Interlock and Deadtime module (2L)

The interlock and dead time IP-Core prevents the TOP and BOT gate signal being high at the same time and introduces a variable dead time between high states. The dead time has a range of \(0\,\mu s\) to \(10.23\,\mu s\) with \(10\,ns\) resolution if the IP-Core is driven by a \(100\,MHz\) clock. If the requested dead time is not an integer multiple of the inverse IP-Core clock frequency (e.g., \(10\,ns\)) the driver rounds up using ceil.

Warning

It is possible to set the dead time to \(0\,\mu s\)! Check if your power electronics can handle this!

The module features three legs, i.e., is intended for two level voltage inverters. IP-Core is generated using Simulink HDL-Coder version 2021a.

Software Driver

The software driver for the module is located at ultrazohm_sw/vitis/export/Baremetal/IP_Cores/uz_interlockDeadtime2L. The driver interface is located in uz_interlockDeadtime2L.h and has four public methods:

• uz_interlockDeadtime2L_set_enable_output

• uz_interlockDeadtime2L_get_enable_output

• uz_interlockDeadtime2L_set_deadtime_us

• uz_interlockDeadtime2L_get_deadtime_us

Additionally, the static allocator has to be used for initialization and allocation of instances of the struct.

How-to use

An example initialization and usage is listed in the following.

Listing 175 Example initialization and enable output

#include "IP_Cores/uz_interlockDeadtime2L/uz_interlockDeadtime2L_staticAllocator.h"
int main(void){
uz_interlockDeadtime2L_handle deadtime_slotd1 = uz_interlockDeadtime2L_staticAllocator_slotD1();
uz_interlockDeadtime2L_set_enable_output(deadtime_slotd1, true);
}

In configure the configuration values in the static allocator function using the base address from xparameters.h.

Listing 176 Example configuration with deadtime of \(1\,us\) and no inverted bottom switch signals. Code snippet from uz_interlockDeadtime2L_staticAllocator_slotD1

static uz_interlockDeadtime2L interlock_slotD1 = {
    .base_address = XPAR_GATES_UZ_INTERLOCKDEADTIME_0_BASEADDR,
    .clock_frequency_MHz = 100,
    .deadtime_us = 1,
    .inverse_bottom_switch = false
};

To change the dead time of the module at runtime disable the output and set the dead time:

Listing 177 Changing the dead time at runtime

uz_interlockDeadtime2L_set_enable_output(deadtime_slotd1,false);
uz_interlockDeadtime2L_set_deadtime_us(deadtime_slotd1,1.0f);
uz_interlockDeadtime2L_set_enable_output(deadtime_slotd1,true);

It is not possible to change other values of the module after initialization.

IP-Core Hardware

Fig. 321 Top view of the Module.

Fig. 321 shows the module. The module takes the gate signals of a three phase inverter S0..S5 as input and outputs them as S0_out..S5_out. The output is enabled if AXI_EnableOutput is true. The enable signal is routed to enableFB to be used by other IP-Cores in the PL. The Interlock prevents TOP and BOT (S0 & S1, S2 & S3, S4 & S5) of each signal to be true at the same time. The Deadtime adds a variable length delay to each rising edge of the input signal. The number of IP-Core clock cycles added is determined by AXI_DelayCycles. It is possible to inverse the signal of the bottom switch by setting AXI_InverseBotSwitch to true, see Inverse Bottom switch. New values for IP-Core are written by the Software Driver.

Interface

Table 102 Interfaces of interlock deadtime module

Port Name	Port Type	Data Type	Target Platform Interfaces
S0	Inport (TOP)	boolean	External Port
S1	Inport (BOT)	boolean	External Port
S2	Inport (TOP)	boolean	External Port
S3	Inport (BOT)	boolean	External Port
S4	Inport (TOP)	boolean	External Port
S5	Inport (BOT)	boolean	External Port
s0_out	Outport	boolean	External Port
s1_out	Outport	boolean	External Port
s2_out	Outport	boolean	External Port
s3_out	Outport	boolean	External Port
s4_out	Outport	boolean	External Port
s5_out	Outport	boolean	External Port
enableFB	Outport	boolean	External Port
axi_fb_InverseBotSwitch	Outport	boolean	0x100
axi_fb_DelayCycles	Outport	fi(0;10;0)	0x104
axi_fb_enable	Outport	boolean	0x108
axi_InverseBotSwitch	Inport	boolean	0x10C
axi_EnableOutput	Inport	boolean	0x110
axi_DelayCycles	Inport	fi(0;0;0)	0x114

Inverse Bottom switch

Fig. 322 Inverses the signal of the BOT switches (S1, S3, S5), if AXI_fb_InverseBotSwitch is true.

Interlock

Fig. 323 Interlock prevents the TOP/BOT to switch to true if BOT/TOP is already true.

Deadtime

Fig. 324 Deadtime module

The deadtime module adds a delay to every rising edge on the signals S0..S5. If TOP_IN/BOT_IN is true the 10 bit counter starts counting until the value of DelayCycles is reached. The switch changes to pass through input one, which in turn makes the AND switch to true. The true signal is held by the resettable delay block. As soon as TOP_IN/BOT_In switches to false the AND switches to false. The counter for the delay is reset after TOP_IN/BOT_IN switches from true to false.

Vivado Example

Fig. 325 Screenshot of IP-Core in Vivado.

The clock frequency for IPCORE_CLK and AXI4_Lite_ACLK is 100 MHz.

Table 103 Vivado block design interfaces of interlock deadtime module

Port Name	CLK	Usage
AXI4_Lite	100 MHz	Connecto to AXI_smartconnect
IPCORE_CLK	100 MHz	Connect to 100 MHz clock
IPCORE_RESETN	100 MHz	Connect to 100 MHz reset
AXI4_LiteACLK	100 MHz	Connecto to IPCORE_CLK
AXI4_Lite_ARESETN	100 MHz	Connect to IPCORE_RESETN