Dead-Time Compensator

Overcome dead-time effect by modifying reference voltages

Since R2024a

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Libraries:
Motor Control Blockset / Signal Management

Description

The Dead-Time Compensator block compensates for the inverter dead-time. Use this block to compensate for the dead-time effect of a three-phase inverter.

Three-phase inverters used in motor drive applications are nonlinear in nature. Dead time in an inverter (that is added to avoid short circuit in the inverter legs) contributes significantly to this nonlinearity. Even though dead time ensures safe operation of the inverter, it can adversely affect the performance of the inverter. This causes the inverter output voltage waveform to deviate from its originally expected form.

The block accepts three-phase reference voltages, measured motor currents, PWM frequency, and inverter DC voltage as inputs. It provides a three-phase voltage output that compensates for the dead-time effect of the inverter. The compensation helps reduce the noise or ripple in motor torque or currents, and therefore, improves the motor drive performance.

The following image shows the block position inside a motor control algorithm.

Ports

Input

V_abc — Reference voltages
scalar

Three-phase reference voltages (in volts).

Data Types: single | double | fixed point

I_ab — Measured motor currents
scalar

Measured values of phase-a and phase-b currents of the motor (in amperes).

Data Types: single | double | fixed point

f_PWM — PWM frequency
scalar

Frequency (in hertz) of the carrier wave used to perform pulse-width modulation.

Data Types: single | double | fixed point

V_dc — Inverter DC voltage
scalar

DC voltage supply of the inverter (in volts).

Data Types: single | double | fixed point

Enable — Signal to enable block outputs
scalar

Signal that enables block outputs:

1 — Enable compensation (block outputs compensated voltages).
0 — Disable compensation (block outputs input voltages).

Dependencies

To enable this port, select the Show enable port parameter.

Data Types: single | double | fixed point

Output

V_abc ± Δ — Compensated three-phase voltages
scalar

Motor three-phase voltages (in volts) that is compensated for inverter dead-time effect.

Data Types: single | double | fixed point

Parameters

Dead time (s) — Inverter switching dead-time
`1e-6` (default) | scalar

Dead time in Inverter switches (in seconds).

Enable hysteresis for currents near zero-crossing — Option to enable hysteresis algorithm for currents near zero-crossing
`off` (default) | `on`

Select this parameter to enable hysteresis algorithm near the region of zero-crossing of the input motor phase currents.

The block detects motor current polarity to determine voltage compensation. Using a hysteresis band near zero-crossing of currents aids in better detection of current polarity when motor currents are noisy.

Current hysteresis band (A) — Current hysteresis band around zero-crossing
`0.1` (default) | scalar

Hysteresis band, h, for the current controller. The switch-on point is h and the switch-off point is -h.

Dependencies

To enable this parameter, select Enable hysteresis for currents near zero-crossing.

Motor current input — Type of motor current input
`Two currents (Ia,Ib)` (default) | `Three currents (Ia,Ib,Ic)`

Number of motor current inputs. You can select one of the following options:

Two currents (Ia,Ib)
Three currents (Ia,Ib,Ic)

Inputs

Show enable port — Option to enable input port
off (default) | `on`

Select this parameter to show the input port Enable.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

HDL Code Generation
Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic.

HDL Architecture

This block has one default HDL architecture.

HDL Block Properties


ConstrainedOutputPipeline	Number of registers to place at the outputs by moving existing delays within your design. Distributed pipelining does not redistribute these registers. The default is `0`. For more details, see ConstrainedOutputPipeline (HDL Coder).
InputPipeline	Number of input pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is `0`. For more details, see InputPipeline (HDL Coder).
OutputPipeline	Number of output pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is `0`. For more details, see OutputPipeline (HDL Coder).

Restrictions

The block does not support HDL code generation when you select the Enable hysteresis for currents near zero-crossing parameter.

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.

Version History

Introduced in R2024a

See Also

PWM Reference Generator