
  An example is introduced to PM100DSA120. PM100DSA120 is a D-type IPM, internal package of two IGBT, work in 1200V/100A less power device switching frequency up to 20kHz. IPM built the driver circuit, compared with the IGBT drive circuit design, the external drive circuit design more convenient, as long as you can provide 15V DC voltage.
  But the IPM on the drive circuit output voltage requirements are very strict? Smoked specific as follows: ? drive voltage range of 15V ± 10%? Smoked voltage is below 13.5V voltage protection occurs, the voltage higher than 16.5V would damage the internal parts. ? voltage isolated from each other in order to avoid ground noise. ? drive power isolation voltage is at least the value of IPM reverse voltage between poles twice (2Vces). ? can see the device drive current 20kHz given drive current requirements, according to the actual switching frequency to be amended. ? drive circuit output filter capacitor can not be too large, this is because when more than 100pF parasitic capacitance, the noise may trigger the internal drive circuitry error.
  Here are a 15V power supply high-quality programs available. The program driver circuit is not only compact, simple, and anti-interference ability, typical circuit shown in Figure 5.

 

Figure 5 IPM drive circuit and external isolation circuit Click to enlarge
  Diagram of the device type and parameters have been marked, which, M57140-01 and its IPM Mitsubishi M57120L is a series of products specifically configured voltage transformation module. Increase the input in M57120L way 113V ~ 400V DC output voltage can be all the way to 20V DC voltage, in the M57140-01 all the way to increase the input DC 18V ~ 22V voltage output can be isolated 15V 4 voltage, easy for the IPM power; HCPL4504 and high-speed optocoupler PC817, electrical isolation play the role of IPM and the external circuit, IPM control signal Cin and the fault output signal FO transmission through the optocoupler.
  In the application of less demanding situations can also be used in the rectifier circuit by the 20V DC voltage to replace M57120 M57140-01 as the input rectifier circuit can also be used directly from the 15V DC power supply voltage is PM100DSA120, but the effect is not as good as Figure 5 shown in the program, practical application proves this point.
  3 IPM Protection Circuit
  Comprehensive IPM system protection can not just rely on the internal protection mechanisms, need assistance outside of the protection circuit, which can be achieved by the hardware, the software can also be achieved.
  3.1 IPM hardware protection circuit
  Way to achieve a lot, to cite two examples.
  Pre-program a PWM interface circuit 74HC245, 74HC244 other side of the tri-state with control transceiver, shown in Figure 6. IPM control signal input through the 74HC245, 74HC245, after the output sent to IPM interface circuit; various IPM fault output signal obtained by the opto isolated output high FO, into or door, or gate output through the RC low-pass filter converters, into the 74HC245 enable terminal OE. IPM work, or gate output is low, 74HC245 strobe; IPM fault alarm, or gate output is high, 74HC245 all outputs into high impedance, blocking all IPM control signal, shutdown IPM, to achieve the protection.

  Program two-level PWM interface circuit with the control side of the front coupler, such as the 6N137. Second, the principle of the program with a similar program, but because the high level to enable control of optical coupling 6N137, or a door or door replaced, and its output through the RC low-pass filter, the light coupled into a controllable light 6N137 coupling Enable VE, but in the same block IPM IPM failure alarm control signal path to achieve the protection.
  Note that, in order to shorten the response time of failure, RC low-pass filter time constant should be small. Two extended response time of the optocoupler should be used in high-speed optocoupler.
  These two programs are blocked by IPM IPM fault output signal to control signal path, which make up the IPM's own lack of protection, effective protection of the device.
  3.2 IPM software protection circuit
  The basic idea is to software: IPM fault alarm, fault output signal to the controller processing, the processor is confirmed, the software shut down IPM using the control signal, so as to achieve conservation.
  In summary, no additional hardware, software protection, user-friendly, but may be subject to software design and computer failures; hardware protection is responsive, reliable work. Practical application software and hardware combination of protection to better improve the system reliability.

 

4 IPM drive and protection circuit design examples
  I switched reluctance motor control in the DSP project, use IPM as the main power converter switching devices, the controller uses a Texas company TMS320F240 digital signal processor, power driver circuit input (ie, IPM control signal) from TMS320F240 containing the full compare unit corresponding to the PWM1 ~ PWM4 generated.
  TMS320F240 the event manager module includes a power drive protection pin (PDPINT), when the pin is pulled low, all of the event manager hardware output pins are set to high impedance, so PDPINT can be used to monitor program provides motor abnormalities, and to achieve fault protection.
  Drive circuit shown in Figure 4. Protection circuits used software protection, the four IPM power device failure signal through the opto isolated, sent to the NOR gate CD4078, the output low-pass RC filter connected to the DSP's PDPINT pin. When the IPM fault alarm, PDPINT pin is pulled low, DSP internal timer to stop work immediately, all PWM outputs high-impedance state, blocking IPM control signal; also generate an interrupt signal to notify the DSP has failed to happen, in the the interrupt service routine to determine what kind of failure occurs, and displays the fault code.
  Figure 7 shows the load current of 8A, SRM running IPM's rated speed 15V drive voltage waveform.
  Actual operating results show, IPM power supply stability, IPM works well to protect the circuit can reliably protect the power devices.
  IPM work very demanding on the power supply, the paper describes the driving circuit can work well to meet the requirements of IPM; IPM protection circuit does not have its own preservation, protection must improve the system, auxiliary external protection circuit; use of IPM's own fault IPM output control signal input block can be easily and effectively protect the device.