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Low Component Cost Single Tube Induction Cooker 

 

WAS-2041EN  V1.00 

1 / 19 

February 25, 2021 

Low Component Cost Single Tube 

Induction Cooker 

D/N: WAS-2041EN 

Introduction 

A traditional kitchen stove heats foods over an open flame while the induction cooker utilises an 
electromagnetic induction method to implement a heating function. In this way foods are cooked 
by the heat of the cookware itself. Compared to the open flame heating method, an induction cooker 
can increase the heating efficiency by 90%. As a safety feature, the induction cooker will be 
automatically  shut  off  if the cookware has been removed for a certain period of time.  During 
cooking, the cooktop surface temperature is much lower than a traditional kitchen stove and in 
addition, the induction cooker and cookware are more easily cleaned than a traditional stove. 

A traditional single-tube induction cooker pursues a higher power, however in an IGBT resonance 
circuit the reverse interference signal is also increased. The traditional way to solve this is to improve 
the component specifications to enhance the induction cooker EMI circuit reverse interference signal 
filtering capabilities. This reference design utilises a frequency jittering function to adjust the induction 
cooker IGBT switching frequency, thus effectively decreasing the reverse voltage generated due to the 
induction cooker IGBT switching as well as reducing the EMI CE conducted interference. In this way, 
a lower component cost EMI circuit solution is provided. As the HT45F0058 includes an integrated 
hardware frequency jittering circuit, this can effectively reduce the software load when compared with 
the method whereby a software frequency jittering function is used. 

 

Figure 1. Application Block Diagram 

Summary of Contents for HT45F0058

Page 1: ...ookware are more easily cleaned than a traditional stove A traditional single tube induction cooker pursues a higher power however in an IGBT resonance circuit the reverse interference signal is also increased The traditional way to solve this is to improve the component specifications to enhance the induction cooker EMI circuit reverse interference signal filtering capabilities This reference des...

Page 2: ...s The HT45F0058 includes several integrated comparators and an operational amplifier which can be used for induction cooker over voltage and over current protection In addition to reduced external components the PCB layout is also simplified Enabling the hardware frequency jittering function when the induction cooker operates at its maximum power can effectively reduce the IGBT reverse voltage and...

Page 3: ...5V 50 60Hz Standby power consumption 5W Communication interface I2 C the power heating board is the software emulated master while the touch display board is the hardware circuit slave Heating power 100W 2000W 1000W continuous heating is used 1000W intermittent heating is used Protection functions over under voltage protection over current protection cooktop surface overheating protection IGBT ove...

Page 4: ...0 minutes in 10 minute increments Porridge mode The heating temperature in the pot can be adjusted ranging from 60 to 240 in 20 C increments Hot Pot 100W 2000W adjustable power 1000W continuous heating is used 1000W intermittent heating is used Super High Heating 2000W output power Table 1 Solution Function Table Error Code Description Error Code Description E0 No cookware Triggered when no cookwa...

Page 5: ...e and power setting The induction cooker function error is also displayed on the touch display board In this solution when the induction cooker operates at a high power level of 1600W 2000W the IGBT switching frequency can be adjusted by a frequency jittering function thus reducing the maximum reverse voltage across the IGBT VCE and the EMI conducted interference Hardware Description 1 5 2 3 8 10 ...

Page 6: ...oktop surface overheating protection circuit 6 and an IGBT overheating protection circuit 7 etc When any of the above protection functions are triggered during induction cooker operation the system determines whether to reduce power or stop heating for safety reasons Touch display board The power heating board provides the power supply to the touch display board via the communication circuit This ...

Page 7: ... high power area and the low power zone should be separated via the KEEPOUT layer 4 The IGBT E pin and the ground of the bridge rectifier IC should be widened and a single point connected via a constantan wire which is then single point routed to the current detection circuit Figure 7 Power Heating Board PCB There are some considerations for the Touch MCU BS86D12C on the touch display board 1 The ...

Page 8: ...Low Component Cost Single Tube Induction Cooker WAS 2041EN V1 00 8 19 February 25 2021 PCB BOM Table Table 3 Power Heating Board PCB BOM Table ...

Page 9: ...C zero crossing detection 6 PCK passive buzzer signal source 7 I Os I2 C Master end emulation 1 Touch Keys KEY1 KEY8 2 I2 C 3 I Os for 7 segment display and LED display Table 5 Software Resource Utilisation Power Heating Board Main Program Flowchart Description As shown in Figure 9 the power heating board main program first executes initialisation which includes the I O port settings related to th...

Page 10: ...errupt Comparator hardware protection interrupt Y Figure 9 Power Heating Board Main Program Flowchart Induction Cooker Main Function Control Flowchart Description As shown in Figure 10 the induction cooker main function control flowchart executes specific functions in several fixed periods Over current protection detection IGBT overheating protection detection NTC detection and protection release ...

Page 11: ... as well as the induction cooker state code to the touch display board It also receives the current selected induction cooker function from the touch display board Cookware detection The system sends a pulse signal to the coil panel through the IGBT switch and detects the number of times the Comparator 0 output state changes within a 2ms period If the number is less than a fixed value this is take...

Page 12: ...xecute key actions Update LED display Error code processing and Function menu processing In the Execute key action procedure it should be determined which touch key is pressed for which the corresponding descriptions are listed in Table 6 The system executes the relevant key function according to the touch function returned value and updates the data to be transmitted for the next I2 C communicati...

Page 13: ...it Function Name void PowerCalculation_Init Function Power calculation curve initialisation Input NULL Output NULL Description initialise the relevant variables of power control Table 7 PowerCalculation_Init Function Description 2 PowerControl_Task Function Name void PowerControl_Task Function Power Control Function Input AD_Iac AD_Vac PowerStep bPowerStepChanged Output PPGTA_copy Description 1 Th...

Page 14: ... the R W bit Values in the data field are all in 1 byte format The Checksum is the sum of the data values in the data filed The P indicates the I2 C stop bit Table 11 shows the data format in the power heating board data field The IGBT value and BOT Value are temperature A D values the IHStatus includes the cookware detection condition and induction cooker operating state error codes Table 12 show...

Page 15: ...ing power and heating mode Data Field Parameter Data Content ControlSet Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Checksum ON OFF BUZ 1 0 FAN One s complement of the ControlSet 3 0 value Switch control 0 Off 1 On Buzzer 00 No sound 01 Sounds for 200ms 10 Sounds twice continuously 11 Sounds for 1s Fan control 0 Off 1 On PowerStep PowerStep is used for both power and temperature Values 1 9 are for tem...

Page 16: ...on the IGBT VCE voltage when using frequency jittering can be effectively reduced by about 48V Table 13 Waveform Differences with without Frequency Jittering CE Data Comparing the following table data when the power is 2000W the CE minimum average margin without frequency jittering is only 1 39dB while the one with frequency jittering is 2 82dB This shows that the minimum average margin with frequ...

Page 17: ...ns adopted are the EU certification EN55014 1 There may by 1 2dB difference in test results between different laboratories Table 16 Difference Comparison of Frequency Jittering Influence on EMI Solution Comparison Compared with traditional solutions the HT45F0058 frequency jittering solution can reduce the IGBT reverse voltage value by about 48V using its integrated frequency jittering function wi...

Page 18: ...n cooker operates at a high power level a voltage drop will be generated across the C and E terminals of the IGBT due to the resonance circuit charging and discharging Here a frequency jittering function can be used to effectively reduce the maximum voltage across the IGBT C and E terminals In addition the frequency jittering function can reduce the influence of EMI CE conducted interference As a ...

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