August 20, 2007

IPM for Controlling Three-Phase Motor Inverters for Air Conditioners and Other Home Appliances
SCM1100M Series
= Allows to configure the inverter main circuit with fewer discrete parts thanks to its diverse functions =

Sanken Electric Co., Ltd. has developed and started mass production of SCM1100M Series (withstand voltage: 600 V, output current: 5 to 15 A, 6 types) IPM in July optimal for 3-phase motor control inverters of white home appliances such as air conditioners, refrigerators, and washing machines, which gradually shift to inverter types. The production was started with 30k units/month, and then will be ramping up to 200k units/month in April, 2008. The sample price (exclusive of tax) is between 1,200 and 2,000 yen (details are given at the end of this news release).
   
1. Development background and product overview
  In Japan, the use of inverters in white home appliances such as air conditioners, etc. has advanced considerably, but on a worldwide basis the percentage of inverters products is still low, and from the viewpoint of energy conservation, the use of inverters is considered to increase rapidly from now on. Sanken Electric has developed the SCM1100M Series IPM with a new small DIP package optimal for 3-phase motor control inverters of the compressors of air conditioners and refrigerators, and the main motors of washing machines.

The SCM1100M series allows the main circuit of the inverter to be configured with fewer discrete parts by integrating the following elements into a single package: the elements such as six power devices (IGBTs), three pre-drive ICs, and six flywheel diodes necessary for configuring the main circuit of the inverter, and also a bootstrap circuit (three bootstrap diodes and three boot resistors) as a high side drive power supply.

The SCM1100M Series supports the 3-shunt method in which a shunt resistor is used in each phase. This enables low currents to be detected and highly accurate inverter control to be realized, thus contributing to low motor noise. In addition, each of the three phases contains an overcurrent protection circuit, thus enabling the area of the board used for the main circuit of the inverter to be reduced by about 15%, and its component count to be reduced by about 50% when the 3-shunt method is used.

The period of the alarm signal output during overcurrent protection can be set to a maximum of 10 ms. This enables the general-purpose I/O (input/output) port of the control microprocessor to be used and thus eliminates the need for a special interrupt port. In addition, the difference in the delay time between the high side and the low side drive circuits can be reduced, enabling the set dead time to be reduced to 1μs. Also, the IPM is provided with diverse functions such as a prevention function for simultaneous turn-on of high side/low side IGBTs, enabling a highly reliable inverter main circuit to be designed using only fewer discrete parts.

As a result of the development of the SCM1100M Series, the lineup of our 3-phase motor inverter control IPM is as shown below.

 
2. Features
 
(1)

Allows the main circuit of an inverter to be configured with only fewer discrete parts by employing a single package solution.
Six power elements (IGBTs), three pre-drive ICs and six flywheel diodes required for configuring the main circuit of the inverter, and also a bootstrap circuit (three 600 V/1 A bootstrap diodes and three 22Ω boot resistors) as a high side drive power supply are included in a single small DIP package (dimensions of resin part: 47×19×4.4 mm), enabling the main circuit of the inverter to be configured with fewer discrete parts.

(2) Supports 3-shunt method, and contains an overcurrent protection circuit in each phase
  • • In contrast to the 1-shunt method in which 3-phase current detection is performed using a 1-shunt resistor, this IPM supports the 3-shunt method in which a shunt resistor is used in each phase. When the 3-shunt method is used, lower currents can be detected and highly accurate inverter control can be realized, thus contributing to low motor noise. Also, because 3-shunt resistors detect the rotational position of the motor, there is no need for a rotation position sensor as in the case of the 1-shunt method.
  • • Because an overcurrent protection circuit is incorporated in each of the three phases, there is no need for an external circuit for overcurrent protection when the 3-shunt method is used.
(3) Allows the period of the alarm signal output during overcurrent protection to be set to a maximum of 10 ms.
The period of the alarm signal output to the control microprocessor during overcurrent protection can be set to a maximum of 10 ms. This enables the general-purpose I/O port of the control microprocessor to be used and thus eliminates the need for a special interrupt port.
(4)  Half bridge configuration of a drive circuit
  • • Because the drive circuit is of a half bridge configuration, the gates of not only the low side IGBT but also the high side IGBT as well can be turned off during an overcurrent or at the undervoltage of the control power supply, thus permitting more secure shutdown.
  • • Also, the difference in delay time between the high side and the low side drive circuits can be reduced, thus enabling the setting of the dead time to be reduced to 1μs (between 1/5 and 1/10 of that of the conventional IPM).
(5) Prevention function for simultaneous turn-on of high side/low side IGBTs
Employing a prevention function for simultaneous turn-on of high side/low side IGBTs prevents the high side/low side IGBTs from short-circuiting even when a microprocessor runaway occurs or when noise superposition occurs, thus preventing a malfunction or destruction of the main circuit of the inverter.
(6) Possible to shut down (all elements OFF) by an external signal.
It is possible to shut down the IPM by turning off the gates of the high side and low side IGBTs by means of an external alarm signal (overheating, etc.).
(7) Built-in soft shutdown function
By employing a soft shutdown function that shuts off the gate more slowly than the normal shut-off operation when an overcurrent occurs, IC is prevented from being destroyed by back EMF that is generated by the sudden shut-off.
(8) Built-in undervoltage protection circuit for control power supply voltage (self restoration)
(9) Outputs a fail signal when each protection circuit operates.
  • • When the undervoltage protection circuit for control power supply voltage operates (low side only)
  • • When the overcurrent protection circuit operates
  • • When the prevention function of simultaneous turn-on operates
(10) Adjustable overcurrent protection retaining time (Needs external capacitors)
(11) Lineup for high speed (16 kHz to 20 kHz) and low speed (3 kHz to 5 kHz) applications to comply with the drive frequency on both 10A and 15A types
   
3. Lineup
 
Part Number Withstand voltage Current Vsat(Speed) Sample price
SCM1103M 600V 5A 1.6V typ (-) 1,200 yen
SCM1104M 600V 8A 1.6V typ (-) 1,500 yen
SCM1101M 600V 10A 1.6V typ (Low) 1,800 yen
SCM1106M 600V 10A 2.2V typ (High) 1,800 yen
SCM1105MF 600V 15A 1.6V typ (Low) 2,000 yen
SCM1110MF 600V 15A 2.2V typ (High) 2,000 yen
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