Induction hobs have become a part of our life and have been “registered” in kitchens. Due to the speed of work, they significantly save time, are easy to clean and are quite safe. Unlike conventional cast iron burners, induction hobs quickly change the cooking power and bend in setting its value. In the material, we will consider the methods of power regulation, what they are and how they differ from each other.
Induction hob power supply
In this article, we looked at what an induction hob is , how it works and how it works. Now we will shift the focus towards regulating the power of the induction hob.In stores: in 90 stores
It’s no secret that cooking modes can change at different stages of cooking. For example, the maximum power of the burner is used for roasting meat or quickly boiling water, and the minimum power is used for stewing or simmering food.
Unlike classic burners, in which the power is regulated by changing the current flowing through their windings, the power supply system of the induction hob is different. The main violin in it is played by an inverter, which converts the previously rectified voltage back into alternating voltage, but with a much higher clock frequency. As a rule, the operating frequency of the induction coil is in the range of 20-120 kHz.
Power control methods
Changing the frequency of the magnetic field
Metal dishes placed in an alternating magnetic field provoke eddy currents in it, which provide heating of the bottom. The higher the frequency of the magnetic field, the greater the currents are induced in the thickness of the material of the cookware, and, therefore, in the end it is possible to obtain a greater heating of its surface.
Weissgauff HI 32 induction hob
Induction hob Electrolux IPE6440KFFrom this follows the first method of controlling the power of an induction cooker, called the method of changing the frequency of the magnetic field.
The power is regulated by changing the frequency of the supply voltage of the induction coil. The schematic diagram of the voltage inverter is shown in the figure.The alternating voltage is obtained by pairwise opening of transistors VT1-VT4 and VT2-VT3 with the desired frequency.
The disadvantage of this control method is the use of a control board that opens key pairs with the required frequency. It significantly increases the cost of the hob. Nevertheless, this method is considered the most convenient, since only it provides smooth power control and maintaining the set temperature, but we will talk about this a little later.
Cyclic power regulation
A more budgetary option for regulating the power of an induction cooker is to use an inverter without frequency adjustment. That is, the coil of the cooking zone always operates with a voltage of a fixed frequency and induces a magnetic field of a constant frequency. As a rule, the voltage frequency is set such that the maximum possible power is obtained on the
In the case when the full power is not needed, the supply voltage is supplied to the coil by pulses, alternating between the moments of switching on the inductor at full power and pauses in its operation. That is, if within one cycle the operating time and the idle time of the induction coil are equal, then the power “removed” from it will be 50% of the maximum.
This method of power control is called cyclic. The inductor is always turned on at full power during strictly defined time intervals.
It is quite easy to define an induction hob with cyclical power regulation. When the burners are operating at low powers, the clicks of the operation of the power relay, which supplies voltage to the inductor’s power supply circuit, are clearly audible.
The cyclical method is the easiest to implement and the most cost-effective, therefore it is widely used in models of the middle and budget price segments. However, the cyclic mode is fraught with a lot of inconvenience when cooking, especially when working at low power. There is no need to talk about any uniform stewing or languishing of dishes. This effect is especially noticeable when cooking small portions of food. At the moment the induction coil is turned on, they quickly boil, and then, when the inductor is idle, the products simply cool down in the dishes. Since the pauses between the switching on of the inverter are small enough, in fact it turns out that excess power is applied to the products, which radically changes the cooking technology.
For example, to bake pancakes in a skillet with a thin bottom or melt chocolate without using a water bath, the cook will have to work hard. The pancake dough will be at rest for a long time, then it will boil overnight and burn to the dishes. The same fate awaits the chocolate bar, and other dishes that should be brought to readiness over low heat. In such a culinary experience, the result is absolutely not guaranteed, and the process itself will surely take away a lot of nerve cells.
A way out of the situation can be dishes with a thick bottom. It has a certain inertness and is not able to instantly heat up and lose heat just as quickly.
Unlike the cyclic method, the frequency control of the burner power does not conceal such pitfalls. It will ensure the exact observance of the temperature and cooking technology of the product.
Induction hob DEXP EH-I2MA / B 8 499 *
Combined power control
There is a third way to adjust the power of the hotplate. It combines the first two methods. At medium and high power levels of the inductor, regulation is carried out by changing the frequency of the magnetic field of the induction coil, and at low powers – by cyclic supply of the supply voltage.
This is done in order to expand the adjustment range, especially in the area of low power values. The fact is that the lower threshold of the regulation frequency is limited to a value of 20 kHz. Everything below it becomes audible to the human ear, and in order not to cause discomfort to users, the lower power range of the inductor is adjusted to this value, and then the induction coil is switched on and off alternately.
It just so happened that the manufacturer is not particularly keen to devote the user to the technical details of their solutions. It is almost impossible to obtain information on the method of power regulation. It is not available on the websites of equipment manufacturers, or in the operating instructions. As an illustrative example, below are excerpts from instructions for budget and rather expensive induction hobs, which provide advice on choosing a power level for cooking various dishes.
They also provide manufacturers’ recommendations for using the hob power modes. As you can see, in fact, in both cases, the text is identical – it does not contain a word about the power adjustment method used.
It would be most correct to focus on the cost of a particular model: the higher it is, the more convenient and “correct” technical solutions are implemented in the device. And, of course, when choosing a hob, you should carefully study the reviews of the models you like and the experience of using them by other users. Or trust the competence of the seller, because the most responsible of them indicate the parameter of interest to us in the filters.