- 您现在的位置：买卖IC网 > Sheet目录1211 > DM300021 (Microchip Technology)MODULE PWR DSPICDEM MC1H HV 3PHS
Set Up and Operation
Given the high side and low side switches of the inverter are connected in series
across the DC bus (see Figure 2.1), both switches should never be turned on at the
same time. Turning both switches on effectively places a short circuit across the DC
bus and is called “Shoot Through”. Shoot Through should be avoided at all costs. In
order to avoid Shoot Through, an appropriate time delay must be inserted between
the turn off command to one device and the turn on command to the other device of
the same inverter leg. This time is called the “Dead Time”. The required Dead Time
depends on the switching speeds of the power devices and the timing delays due to
the optocouplers and the gate drive circuits.
Note:
No hardware Dead Time is included in the design as it is included as a
feature of the Motor Control PWM Module of the dsPIC device. A minimum
Dead Time of 2 μ s should be used. This applies to both turn on and turn off
of both devices.
Writing to the appropriate registers in the dsPIC device (DTCON1 and DTCON2) sets
the dead time. Refer to the dsPIC30F Family Reference Manual (DS70046) for details.
Although not necessary for correct operation of the system, it is common practice to
eliminate very narrow firing commands. This is because they will have negligible effect
on the output waveform but incur additional switching loss. It is suggested that a duty
cycle that gives transistor on or off times of less than 100 ns be eliminated by rounding
the duty cycle up or down as appropriate. Note that pulses, which are narrower than
the dead time set in the Motor Control PWM Module, are automatically eliminated.
Note:
The user should verify that all PWM frequencies and dead time settings are
correct using an oscilloscope before connecting the control signals to the
power module.
In order to provide an economic design, so-called bootstrap power supplies are used
for the high side inverter switches (see Section 1.4.3.3 “Gate Drive” for details). As
the charging path for these is only made when the corresponding low side switch or
diode conducts, this places some minor restrictions on modulation. These are as
follows:
1. When the power module is first energized after a period of time where no
modulation has taken place, all low side switches should be turned on for 2-3 μ s.
This ensures the bootstrap supplies are “primed”. This can be simply done by
using the output override facility in the dsPIC Motor Control PWM module by
setting the correct bits in the OVDCON register. Care should be taken to ensure
a shoot through does not accidentally occur. The possibility of a shoot through
fault will be minimized if the dsPIC PWM module is operated in the
complementary Output mode (module default).
2. If the user is continuously modulating all the low side switches as part of their
PWM strategy, the “priming” step is not strictly necessary, as it will happen
automatically. There will however be a delay of variable duration before the high
side switches actually fire. The delay will depend on the particular operating
circumstances and whether it is acceptable or not will depend on the particular
application.
3. In extreme circumstances, it is possible that the high side bootstrap supply will
discharge while the system is running. This will not happen for typical sinusoidal
modulation schemes provided an inductive load (e.g., a motor) is connected. If a
bootstrap supply collapses, an under-voltage lockout will automatically occur to
protect the high side switch entering the linear region of operation. The high side
switch is turned off whatever the command. The lockout is automatically cleared
when the bootstrap supply is restored and the next turn-on edge occurs. If
necessary, the user should periodically apply a refresh pulse to the low side
switch in a similar manner to that described for priming above.
? 2003 Microchip Technology Inc.
DS70096A-page 11
发布紧急采购，3分钟左右您将得到回复。
相关PDF资料
DM300022
MODULE PWR DSPICDEM MC1L LV 3PHS
DM320002
BOARD EXPANSION PIC32 I/O
DM320003-2
KIT EVAL PIC32 USB II STARTER
DM320003
BOARD DEMO USB PIC32 OTG
DM320005
BOARD EXPANSION FOR PIC32 KIT
DM320011
BOARD AUDIO DEV FOR PIC32
DM330015
KIT STARTER MOTR CTRL DSPIC33E
DM330021
KIT DEMO DSPIC33 MCLV
相关代理商/技术参数
DM300021
制造商:Microchip Technology Inc 功能描述:MODULE dsPICDEM MC1H 3 PHASE
DM300022
功能描述:开发板和工具包 - PIC / DSPIC Low V Pwr Module RoHS:否 制造商:Microchip Technology 产品:Starter Kits 工具用于评估:chipKIT 核心:Uno32 接口类型: 工作电源电压:
DM300023
功能描述:开发板和工具包 - PIC / DSPIC dsPICDEM SMPS Buck Demo Brd RoHS:否 制造商:Microchip Technology 产品:Starter Kits 工具用于评估:chipKIT 核心:Uno32 接口类型: 工作电源电压:
DM300024
功能描述:开发板和工具包 - PIC / DSPIC dsPICDEM 1.1 GP RoHS:否 制造商:Microchip Technology 产品:Starter Kits 工具用于评估:chipKIT 核心:Uno32 接口类型: 工作电源电压:
DM300027
功能描述:开发板和工具包 - PIC / DSPIC 16-bit Starter Demo Board RoHS:否 制造商:Microchip Technology 产品:Starter Kits 工具用于评估:chipKIT 核心:Uno32 接口类型: 工作电源电压:
DM-3-000-K
制造商:PacTec 功能描述:Case, Plastic; ABS; Black; 11.46 in.; 3.38 in.; 10.4 in.; UL 94-HB Rated 制造商:PacTec 功能描述:ENCLOSURE, DESKTOP, PLASTIC, BLACK; Enclosure Type:Desktop; Enclosure Material:Plastic; Body Color:Black; External Height - Imperial:3.38"; External Height - Metric:86mm; External Width - Imperial:10.4"; External Width - Metric:264mm;RoHS Compliant: Yes
DM-300-C
制造商:Greenlee Textron Inc 功能描述:DMM 1000V RMS
DM-301
制造商:Labfacility Limited 功能描述:SENSOR PT100 THIN FILM 2X2.3MM CL B 制造商:LABFACILITY 功能描述:SENSOR, PT100, THIN FILM, 2X2.3MM, CL B 制造商:LABFACILITY 功能描述:TEMPERATURE RTD SENSOR, -70C to +500C, 100 OHM; Sensing Temperature Min:-70C; Sensing Temperature Max:+500C; Resistance:100ohm; Sensor Terminals:Through Hole; Temperature Sensing Range:-70C to +500C ;RoHS Compliant: Yes