Three Phase NPC Inverter

A block diagram and input parameters for this inverter-rectifier block are given in Table 1.

Table 1. Three-phase three-level NPC inverter block in the Schematic Editor core library

component	component dialog window	component parameters
Three phase three level NPC inverter		General Control (Digital inputs, Internal modulator, Internal modulator separated, Model) Phase A S1 (1..32) Phase A S2 (1..32) Phase A S3 (1..32) Phase A S4 (1..32) Phase B S1 (1..32) Phase B S2 (1..32) Phase B S3 (1..32) Phase B S4 (1..32) Phase C S1 (1..32) Phase C S2 (1..32) Phase C S3 (1..32) Phase C S4 (1..32) gate_logic (active high, active low) PWM Switching enabled (enables usage of external digital signal to enable the switching) Sen (digital input selection for PWM enable) DTV detection Weight = 3

A schematic block diagram of the inverter switching block is given in Figure 1 with corresponding switch arrangement and naming.

Digital inputs, when selected as the Control parameter, enables you to assign gate drive inputs to any of the digital input pins (from 1 to 32). For example, if Phase A S1 is assigned to 1, the digital input pin 1 will be routed to the Phase A S1 switch gate drive. In addition, the gate_logic parameter selects either active high (i.e. high-level input voltage VIH turns on the switch), or active low (i.e. low-level input voltage VIL turns on the switch) gate drive logic, depending on your external controller design.

Internal modulator, when selected as the Control parameter, enables you to use internal PWM modulator for driving the converter's switches instead of digital input pins. In this configuration, four additional component inputs will be present. En input is used to enable/disable PWM modulator control, while InA, InB, and InC are used as referent signal inputs for the internal PWM modulator. Overall, 6 PWM channels are used to drive the three level three phase NPC converter, 2 per phase. Reference signals for 2 modulators that control the switches of a single phase leg, are created from a single reference input. A block diagram of one phase leg controlled by PWM modulators is shown in Figure 2. The input reference signal is in range from -1.0 to 1.0. This signal is split into two reference signals for two modulators, and set to a range from 0.0 to 1.0.

Internal modulator separated, when selected as the Control parameter, enables you to use the internal PWM modulator for driving the converter's switches instead of digital input pins. Additional component inputs and the number of created internal PWM modulators are the same as described in the Internal modulator section. Reference signals for 2 modulators that control the switches of a single phase leg are provided to the component through a vectorized input (i.e. the value on index 0 controls the PWM_A_Ch1 modulator, while the value on index 1 controls the PWM_A_Ch2 modulator). A block diagram of one phase leg separately controlled by PWM modulators is shown in Figure 3. The input reference signal range is adjustable from the component properties.

Model, when selected as the Control parameter, enables you to set the IGBT gate drive signals directly from the signal processing model. The input pin gates appears on the component and requires a vector input of twelve gate drive signals in the following order: [Phase A S1, Phase A S2,…, Phase B S1, Phase B S2,…, Phase C S1, Phase C S2,…]. When controlled from the model, the logic is always set to active high.

PWM Switching enabled, when selected, enables use of an external PWM enabling digital signal.

DTV detection, when selected, causes DTV detection to be signalized during simulation runtime.

Timing

When Enable delays is enabled, the turn on and turn off delay of the IGBTs will be included in the simulation. More information about this feature can be found in the dedicated switching delay section.

Losses calculation

When the Losses calculation property is enabled, the component will calculate switching and conduction power losses for all switching elements (IGBTs and Diodes or MOSFETs). For MOSFET switching elements, the diode characteristic represents the internal MOSFET body diode. Switching power losses are calculated as a function of current, voltage, and temperature using 3D lookup tables. Also, 2D input for losses is supported. When a 2D losses table is inserted, it assumes only current (I) and temperature dependence. From version 2020.3, conduction power losses can be defined as a function of current and temperature using Vt and Vd lookup tables (LUTs) (the previous option of using Vce, Rce, Vd, and Rd properties are removed). These LUTs can be 1D or 2D tables. If the LUT is a 1D table, forward voltage drop depends only on current, but if LUT is a 2D table, forward voltage drop dependence on the junction temperature is also considered. In the MOSFET case under reverse current conduction, a current sharing calculation between the MOSFET channel and the internal body diode is performed. Import options and an explanation how to correctly fill all necessary power losses parameters is described in the import power losses section.

Temperatures calculation

Digital Alias

If a converter is controlled by digital inputs, an alias for every digital input used by the converter will be created. Digital input aliases will be available under the Digital inputs list alongside existing Digital input signals. The alias will be shown as Converter_name.Switch_name, where Converter_name is name of the converter component and Switch_name is name of the controllable switch in the converter.