Variable speed motor drive can improve the energy efficiency of machinery, but in order to reduce costs, improve market responsiveness and increase efficiency, but also in several aspects to improve the design of variable speed drive. Including IGBT critical linear current feedback and overcurrent protection features, these two functions are traditionally through the use of bulky, expensive and difficult to assemble the components to achieve. Latest HVIC (high voltage integrated circuit) technology makes the most of the necessary feedback, and protect the device can be fabricated on a substrate, so that you can in the broader markets and applications in order to achieve low cost and compact can be variable speed drive. Electrical and electronic sensing method
Converter-and motor phase current sensing on the current mode control is essential, this model requires a very high accuracy and linearity. This sensor is also important to the over-current protection, over current protection requirements for faster response. fake ebel 1911 for sale To meet these requirements, fake omega speedmaster watches plus the unique location of current signal sampling, requires complex circuit design and signal processing. In fact, the current signal can be connected with the following nodes were sampled: positive or negative DC bus, a single IGBT phase leg, or the motor phase lead, vacheron constantin replica watches as shown in Figure 1. No matter in which DC bus current signal sampling are all IGBT phase leg current vector. Figure 1 circuit sensing method IGBT phase leg in a single sample of the current look easy, but in fact it can not reduce the frequency of the carrier sample processing requirements. To date, the most simple, easy access to the current signal from the motor phase lead, the signal content is only the basic inverter motor current. An important factor to consider is that the small differential signal within a few millivolts, between the 600 ~ 1200V voltage changes. In addition, because the role of phase IGBT converter, common mode voltage to a maximum 10V/ns the dV / dt rate of the inter-DC to + DC changes. HVIC: bit quasi-Mobile (Level shifting) HVIC technology makes it possible to move digital standard, that is sensing a drift in the large common mode voltage on the small differential voltage, even when the fast transient. Therefore, fast and accurate current sensing in the motor phase lead can be achieved, which can reduce the hardware design and signal processing work. Specific implementation method is a low-side grounded CMOS circuit and a high-side floating CMOS production together, through the cheap blancpain leman for sale N or P channel LDMOS isolated region. The role of LDMOS is a quasi-mobile, aimed at the low side and high side of the circuit across the high voltage grid to pass between the control signal. Digital circuits are not up to standard mobile 50V/ns fast transient effects, also not from the typical 10V/ns IGBT converter noise. HVIC linear-phase current sensing Electrical current is through the use of an external shunt transistor sensing, HVIC can be a small differential voltage (�� 250mV) into the circuit through a precision time interval, this precision circuit function can display the ripple removal small group delay. Time interval is fast transients, replica watches wholesale the output will be taken. This current measurement can be obtained with the corresponding analog output voltage for comparison with the external reference voltage, the maximum sampling rate of 40kSPS. For frequencies up to 20kHz asymmetrical PWM modulation is concerned, the sampling rate of the rich more than the rich. 20kHz maximum delay time of less than 7.5s, to be used for current sensing IGBT protection signal is plenty quick. Figure 2 is a current sensing circuit. Figure 2 HVIC applications Transfer Phase current sensing circuit IGBT protection IGBT over-current condition is divided basically three modes: line short circuit, ground fault and the switch breakdown. In considering the current protection program must be assessed on two important factors: the first is to provide over-current protection mode and how to shut down, another one is the control architecture. Control structure greatly influence the way over-current protection and implementation. IGBT protection circuit is cheap cuervo y sobrinos habana watches usually in the hardware implementation, according to the conditions of over-current protection mode, the specific circuit and over-the type of sensing device will be different. The reason is that, in each over-current mode and the current flow path is not the same. Figure 3a to 3c shows the pattern for each over-current conditions typical of current flow in the main power circuit and the path of current flow depends on the mode over-current. Breakdown between the switch and line short-circuit current under short circuit conditions always flow to DC bus capacitors. However, the ground fault current is usually from the AC line input, through the positive DC bus and high-side IGBT, the flow of the access site failure occurs. No current flows through the bus capacitor. Figure 3 IGBT over-current protection in three ways Protection circuit also depends on the control architecture. For the breakdown and line switch for short circuit over current, conventional, non-HVIC solutions, over-current detection means that across the shunt transistor into a Hall sensor or a linear light separate devices, and the negative DC bus. If you need ground fault protection, the AC line input or DC bus is to put another Hall-effect sensor leakage. By using fast comparator circuit protection can be achieved. If the Hall sensor in the motor phase output, because the line between the short-circuit conditions, current flow is negative there, so each Hall sensor requires two comparators. Not trained to protect the IGBT current damage, we must consider the total turn-off delay of transmission. Driving in the door with optical isolation devices, and optical isolation devices and Hall sensors generally greater than the delay time 2 s. Therefore, no matter how the protection circuit design, this delay must be added to the delay circuit to go, to meet the requirements of IGBT short circuit duration. HVIC and not an alternative to using discrete devices, in the second optical gate drive down the high-end Side of a IGBT saturation (de-saturation) circuit. Thus, when the device is fully open state, can detect the collector and emitter voltage of accumulation, if this voltage exceeds limit will turn off the gate signal. Discrete program requirements must be compared with a reference voltage device, but also a high-voltage diodes, transistors and capacitors.
IGBT protection structure which can also increase the circuit, the detection of soft overcurrent shutdown SSD (SoftShutDown). SSD avoid circuit parasitic inductance in the IGBT collector and emitter peak voltage between the generated, thereby, guarantee short We are high quality suppliers, our products such as China small notebook laptop , touch panel laptop for oversee buyer. To know more, please visits touch screen umpc.